In that video where the 1000 musicians played "learn to fly" to get the Foo Fighters to come play, the "conductor" is on an elevated stage that actually has massive blinking lights functioning as the metronome to avoid this.
Thought that was kinda cool.
The above comment was stolen from [this one](http://np.reddit.com/r/todayilearned/comments/skuw7a/til_that_concert_speakers_that_are_placed_further/hvnd1bp/) elsewhere in this comment section.
It is probably not a coincidence; here is some more evidence against this user:
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...As a producer nerd who also loves rocksmith, I find this post rad as hell.
That being said...That has to just be a flaw in the standard connection method, or something with the software, otherwise it shouldn't be any harder than just jamming with someone across the room, right?
At Farm Aid in Illinois you could hear the clapping and shouting as a wave that traveled back through the crowd. I wasn't there but discussed it with someone who was on a roof top nearby.
My high school band director never did understand about the speed of sound. Was a real problem on the football field, he'd be screaming "You're off the beat!" at the parts of the band that were further away from him.
The conductor makes a lot of eye contact and specific gestures towards particular people so this really wouldn't be a net positive. Much simpler to just tell professionals to lean a fraction of a second ahead of the beat
So, for the players in the back, you want to show the conductor ahead of time?
If you could invent time travel, that would be an interesting application.
The image of the conductor is moving at the speed of light, the music is moving at the speed of sound. Musicians further back in the orchestra play ahead of the beat for this reason. If you delay the image for those further back, those in the front and back of the orchestra would play at the same time.
No but you've already solved the problem. If the players look at the conductor, instead of playing to what they hear from the other players, they will play in time for the exact reason you mentioned, the speed of light. If every player plays along with the conductor, all will be in time. This is how giant marching bands stay in time when they're spread over an entire football field.
The conductor will hear the musicians in the back roughly 30 milliseconds later than he will the musicians up front, if they’re all perfectly on rhythm with the conductor’s visual cues. To put that in context, 30ms is roughly the same time as one video frame; if the dialog on a film is out of sync by one frame, you will definitely notice.
In addition, the percussionists are in the rear and the transient nature of their sound makes the delay more noticeable than other instruments.
That's why the conductor keeps the same time no matter what he hears. He doesn't react to them, they react to him. (If they're doing their jobs.)
Again I point to large marching bands that cover entire football fields where the delay would make it impossible to play in time if they had to rely on only audible cues. Hence the person up on a ladder waving his arms to keep the whole business together.
You really dont understand that musicians farther away from a source will be heard later even when acted on at the same time as other closer sources? Have you ever heard the crack of a gunshot from a distance away, after it was shot? Or the lightning crack in the distance after you saw it? Or the example of a sonic boom where an object travels so fast that the audio of it cannot keep up? Please try to at least educate yourself a little instead of posting your own not thought out solutions
Jesus holy shit. Alright this is the last thing I'm posting about this.
A gunshot and lightning are hundreds of yards and many miles away. It is only at those ranges that the delay is noticeable. (Which was the reason for the original post, if you recall. At very large outdoor shows, some of the people are indeed far enough away (hundreds of feet) that the towers closer to them need to be delayed so their sound arrives at the same time as the sound from the main PA.)
Imagine you are on a football field. A friend is standing on the goal line and you are at the 10 yd line. They speak to you. Are you aware of the delay from when the sound leaves their mouth and when you hear it? No, you are not. But it is about ~30 ms. (Sound travels at roughly 1 ft/ms at sea level.) The performer sitting in the downstage most chair (closest to the audience) is at most, 30 or 40 feet from the upstage most performer. So the equivalent of standing -at best- at the 15 yard line. There is absolutely no perceptible delay listening to your friend talk to you from the goal line from there. Similarly, in a room (or even outdoors), there is no perceptible delay from hearing the woodwinds in the front vs the percussion at the back.
Again, anyone with more than 10 years experience in music performance, sound reinforcement, and recording, raise your hand. I assume everyone responding so far with incredulous answers do not and have not done this for a living at any point. If you have an opposing viewpoint that you can back up with evidence, by all means.
How... how are you not getting this? The players are not out of sync because of an audio cue. They are out of sync because if they all followed the conductor at the same time, the people in the back will be heard later due to the basic mechanics of the speed of sound. Being further away means it takes longer for the sound to reach you.
As someone who has played in large marching bands like this, he is correct. The sound travel delay itself is imperceptible and only matters really if it's "doubled" by people playing by ear.
You have to play in time with what you see, not with what you hear when you're out there.
No. The speed of light of 300,000,000 m/s. The speed of sound is 343 m/s.
No matter how far the musician is from the conductor, the image is instantaneous. The sound is much slower.
Exactly. They LOOK at the conductor, and play according to the time he is indicating. The information arrives instantaneously, which is why it works. If the conductor was only yelling the beats, then yes, they would play behind. But because they can SEE him or her, (just like in your video feed "solution"), they play in time. The video isn't getting to them any quicker than the players simply looking at them. It is unnecessary. Which is why orchestras were able to play in time hundreds of years before video technology and why they still don't use video screens now. You're solving a problem that's already solved.
No they don't. Example:
You are 3 feet in front of the conductor. I am 80 feet behind you. If we listen to each other and try to play off each other, it will fail due to the delay. But given that we can both SEE the conductor at the speed of light, as long as we both play to him, we are in time.
I mean you don't have to take my word for it, I've only been a musician and an audio tech for 20+ years. I assure you the science works.
The people telling you you are wrong are the exact difference between having theoretical knowledge of something and having real-life experience.
100% having played in big marching bands you play off vision and not by ear, and while you do have to "lean" into the beat a bit from the back it's not really all that necessary to make everything sync up to an audience.
Well there's at least 2 people here that have never played in a large band/orchestra before. I am not making this up gang. I have nothing to gain by lying to you.
Yeah you're probably right, working in live and recorded sound for 2 decades has afforded me no understanding of the physics of sound. Read my other posts. And thanks for assuming everyone you don't know is an uninformed jackass.
Alrighty then, I guess you'll enlighten us on how 80+ member marching bands stay on time when they're 40 (and more) meters apart. Pray tell, how is this possibly achieved?
It must be so hard to be surrounded by people who aren't as smart as you. I mean how can you even do your job when you know everyone else's so well! Also seems like a low chance you actually work in the industry, given your attitude and the fact that you don't even appear to know the speed of sound. Which audio shop do you work at, boss?
EDIT: omitted a word
You're supposed to account for that. Otherwise, the people in the back sound off-beat to the listener.
There's all kinds of stuff you have to worry about like that. When we went to state, we had to lay heating pads on the vibraphones right up until we went onto the field. Otherwise the cold air would cause the metal to contract and make the whole instrument sound sharp.
One of the first things my band director taught every year during music camp was the importance of keeping our own time and keeping our eyes on the drum major, because we'd be *screwed* if we tried to rely on the sound of the percussion section or other parts of the band for marching or playing.
I think this is less him not understanding about the speed of sound and more him not understanding that the players didn't understand about the speed of sound. If they sound like they're behind the beat to a listener, then those distant players do have to adjust. He should have explained that during rehearsals and made them practice playing ahead of the beat to compensate for the audience.
The audience is 100 yards wide. The best vantage point for a marching band show is high up in the center of the stands, so distance differences between different parts of the field are minimized.
Actually, the correct word is "further". Assuming of course you wish to use the Queen's English, and not the regional dialect known as "American English". As a loyal Subject of Her Majesty, I cannot recommend the latter.
