Re: making a sound unrecognizable (Nicolas Grimault )


Subject: Re: making a sound unrecognizable
From:    Nicolas Grimault  <ngrimault@xxxxxxxx>
Date:    Wed, 13 Sep 2006 10:46:33 +0200

This is a cryptographically signed message in MIME format. --------------ms050908060300070505050003 Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 8bit Dear Ursula, Few years ago, I tried a MATLAB code to prevent a speech sounds to be recognizable. The overall spectrum and the temporal envelope (up to 60 Hz) of the initial sound are roughly preserved by this code. Be aware that neither the spectrum nor the temporal envelope of the output are exactly the same than the input ! Below is the MATLAB code (the MATLAB signal toolbox is required). This code is not guaranteed ! Hope this help. Nicolas Grimault ***************** function new=SigToNoise(N);%N is the filename (including path) of the wav file (the input signal) to be transformed [sig fe bit]=wavread(N);%read the input signal (from a wav file) rmssig=sqrt(sum(sig(:,1).^2)/length(sig(:,1))); %RMS of the input signal [Fparam1 Fparam2]=butter(1, 60/(0.5*fe)); %low-pass filter Fc=60 Hz LPsig=filter(Fparam1,Fparam2,abs(sig(:,1)));%rectified temporal envelope of the input signal (Fc=60 Hz) phasefftnoise=2*pi*rand(length(sig),1);%a random phase vector fftsig=abs(fft(sig(:,1)));%FFT magnitude of the input signal fftnew=fftsig.*exp(-j*phasefftnoise);%the output signal is generated here in the frequency domain. The output has the same magnitude than the input signal but random phases new=real(ifft(fftnew));%output in the time domain (by FFT-1) new=new.*LPsig;%the temporal envelope of the input is applied to the output rmsnewsig=sqrt(sum(new.^2)/length(new));%RMS of the output signal new=rmssig*new/rmsnewsig;%the RMS of the output is adjusted to be the same than the RMS of the input if max(abs(new))>1 | max(abs(sig(:,1)))>1 %check for saturation disp('Error: saturation...'); disp(['Maximum = ' int2str(max(abs(new)))]); end wavwrite(new,fe,bit,['new_' N]); %write the output in a wav file end ******************** > Dear list members, > > I'm looking for a possibility to change/edit a environmental or at > least natural sound in a way that it is not any longer recognizable > as what it is, but, however, for doing this with changing as less > acoustic parameters as possible. ;-) The intention is to use these > sounds in a MMN paradigm and it is important that both "versions" of > the sound are acoustically as similar as possible. > The main point is that the sound (that can also be a more complex > thing