Re: comodulation release of masking (CMR)

[Neil Todd <TODD@xxxxxxxxxxxxxxxxx>]

Dear Steven



Date:          Fri, 2 Oct 1998 15:38:24 +0200
Reply-to:      par@IPO.TUE.NL
From:          par@IPO.TUE.NL
Subject:       Re: comodulation release of masking (CMR)


>>
>I think there is no consensus about the processing of CMR
>stimuli although we recently argued that the envelope cross correlation
>(not to mistake with the envelope cross covariance or correlation
>coefficient) may be helpful in accounting for CMR data
>(van de Par and Kohlrausch, 1998a/b: JASA 103 pp 3605-3620; 1573-1579).
>In the paper on page 3605 we even describe a model that accounts
>for CMR data.
>
>Steven
>
>

I think we are agreed that some form of cross-correlation mechanism is
 probably a good horse to bet on, I wonder though if you could clarify
your distinction between different forms of cross-correlation. The
cross-correlation mechanism I proposed in Todd (1996, Network: Computation
in Neural Systems. 7, 349-356) was  a product-moment on the cosine phase
 of the envelope modulation power spectrum. This had the advantage that
one didn't need to have delay lines or some other storage mechanism since
if one uses acausal impulse response function (or non-linear phase response
transfer function) for the modulation filter, this is effectively a kind of
memory. Further, the cosine phase spectrum locks into that of the envelope
thus preserving sensitivity to phase effects in streaming (e.g. in an
alternating A B A B sequence). I did play around with some other metrics,
e.g. Euclidean distance, but  did not conclude that there was any advantage
over the product-moment, although I did consider how such a cross-correlation
 mechanism might be instantiated neurally.

Best wishes

Neil

University of Manchester
Manchester
M13 9PL
UK
Tel. +44 (0)161 275 2557

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