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Re: About importance of "phase" in sound recognition

Hello James,
Now I have studied the paper that you recommended,
R. Plomp and H.J.M. Steeneken,
"Effect of Phase on the Timbre of Complex Tones",
J. Acoust. Soc. Am. 46 (1969) 409-421.
Some interesting sentences from that paper:
Page 413: "The experiment was carried out with nine subjects, all with normal hearing. One of them could not observe any difference between the stimuli, so his results were left out of consideration."
Page 420 (Conclusions): "For a fundamental of 292.4 Hz, the maximal effect of phase on timbre is, averaged over eight subjects, quantitatively equal to the effect of changing the SPL by about 2 dB."
In the last point of their conclusions, Plomp and Steeneken attribute the effect of phase on timbre to the "[...] correlation [...] between the vibration patterns at different locations along the basilar membrane and the corresponding time patterns of the nerve impulses."
Since, according to that paper, the just mentioned effect is comparatively strong at low frequencies, I redid my synthesizer experiment described earlier for a one-octave sine-tone dyad of 110 and 220 Hz. Now I did hear a slight variation of the timbre from one try to the next (in contrast to the 440-880-Hz-case studied before).

----Ursprüngliche Nachricht----
Von: jwbeauch@xxxxxxxxxxxxxxxxxxxxxx
Datum: 07.10.2010 19:06
An: <AUDITORY@xxxxxxxxxxxxxxx>
Betreff: Re: About importance of &quot;phase&quot; in sound recognition

[...] To me, the definitive paper on phase discrimination on steady-state complex tones was by Plomp and Sieeneken in 1969:
R. Plomp and H. J. M. Sieeneken, "Effect of phase on timbre of complex tones", J. Acoust. Soc. Am. 46, No. 2 (pt.2), 409-421 (1969).
The prototype signal was a sawtooth but with only 10 harmonics in the Fourier series. Phase angles on the harmonics were random multiples
of pi/16. The conclusions were:
(1) The timbre difference between a tone consisting of only sine or cosine terms and a tone consisting of alternative sine and cosine
terms represents the maximal possible effect of phase on timbre;
(2) the maximal effect of phase on timbre is quantitatively smaller than the effect of changing the slope of the amplitude pattern by
2 dB/pct and is less for higher than for lower frequencies;
(3) the effect of phase on timbre appears to be independent of the effect of amplitude pattern and of the loudness factor. [...]
Jim Beauchamp
Univ. of Illinois