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Re: About importance of "phase" in sound recognition

Hello James (et al.),

I have not yet read Plomp and Sieeneken (1969), but shall do so as soon as possible. In the meantime, my newest synthesizer experiment may be of some interest:

In the case of a one-octave two-tone (440 Hz, 880 Hz) composed of two sinusoidal tones, I hear, both at the onset and later, no dependence of the loudness and the timbre on the delay (i.e., the phase) between the two tones, although the waveform of the complete signal does depend on that delay. These two sine tones form a harmonic complex tone, and the strengths of its two partials are delay-independent.
With two harmonic complex tones (harmonica voice), however,  timbre and loudness of the one-octave two-tone vary from one try to the next. The variation is weaker than in the case of two equal frequencies. Constructive and destructive interference among a part of the harmonics takes place.
The results for a one-just-fifth two tone (440 Hz, 660 Hz) are similar. The variation of timbre and loudness in the case of harmonic complex tones is now fairly weak, however.

----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

The subject title says "recognition", which is a lot different than
"discrimination", but I don't get the sense that recognition is all
that people are talking about on this thread.

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.

There have been a lot of papers about the importance of phase in
musical contexts. Here are a couple:

T. H. Andersen and K. Jensen, "Importance and representation of phase
in the sinusoidal model" J. Audio Engr. Soc. 52, No. 11, 1157-1169 (2004)

S. Dubnov and X. Rodet, "Investigatioi of phase coupling phenomena in
sustained portion of musical isntruments sounds", J. Acoust. Soc. Am.
113, No. 1, 348-359 (2003).

Jim Beauchamp
Univ. of Illinois


Reinhart Frosch,
Dr. phil. nat.,
CH-5200 Brugg.
reinifrosch@xxxxxxxxxx .