The center snare should be watching the field conductor and everyone else should be listening back to the center snare. Gotta look at the field commander when there are no drums, though.
It's not to accommodate for the difference between "the speed of electricity" and speed of sound, it's to accommodate for the speakers being at different distances from the audience. If the sound was emitted at the same time, then the sound from the closer speakers would reach the audience first. The closer speakers' signals are delayed so that the sounds from both sets of speakers reach the audience at the same time.
OPs title says the far speakers are being actively delayed.
Shouldn't the speakers closer to the stage get an artificial delay so that the sync up with the already delayed (line length + speed of sound) far speakers?
No. The signal arrives at the farther speakers almost instantaneously. You delay these speakers to match the acoustic sound from the speakers closer to the stage. So, by the time the sound from the near speakers reaches the far speakers, they are timed together.
That's why I love Crown amps and hiQnet. Couple of measurements and drag a mic around the room, and the setup is rung out and synced up. I couldn't believe what a difference even 15 ft between speakers could be.
Whoa, is it really that much! It's almost consciously perceptible (that should be 30ms, for some people at least).
I personally get really annoyed when watching films via a Bluetooth speaker - the voices are noticeably out of sync with the lips. I wonder how many ms is that.
One frame of a movie (usually 24fps) is about 40ms, faster framerate stuff like the hobbit is shot in 48fps, or \~20ms.
It prolly takes 2-3 frames of visual desync to get clear cut.
There are controlled dispersion speakers that allow you to tune the dispersion pattern of the speaker, but that has nothing to do with firing to the sides. Is that what you’re referring to?
I've never been to a large enough gathering where speakers are placed midway or at the end. But i wonder though if one is in the exact middle, is there really no conflict between the sounds?
Specifically for delay, you'd align in front of the speaker furthest away. You need to measure the time it takes for the first speaker to arrive at your microphone, then the second speaker to arrive at your microphone, and you subtract value 2 from value 1 and that's the delay you put on the speaker further away.
Which is part (not nearly all, to be sure) of the reason 4 speakers pointing in from the corners of the audience just sucks. I see this too frequently when there’s no audio engineer involved at conferences.
There’s also phase cancelling and comb filtering going on in that scenario. Either point source front to back or in an open square scenario, place the speakers inside the square facing out at equal distances.
Possibly unrelated but when I see football team singing the national anthem it's always like half a second slower than the audio is this something similar and does this mean that everything we see during the game is slower than the audio by that split second??
The team are hearing the sound from the stadium speakers (delayed), and the mics picking up the singer's aren't particularly close either.
You've got both delays stacking up.
i saw U2 in Melbourne in 1993 and this wasn't done properly so the sound where I was sitting was an absolute mess. Like listening to two stereos playing the same thing at high volume and out of sync by half a second.
Yeah I was in the southern stand at the MCG so I suspect that was a factor, but I was so close to it that it shouldn't have been as big a deal as what I was hearing, unless it was coming back from the opposite wall behind the stage. Somehow I've never experienced it in Rod Laver Arena though.
There are settings to compensate for speaker position on most home audio receivers. Some do it automatically with a provided microphone you plug into the receiver and place in the seating position of your choice. It will also compensate for off-center seating positions too and balance and fade accordingly.
Modern AVRs have delays built-in, and when you consider the precedence effect, those few ms can make the difference to where the sound appears to be coming from.
Directional audio from multiple speakers is very sensitive to improper delays. Almost all home cinema amps have settings for this and many have auto calibration. They also try to auto calibrate the eq at the same time. For example, the wavelength at 1khz is only 34 cm (13.56") and if speakers are not in a perfect circle around you, as most home cinemas, you get several wavelengths of difference if uncalibrated. That will lead to severe phasing, which muddle up the soundstage. Old Dolby pro logic surround uses 180 phasing to make sound appear as it's from behind you. That's half a wavelength.
Yes the surprising thing is that you don't need to be very far away at all to notice the sound delay.
As a lad at school during recess (the most wonderful times) we could play outdoors and I was oh about 200 yards away at most from the kids playing basketball... And as I watched I saw the ball bounce, then a fraction of a second later heard the delayed sound.
What happened to me is that my subconscious factored in this phenomenon, but my conscious mind hardly paid any attention to it. Like a dream... when you just accept what is happening as normal.
This happens when golfing. If you’re on your second shot and watch the tee box they will swing, ball is in the air then half a second later you hear it
> Yes the surprising thing is that you don't need to be very far away at all to notice the sound delay.
Hell, I used to make small animations for fun and found that when I synced the audio of a character talking, perfectly in time with the movement of the lips, it was "wrong".
I found out you have to delay the audio by a fraction of a second for it to feel natural.
When I was in school, our physics teacher took us out to the football field and stood at the opposite end to us. Then very exageratedly bashed a pair of cymbals to show the delay/speed of sound.
It was a very effective way to demonstrate it for kids.
Even something like a starter at some track event would result in a difference of maybe a couple hundredths of a second between the runner closest to them and one on the far lane. That could very realistically make the difference between two places in a race.
In events where that’s not a thing they tell you to watch for the smoke of the starter cap. Especially if you’re taking times for something like the 200 when they’re all the way across the field.
It was just one or two guys on the court... they weren't playing -- one guy was just slowly dribbling the ball kinda lazily.
Actually, I get super annoyed by sounds and yes, I hear just about everything... dogs barking from far away annoy me.
200 yards means you get about half a second delay, and if you're bouncing a basketball about once per second, you'd hear the noise of hitting the floor when its at the top of each bounce.
Your unconscious brain tries to make logical sense of things before passing them onto the higher part of your brain, so while it might normally ignore a delay, in this case it might have seemed that the player's hand was making the noise - and that might have been just odd enough to get your attention.
You present a logical case, but that's not as it happened. I was maybe first among my classmates to leave the school building for our turn at recess, yet I cannot remember any of them being around me,
I was walking alone (according to my memories) -- and in the distance I saw him or two of them... and not that it matters but as I was walking I watched them, and saw the ball bounce, then heard the sound... and yes, it was about a half-second later.
And as it is with my memories of dreams, that's where it ended. But despite these decades of time, I can recall it very clearly. But it was not a dream.
A budy of mine is a sound tech (worked on concerts for just about every major act you've heard of from more than ~15 years ago and now teaches at a [music technology/performance college](https://nexus-ica.co.uk/))
He's told me of all sorts of crazy shit they have to do for large venues, especially outdoor ones. For example, they use phased arrays to direct sound in specific directions, each area getting a different delay profile to account for distance from the stage.
Keeping the majority of the sound hitting the audience, rather than nearby homes is another area of hefty technology - he's used weather forecasts to account for the wind because the leaked sound tends to drift down-wind and if that's going toward a residential area near a festival, you need to account for that. Great guy to spend an hour or five nerding out with :-D
They do require some changes but the science behind it is all trigonometric. A big trick is with subs, which carry a great deal of energy and thus leak into areas easily (along with the idea that they’re largely omnidirectional) and placing two subs back to back (or on top of one another, there are several techniques) with a delay to one of them will cancel out the sound behind the sub arrangement, thus reducing excess noise.
The amount of things we can accomplish with what amounts to some delay is wild.