as the sound of a barking dog or a something like that) should > be not possible to be recognized as what it is. > > I would be very happy about ideas or would like know if maybe somebody > has already tried something like this? I would also be very happy > about recommations for software or matlab scripts that could be > helpful in respect to this. For example I'm looking for a way to > transfer the amplitude envelope from one sound to another (I already > wrote a matlab routine for this, but its not yet functioning perfectly > fine and the result is not completely convincing). > > So if anybody has a an idea I would be grateful. > > best regards and thanks a lot, > Ursula Kirmse > -- ------------------------------------------------------------------------ Nicolas Grimault Cognition Auditive et Psychoacoustique UMR CNRS 5020 Neurosciences et Systèmes Sensoriels 50 Av. Tony Garnier 69366 Lyon Cedex 07 France Vocal: 33 (0)4 37 28 74 89 Fax: 33 (0)4 37 28 76 01 Email: nicolas.grimault@xxxxxxxx Web: http://olfac.univ-lyon1.fr/unite/equipe-02/grimault/grimault-f.html ------------------------------------------------------------------------ --------------ms050908060300070505050003 Content-Type: application/x-pkcs7-signature; name="smime.p7s" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="smime.p7s" Content-Description: S/MIME Cryptographic Signature MIAGCSqGSIb3DQEHAqCAMIACAQExCzAJBgUrDgMCGgUAMIAGCSqGSIb3DQEHAQAAoIIIQTCC A20wggJVoAMCAQICAQIwDQYJKoZIhvcNAQEEBQAwKzELMAkGA1UEBhMCRlIxDTALBgNVBAoT BENOUlMxDTALBgNVBAMTBENOUlMwHhcNMDEwNDI3MDU0NjQ5WhcNMTEwNDI1MDU0NjQ5WjA0 MQswCQYDVQQGEwJGUjENMAsGA1UEChMEQ05SUzEWMBQGA1UEAxMNQ05SUy1TdGFuZGFyZDCC ASIwDQYJKoZIhvcNAQEBBQADggEPADCCAQoCggEBANzhHiE9BovqvV60iNsPk5e0bQc9hmIA Lcr/tUqO51akj2Es8aAqq/Yq3Xwsv+91VQusCU7nTmHA5wzwkBVFEgLCjOvDEmTiYxAYLssH MdmB5dwpgpsxVuKBHopvp+ipWBFEVoNds054cC3ftv1ygUXV8e5Nzu++1T0MkCBFmgmArw9M 2iAOgL86s+sngMC5D8ChTkDcOv1qKr9A1SxxgPn4umvk6ioAqy++mvCndm2YKZwPL/BC8hiX W8n2zBlfusK+EtJcsJCUwLfLBgTvjzDtMi16SveTu6AJpLTuM8vQg5u1tbOQ3o6QHlmcINVL Hu3XTE+G+hw6KqHprAWgnb8CAwEAAaOBkjCBjzAMBgNVHRMEBTADAQH/MB0GA1UdDgQWBBRn WaXlB3RJA+8Fz8wupBjVEMiePDBTBgNVHSMETDBKgBRW62i50lx+mLWlU8ORb2NYxPlrt6Ev pC0wKzELMAkGA1UEBhMCRlIxDTALBgNVBAoTBENOUlMxDTALBgNVBAMTBENOUlOCAQAwCwYD VR0PBAQDAgEGMA0GCSqGSIb3DQEBBAUAA4IBAQAGA0eDckWQwk7hIderF6kBVQbKQG1Voh1e 6+IUI1nkCeKQ9jyNNgYPS6cmI2XC6gaacru4jMuKX+95NiV+ANfzBpT7g0QpJjfH7umHzmyG gBtxPdJir/bNYmxTD+Z6kwCMey4z4EEdqr5lmHbxlQd0s+Y/U3XVSwY2SynE9tyOE4BAEHOC rRV7BHFQtTcz8shku6EQfjbGra9vcFKm0a7MzLqw6FkSj2INrQPdSyroiTmIUS/tYei3MIfb J1VtZoejUQmAYXFRBb4THdlBMPx1XwqWmxj/vpCBtBPAchEI/Wqaage99IMstGA2ZAf6PWqn