Re: Critical bands v hearing loss

[beaucham <beaucham@xxxxxxxxxxxxxxxxxxxxxx>]

On Thu Sep 22 01:26:43 2005 Vinay S.N wrote:
>The human ear can only make sense of one signal per critical band. For
>example, if two sine tones of 100Hz and 110Hz are played, two distinct
>tones are not heard. This is because the critical bandwidth at 100Hz is
>about 80Hz, and the two tones would be within the same critical band; one
>will only hear two distinct tones when the two excitations exist in
>separate critical bands. Hence there is no point in having controllable
>bands which are finer in resolution  than a critical band.

I don't think this is true in general. If the tones are too close
together (less than 20 Hz) beats will be heard. Between 20 and 40 Hz
difference a roughness sensation is heard. Beyond that two tones can
be heard. Also, if there are three tones, the relative phases can be
aligned to imitate amplitude OR frequency modulation, and they sound
entirely different. The question is how much detail can be heard
within a critical band. The case I referred to in my previous note
was the harmonic spectrum case, which I neglected to mention.) I'm
sure this question has been explored, and I'd like to see some
discussion on this topic by people in the psychoacoustic area.

Jim