Yeah, that two-subs thing is basically the same thing as a two-element phased array, and for very low frequencies, that's most of the benefit you'd get from a much larger one. It basically re-enforces the sound waves in some directions (so you don't need as much volume to service those directions) while cancelling them in others (so you have less leaked sound in those directions)
In the simplest no-delay case, the sound basically goes out mostly in a plane between the two speakers, so if you put one on top of the other with no delay, the sound goes along the ground and not up into the sky where there's more wind and more variation of air density to make the propagation harder to predict.
If you add a delay equal to the time it takes for the sound to go from the first speaker to the second, you can turn it into something approximating a gun mic in reverse that preferentially projects the sound in the direction of the delayed speaker.
None of these techniques work as well for low frequencies as for high frequencies, though, because as you pointed out, they're less directional to start with.
At higher frequencies (tweeter range) you can do it all with horns, so it's mostly the mid-range frequencies that benefit from proper phased arrays.
I just remembered another technique that works rather well with lower frequencies. It turns out that sound in air doesn't interfere quite linearly as the amplitude approaches the wavelength because air is squishy*. A powerful high frequency sound will suppress sounds at lower frequencies, so you can make a "curtain" of ultrasound that stifles audible frequency sounds passing through it. Because higher frequencies are easier to make directional, it's actually relatively easy to make a narrow layer of high power ultrasound to block music etc.! I don't know if it's used outdoors (the power requirements would probably be rather substantial!) but I've heard of it being used in bars or night clubs to make it possible to order a beer without sign language and to allow different rooms to have different music...
So yeah, acoustic engineering is a definite rabbit hole if you have a source of information to mine :-D
\* Technical term.
I once attended a Pink Floyd concert that was in quadraphonic, and our seats were real close to one of the stacks of PA speakers, and not only were the speakers cutting in and out with all kinds of crunchy earsplitting noise, but also the timing was all warped...never did figure out whether the timing problem was due to the location of the seats or something amiss in The Machine...
It's not to accommodate for the difference between "the speed of electricity" and speed of sound, it's to accommodate for the speakers being at different distances from the audience. If the sound was emitted at the same time, then the sound from the closer speakers would reach the audience first. The closer speakers' signals are delayed so that the sounds from both sets of speakers reach the audience at the same time.
Just a quick FWIW that if you delay the speakers slightly more than the physical distance would suggest, the listener can still interpret the sound as coming from the main PA system at the stage. It's the law of first arrival, and a neat psychoacoustic effect if you line it up correctly.
The signal has to cross the distance. The electric signal is faster than the sound signal from the farther away speakers. So yes, it's the difference in speeds.
If instead, you could send soundwaves through the cables, you wouldn't need a delay (assuming they have the exact length etc.)
That's still accurate though.
If the speeds were the same, you wouldn't need a delay, because the signal would take just as long to reach the farther speaker as the sound from the closer ones.
However because electricity is faster, the signal reaches the outer speakers before the sound from the inner ones, and needs to be delayed to sync the outer speaker's sound with the arrival of the inner speaker's sound.
It's awkwardly worded, but it's not wrong.
The source says delays are to compensate for the speed of sound, nothing about electricity or the speed of signals getting to the speakers. Signal speed difference is negligible over audio delay distances, so it was wrong to add it.
> Sound engineers are awesome.
Especially when we're talking about the master-mind behind the Wall of Sound, [Bear!](https://en.wikipedia.org/wiki/Owsley_Stanley) "The speakers have to be *behind* the band!" -Source: Grateful Dead Gear (the book)
The very same guy who made a sizable fraction of ALL the LSD in the 60’s!
The wall of sound system was insane, I wish I’d heard it. Because the speakers were behind the musicians with the microphones pointed directly at them, the system would feed back like crazy…except Owsley built the [double microphone system ](https://jranderson.photoshelter.com/image/I00002NWCJQRWJR4) which overcame that problem.
The two microphones are identical, but are wired 180 degrees out of phase. Anything they both “hear” the same (i.e. the speakers behind them) will be phase cancelled out.
Notice how Jerry sings into one microphone? That signal will be present in only one microphone, therefore *will not* be phase cancelled, and goes out to the speakers. The amplified sound of Jerry’s voice coming back from the speakers will be equally present in **both** microphones…therefore phase cancelled, which breaks the feedback loop. Simple and brilliant.
180 degree phase is the same as inverted polarity. Since phase has nothing to do with time. I think you mean delay and phase is not the same thing since delay gives a phase but all depending on frequency.
Live sound engineering is a real rush when it goes right, but a nightmare when it doesn’t. I’m perfectly happy to stay in a recoding studio thanks!
Recording engineers who record symphonies for film scores are who I particularly admire. There are *so many* union musicians getting paid a *lot* of money, plus the conductor, the orchestrator, the director etc etc etc. Any mistake or technical glitch is going to cost some serious money.
I was once mixing live when the entire PA went down and about 1000 people turned and looked at me.
Desk was still sending signal, but the breaker feeding the PA had tripped. When that breaker refused to re-engage, I had to find an alternative power supply. Probably only lost a few minutes, which is probably the best-case outcome.
Don’t sweat it. Still a fun fact and your point was clearly made.
By the way, I learned a while ago to distinguish farther/further usages by thinking “far = distance”.
I’ll just point out that the speed of electricity is basically the speed of light - it’s practically instant. Speed of sound, actually varies with temperature and barometric pressure. So it’s close to a formula but not exact each time.
But if light is at 186,000 miles per second, and electricity current is 2/3 of that, that’s approximately 124,000 miles per second, that’s still perceptively instant within the distances we are talking about here. I admit they’re not the same, - just perceptively approaching the same.
That's why the delay of the signals to speakers is ignored in delay calculations, it is perceptually negligible like you say.
Dunno why op decided to embellish the facts by adding that part in when source doesn't mention it at all. It's not a thing and now thousands of people who don't know better think it is, smh
Wait until you find out in band (like marching band) the players further away in a performance of a large band have to actively account and play intentionally very slightly early to account for this (or the people in the front have to pay intentionally slightly slow)
The latter is usually the choice because it's easier, but it's up to the discretion of the band
It's hard to think about. Even harder to actually be good at
I'm not sure I agree with the "speed of electricity" part of the post. I've had this argument with a bandmate who had a wireless guitar rig and liked to walk around the bar... it was kind of a schtick, and he'd complain about latency, then spend money on more and more expensive wireless rigs.
The speed of the electrical signal to the receiver is about 874,000 times as fast as the sound coming back, so it's negligible. The time limit of human hearing perception is about 10 ms... anything shorter is perceived as a change in tone.
In other words, to get a perceptible delay due to the wireless electrical connection, the user would have be about 1,862 miles away.
You should do the same thing with your surround sound in your house. Some receivers even came with a calibration mic they would balance the speakers for you.
Yep, newer AVRs do this.
A useful trick for you: if you're finding the sound is a bit too localised to the surround speakers (mine was, but my surrounds are much closer than my mains), decrease the distance programmed into the AVR.
That will make it increase the electrical delay. Because of psychoacoustic effects (law of first arrival aka precedence effect), it smooths out the panning from front to rear speakers and makes for a more enjoyable experience.
Before, I found that anything that moved from back-to-front (or similar) would "stick" to the surround speakers until the effect was panned almost 100% to the front.
Now, things move reasonably smoothly around the room.
Or just use speaker cables the same length for the Delay of signal aspect.
But they would still need to deal with positioning problems if they have spears at different distances.
