wolffd@0: function output = ERBFilterBank(x, fcoefs)
wolffd@0: % function output = ERBFilterBank(x, fcoefs)
wolffd@0: % Process an input waveform with a gammatone filter bank. This function 
wolffd@0: % takes a single sound vector, and returns an array of filter outputs, one 
wolffd@0: % channel per row.
wolffd@0: %
wolffd@0: % The fcoefs parameter, which completely specifies the Gammatone filterbank,
wolffd@0: % should be designed with the MakeERBFilters function.  If it is omitted,
wolffd@0: % the filter coefficients are computed for you assuming a 22050Hz sampling
wolffd@0: % rate and 64 filters regularly spaced on an ERB scale from fs/2 down to 100Hz.
wolffd@0: %
wolffd@0: 
wolffd@0: % Malcolm Slaney @ Interval, June 11, 1998.
wolffd@0: % (c) 1998 Interval Research Corporation  
wolffd@0: % Thanks to Alain de Cheveigne' for his suggestions and improvements.
wolffd@0: 
wolffd@0: if nargin < 1
wolffd@0: 	error('Syntax: output_array = ERBFilterBank(input_vector[, fcoefs]);');
wolffd@0: end
wolffd@0: 
wolffd@0: if nargin < 2
wolffd@0: 	fcoefs = MakeERBFilters(22050,64,100);
wolffd@0: end
wolffd@0: 
wolffd@0: if size(fcoefs,2) ~= 10
wolffd@0: 	error('fcoefs parameter passed to ERBFilterBank is the wrong size.');
wolffd@0: end
wolffd@0: 
wolffd@0: A0  = fcoefs(:,1);
wolffd@0: A11 = fcoefs(:,2);
wolffd@0: A12 = fcoefs(:,3);
wolffd@0: A13 = fcoefs(:,4);
wolffd@0: A14 = fcoefs(:,5);
wolffd@0: A2  = fcoefs(:,6);
wolffd@0: B0  = fcoefs(:,7);
wolffd@0: B1  = fcoefs(:,8);
wolffd@0: B2  = fcoefs(:,9);
wolffd@0: gain= fcoefs(:,10);	
wolffd@0: 
wolffd@0: output = zeros(size(gain,1), length(x));
wolffd@0: for chan = 1: size(gain,1)
wolffd@0: 	y1=filter([A0(chan)/gain(chan) A11(chan)/gain(chan) ...
wolffd@0: 		   A2(chan)/gain(chan)], ...
wolffd@0: 				[B0(chan) B1(chan) B2(chan)], x);
wolffd@0: 	y2=filter([A0(chan) A12(chan) A2(chan)], ...
wolffd@0: 				[B0(chan) B1(chan) B2(chan)], y1);
wolffd@0: 	y3=filter([A0(chan) A13(chan) A2(chan)], ...
wolffd@0: 				[B0(chan) B1(chan) B2(chan)], y2);
wolffd@0: 	y4=filter([A0(chan) A14(chan) A2(chan)], ...
wolffd@0: 				[B0(chan) B1(chan) B2(chan)], y3);
wolffd@0: 	output(chan, :) = y4;
wolffd@0: end
wolffd@0: 
wolffd@0: if 0
wolffd@0: 	semilogx((0:(length(x)-1))*(fs/length(x)),20*log10(abs(fft(output))));
wolffd@0: end