Re: Trasients when playing silence with Matlab

[Sylvain Choisel <SYC@xxxxxxxxxxxxxxx>]

Enrique,

If you want to exclude the possibility
that these clicks come from Windows (if that is the OS
you are using), I suggest you try the
user-contributed function "pa_wavplay" that makes 
use of the ASIO drivers.  It has
the advantage of bypassing the Windows sound mixer. 
You can find this function here:
http://www.mathworks.com/matlabcentral/fileexchange/loadFile.do?objectId=4017&objectType=file

Another source of clicks is a change
of sampling frequency, that will cause the soundcard 
to loose the clock for a short while.
Check the clock settings in the sound card's control panel,
you can monitor the current sampling
frequency, and see if it changes at the same time as
you hear the click. 

Best regards,

Sylvain


AUDITORY - Research in Auditory Perception <AUDITORY@xxxxxxxxxxxxxxx>
wrote on 07/02/2008 17:25:40:

> Dear Enrique,
> 
> the issue your are experiencing may come from many things. I would
> suggest you to try with a different soundcard first to discard the
> soundcard issue.
> 
> Then, Matlab does not handle sound cards directly, but rather uses
some 
> OS calls. So your issue may also come from your operating system (Linux,
> Mac OS X, ...). If you replicate the same behavior with a different
> soundcard,  I would suggest to contact Matlab support directly
with a 
> complete description of your issue with code, they usually answer
in a 
> day or two.
> 
> That said, I know that the command "sound" is very brittle
on many OSes. 
> You can try the "audioplayer" that uses JAVA calls and may
behave better 
> for your purpose (type "doc audioplayer" in your Matlab
command prompt 
> for usage).
> 
> Cheers,
> 
> Mathieu Lagrange
> Lopez-Poveda, Enrique A. a écrit :
> > Dear friends,
> >
> > Here is a technical question on a problem that is driving us
crazy.
> >
> > We want to play sounds from Matlab through an RME Fireface 400
sound 
> > card. The problem is that when we play a "silence"
interval (array of 
> > zeros) we can hear (and even record) a clear transient at the
onset of 
> > the _silence_ signal. We would very much like to get rid of that
onset 
> > transient. Any cues as to how to get rid of it?
> >
> > Thank you so much in advance.
> >
> > - Enrique
> >
> > Enrique A. Lopez-Poveda, Ph.D.
> > Instituto de Neurociencias de Castilla y León
> > Universidad de Salamanca
> > Av. Alfonso X El Sabio S/N, 37007 Salamanca, Spain.
> > Phone: (+34) 923 294 500 ext. 1957
> > Fax: (+34) 923 294 750
> > E-mail: ealopezpoveda@xxxxxxx
> > http://web.usal.es/~ealopezpoveda/ 
>