[Noisebridge-discuss] why a sine wave?

[Michael Shiloh]

I think you're *ahem* splitting hairs...

William Nye_COMCAST wrote:
> Josh Myer wrote:
>> Michael Shiloh wrote:
>>> Why do we perceive a sine audio wave as a "pure" tone? Does it have to
>>> do with the mechanical vibrations in our ear? Does any non-sine wave
>>> introduce harmonics, vibrations other than the fundamental, which our
>>> brain perceives as non-pure?
>>> Regardless of mechanics, what is the perceptive reason a sine wave
>>> sounds pure?
>> That's a fun question; here's a Cliff's Notes version of the thorough 
>> reply.
>> Note that it is just mechanics, though.
>> We perceive sound with hairs in a tube in your ear getting nudged by 
>> sound
>> waves.  Those vibrations are described most closely by a sine wave (but
>> they're probably not _perfectly_ sinusoidal, since the tube isn't 
>> perfectly
>> cylindrical, etc).  Because different sound waves stimulate different 
>> hairs,
>> everything you hear is being perceived as a set of sine waves, all 
>> laid on
>> top of each other.  ...
> 
> I have always argued (somewhat scientifically) that if
> you need to move an object periodically between two
> different positions, having it move sinusoidally vs time
> will require the minimum amount of force and energy.
> 
> Now I'm going to start saying (nonscientifically, and probably
> not what Josh intended) that a pure sine wave only vibrates
> a single hair -- the one of the correct length -- and other
> waveforms vibrate multiple hairs and thus sound less pure.
> 
> Maybe this -- and Josh's hair -- can give you some long ideas. :-)
>    -Bill
> 
>