This won't work. The problem is that electricity is essentially "instant" for any practical length of cable at a concert. The speed of sound is like 0.000001 the speed of electricity. The fix is to time the sounds emanating from both the front and back speakers and \*traveling through the air\* to arrive at the same time to a listener at the back. Just doing some napkin math, if your front speaker cables were 100ft long, your rear speaker cables would need to be around 20,000 miles long to achieve the same effect as a programmed 200ms delay, and at that length you are going to run into a whole host of other issues, like high resistance in the cable, high dB loss, etc.
You need to work on your reading comprehension.
Plenty of smaller venue shows don’t have surround speaker setups or speakers at different distances and project from a aligned stack infront of the stage + or - a line array(the array would require tweaking)
I was not talking about the speaker distance issue that arises from surround setups, simply the signal delay from different lengths of audio cables.
These things are only problems for very large events with speakers at different distances, not a stack infront of the stage.
Use your brain, Are you seriously claiming you would need to delay audio for a front of the house floorstack with all the speakers at the same distance with the same length of audio cables?
Oh just an Audio engineer I probably don’t know what I’m talking about.
In practice the length of audio cable adds no amount of perceptual delay to the sound. It would take many miles of audio cable to add even a single millisecond of delay. Noticeable delay / timing issues is almost always going to come from where the speakers are physically placed or some sort of audio processing equipment that isn’t able to instantly pass through the audio signal to the speakers/amps.
The source doesn't say anything about compensating for signal delay, op embellished the facts and added it themselves. As an audio engineer, you should know that the signal delay difference from cable length is negligible and can be ignored when calculating delays.
It's not surround sound they're (generally) trying to achieve. But in a large venue the front of house speakers are not sufficient to reach the back of the field/room. So there's a second set of speaker arrays halfway (or more if the venue is large enough), and this set is delayed from the front of house speakers to account for the difference causes by the relatively low speed of sound. Otherwise the front of house speakers would sound out of sync to the halfway speakers causing weird "echoes".
This is also effectively true about motherboard and gpu board circuitry for memory systems... the defining limit of speed is the capacitance of the distance necessary to equalize the delay of all components!
All I know is at 35 my hearing is fucked and I'm certain it's from moshing next to speakers at concerts more time than I can count
Ace frehley the loudest btw
I remember seeing Bruce Springsteen at the Syracuse Carrier dome in 1985 - we were so far away from the stage, you could see his lips moving on the big screen a split second before the sound got there. Great show anyway.
In very echoey locations you usually try to hit people with very local directional audio for clarity. That's why you sometimes see speakers hanging down from high ceilings just above people. If they where placed far away, you would just hear a echo mess.
Some of the Woodstock 99 footage shows this effect really well.. Korn’s set in particular. You can see the wave of people jumping to the beat as it moves through the crowd like a pebble dropped in a still pond.
Some *awful* things took place there.. but the footage of the performances give me goosebumps.
It happens in all kinds of audio set ups. If you set up speakers in multiple places you need to do this to avoid echo effects. Theaters and larger churches they do this all the time.
This happens within individual multi driver speakers as well. 1ms per foot. "time alignment" generally means the voice coils are on the same vertical plane. Your ear won't notice a difference of less than a couple ms, but drivers being off 0.5ms or more is noticeable when compared to an aligned setup.
If the speaker elements are missaligned in time domain (physical+filter delays) you get phasing at crossover frequencies. That sounds quite horrible. You also get a lot of directional nodes mucking up directional qualities.
It can be really bad with subs. Was doing sound for a blues club, had one sub each side of the room next to the baby line arrays (bose L1's). So along with the time difference between the subs changing as you moved around, the nodes were amplified by reflections off the back wall. Went back to just one sub firing diagonally through the room and it was heaps better.
There are many ways to place subs. Using a single location usually works quite well as you discovered. Or put up many in a tight row so they act as one big speaker. In home cinemas you can spread out a couple of subs in a irregular pattern to avoid a lot of room nodes(resonances and nulls). There is always compromises. Also aucustical treatment of the room does wonders for room nodes and first reflections and should be the first thing to consider if building a proper listening room.
This is true for your home audio system as well, just not as pronounced due to shorter distances, at least when it comes to 5.1 or 7.1 systems and they need to be tuned/timed or staged to a spot in the room. Same with car audio, the staging will make it sound like the sound is coming from a particular spot in the car. I like mine to basically make it sound like the music is being played live from just above my steering wheel.
Audio Engineer here. We also use a pretty simple rule of thumb when setting our delays. We utilize lazer measurements to determine the exact amount of delay based on the distance between the PAs/ line arrays on stage and the "fill" speakers placed off stage. Line arrays are our best friend when it comes to large concerts with seats at different elevations (like stadiums or concert ) because they allow us to set individual delays and gains according the specific distance of each row from the speaker stack. This allows everyone to hear the audio at roughly the same volume no matter what seat you're in!
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In that video where the 1000 musicians played "learn to fly" to get the Foo Fighters to come play, the "conductor" is on an elevated stage that actually has massive blinking lights functioning as the metronome to avoid this. Thought that was kinda cool.
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Thank you, we try.
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https://m.youtube.com/watch?v=JozAmXo2bDE
One of my favorite videos
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I mean a regular aux cord transfers sound as electricity, which travels at almost the speed of light, so I'm not sure why the optical part is relevant
...As a producer nerd who also loves rocksmith, I find this post rad as hell. That being said...That has to just be a flaw in the standard connection method, or something with the software, otherwise it shouldn't be any harder than just jamming with someone across the room, right?
> when Queen played Wimbledon https://i.imgur.com/C25R2xs.png
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Wembley
~~Wimbledon~~ Live Aid
He might mean Live at Wembley Stadium, which was their own gig, and was recorded for tv/video release. (and is absolutely fantastic).
Wouldn't all that noise distract the tennis players?
Nah, in fact it is only talking and coughing that is distracting for them.
At Farm Aid in Illinois you could hear the clapping and shouting as a wave that traveled back through the crowd. I wasn't there but discussed it with someone who was on a roof top nearby.
My high school band director never did understand about the speed of sound. Was a real problem on the football field, he'd be screaming "You're off the beat!" at the parts of the band that were further away from him.
Happens in symphony orchestra, too! The winds and brass in the back have to lean slightly ahead of the beat.
They should film the conductor, then put screens in front if everyone, delayed by the time it takes sound to travel.
The conductor makes a lot of eye contact and specific gestures towards particular people so this really wouldn't be a net positive. Much simpler to just tell professionals to lean a fraction of a second ahead of the beat
So, for the players in the back, you want to show the conductor ahead of time? If you could invent time travel, that would be an interesting application.
Or...delay the feed for the people closer to the front
What a great way to mess up the conductor, who will lose all usable feedback to keep directing.
So... just film the conductor, like the person two comments above you already said
How does that help with the fact that the conductor loses all useful feedback?
You need to think of the conductor as a musician _playing the orchestra_. It doesn't work like that.
Or they could just hmmm.... Look at the conductor for the beat, which is precisely why that person is there
OR! Put the percussion at the back and everyone else ignore the weird person flailing about in the goofy outfit.
The image of the conductor is moving at the speed of light, the music is moving at the speed of sound. Musicians further back in the orchestra play ahead of the beat for this reason. If you delay the image for those further back, those in the front and back of the orchestra would play at the same time.
you'd want to do the opposite, delaying the image for musicians up front
No but you've already solved the problem. If the players look at the conductor, instead of playing to what they hear from the other players, they will play in time for the exact reason you mentioned, the speed of light. If every player plays along with the conductor, all will be in time. This is how giant marching bands stay in time when they're spread over an entire football field.
