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Re: two-tone suppression
At 4:21 PM +0100 9/21/05, Ben Lineton wrote:
Two-tone suppression can also arise from cochlear nonlinearity, as
evidenced by mechanical measurements of basilar membrane 2TS (sorry
I can't remember the reference), and by measurements of 2TS in
otoacoustic emissions (e.g. Brass and Kemp, Suppression of stimulus
frequency otoacoustic emissions, J Acoust Soc Am. 1993
Put simply, the suppressor tone drives the cochlear amplifier into
saturation, so that its response to the probe tone is reduced.
I agree that the main source of 2TS is cochlear nonlinearity. But
the nature of that nonlinearity is not "saturation". Rather, it's
more like an automatic gain control, in which the mechanical gain
gradually reduces as a function of mechanical response level over a
very wide dynamic range of input power levels. I think all the good
mechanical BM data of recent decades support this view pretty well.