Audio Signals and Harmonics

Discussion in 'General Electronics Chat' started by zippoinc, Jun 9, 2011.

  1. zippoinc

    Thread Starter New Member

    Apr 4, 2011
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    I'm having quite a time trying to figure out how to ask a seemingly simple question concisely enough to get anything useful out of google.

    I'm a recording musician and all throughout AC analysis I've invoked visions of audio waves and harmonics in the context of recording with multi track software.

    First, when the various tracks of audio, say 3 tracks (guitar, vocals, drums) are mixed down to one track, are there three waveforms now? Or are they summed to one signal?

    Second, when I zoom way in on the audio waves they ultimately are only one waveform. Where are the harmonics? (Seems to me the signal I recorded contained the harmonics, so the signal I'm viewing is the result of the base frequency and all the harmonics as recorded by the microphone. If that's true, then I have a follow up..)

    Anybody help a fella understand?
     
  2. #12

    Expert

    Nov 30, 2010
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    1) they are all summed.
    2) The harmonics show up as waves that are not sine waves. Any deviation from a sine wave involves harmonics. You can zoom in on any hump or valley and it looks like a nice curve if you zoom enough, but it usually is not a pure sine wave.
     
  3. zippoinc

    Thread Starter New Member

    Apr 4, 2011
    22
    0
    Thank you. It just seems so odd to me that three different signals could be summed to one signal, without any apparent loss in those signals (although I guess it could just "sound" that way).

    For instance, a guitar chord struck simultaneously with a snare hit. It started as two dedicated signals. Yet somehow *one* signal is playing guitar sounds and the snare sounds all in the same time instant - all in one waveform.

    Just hard to wrap my head around how a single signal can do what multiple signals were doing - playing multiple sounds in the same instants of time.
     
  4. kubeek

    AAC Fanatic!

    Sep 20, 2005
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    What you lose is the ability to take them apart again. Once you sum them, there is no way to turn it back into separate instruments, unlike the human ear which can still tell which part of the sound belongs to what, but that is only because you have experience what things sound like.
     
  5. #12

    Expert

    Nov 30, 2010
    16,278
    6,790
    Ain't electronics wonderful!

    But seriously, a mixer is just doing the same thing that happens in the air in front of the band. The air pulses are summed...the mic signals are summed...your ear hears the same thing.
     
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