[sdiy] Phase shifts and instantaneous frequency

[Ian Fritz]

At 08:00 AM 7/15/2008, cheater cheater wrote:
>No, the beats are a normal physical phenomenon. Back to physics books, Ian ;)

Sorry, you aren't even close to understanding this.  A 100 Hz sine wave and 
a 201 Hz sine wave when added linearly do not give low frequency 
beats.  The sum and difference frequencies (beats) are 301 Hz and 101 Hz.


>The original thread's question was about a constant phase relationship
>- not a variable one. Of course you can hear a variable phase
>relationship, which is called pitch bending. :P


First, the relative phase is being changed very slowly, so it is 
effectively constant (quasi static).  Second, what is heard is amplitude 
beating at 1 Hz, not pitch bending.  The pitches heard are steady since the 
phase shift is increasing at a constant rate.  There may be a (small) pitch 
shift but it is constant, not changing at a 1 Hz rate.

Oh, and BTW, I have a PhD in physics, so you're not in a position to argue 
with me about this.  I'll be happy to answer any further questions you 
might have, though.  :-)

  Ian