two sine tones simultaneously within one critical band

[Martin Braun <nombraun@xxxxxxxxx>]

Jan Schnupp wrote:

> If you play two sine tones simultaneously within one critical band, then
> the tones will interfere. Alternating constructive and destructive
> interference will cause an amplitude modulation known as "beating". They
> will be perceived as a single tone that "warbles" or "flutters" at a
> frequency equal to the frequency difference. That's just physics.

Physics, yes. But the "beating" effect has nothing to do with the critical
band (CB). You hear a "beating", if the two tones are separated by a small
frequency difference (up to ca. 15-20 Hz). If the frequency difference is
larger than this, the "beating" effect disappears and you hear two tones in
dissonance.

The border between beating and non-beating is determined by the temporal
resolution of the auditory system. This border has no relation to the CB at 
all.

The CB border, for the case of two tones, is the border between consonance
and dissonance. Two sine tones are perceived as consonant, if their
frequency difference is > CB, and as dissonant, if their frequency
difference is < CB. And you hear two tones in both cases.

Martin
----------------------------
Martin Braun
Neuroscience of Music
S-671 95 KlÃssbol
Sweden
web site: http://w1.570.telia.com/~u57011259/index.htm