mfcc filters gain

[Guillaume Lemaitre <lemaitre@xxxxxxxx>]

Dear list,
In the Malcom Slaney's Matlab implementation of mel frequency cepstral
coefficients, triangular filters are normalized "so that each filter has
unit
weight". Parsing some papers dealing with mfcc, I noticed that most of
authors does not mention this normalization step (a few of them do, but
without explanation).
I am wondering what does this normalization correspond to. If I am
correct, and if triangular filters were supposed to approximate critical
band filtering, they all should have the same unit height, just as third
octave, or Patterson's gammatone filterbank. Am I wrong ?

I am also wondering if some work has already be done to improve
mfcc-like processing. As it is suggested in [1], Moore's ERB scale or
Bark scale seems to be more appropriated than the mel scale, and
gammatone filterbank should be much more accurate (even if probably more
computationaly expensive) than a triangular filterbank ?

Regards
Guillaume

[1] M. D. Skoweonski and J. G. Harris
"Improving the filterbank of a classic speech feature extraction algorithm"
IEEE Int. Symp. on Circuits and Systems, Bangkok, Thailand, 2003

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Guillaume Lemaitre, Ph.D.
Post-doctoral fellow
Project-team REVES (REndering and Virtual Environments with Sounds)
INRIA Sophia-Antipolis                 tel: (+33) (0)4 92 38 50 83
2004 route des Lucioles               fax: (+33) (0)4 92 38 50 30
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Guillaume.Lemaitre@sophia.inria.fr,
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