Thanks, man, for writing back with some real meat on this! That sounds like a very interesting experimental setup -- and actually I have done some reading on HRTF's, both for a computer music class, and for "fun".
However, I was guessing that the pitch-shifting operation I'm perceiving here is independent of any filtering or resonances in the headphone and head. It sounds to me as if the filters you describe here, in terms of zeroes and poles on a complex plane, really can't accomplish that -- their magnitude responses at one frequency are independent of those at another frequency. The transfer function of such a filter is a representation of how a single frequency's magnitude is affected by the filter, and as far as I know, these filters don't shift signals from one frequency to another. That's why I thought this could be neatly explained by a Doppler shift, but when my headphones aren't even #%@& moving, that seems an unlikely explanation. ;-)
And what are we to make of the tempo-shifts that other people have noticed when they put on headphones or go to a different room? Whoa.
Peter
P.S. You programmed in M? Funky.
P.P.S. Oh yeah, and an IIR filter actually is stable as long as all of the poles are within the unit circle, right?
quoted 5 lines in regards to psychoacoustics, do a search on HRTF. (head related transfer functions) we>in regards to psychoacoustics, do a search on HRTF. (head related transfer functions) we
>studied the effects of speaker placement and sonic perception at the army research lab (no, i'm
>not a soldier...) along with the 'effects' created by headphones. if you really want to get
>into all that stuff, you have to study transfer functions (fft and ifft among others) and be
>willing to read through A LOT of literature.!quoted 4 lines lots of pole / zero plotting and z-transform analysis which, to my belief, was only truly>lots of pole / zero plotting and z-transform analysis which, to my belief, was only truly
>understood by the scientist i was working with. (smartest man i've EVER met) 'folding'
>imaginary Xs (poles) back into a circle representing real and imaginary numbers in a three
>dimensional plane can be a bit, um, confusing. (like this message...hehe)quoted 2 lines the research lab had the facilities to make some INCREDIBLE sounds... enough equipment and>the research lab had the facilities to make some INCREDIBLE sounds... enough equipment and
>software to make any electronic music 'fan' grin in envy
I'm grinning right now.
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