Interesting realization about latency.

Discussion in 'Electronic Drum Zone' started by vinito, Nov 12, 2017.

  1. vinito

    vinito Well-Known Member

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    Maybe this is old news to you guys. If so, excuse showing my novice ignorance.

    I was wondering how much latency is acceptable in relatable terms rather than depending on the number of milliseconds some guy in a lab coat says is "imperceptible by most people". I figured the speed of sound might be a good starting point and did a little basic math to find out something I never realized before.

    So since sound travels at 1130 feet per second, then it takes .85 milliseconds to travel a single foot. You can manipulate it as many ways as you want, but obviously we seem to perceive sounds happening instantly most of the time because most things we are paying attention to are fairly close by. You can be only one or two hundred feet away from the source of a sound before it becomes interestingly noticeable. But anyway, most places such as small bars and such (i.e. gigs) sounds tend to be perceived to match the event pretty much on the money. I've been at concerts where I was far enough away that I could see a slight lag. But you have to be a fair distance, say 50 feet? before it seems to be an issue. Of course it might be more noticeable when something at your feet has even the slightest lag, i.e. it would be weird and noticeable for the 50-foot lag to happen when your brain is expecting a 5-foot lag.

    So the magic "acceptable latency" number I see is always 25 milliseconds. That equivalently translates to being 28 feet away from the source of a sound.

    I'm not sure if I by that, so...

    I'm going to go outside tomorrow and throw some rocks at the neighbor kids or something and see if I notice a noticeable latency if they are only 30 feet away. Their yelps are likely to lag slightly behind the thwack! of the initial impact, so I need to ignore any sounds that come after. I might have to try several times to learn at filtering out and ignoring the extraneous sounds I might generate.

    [​IMG]
     
  2. LJT 1982

    LJT 1982 Member

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    Are you describing latency as the minimal perceived audible difference that somebody can hear?

    Would you say its correlated to fequency and time domains? Im thinking along the lines of digitail time alignment and delays in regards to speaker setups.

    Latency is something I have always associated with timing speeds of A/D and D/A in audio interfaces and the ability to play along live to a sound source and hear yourself in close to real time so it feels natural.
     
  3. Bongo Brad

    Bongo Brad Very well Known Member

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    I'd love to see some pics of the rocks you will be throwing, with gram weight please.
     
  4. dcrigger

    dcrigger DFO Master

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    As musicians, keep in mind that unlike someone just listening and seeing, we have a tactile component involved as well.

    When we sit in front of a snare drum, we feel the strike and then hear the strike within a few of milliseconds later (our ears being say, three feet from the snare). But put on isolation phones - so we're hearing the snare almost entirely from the headphones - and send the mic'd snare sound to them with 30 ms. latency and it will be bothersome. To the point of making it difficult to play. (Same applies to hitting a midi pad and having the sample sound coming back late).

    At lower amounts of latency, this would be less bothersome - and with low enough numbers it would cease being bothersome at all.

    But it is an issue - with synth/modules - but even more so these days with digital recording and sound systems. Where there is always some degree of latency going-in and an additional amount coming out.
     
  5. xsabers

    xsabers World's Second Most Okayest Drummer

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    My timing is so questionable, even my acoustic drums have latency...
     
  6. dboomer

    dboomer Very well Known Member

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    when two sounds are 25ms apart is the rule pf thumb value that most people hear them as two independent sounds. We tested a number of players and determined that the magic number when you cant play in time is when your sound about 11ms late to your ears.

    But the normal way you hear an acoustic drum kit is with about 3ms delay (the time necessary for a remote source to reach your ears. But an i teresting fact is if you are wearing in-ears and your drums are close micd (in a; all analog system) you will actually hear the drums with almost zero latency.

    But even an acoustic piano has latency as it takes some time for all the parts to move and hit the string from the time you press a key. Synths typically take 3-7ms. And any time you run through something digital you will always receive some latency.

    But somehow we play with our bass player 10 feet away and the keyboard player even farther and werre never bothered.
     
  7. dcrigger

    dcrigger DFO Master

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    I think we are able to more easily compensate to playing with that bass player that's 10 feet away, because he's not part of our direct sensory feedback loop involving our own playing. Feeling the stick hit the drum, yet not hearing the sound we're producing until later than we are acoustically use to is very unsettling. And really hard to simply will ourself to compensate for.
     
  8. JDA

    JDA DFO Master

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    What's milk got to do with this?
     
  9. xsabers

    xsabers World's Second Most Okayest Drummer

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    On my old phone, I had a goofy app that would delay your voice by varying degrees. With noise cancelling earphones plugged in, the slightest delay would have me sounding like a brain damaged drunken sailor to anyone listening to my actual voice. I'm sure I would have been able to eventually learn to compensate, but man, the brain needs its points of reference to function normally.

    In a similar vein, the other morning about 4am, I was driving to work and came across a disabled RV with no lights on a blind curve on an exit ramp, hanging out into traffic lanes. The driver was under the hood making repairs. I called 911 and they transferred me to the Highway Patrol. Somehow, the transfer created a massive echo effect on my voice. In the end, I was concerned the Highway Patrol would be out looking for the obviously drunk guy, stammering and slurring his words at 4am instead of checking on the disabled RV!
     
  10. wolfereeno

    wolfereeno Well-Known Member

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    Latency really disrupts your time when playing live.

    As for recording and latency, that's actually less important because you can easily nudge a track or series of tracks to compensate for it.

    What I do is when I'm recording electronic drums I tend to monitor the module's live sound even if I intend to use a plug in. So I might record vdrum direct, midi, and plug in all at once. ALthough usually I listen to a mix of the vdrums and the plug ins.

    Then my timing isn't tossed off and I can get the sound I'm after later.

    I'd do the similar with vocals or other instruments. Ie, try to listen to the more live sound and add more effects later.

    With vocals, since most singers like to hear some reverb on their voice, you can add reverb just for the monitoring, but still record a dry voice.
     

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