sJAEdoPdM8s04heYBAuhMIIEzDCCA7SgAwIBAgICMjwwDQYJKoZIhvcNAQEFBQAwNDELMAkG A1UEBhMCRlIxDTALBgNVBAoTBENOUlMxFjAUBgNVBAMTDUNOUlMtU3RhbmRhcmQwHhcNMDYw MzEzMTIxNjU1WhcNMDcwMzEzMTIxNjU1WjB+MQswCQYDVQQGEwJGUjENMAsGA1UEChMEQ05S UzEQMA4GA1UECxMHVU1SNTAyMDEZMBcGA1UEAxMQR3JpbWF1bHQgTmljb2xhczEzMDEGCSqG SIb3DQEJARYkbmljb2xhcy5ncmltYXVsdEBvbGZhYy51bml2LWx5b24xLmZyMIIBIjANBgkq hkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAs58I6pvF/QqCP68wucZFS9VPt5qyLuU7c2h9945e 42LmCYW+6TFbtDfRRfub2CZVL0sowdZPrjsHbbduyncYnCC9PqcfmZpk5eC91Zjb6CPays/O vnJYgAB/4F0xO9D33/kjk25ZqjqC8PsqZMxhv9QpRysWlxHP9hc07Ns9w7ZmhR+/ldvRzTg0 3xeTnAvvyE1OIn9E84gWg4cIQqY/jylCy+kGFCGsmgBWVcuVQEYAloN3I3Mbl7Gj5exGal5N aUK6ahD6Q1DoyEiFRkStGt69uqyd36lmCH68aXl0yLwECk6fQWssJK+vJWxoeoimWxUJMcbo y4Q6i7JITKtNkwIDAQABo4IBnDCCAZgwDAYDVR0TAQH/BAIwADARBglghkgBhvhCAQEEBAMC BLAwDgYDVR0PAQH/BAQDAgXgMHgGCWCGSAGG+EIBDQRrFmlDZXJ0aWZpY2F0IENOUlMtU3Rh bmRhcmQuIFBvdXIgdG91dGUgaW5mb3JtYXRpb24gc2UgcmVwb3J0ZXIg4CBodHRwOi8vaWdj LnNlcnZpY2VzLmNucnMuZnIvQ05SUy1TdGFuZGFyZC8wHQYDVR0OBBYEFM1ijoWbtHdtC0XR P2uAZrpMc2j0MFMGA1UdIwRMMEqAFGdZpeUHdEkD7wXPzC6kGNUQyJ48oS+kLTArMQswCQYD VQQGEwJGUjENMAsGA1UEChMEQ05SUzENMAsGA1UEAxMEQ05SU4IBAjAvBgNVHREEKDAmgSRu aWNvbGFzLmdyaW1hdWx0QG9sZmFjLnVuaXYtbHlvbjEuZnIwRgYDVR0fBD8wPTA7oDmgN4Y1 aHR0cDovL2NybHMuc2VydmljZXMuY25ycy5mci9DTlJTLVN0YW5kYXJkL2dldGRlci5jcmww DQYJKoZIhvcNAQEFBQADggEBAITmYuGFPKq2ZQMdwV1gTSsBAm31mUd0cnOJRqirUZ4ZFjbR Bm2c7YEQ5f/w82wBWoOf987l6uXGDYi2PqK+8fMvGcdOC/AKkKrPba4PshhQjCdmXNkc7dq3 6wQnXb9JZU/FUJm9AsudZM4fJbgBkCxaCHr7wT06EiFkciYonzPQRb1uq+r+2mrG7QwW9mjv FSt+Ijws+MgxiQaMo1UDlGdVpj4JstU+d0i/Odfb4ChujAGDqYY0Su4HsbFjRJYQPgaovrJ5 d9zaFfC02ZE+Vf88cudZ2gGAqNCaTNYgn8Se0ri0DbIdr/MMx8UkPYPmxErTDT4z0VFYtBou UEeRlesxggIVMIICEQIBATA6MDQxCzAJBgNVBAYTAkZSMQ0wCwYDVQQKEwRDTlJTMRYwFAYD VQQDEw1DTlJTLVN0YW5kYXJkAgIyPDAJBgUrDgMCGgUAoIGxMBgGCSqGSIb3DQEJAzELBgkq hkiG9w0BBwEwHAYJKoZIhvcNAQkFMQ8XDTA2MDkxMzA4NDYzM1owIwYJKoZIhvcNAQkEMRYE FK3yHNkn3rGL1/Lnf0JqasMXHS/rMFIGCSqGSIb3DQEJDzFFMEMwCgYIKoZIhvcNAwcwDgYI KoZIhvcNAwICAgCAMA0GCCqGSIb3DQMCAgFAMAcGBSsOAwIHMA0GCCqGSIb3DQMCAgEoMA0G CSqGSIb3DQEBAQUABIIBAK3yd1WMfU/7TddLDjTt1aCJNmasnKBavLgoeQSf20T1fnjHHw2e KnJz7bC0Ex48uJwyRCYnTdlNdW280JVPIRPEXdm3y0MuYiY3VRiGt3eK3mMItn14nwv7an4W HfDSOUmRWsKtQkN2prgK6d+wYUcAaqp4UDF/mlRN676B5skznzJZtJDIVUl1/+AaPtksd6+x GCXzMeDGCc/OlM2aNWUU6VesVPnkqMiYoP+oxTPZB+n7OT3AiehqKaoUsqc3y2t3UeiTAm/u Y2aJvEy4pfSUy52jXixVRbxsPgA+Ztqhh/JQGkO5ztOs4IUUL2VECd0P8tsFgRqPgU8Qy092 BRIAAAAAAAA= --------------ms050908060300070505050003--


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