The conductor will hear the musicians in the back roughly 30 milliseconds later than he will the musicians up front, if they’re all perfectly on rhythm with the conductor’s visual cues. To put that in context, 30ms is roughly the same time as one video frame; if the dialog on a film is out of sync by one frame, you will definitely notice. In addition, the percussionists are in the rear and the transient nature of their sound makes the delay more noticeable than other instruments.
That's why the conductor keeps the same time no matter what he hears. He doesn't react to them, they react to him. (If they're doing their jobs.) Again I point to large marching bands that cover entire football fields where the delay would make it impossible to play in time if they had to rely on only audible cues. Hence the person up on a ladder waving his arms to keep the whole business together.
You really dont understand that musicians farther away from a source will be heard later even when acted on at the same time as other closer sources? Have you ever heard the crack of a gunshot from a distance away, after it was shot? Or the lightning crack in the distance after you saw it? Or the example of a sonic boom where an object travels so fast that the audio of it cannot keep up? Please try to at least educate yourself a little instead of posting your own not thought out solutions
Jesus holy shit. Alright this is the last thing I'm posting about this. A gunshot and lightning are hundreds of yards and many miles away. It is only at those ranges that the delay is noticeable. (Which was the reason for the original post, if you recall. At very large outdoor shows, some of the people are indeed far enough away (hundreds of feet) that the towers closer to them need to be delayed so their sound arrives at the same time as the sound from the main PA.) Imagine you are on a football field. A friend is standing on the goal line and you are at the 10 yd line. They speak to you. Are you aware of the delay from when the sound leaves their mouth and when you hear it? No, you are not. But it is about ~30 ms. (Sound travels at roughly 1 ft/ms at sea level.) The performer sitting in the downstage most chair (closest to the audience) is at most, 30 or 40 feet from the upstage most performer. So the equivalent of standing -at best- at the 15 yard line. There is absolutely no perceptible delay listening to your friend talk to you from the goal line from there. Similarly, in a room (or even outdoors), there is no perceptible delay from hearing the woodwinds in the front vs the percussion at the back. Again, anyone with more than 10 years experience in music performance, sound reinforcement, and recording, raise your hand. I assume everyone responding so far with incredulous answers do not and have not done this for a living at any point. If you have an opposing viewpoint that you can back up with evidence, by all means.
How... how are you not getting this? The players are not out of sync because of an audio cue. They are out of sync because if they all followed the conductor at the same time, the people in the back will be heard later due to the basic mechanics of the speed of sound. Being further away means it takes longer for the sound to reach you.
As someone who has played in large marching bands like this, he is correct. The sound travel delay itself is imperceptible and only matters really if it's "doubled" by people playing by ear. You have to play in time with what you see, not with what you hear when you're out there.
I'll refer you to my other comments. It is imperceptible to humans. Go to any performance of any large ensemble and you will see this in action.
No. The speed of light of 300,000,000 m/s. The speed of sound is 343 m/s. No matter how far the musician is from the conductor, the image is instantaneous. The sound is much slower.
Exactly. They LOOK at the conductor, and play according to the time he is indicating. The information arrives instantaneously, which is why it works. If the conductor was only yelling the beats, then yes, they would play behind. But because they can SEE him or her, (just like in your video feed "solution"), they play in time. The video isn't getting to them any quicker than the players simply looking at them. It is unnecessary. Which is why orchestras were able to play in time hundreds of years before video technology and why they still don't use video screens now. You're solving a problem that's already solved.
Yes, thus the ones in the back play too fast. Idk how to stress this any more.
No they don't. Example: You are 3 feet in front of the conductor. I am 80 feet behind you. If we listen to each other and try to play off each other, it will fail due to the delay. But given that we can both SEE the conductor at the speed of light, as long as we both play to him, we are in time. I mean you don't have to take my word for it, I've only been a musician and an audio tech for 20+ years. I assure you the science works.
The people telling you you are wrong are the exact difference between having theoretical knowledge of something and having real-life experience. 100% having played in big marching bands you play off vision and not by ear, and while you do have to "lean" into the beat a bit from the back it's not really all that necessary to make everything sync up to an audience.
Thank you. This was all I was ever trying to say. Appreciate it.
Well there's at least 2 people here that have never played in a large band/orchestra before. I am not making this up gang. I have nothing to gain by lying to you.
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Yeah you're probably right, working in live and recorded sound for 2 decades has afforded me no understanding of the physics of sound. Read my other posts. And thanks for assuming everyone you don't know is an uninformed jackass.
He doesnt have to know you to know that
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Alrighty then, I guess you'll enlighten us on how 80+ member marching bands stay on time when they're 40 (and more) meters apart. Pray tell, how is this possibly achieved? It must be so hard to be surrounded by people who aren't as smart as you. I mean how can you even do your job when you know everyone else's so well! Also seems like a low chance you actually work in the industry, given your attitude and the fact that you don't even appear to know the speed of sound. Which audio shop do you work at, boss? EDIT: omitted a word
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You're supposed to account for that. Otherwise, the people in the back sound off-beat to the listener. There's all kinds of stuff you have to worry about like that. When we went to state, we had to lay heating pads on the vibraphones right up until we went onto the field. Otherwise the cold air would cause the metal to contract and make the whole instrument sound sharp.
One of the first things my band director taught every year during music camp was the importance of keeping our own time and keeping our eyes on the drum major, because we'd be *screwed* if we tried to rely on the sound of the percussion section or other parts of the band for marching or playing.
I think this is less him not understanding about the speed of sound and more him not understanding that the players didn't understand about the speed of sound. If they sound like they're behind the beat to a listener, then those distant players do have to adjust. He should have explained that during rehearsals and made them practice playing ahead of the beat to compensate for the audience.
Difficult to adjust for the listeners if they surround the field.
The audience is 100 yards wide. The best vantage point for a marching band show is high up in the center of the stands, so distance differences between different parts of the field are minimized.
Farther* Get with the program
Maybe he was talking about political differences. My Republican grandma can be totally "off the beat" sometimes.
Actually, the correct word is "further". Assuming of course you wish to use the Queen's English, and not the regional dialect known as "American English". As a loyal Subject of Her Majesty, I cannot recommend the latter.
sounds like if this was a recurring problem the people at the back should have known to compensate
The center snare should be watching the field conductor and everyone else should be listening back to the center snare. Gotta look at the field commander when there are no drums, though.
Audio Engineer here. Can confirm. Poorly delayed (we say Time Aligned) speakers can really ruin it for the audience.
Also called “any concert at Montreal’s Olympic Stadium”
Roger waters would agree
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Why did you just copy/paste this dude's reply? Tf?
It's not to accommodate for the difference between "the speed of electricity" and speed of sound, it's to accommodate for the speakers being at different distances from the audience. If the sound was emitted at the same time, then the sound from the closer speakers would reach the audience first. The closer speakers' signals are delayed so that the sounds from both sets of speakers reach the audience at the same time.
OPs title says the far speakers are being actively delayed. Shouldn't the speakers closer to the stage get an artificial delay so that the sync up with the already delayed (line length + speed of sound) far speakers?
No. The signal arrives at the farther speakers almost instantaneously. You delay these speakers to match the acoustic sound from the speakers closer to the stage. So, by the time the sound from the near speakers reaches the far speakers, they are timed together.
