Re: Speech shaped noise

[Pierre Divenyi <pdivenyi@xxxxxxxxx>]

Hi Richard,

The problem with Bernhard's routine is that it **assumes** to know the
speech spectrum. It is easy to write Matlab code that generates a speech
spectrum noise using the canned fftfilt script. If it is placed in an
overlap-add loop, you can generate a speech noise file of arbitrary length
(minutes, if you so wish) by filtering a white noise vector (or file) with
the spectrum of any speech sample of virtually any length.

Pierre

Here it is:

At 10:54 AM 2/20/2005, Bernhard Seeber wrote:
> Hi Richard,
>
> here is a matlab-program to make CCITT-speech shaped, but not
> speech-modulated noise from white noise. A sample of Fastl noise
> (noise-like in long term spectrum and temporal envelope) can be
> downloaded from:
> http://www.mmk.ei.tum.de/persons/fas.html
>
> Bernhard
>
>
>
> > Date:    Sat, 19 Feb 2005 21:30:59 -0000
> > From:    "Richard H." <auditory@xxxxxxxxxxxxxx>
> > Subject: Speech shaped noise .WAV or other sample?
> >
> > Hi,
> >
> > I am trying to test some modern digital hearing aids ... but they keep
> > (sensibly) identifying my puretones as feedback or noise, and
> > my broadband noise as junk too.
> >
> > I really need to use speech flavoured noise to prevent the anti-feedback
> > and anti-noise algorithms from activating.
> >
> > So ... does anyone know where I can find a 30-second or longer chunk of
> > speech-shaped noise to do my testing?
> >
> > Thanks!
> >
> > Richard (UK)
>
>
> --
> Dr.-Ing. Bernhard U. Seeber
> Department of Psychology
> University of California, Berkeley
> 3210 Tolman Hall #1650
> Berkeley, CA 94720-1650, USA
> ph.: +1 510-643-8408
> fax: +1 510-642-5293
> http://www.bseeber.de
>
>
> function y = ccitt_filter(sig)
> % function y = ccitt_filter(sig)
> %
> % CCITT (ITU) standard G.227 defines a 'conventional
> % telephone signal' which equals the long-term spectrum
> % of speech. The standard defines a filter to simulate
> % the speech spectrum which is applied to the input signal
> % sig.
> %
> % sig    Input signal sig at 44100 Hz sampling rate
> % y      CCITT filtered signal sig
> %
> % Bernhard Seeber, 2005
>
> fs = 44100;
>
> %Generate filter coefficients
> %in S/Omega-plane
> %num_paper = [11638, 54050, 91238, 67280, 18400];
> %denom_paper = [1, 130, 4001, 36040, 400];
>
> %make inverted freq-response and shift to 0dB @ 600Hz
> %num_coeff = ((2*pi*1000).^(-[4:-1:0])).*denom_paper;
> %denom_coeff = ((2*pi*1000).^(-[4:-1:0])).*num_paper;
>
> %for comparison, converted to Omega
> %num_coeff = [7.46722e-12, 2.17899e-7, 2.311086e-3, 10.7079, 18400];
> %denom_coeff = [6.41624e-16, 5.24087e-10, 1.01347e-4, 5.7359, 400];
>
> %scale coefficients
> %num_coeff = num_coeff / denom_coeff(1) * 10^(3.25/20);
> %denom_coeff = denom_coeff / denom_coeff(1);
>
> %freqs(num_coeff, denom_coeff);
>
> %convert to z-plane
> %[num_z, denom_z] = bilinear(num_coeff, denom_coeff, fs);
>
> %freqz(num_z, denom_z, 1024, fs);
>
> num_z =
> [0.00396790391508   0.00032556793042  -0.00314367152058  -0.00104604251859
> -0.00008875919940];
> denom_z =
> [1.00000000000000  -3.39268359295324   4.31295903323020  -2.43473845585969
>  0.51493759484342];
>
> y = filter(num_z, denom_z, sig);