You are right to question auditory models with transduction filters
whose cutoff is below about 1000 Hz. They are often just trying to
explain amplitude modulation detection without concern for other
aspects of auditory processing.
There is a discussion of the different methods of
envelopes in Yost et al. 1998, reference below. It concludes that if
to be able to explain the pitch shift of the residue, there is only one
methods that can be used to represent auditory processing, and that is
half-wave rectification followed by lowpass filtering. The filter needs
a relatively high cutoff frequency, 800-1200 Hz and beyond the cutoff,
filter should fall about 24 dB per octave.
Regards Roy P
Yost, W.A., Patterson, R.D. and Sheft, S. (1998).
The role of the envelope in processing iterated rippled noise. J.
Soc. Am. 104 2349-2361.
Hornsby, Benjamin Wade Young wrote:
I hope the answer to this question is not too obvious
We have recently been talking about auditory processing models, in
processing models, many of which incorporate an envelope extraction
do this I’ve seen in many cases the use of half wave rectification
followed by a low pass filter. The cutoff for this filter is generally
low frequency, say around 50 Hz or so. A colleague suggested that the
frequency should be based on the assumed time constant of the system or
subsystem being evaluated. I’ve been trying to determine the
for such a low frequency filter (slow time constant) in models of
processing. Neural processing limitations like the refractory period of
neuron are much faster than this. Anyone have a reference or two that
help explain the physiologic rational for this low frequency filter
* ** *** * ** *** * ** *** * ** *** * ** *** *
Roy D. Patterson
Centre for the Neural Basis of Hearing
Department of Physiology, Development and Neuroscience
University of Cambridge
Downing Street, Cambridge, CB2 3EG
phone: +44 (1223) 333819 office
fax: +44 (1223) 333840 department