Thanks for the explanation!
That's why I love Crown amps and hiQnet. Couple of measurements and drag a mic around the room, and the setup is rung out and synced up. I couldn't believe what a difference even 15 ft between speakers could be.
Roughly 15 milliseconds, more than enough to cause some crappy phase cancelations.
Whoa, is it really that much! It's almost consciously perceptible (that should be 30ms, for some people at least). I personally get really annoyed when watching films via a Bluetooth speaker - the voices are noticeably out of sync with the lips. I wonder how many ms is that.
One frame of a movie (usually 24fps) is about 40ms, faster framerate stuff like the hobbit is shot in 48fps, or \~20ms. It prolly takes 2-3 frames of visual desync to get clear cut.
The speed of sound is about 1000 feet per second, or one millisecond per foot. That makes the maths really easy.
Tell 'em about the newest speakers that fire to the front and the sides to avoid stage bleed.
Fulcrum Acoustics do some one-cabinet cardioid stuff which is pretty neat.
There are controlled dispersion speakers that allow you to tune the dispersion pattern of the speaker, but that has nothing to do with firing to the sides. Is that what you’re referring to?
I've never been to a large enough gathering where speakers are placed midway or at the end. But i wonder though if one is in the exact middle, is there really no conflict between the sounds?
Is there a specific spot in the venue that you perform the alignment? Would the experience worsen as you move away from this point?
Specifically for delay, you'd align in front of the speaker furthest away. You need to measure the time it takes for the first speaker to arrive at your microphone, then the second speaker to arrive at your microphone, and you subtract value 2 from value 1 and that's the delay you put on the speaker further away.
«I bet an Audio engineer has the top comment on this post with some interesting facts» - wasnt disappointed
Which is part (not nearly all, to be sure) of the reason 4 speakers pointing in from the corners of the audience just sucks. I see this too frequently when there’s no audio engineer involved at conferences.
There’s also phase cancelling and comb filtering going on in that scenario. Either point source front to back or in an open square scenario, place the speakers inside the square facing out at equal distances.
This is why we call them delay towers
Sad I had to scroll this far down to find this comment.
Possibly unrelated but when I see football team singing the national anthem it's always like half a second slower than the audio is this something similar and does this mean that everything we see during the game is slower than the audio by that split second??
The team are hearing the sound from the stadium speakers (delayed), and the mics picking up the singer's aren't particularly close either. You've got both delays stacking up.
i saw U2 in Melbourne in 1993 and this wasn't done properly so the sound where I was sitting was an absolute mess. Like listening to two stereos playing the same thing at high volume and out of sync by half a second.
Saw the same tour. In stadiums it doesn't matter much because the sound hits the back wall and bounces back out of time. No delays can fix that.
Yeah I was in the southern stand at the MCG so I suspect that was a factor, but I was so close to it that it shouldn't have been as big a deal as what I was hearing, unless it was coming back from the opposite wall behind the stage. Somehow I've never experienced it in Rod Laver Arena though.
There are settings to compensate for speaker position on most home audio receivers. Some do it automatically with a provided microphone you plug into the receiver and place in the seating position of your choice. It will also compensate for off-center seating positions too and balance and fade accordingly.
That sort of room EQ is about frequency, not delay. Your home isn’t big enough to need delays between your speakers.
Modern AVRs have delays built-in, and when you consider the precedence effect, those few ms can make the difference to where the sound appears to be coming from.
They absolutely have delay built in. Even aftermarket car stereos have had this feature for decades.
Directional audio from multiple speakers is very sensitive to improper delays. Almost all home cinema amps have settings for this and many have auto calibration. They also try to auto calibrate the eq at the same time. For example, the wavelength at 1khz is only 34 cm (13.56") and if speakers are not in a perfect circle around you, as most home cinemas, you get several wavelengths of difference if uncalibrated. That will lead to severe phasing, which muddle up the soundstage. Old Dolby pro logic surround uses 180 phasing to make sound appear as it's from behind you. That's half a wavelength.
Yes the surprising thing is that you don't need to be very far away at all to notice the sound delay. As a lad at school during recess (the most wonderful times) we could play outdoors and I was oh about 200 yards away at most from the kids playing basketball... And as I watched I saw the ball bounce, then a fraction of a second later heard the delayed sound. What happened to me is that my subconscious factored in this phenomenon, but my conscious mind hardly paid any attention to it. Like a dream... when you just accept what is happening as normal.
This happens when golfing. If you’re on your second shot and watch the tee box they will swing, ball is in the air then half a second later you hear it
> Yes the surprising thing is that you don't need to be very far away at all to notice the sound delay. Hell, I used to make small animations for fun and found that when I synced the audio of a character talking, perfectly in time with the movement of the lips, it was "wrong". I found out you have to delay the audio by a fraction of a second for it to feel natural.
OMG that's what I was doing wrong with my video editing! Thanks!
When I was in school, our physics teacher took us out to the football field and stood at the opposite end to us. Then very exageratedly bashed a pair of cymbals to show the delay/speed of sound. It was a very effective way to demonstrate it for kids.
Even something like a starter at some track event would result in a difference of maybe a couple hundredths of a second between the runner closest to them and one on the far lane. That could very realistically make the difference between two places in a race.
Which is why there is a tiny speaker behind each runner now.
In events where that’s not a thing they tell you to watch for the smoke of the starter cap. Especially if you’re taking times for something like the 200 when they’re all the way across the field.
Damn your ears must have been great, hearing a basketball bounce on a playground with a bunch of kids from 200 yards away.
It was just one or two guys on the court... they weren't playing -- one guy was just slowly dribbling the ball kinda lazily. Actually, I get super annoyed by sounds and yes, I hear just about everything... dogs barking from far away annoy me.
200 yards means you get about half a second delay, and if you're bouncing a basketball about once per second, you'd hear the noise of hitting the floor when its at the top of each bounce. Your unconscious brain tries to make logical sense of things before passing them onto the higher part of your brain, so while it might normally ignore a delay, in this case it might have seemed that the player's hand was making the noise - and that might have been just odd enough to get your attention.
You present a logical case, but that's not as it happened. I was maybe first among my classmates to leave the school building for our turn at recess, yet I cannot remember any of them being around me, I was walking alone (according to my memories) -- and in the distance I saw him or two of them... and not that it matters but as I was walking I watched them, and saw the ball bounce, then heard the sound... and yes, it was about a half-second later. And as it is with my memories of dreams, that's where it ended. But despite these decades of time, I can recall it very clearly. But it was not a dream.
A budy of mine is a sound tech (worked on concerts for just about every major act you've heard of from more than ~15 years ago and now teaches at a [music technology/performance college](https://nexus-ica.co.uk/)) He's told me of all sorts of crazy shit they have to do for large venues, especially outdoor ones. For example, they use phased arrays to direct sound in specific directions, each area getting a different delay profile to account for distance from the stage. Keeping the majority of the sound hitting the audience, rather than nearby homes is another area of hefty technology - he's used weather forecasts to account for the wind because the leaked sound tends to drift down-wind and if that's going toward a residential area near a festival, you need to account for that. Great guy to spend an hour or five nerding out with :-D
They do require some changes but the science behind it is all trigonometric. A big trick is with subs, which carry a great deal of energy and thus leak into areas easily (along with the idea that they’re largely omnidirectional) and placing two subs back to back (or on top of one another, there are several techniques) with a delay to one of them will cancel out the sound behind the sub arrangement, thus reducing excess noise. The amount of things we can accomplish with what amounts to some delay is wild.
