Daniel@0: function cfArray = ERBSpace(lowFreq, highFreq, N)
Daniel@0: % function cfArray = ERBSpace(lowFreq, highFreq, N)
Daniel@0: % This function computes an array of N frequencies uniformly spaced between
Daniel@0: % highFreq and lowFreq on an ERB scale.  N is set to 100 if not specified.
Daniel@0: %
Daniel@0: % See also linspace, logspace, MakeERBCoeffs, MakeERBFilters.
Daniel@0: %
Daniel@0: % For a definition of ERB, see Moore, B. C. J., and Glasberg, B. R. (1983).
Daniel@0: % "Suggested formulae for calculating auditory-filter bandwidths and
Daniel@0: % excitation patterns," J. Acoust. Soc. Am. 74, 750-753.
Daniel@0: 
Daniel@0: if nargin < 1
Daniel@0: 	lowFreq = 100;
Daniel@0: end
Daniel@0: 
Daniel@0: if nargin < 2
Daniel@0: 	highFreq = 44100/4;
Daniel@0: end
Daniel@0: 
Daniel@0: if nargin < 3
Daniel@0: 	N = 100;
Daniel@0: end
Daniel@0: 
Daniel@0: % Change the following three parameters if you wish to use a different
Daniel@0: % ERB scale.  Must change in MakeERBCoeffs too.
Daniel@0: EarQ = 9.26449;				%  Glasberg and Moore Parameters
Daniel@0: minBW = 24.7;
Daniel@0: order = 1;
Daniel@0: 
Daniel@0: % All of the followFreqing expressions are derived in Apple TR #35, "An
Daniel@0: % Efficient Implementation of the Patterson-Holdsworth Cochlear
Daniel@0: % Filter Bank."  See pages 33-34.
Daniel@0: cfArray = -(EarQ*minBW) + exp((1:N)'*(-log(highFreq + EarQ*minBW) + ...
Daniel@0: 		log(lowFreq + EarQ*minBW))/N) * (highFreq + EarQ*minBW);
Daniel@0: