Re: Critical bands v hearing loss

[Martin Braun <nombraun@xxxxxxxxx>]

Jan Schnupp asked:

> ......... the impression I
> have is that, when it comes to auditory scene segmentation, critical
> bands are not that critical. Or am I wrong there?

You are probably right. The critical band (CB) anatomy can support scene
segmentation, but it is not a necessary element in it. Scene segmentation is
mainly accomplished on the basis of temporal disparities between signal
streams. And such disparities are largely extracted and coded already in the
cochlear nuclei, that is before the CB anatomy in the midbrain is involved.

The main function of the CB anatomy seems to be spectral segmentation for
pitch extraction and timbre recognition.


As to the issue of frequency resolution and CB (Reinhart Frosch):

-- Difference limen for frequency (DLF) in the range of 0.5 to 2 kHz is ca 3
Cent.
-- CB in the range of 1 to 4 kHz is 260-280 Cent.

Original CB data:
Zwicker, E., Fastl, H., 1990. Psychoacoustics: Facts and Models.
Springer-Verlag, Berlin. (Table 6.1)

Original DLF data:
Wier, C.C., Jesteadt, W., Green, D.M., 1977. Frequency discrimination as a
function of frequency and sensation level. J. Acoust. Soc. Am. 61, 178-184.
(Table II)

Transformation of the CB and DLF data into Cent:
Braun, M., 1999. Auditory midbrain laminar structure appears adapted to f0
extraction: further evidence and implications of the double critical
bandwidth. Hear. Res. 129, 71-82. (Fig. 5)


Martin

----------------------------

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