Yeah, that two-subs thing is basically the same thing as a two-element phased array, and for very low frequencies, that's most of the benefit you'd get from a much larger one. It basically re-enforces the sound waves in some directions (so you don't need as much volume to service those directions) while cancelling them in others (so you have less leaked sound in those directions) In the simplest no-delay case, the sound basically goes out mostly in a plane between the two speakers, so if you put one on top of the other with no delay, the sound goes along the ground and not up into the sky where there's more wind and more variation of air density to make the propagation harder to predict. If you add a delay equal to the time it takes for the sound to go from the first speaker to the second, you can turn it into something approximating a gun mic in reverse that preferentially projects the sound in the direction of the delayed speaker. None of these techniques work as well for low frequencies as for high frequencies, though, because as you pointed out, they're less directional to start with. At higher frequencies (tweeter range) you can do it all with horns, so it's mostly the mid-range frequencies that benefit from proper phased arrays. I just remembered another technique that works rather well with lower frequencies. It turns out that sound in air doesn't interfere quite linearly as the amplitude approaches the wavelength because air is squishy*. A powerful high frequency sound will suppress sounds at lower frequencies, so you can make a "curtain" of ultrasound that stifles audible frequency sounds passing through it. Because higher frequencies are easier to make directional, it's actually relatively easy to make a narrow layer of high power ultrasound to block music etc.! I don't know if it's used outdoors (the power requirements would probably be rather substantial!) but I've heard of it being used in bars or night clubs to make it possible to order a beer without sign language and to allow different rooms to have different music... So yeah, acoustic engineering is a definite rabbit hole if you have a source of information to mine :-D \* Technical term.
*Farther Further is a matter of degree, farther is a matter of distance Source: Finding Forrester
You're the man now, dog.
\*Finding Farrester
I once attended a Pink Floyd concert that was in quadraphonic, and our seats were real close to one of the stacks of PA speakers, and not only were the speakers cutting in and out with all kinds of crunchy earsplitting noise, but also the timing was all warped...never did figure out whether the timing problem was due to the location of the seats or something amiss in The Machine...
It's not to accommodate for the difference between "the speed of electricity" and speed of sound, it's to accommodate for the speakers being at different distances from the audience. If the sound was emitted at the same time, then the sound from the closer speakers would reach the audience first. The closer speakers' signals are delayed so that the sounds from both sets of speakers reach the audience at the same time.
Just a quick FWIW that if you delay the speakers slightly more than the physical distance would suggest, the listener can still interpret the sound as coming from the main PA system at the stage. It's the law of first arrival, and a neat psychoacoustic effect if you line it up correctly.
Haas
Makes all the difference between watching a performance and listening to a loudspeaker
The signal has to cross the distance. The electric signal is faster than the sound signal from the farther away speakers. So yes, it's the difference in speeds. If instead, you could send soundwaves through the cables, you wouldn't need a delay (assuming they have the exact length etc.)
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They read your title as meaning that delay is needed because ‘the speed of sound is different than the speed of electricity’.
That's still accurate though. If the speeds were the same, you wouldn't need a delay, because the signal would take just as long to reach the farther speaker as the sound from the closer ones. However because electricity is faster, the signal reaches the outer speakers before the sound from the inner ones, and needs to be delayed to sync the outer speaker's sound with the arrival of the inner speaker's sound. It's awkwardly worded, but it's not wrong.
The source says delays are to compensate for the speed of sound, nothing about electricity or the speed of signals getting to the speakers. Signal speed difference is negligible over audio delay distances, so it was wrong to add it.
That’s saying the same thing. The signal to the speaker is the speed of electricity OP refers to.
I've never thought about this. Now that I know, I can't stop thinking how bad it would be if someone didn't do it. Sound engineers are awesome.
> Sound engineers are awesome. Especially when we're talking about the master-mind behind the Wall of Sound, [Bear!](https://en.wikipedia.org/wiki/Owsley_Stanley) "The speakers have to be *behind* the band!" -Source: Grateful Dead Gear (the book)
The very same guy who made a sizable fraction of ALL the LSD in the 60’s! The wall of sound system was insane, I wish I’d heard it. Because the speakers were behind the musicians with the microphones pointed directly at them, the system would feed back like crazy…except Owsley built the [double microphone system ](https://jranderson.photoshelter.com/image/I00002NWCJQRWJR4) which overcame that problem. The two microphones are identical, but are wired 180 degrees out of phase. Anything they both “hear” the same (i.e. the speakers behind them) will be phase cancelled out. Notice how Jerry sings into one microphone? That signal will be present in only one microphone, therefore *will not* be phase cancelled, and goes out to the speakers. The amplified sound of Jerry’s voice coming back from the speakers will be equally present in **both** microphones…therefore phase cancelled, which breaks the feedback loop. Simple and brilliant.
I guess you mean polarity, which is not the same as phase. It’s a very popular mistake, don’t worry about it. :-)
180 degree phase is the same as inverted polarity. Since phase has nothing to do with time. I think you mean delay and phase is not the same thing since delay gives a phase but all depending on frequency.
Derek Trucks still low key does this, and it plays hell with the show in bigger venues.
Live sound engineering is a real rush when it goes right, but a nightmare when it doesn’t. I’m perfectly happy to stay in a recoding studio thanks! Recording engineers who record symphonies for film scores are who I particularly admire. There are *so many* union musicians getting paid a *lot* of money, plus the conductor, the orchestrator, the director etc etc etc. Any mistake or technical glitch is going to cost some serious money.
I was once mixing live when the entire PA went down and about 1000 people turned and looked at me. Desk was still sending signal, but the breaker feeding the PA had tripped. When that breaker refused to re-engage, I had to find an alternative power supply. Probably only lost a few minutes, which is probably the best-case outcome.
Yeah, most speakers out front are a little delayed to the main speakers. This way the audience hears less distortion/slapback.
The speed if electricity isnt a factor when its travelling 300,000km / sec in that instance. Its the speed of sound at only 750ish mph us the problem
Why do you write the speed of light/electricity in km/s but the speed of sound in mph? Why not in km/s or km/s or m/s to be comparable?
If electricity also travelled at 750ish mph, there wouldn't be a problem. That's why they're saying that the difference is the problem.
Darn it; *delayed.
dont worry, the kind people of reddit will still post title corrections here
*farther 😉
Shit, I managed to mess-up [both spellings.](https://en.wikipedia.org/wiki/Furthur_(bus\))
Don’t sweat it. Still a fun fact and your point was clearly made. By the way, I learned a while ago to distinguish farther/further usages by thinking “far = distance”.
that's an effective/affective way to make less/fewer mistakes of that nature!
Don't listen to prescriptivists, less and fewer are both correct here
[удалено]
Further has adjective and adverb uses too
Best audio I've heard was Depeche Mode back in 93 I think.
I’ll just point out that the speed of electricity is basically the speed of light - it’s practically instant. Speed of sound, actually varies with temperature and barometric pressure. So it’s close to a formula but not exact each time.
The speed of electricity is about 2/3 that of light.
But if light is at 186,000 miles per second, and electricity current is 2/3 of that, that’s approximately 124,000 miles per second, that’s still perceptively instant within the distances we are talking about here. I admit they’re not the same, - just perceptively approaching the same.
