[AG-TECH] Echo canceller

John Shalf jshalf at lbl.gov
Tue Jul 22 13:35:04 CDT 2003

On Tuesday, July 22, 2003, at 08:30 AM, Robert Olson wrote:
> And if you're clever, you can make the button cause the gentner to  
> mute the mic, and make the gentner drive the LED based on mute status.  
> This way, the gentner is always listening on the mic and doing it's  
> EC/ambient noise level adaptation measurements.

That is way cool Bob!  Sometimes, if the desktop mic is muted for too  
long, it can inhibit the Gentner's training.  It looks like we will  
need to run some additional wires through the floor to take advantage  
of this, but it sounds like it will be worth it.

Also, the tech note points out that I should have said MX392 instead of  
312 in my suggestion below.  The 412D has very similar logic on board  
(if not identical), so this solution will likely be applicable to that  
model as well.  The 412 has some advantages over the 392 and the  
boundary mics because it is off the table and doesn't get buried under  
paper or oversized notebook computer screens.

> There's an appnote on the gentner/clearone website on doing this.


Thanks Bob!

> At 08:00 AM 7/22/2003 -0700, John Shalf wrote:
>> On Monday, July 21, 2003, at 09:37 PM, Markus Buchhorn wrote:
>>> At 14:43 21/07/2003 -0700, Ed Ritenour wrote:
>>> I'd agree with this sentiment, on the impact of background noise -  
>>> we decided to use ceiling mounted boundary mikes to cover the rooms  
>>> in all 3 of our nodes (so far), with no ceiling mikes and no lapel  
>>> mikes wanted or needed. I've seen a few sites where desktop mikes  
>>> and poor autogating just killed the experience. But, muting mikes  
>>> on-demand is a pain for somebody to manage. People are still the  
>>> most expensive asset in a node.
>> Desktop mics like the Shure 412D or the 312 series have a  
>> touch/toggle switch on the front of the mic.  A green LED indicates  
>> whether the mic is on or not.  No need to have the operator do the  
>> muting.

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