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Re: Rationale for Critical Bands



The point of the books link is that there are easy online resources for information about the level dependence of critcal bands, or critical bandwidth. Here's a better one, perhaps:
http://www.google.com/search?hl=en&tbs=bks:1&q=%22critical+bandwidth%22+%22level+dependence%22

Maybe the search gives different results in different locales? I see the first hit as a link to a paper titled "LEVEL DEPENDENCE OF CRITICAL BANDWIDTH". And here's one that's found in both searches, which backs up my statement that "some methods show a level dependence of the measured critical bandwidth": http://books.google.com/books?id=TDPIO01DLSUC&pg=PA236&dq=%22critical+bandwidth%22+%22level+dependence%22&hl=en&ei=8HoWTKjkGIOOMtCv5ZkL&sa=X#v=onepage&q=%22critical%20bandwidth%22%20%22level%20dependence%22&f=false (in case it doesn't work where you are, it's p. 236 in Handbook of Signal Processing in Acoustics by David Havelock, Sonoko Kuwano, Michael Vorländer).

On the level dependence of auditory filters, there are many papers by Patterson, Glasberg and Moore, Rosen and Baker, and many others, that explore auditory filter level dependence within the paradigm of detection of tones in noise maskers. Here's one by Pick, 1980: http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JASMAN000068000004001085000001&idtype=cvips&gifs=yes&ref=no

and Rosen, Baker, and Darling 1998:
http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JASMAN000103000005002539000001&idtype=cvips&gifs=yes&ref=no which starts the abstract with "Auditory filters broaden with increasing level".

and this one by Glasberg and Moore 2000 specifically talks about the derived psychophysical filters resembling filtering at the basilar membrane, including the level dependence:
http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JASMAN000108000005002318000001&idtype=cvips&gifs=yes&ref=no

What I'm not familiar with is the alternate conclusion, that there is a level-independent critical bandwidth. Thanks for the links you sent, some of which do seem to be about that, or assume that. I'm open to the idea that in brainstem, there is less level dependence, or that some kinds of psychophysical experiments give a CB that doesn't vary with level, though I haven't really seen the evidence for it yet. Maybe you can point us toward some.

Dick



Richard F. Lyon wrote:

The "critical bandwidth" is a simplification of the concept of a psychophysical "auditory filter", which is a bandpass filter that can be measured with various experiments, such as detection of probe tones in notch-noise maskers.

There is no difference between the concepts of the "auditory filter" and the "critical bandwidth", let alone in simplicity. Both are extremely oversimplified and loose, and thus have been causing unending confusion.

The concept is a psychological one, and whenever it was not verified by physiological data it has turned out to be pretty much worthless.

Find more in books: http://www.google.com/search?q=%22critical+band%22+%22level+dependence%22&tbs=bks:1

Sorry, this is not a useful link. Or does it mean to put off people from finding something?

If there is support for your claims in the literature, please say where. Thank you.

Martin


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Martin Braun
Neuroscience of Music
S-671 95 Klässbol
Sweden
email: nombraun@xxxxxxxxx
web site: http://www.neuroscience-of-music.se/index.htm




----- Original Message ----- From: "Richard F. Lyon" <DickLyon@xxxxxxx>
To: <AUDITORY@xxxxxxxxxxxxxxx>
Sent: Monday, June 14, 2010 5:42 PM
Subject: Re: Rationale for Critical Bands

The "critical bandwidth" is a simplification of the concept of a psychophysical "auditory filter", which is a bandpass filter that can be measured with various experiments, such as detection of probe tones in notch-noise maskers. These measurements can be done at different levels, and show a clear level-dependence of the psychophysical auditory filter and its bandwidth, or critical band, following a pattern consistent with the variation seen in cochlear mechanics.

Some types of experiments reveal a level dependence in the CB, presumably based directly on the cochlear filtering. Other experiments show a more level-independent CB, and that's what corresponds to the further processing in IC, according to some experimenters.

Find more in books: http://www.google.com/search?q=%22critical+band%22+%22level+dependence%22&tbs=bks:1

Dick