Subject: Re: making a sound unrecognizable From: Bob Masta <audio@xxxxxxxx> Date: Wed, 13 Sep 2006 09:09:28 -0400You could try a simple "speech scrambler" approach. You multiply the signal by another wave. The simplest approach multiplies by a constant sine wave that is in about the same frequency range as the signal. This uses the relationship that the product of sinusoids gives sum and difference terms, so the incoming spectrum is split at the multiplier frequency and the two portions are reversed spectrally. More complex scramblers can use a time-varying singal as the multiplier. But we get a lot of cues from envelopes, and this approach preserves the envelope. There is also the larger issue of what is "acoustically similar" yet still different. Best regards, Bob Masta ---------------------------------------------------- On 12 Sep 2006 at 18:26, Ursula Kirmse wrote: > 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 > > -- > -------------------------------------- > Ursula Kirmse > University of Leipzig > Cognitive & Biological Psychology > Institute of Psychology I > Seeburgstrasse 14-20 > 04103 Leipzig, Germany > Phone +493419735978/Fax +493419735969 > -------------------------------------- > >