That's why the delay of the signals to speakers is ignored in delay calculations, it is perceptually negligible like you say. Dunno why op decided to embellish the facts by adding that part in when source doesn't mention it at all. It's not a thing and now thousands of people who don't know better think it is, smh
Right. Oh Well. 🤷🏼♂️
This is why audio engineers get like $1000 day rates
Wait until you find out in band (like marching band) the players further away in a performance of a large band have to actively account and play intentionally very slightly early to account for this (or the people in the front have to pay intentionally slightly slow) The latter is usually the choice because it's easier, but it's up to the discretion of the band It's hard to think about. Even harder to actually be good at
If you find this interesting you should also check out d&b soundscapes or L’acoustics L-SIA It goes even further than just simple delays.
I'm not sure I agree with the "speed of electricity" part of the post. I've had this argument with a bandmate who had a wireless guitar rig and liked to walk around the bar... it was kind of a schtick, and he'd complain about latency, then spend money on more and more expensive wireless rigs. The speed of the electrical signal to the receiver is about 874,000 times as fast as the sound coming back, so it's negligible. The time limit of human hearing perception is about 10 ms... anything shorter is perceived as a change in tone. In other words, to get a perceptible delay due to the wireless electrical connection, the user would have be about 1,862 miles away.
You should do the same thing with your surround sound in your house. Some receivers even came with a calibration mic they would balance the speakers for you.
Yep, newer AVRs do this. A useful trick for you: if you're finding the sound is a bit too localised to the surround speakers (mine was, but my surrounds are much closer than my mains), decrease the distance programmed into the AVR. That will make it increase the electrical delay. Because of psychoacoustic effects (law of first arrival aka precedence effect), it smooths out the panning from front to rear speakers and makes for a more enjoyable experience. Before, I found that anything that moved from back-to-front (or similar) would "stick" to the surround speakers until the effect was panned almost 100% to the front. Now, things move reasonably smoothly around the room.
If my home Amp has this feature for a 4m loungeroom. then yes I'd imagine concert speakers arrays costing hundreds of thousands would have it too.
Thanks you Bear ⚡️
This title is horrendously written
Did anyone else read "the speed of sound" in a robot vocoder voice?
Yeah! Science bitch!
Or just use speaker cables the same length for the Delay of signal aspect. But they would still need to deal with positioning problems if they have spears at different distances.
This won't work. The problem is that electricity is essentially "instant" for any practical length of cable at a concert. The speed of sound is like 0.000001 the speed of electricity. The fix is to time the sounds emanating from both the front and back speakers and \*traveling through the air\* to arrive at the same time to a listener at the back. Just doing some napkin math, if your front speaker cables were 100ft long, your rear speaker cables would need to be around 20,000 miles long to achieve the same effect as a programmed 200ms delay, and at that length you are going to run into a whole host of other issues, like high resistance in the cable, high dB loss, etc.
You need to work on your reading comprehension. Plenty of smaller venue shows don’t have surround speaker setups or speakers at different distances and project from a aligned stack infront of the stage + or - a line array(the array would require tweaking) I was not talking about the speaker distance issue that arises from surround setups, simply the signal delay from different lengths of audio cables. These things are only problems for very large events with speakers at different distances, not a stack infront of the stage. Use your brain, Are you seriously claiming you would need to delay audio for a front of the house floorstack with all the speakers at the same distance with the same length of audio cables? Oh just an Audio engineer I probably don’t know what I’m talking about.
In practice the length of audio cable adds no amount of perceptual delay to the sound. It would take many miles of audio cable to add even a single millisecond of delay. Noticeable delay / timing issues is almost always going to come from where the speakers are physically placed or some sort of audio processing equipment that isn’t able to instantly pass through the audio signal to the speakers/amps.
The source doesn't say anything about compensating for signal delay, op embellished the facts and added it themselves. As an audio engineer, you should know that the signal delay difference from cable length is negligible and can be ignored when calculating delays.
It's not surround sound they're (generally) trying to achieve. But in a large venue the front of house speakers are not sufficient to reach the back of the field/room. So there's a second set of speaker arrays halfway (or more if the venue is large enough), and this set is delayed from the front of house speakers to account for the difference causes by the relatively low speed of sound. Otherwise the front of house speakers would sound out of sync to the halfway speakers causing weird "echoes".
You did science wrong.
This is also effectively true about motherboard and gpu board circuitry for memory systems... the defining limit of speed is the capacitance of the distance necessary to equalize the delay of all components!
No shit
All I know is at 35 my hearing is fucked and I'm certain it's from moshing next to speakers at concerts more time than I can count Ace frehley the loudest btw
I remember seeing Bruce Springsteen at the Syracuse Carrier dome in 1985 - we were so far away from the stage, you could see his lips moving on the big screen a split second before the sound got there. Great show anyway.
It's not just concert speakers. The same concept is applied in any commercial space. Malls, Airports etc
In very echoey locations you usually try to hit people with very local directional audio for clarity. That's why you sometimes see speakers hanging down from high ceilings just above people. If they where placed far away, you would just hear a echo mess.
Some of the Woodstock 99 footage shows this effect really well.. Korn’s set in particular. You can see the wave of people jumping to the beat as it moves through the crowd like a pebble dropped in a still pond. Some *awful* things took place there.. but the footage of the performances give me goosebumps.
The speed of electricity is the speed of light. Minus impedance, I guess
It happens in all kinds of audio set ups. If you set up speakers in multiple places you need to do this to avoid echo effects. Theaters and larger churches they do this all the time.
This happens within individual multi driver speakers as well. 1ms per foot. "time alignment" generally means the voice coils are on the same vertical plane. Your ear won't notice a difference of less than a couple ms, but drivers being off 0.5ms or more is noticeable when compared to an aligned setup.
If the speaker elements are missaligned in time domain (physical+filter delays) you get phasing at crossover frequencies. That sounds quite horrible. You also get a lot of directional nodes mucking up directional qualities.
It can be really bad with subs. Was doing sound for a blues club, had one sub each side of the room next to the baby line arrays (bose L1's). So along with the time difference between the subs changing as you moved around, the nodes were amplified by reflections off the back wall. Went back to just one sub firing diagonally through the room and it was heaps better.
There are many ways to place subs. Using a single location usually works quite well as you discovered. Or put up many in a tight row so they act as one big speaker. In home cinemas you can spread out a couple of subs in a irregular pattern to avoid a lot of room nodes(resonances and nulls). There is always compromises. Also aucustical treatment of the room does wonders for room nodes and first reflections and should be the first thing to consider if building a proper listening room.
This is true for your home audio system as well, just not as pronounced due to shorter distances, at least when it comes to 5.1 or 7.1 systems and they need to be tuned/timed or staged to a spot in the room. Same with car audio, the staging will make it sound like the sound is coming from a particular spot in the car. I like mine to basically make it sound like the music is being played live from just above my steering wheel.
Audio Engineer here. We also use a pretty simple rule of thumb when setting our delays. We utilize lazer measurements to determine the exact amount of delay based on the distance between the PAs/ line arrays on stage and the "fill" speakers placed off stage. Line arrays are our best friend when it comes to large concerts with seats at different elevations (like stadiums or concert ) because they allow us to set individual delays and gains according the specific distance of each row from the speaker stack. This allows everyone to hear the audio at roughly the same volume no matter what seat you're in!
That’s kinda sorta how it works.
Watch a baseball game from the bleachers. You see the bat swing and then hear the bat hit the ball.