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Re: auditory distortion caused by yawning

Dear Harriet, Martin, Roger, Yi-Wen, and List,

In a recent publication [1] I have proposed a "sensory-
consonance condition b" (few or no large gaps in the pattern 
of partial-tone excitation peaks on the basilar membrane of the 
inner ear), to be added to "condition a"  (i.e., to the Helmholtz 
consonance condition, few or no pairs of partial tones having 
nearly equal frequencies and thus generating disagreeable 
beats). Violation of my condition b, however, is perceived as 
disagreeable in the sense of "hollow", rather than in the sense 
of "dissonant" or "discordant". An increase of dissonance 
through yawning therefore appears to imply an increasing 
violation of the Helmholtz condition, i.e., a level increase of 
those pairs of partial-tone excitation peaks which even in 
comparatively consonant chords have nearly equal frequencies. 

For instance, in the major third consisting of two simultaneous 
harmonic complex tones C4 (264 Hz) and E4 (330 HZ), the sixth 
partial of the deeper tone has 1584 Hz, and the fifth partial of 
the higher tone has 1650 Hz. These two partials generate 66 
beats per second, fairly close to the (broad) roughness 
maximum, discussed in [1], at a beat-rate of 
(1.1 s^-0.5) * sqrt(1617 s^-1) = 44 s^-1 .

Second example: in the minor third consisting of two 
simultaneous harmonic complex tones E4 (330 Hz) and 
G4 (396 Hz), the fifth partial of the deeper tone has 1650 Hz, 
and the fourth partial of the higher tone has 1584 Hz. These 
two partials also generate 66 beats per second, close to the 
(broad) roughness maximum at a beat-rate of 44 s^-1.

How can yawning selectively enhance the cochlear 
amplification at frequencies of about 1.5 kHz and higher? 
Possibly, increased dissonance perceived after yawning is 
caused by the active cochlear amplifier (CA) being turned off 
before yawning and turned on after. Near 300 Hz, the CA 
amplification factor is close to 1.0, whereas in the several-kHz 
region, in a healthy cochlea, that factor can be as high as 
1000 (i.e., 60 dB).


[1] R. Frosch, "Psycho-Acoustic Experiments on the Sensory 
Consonance of Musical Two-Tones", Canadian Acoustics, 
Vol. 35, No. 3 (2007) 38-45.

Reinhart Frosch,
Dr. phil. nat.,
r. PSI and ETH Zurich,
Sommerhaldenstr. 5B,
CH-5200 Brugg.
Phone: 0041 56 441 77 72.
Mobile: 0041 79 754 30 32.
E-mail: reinifrosch@xxxxxxxxxx .

----UrsprÃngliche Nachricht-----------
Von: hjacobster@xxxxxxx
Datum: 17.10.2008 21:24
An: <AUDITORY@xxxxxxxxxxxxxxx>
Betreff: Re: auditory distortion caused by yawning

I wouldn't imagine the hard cochlea being physically altered 
with just a yawn.  I would think it would have more to do with 
change in middle ear pressure and TM mobility...much like we 
yawn to open our Eustachian Tubes.

Prof Roger K Moore wrote:
> Dear List,
> I have often noticed that if I yawn while listening to music, I 
> experience a noticeable distortion of the auditory 
> experience - in particular, the sounds appear to become 
> discordant.  Is this a well known effect, and can it be easily 
> explained as the result of a physical distortion of the 
> cochlea?  If so, what does it say about timing-based theories 
> of timbre perception?
> Best wishes
> Roger K. Moore