[AG-TECH] RAT : "Monodirectional" sound ?

John I. Quebedeaux, Jr johnq at lsu.edu
Thu Mar 26 20:55:31 CDT 2009

Yea, I realized you didn't mean monodimensional, that's a whole other ball
of wax... If you can't hear yourself, the loopback is probably muted (gently
tap the mic, if you hear it on the speakers you know it's looping back) -
besides, you'll get echo internally anyway, so that's probably not it - what
you or the other site is echo canceling could be it. I don't' know!


> From: Thibault Daoulas <thibault.daoulas at canterbury.ac.nz>
> Date: Fri, 27 Mar 2009 14:52:38 +1300
> To: John Quebedeaux <johnq at lsu.edu>
> Cc: <ag-tech at mcs.anl.gov>
> Subject: Re: [AG-TECH] RAT : "Monodirectional" sound ?
> Hi John,
> I couldn't hear myself speaking, and did not check the audio card's
> loopback. I'm going to check all that you mentioned, thanks for your
> suggestions !
> Oh and by the way yes, in the title I meant monodirectional, not
> monodimensional ;)
> Thibault.
> John I. Quebedeaux, Jr wrote:
>> I can think of one instance, yes, when echo canceling is improperly setup -
>> canceling oneself off or the other side off inadvertently.
>> Long ago I remember this happening when someone's audio wasn't configured
>> properly for echo canceling.
>> Be sure that you are using only the audio coming from the remote site for
>> echo canceling reference. This is usually referenced as the 'speaker' as in
>> the audio that comes from your audio speakers - but that can be problematic
>> if you're reinforcing your own audio into your own room - i.e. If you're
>> hearing your own microphone in your speakers. Properly one should only
>> cancel the remote audio (from the computer/rat specifically).
>> One quick test, do you hear yourself when you speak even without any remote
>> sites set to speak? Is the audio card's loopback muted? (on windows, that's
>> the line in channel on the card is muted).
>> The only other thing I can think of is an audio card is monodirectional... I
>> forget the actual term.
>> Perhaps there is something else, but those are off the top of my head... And
>> perhaps they're not related... but I know to check these things!
>> -John Q.

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