# Voice recognition using neural network

Started by July 24, 2007
Hi

I'm currently working on a project, Voice Recognition using neural network. The end result i want to get is the cepstral coefficient so that i can use them to train using neural network. Are there any probelm on this code? I hav problem debugging this line : pspectrum = powspec(samples, sr, wintime, hoptime, dither);

How do i solve it? Thanks

function [cepstra,aspectrum,pspectrum] = melfcc(samples, sr, varargin)
%[cepstra,aspectrum,pspectrum] = melfcc(samples, sr[, opts ...])
% Calculate Mel-frequency cepstral coefficients by:
% - take the absolute value of the STFT
% - warp to a Mel frequency scale
% - take the DCT of the log-Mel-spectrum
% - return the first components
% This version allows a lot of options to be controlled, as optional
% 'name', value pairs from the 3rd argument on: (defaults in parens)
% 'wintime' (0.025): window length in sec
% 'hoptime' (0.010): step between successive windows in sec
% 'numcep' (13): number of cepstra to return
% 'lifterexp' (0.6): exponent for liftering; 0 = none; < 0 = HTK sin lifter
% 'sumpower' (1): 1 = sum abs(fft)^2; 0 = sum abs(fft)
% 'preemph' (0.97): apply pre-emphasis filter [1 -preemph] (0 = none)
% 'dither' (0): 1 = add offset to spectrum as if dither noise
% 'minfreq' (0): lowest band edge of mel filters (Hz)
% 'maxfreq' (4000): highest band edge of mel filters (Hz)
% 'nbands' (40): number of warped spectral bands to use
% 'bwidth' (1.0): width of aud spec filters relative to default
% 'dcttype' (2): type of DCT used - 1 or 2 (or 3 for HTK or 4 for feac)
% 'fbtype' ('mel'): frequency warp: 'mel','bark','htkmel','fcmel'
% 'usecmp' (0): apply equal-loudness weighting and cube-root compr.
% 'modelorder' (0): if > 0, fit a PLP model of this order
% The following non-default values nearly duplicate Malcolm Slaney's mfcc
% (i.e. melfcc(d,16000,opts...) =~= log(10)*2*mfcc(d*(2^17),16000) )
% 'wintime': 0.016
% 'lifterexp': 0
% 'minfreq': 133.33
% 'maxfreq': 6855.6
% 'sumpower': 0
% The following non-default values nearly duplicate HTK's MFCC
% (i.e. melfcc(d,16000,opts...) =~= 2*htkmelfcc(:,[13,[1:12]])'
% where HTK config has PREEMCOEF = 0.97, NUMCHANS = 20, CEPLIFTER = 22,
% NUMCEPS = 12, WINDOWSIZE = 250000.0, USEHAMMING = T, TARGETKIND = MFCC_0)
% 'lifterexp': -22
% 'nbands': 20
% 'maxfreq': 8000
% 'sumpower': 0
% 'fbtype': 'htkmel'
% 'dcttype': 3
if nargin < 2; sr = 16000; end

% Parse out the optional arguments
[wintime, hoptime, numcep, lifterexp, sumpower, preemph, dither, ...
minfreq, maxfreq, nbands, bwidth, dcttype, fbtype, usecmp, modelorder] = ...
process_options(varargin, 'wintime', 0.025, 'hoptime', 0.010, ...
'numcep', 13, 'lifterexp', 0.6, 'sumpower', 1, 'preemph', 0.97, ...
'dither', 0, 'minfreq', 0, 'maxfreq', 4000, ...
'nbands', 40, 'bwidth', 1.0, 'dcttype', 2, ...
'fbtype', 'mel', 'usecmp', 0, 'modelorder', 0);

if preemph ~= 0
samples = filter([1 -preemph], 1, samples);
end

% Compute FFT power spectrum
pspectrum = powspec(samples, sr, wintime, hoptime, dither);

aspectrum = audspec(pspectrum, sr, nbands, fbtype, minfreq, maxfreq, sumpower, bwidth);

if (usecmp)
% PLP-like weighting/compression
aspectrum = postaud(aspectrum, maxfreq, fbtype);
end

if modelorder > 0

if (dcttype ~= 1)
disp(['warning: plp cepstra are implicitly dcttype 1 (not ', num2str(dcttype), ')']);
end

% LPC analysis
lpcas = dolpc(aspectrum, modelorder);

% convert lpc to cepstra
cepstra = lpc2cep(lpcas, numcep);

% Return the auditory spectrum corresponding to the cepstra?
% aspectrum = lpc2spec(lpcas, nbands);
% else return the aspectrum that the cepstra are based on, prior to PLP

else

% Convert to cepstra via DCT
cepstra = spec2cep(aspectrum, numcep, dcttype);

end

cepstra = lifter(cepstra, lifterexp);