Subject: Many thanks !! From: Barbara Muller <bmuller(at)BME.JHU.EDU> Date: Mon, 17 Apr 2000 15:48:51 -0700Dear all who replied, All your mails are very helpful. Thanks a great lot ! I pasted all the replies below (I hope I didn't forget any). Barbara Here's what I got concerning equivalent square noise: Fred Wightman wrote : The equivalent square bandwidth is simply the width of a rectangle that has the same total area (noise power) and the same height as your noise spectrum. So, to get the width, first get the total "power". Let's say it is 80 db SPL. This would simply be what you get when you hook up the noise to a meter of some sort. Now, the next step is not that easy in practice, but easy in principle. You've got to get the "spectrum level" of the noise at the frequency where your noise is at its peak (or in the flat region, if you've got something like a butterworth filtered noise. To get the spectrum level you must pass the noise (at the output of your filter) through some kind of filter whose properties you know exactly. Some spectrum analyzers have 10 Hz "square filters" for example. If the noise reads 30 dB SPL at the output of, say, a 10 Hz square filter, then the spectrum level is 70 - 10 log 10 or 60 dB SPL. So, you've got a noise with a total power of 80 and a spectrum level of 60. Since the total power is equal to the spectrum level times the equivalent square bandwidth (that's how I got 70 - 10 log 10 = 60 above), then you now know your equivalent square bandwidth is 80-60 = 20 in dB terms, or, taking the antilog, 100Hz. Israel Nelken wrote : The equivalent rectangular bandwidth (I assume this is what you mean) is equal to the sum over all frequencies of the energy of your noise band, divided by the spectrum level at the peak of your noise band. Re critical bands: the basic papers were written by Pickles (1975) and Costalupes (1983). I believe Eric Young has copies, at least of the Costalupes paper. Here's what I got concerning critical bandwidth in cats : Donald Greenwood wrote : The first two papers review quite a bit of data on frequency-position functions and human critical bandwidth estimates and what function fits them quite well. Then Part II of 1991 paper reviews some CB data on other species. The discussion in the second part of the1991 paper republishes the cat data of the Pickles, Nienhuys and Clark, and Watson papers and will assist in understanding those data. Pickles' reinterpretation of Watson's data (which I repeat in the 1991 paper) is probably right. See also Schreiner's estimates (from inferior colliculus neural data) of what critical bands may be in the cat. He forgot to compare my function to the data, but I have a modified figure (somewhere) showing my cat function goes right through the center of gravity of their data with nearly the same slope and magnitude. You will be able to "see" that without the figure since (1) Schreiner compares Pickles and Nienhuys-Clark data to the neural data and (2) the 1991 paper above compares the function to the Pickles and Nienhuys-Clark data. In comparing across species bear in mind the 1996 paper in Hearing Research. Greenwood, D.D. (1990) A cochlear frequency-position function for several species - 29 years later. J. Acoust. Soc. Am. 87, 2592-2605. Greenwood, D.D. (1991) Critical bandwidth and consonance in relation to cochlear frequency-position coordinates, Hear. Res. 54, 164-208. Greenwood, D.D. (1996) "Comparing octaves, frequency ranges, and cochlear-map curvature across species, Hearing Reseach, 94, 157-162. Greenwood, D.D. and Maruyama, N. (1965) Excitatory and inhibitory response areas of auditory neurons in the cochlear nucleus. J. Neurophysiol. 28, 863-892. [This paper plots tuning curves and rate contours on cat frequency-position function of that time. That earlier function has same normalized slope constant as current cat f-p function.] Nienhuys, T.G.W. and Clark, G.M. (1979) Critical bands following the selective destruction of cochlear inner and outer hair cells. Acta Otolaryngol. 88, 350-358. Pickles, J.O. (1975) Normal critical bands in the cat. Acta Otolaryngol. 80, 245-254. Pickles, J.O. (1976) Role of centrifugal pathways to cochlear nucleus in determination of critical bandwidth. J. Neurophysiol. 39, 394-400. Pickles, J.O. (1979) Psychophysical frequency resolution in the cat as determined by simultaneous masking and its relation to auditory-nerve resolution. J.Acoust. Soc. Am. 66, 1725-1732. Pickles, J.O. and Comis, S.D. (1973) Role of centrifugal pathways to cochlear nucleus in detection of signals in noise. J. Neurophysiol. 36, 1131-1137. I am not sure that the last Pickles, et al paper is relevant but its inclusion won't hurt and any relevance will be discussed in 1991 paper above. Schreiner, Christoph - Can't recall reference. About five years ago. Suggest you ask him for it. Christoph Schreiner <chris(at)phy.ucsf.EDU> Watson, C. S. (1963) Masking of tones by noise for the cat. J. Acoust. Soc. Am. 35, 167-172. Jont Allen wrote : >This was done at Johns Hopkins by John Costalupes in 1983. >He did it both neurally and psychophysically, on the cat. > > >(at)ARTICLE{Costalupes83, > AUTHOR = "John A. Costalupes", > TITLE = "Broadband Masking Noise and Behavioral Pure Tone > Threshold in >Cats", > JOURNAL = JASA, > YEAR = "1983", > VOLUME = 74, > NUMBER = 3, > PAGES = "758--764", > MONTH = "September"} > >Ask Eric Young about this, or Murray Sachs. You can >read my summary in JASA, Vol. 99, #4, April 1996, Figure 5. >It seems to me there was a paper with Eric as well. > >In humans, the critical ratio is independent of level >over a 60 dB dynamic range. This was shown first by (you >guest it folks) Harvey Fletcher in 1938, Proc.. Nat. Acad. >Sci. vol. 24 pp 265-274. The experiment was repeated by >Hawkins and Stevens (1950) with the same result JASA v22 >pp 6-13. > >Pickles also did the experiment, but he told me there were >some problems with the result. I dont remember what exactly. > > >(at)ARTICLE{Pickles75, > AUTHOR = "J. O. Pickles", > TITLE = "Normal Critical Bands in the Cat", > JOURNAL = "Acta Otolaryngol", > YEAR = "1975", > VOLUME = 80, > PAGES = "245-254"} > > >This is a really important problem, with a lot of controversy. Ask 5 people and you will get 5 different answer. Erv Hafter wrote : >Check out Miller and Watson (or Watson and Miller), circa >1962. Hi to Brad. Matt wrote : >You should look at some papers by D.D. Greenwood in both the JASA and >Hearing research. If you can't find the references then I could rustle them up. Gilad Jacobson wrote : Hi, You should take a look at Pickles, 1979 (JASA 66(6)) Costalupes, 1983 (JASA 74) Good luck! William Yost wrote : The best book covering psychophysical measures on all animals is the Handbook of Animal Psychophysics. It has tables and graphs of every type of pyschophysical measure on all animals. contact Dick Fay at rfay(at)luc.edu. -- * * * PLEASE NOTE MY NEW ADDRESS * * * Barbara S. Muller, PhD. Email : bmuller(at)bme.jhu.edu Postdoctoral Fellow Voice : 410 955-3162 The Johns Hopkins School of Medicine Fax : 410 955-1299 Dept. of Otolaryngology-HNS Traylor Bldg, RM 505 720 Rutland Avenue Baltimore, MD 21205 USA Old address : Barbara Muller University of Geneva FPSE 40, Blvd du Pont d'Arve 1205 Geneva Switzerland