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From: toma@hpsad.HP.COM (Tom Anderson)
Newsgroups: comp.dsp
Subject: Re: What transform to use to get good audio spectra?
Message-ID: <9520015@hpsad.HP.COM>
Date: 8 Oct 90 23:03:07 GMT
References: <1990Oct1.130615.5802@funet.fi>
Organization: HP Signal Analysis Division - Rohnert Park, CA
Lines: 19


> I'd like to see into audio data (50 kHz sampling rate) with qood resolution
> in frequency. While the normal Fourier methods give easily very good results
> in the high end of the spectrum, the low frequency resolution is very poor.

> (Audio data is presented with a logarithmic scale. For example 1024 point

I asked a similar question a while back and got this excellent reply:

Try looking at "An Algorithm and Architecture for Constant-Q Spectrum
Analysis," by Gary W. Schwede.  "Q" refers to the ratio of bandwidth
to frequency, sometimes called the "quality" of a filter.
Constant Q <==> logarithmic frequency.

The paper is in the Proceedings of the IEEE International Conference
on Acoustics, Speech, and Signal Processing (ICASSP), April 1983, pp.
1384-1387.

Tom Anderson      toma@hpsad.hp.com    "It's only hardware"