opaqueice Wrote: > I've become curious about the claim that absolute polarity can be > audible. I'm very skeptical that this is possible in music, but on the > other hand it seems pretty clear to me that with some (rather > artificial) sounds it should be possible. > > There's a free sound editor called Audacity which is quite nice. With > it, I created an asymmetric waveform by first generating a pure tone > (sin wave) and then chopping off the positive half. I then copied > that, reversed the polarity, and pasted it onto the end of the first > sample. So in the end I had a track consisting of two equal parts - > first a sin wave with the positive half chopped off, and second a sin > wave with the negative half removed. I did this both with and without > removing the average DC offset from each half, which didn't make any > audible difference as far as I could tell. > > I tried this first with a 440 Hz sin wave, and couldn't hear a > difference between the two halves. However when I tried it starting > with a 50 Hz sin wave, there is a clear difference. The sound is a > kind of strange (and annoying!) buzz, pretty far from a pure tone, but > the two halves are at a different pitch! In particular played over my > computer speakers or through headphones connected to my sound card, > the second half is lower and has a louder bass component. Played > through the SB into phones the effect is more subtle, but still there. > From SB -> amp -> speakers, oddly, if there is still a difference it > seems reversed - the first half is at a lower pitch. However this was > much harder to hear, and might not be there at all. > > A spectrum analysis plot reveals no differences - and unless there is a > bug in Audacity, there _can't_ be an difference in the spectra, given > how I generated the track. So I guess this must be due to > non-linearities somewhere. > > I don't have time to do a proper blind test, but the difference is > clear - the two tones have a different overall pitch, which is quite > easy to hear. I tried closing my eyes and randomly clicking in > different places on the waveform, and I was right every time - it's > quite audible. > > Finally, let me note that this waveform is kind of maximally > asymmetric, and such a sound could never be generated by a physical > object (and if it could it would be an instrument quite the opposite of > "musical"!). So I don't think this result has any consequences for > music reproduction. Nonetheless, it's kind of intriguing.
You have created a sound wave with embedded DC. That can't be good for your speakers. -- P Floding ------------------------------------------------------------------------ P Floding's Profile: http://forums.slimdevices.com/member.php?userid=2932 View this thread: http://forums.slimdevices.com/showthread.php?t=23759 _______________________________________________ audiophiles mailing list [email protected] http://lists.slimdevices.com/lists/listinfo/audiophiles
