Subject: Re: Robust method of fundamental frequency estimation. From: "Richard F. Lyon" <DickLyon@xxxxxxxx> Date: Wed, 28 Feb 2007 07:54:31 -0800 List-Archive:<http://lists.mcgill.ca/scripts/wa.exe?LIST=AUDITORY>>Arturo - > >>However, what I said about the equivalence of applying a summary >>autocorrelation to the output of a orthonormal linear filterbank and >>applying autocorrelation to the input signal is still true, it just does >>not apply to your model, because of the HWR. > >That's true, but I wouldn't assume that people doing filterbank -> >autocorrelation -> summary are simply misguided. Very often in >addition to nonlinearity there is per-channel normalization (and/or >weighting to emphasize particular subbands/sources), which has a >profound effect. I used gammatones plus nonlinearity normalization in >the pitch tracker in my CASA system, but I felt like I understood it >better when I saw the way that Tolonen & Karjalainen simply whitened >the spectrum (on a suitably coarse scale) then autocorrelated a low >band (with HWR?) and a high band (with envelope extraction?) to avoid >the need for a large number of parallel channels. I think their paper >gets at a lot of the essence of many such pitch models. True. You don't get envelope pitch that way (AM modulated noise, for example), but you do get many other effedts. I agree that a filterbank can be a useful part of a whitening system in front of an ACF. Dick > DAn. > >Tolonen, T. and M. Karjalainen (2000). A computationally >efficient multipitch analysis model. IEEE Transactions on >Speech and Audio Processing 8(6), 708716.