[asterisk-users] Background Noise Elimination

[Jerry Jones]

On Jan 7, 2008, at 6:19 PM, Matt Riddell wrote:

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> Norman Franke wrote:
>> Greetings!
>>
>> We have a somewhat noisy background in our call center, and I'd  
>> like to
>> reduce this. Obviously, we could plaster the walls with sound  
>> absorbing
>> material, but is there anything we can do in software either using  
>> any
>> algorithms for our open source-based SIP library or inside Asterisk
>> itself? Related to this, anyone have a good source for good panels?
>>
>> We are using Plantronics noise canceling headsets, which don't really
>> seem to work all that well. Our ancient system handled noise much
>> better, but I suspect that was partly due to the Dialogic ADPCM
>> algorithm used that just reduced the intelligibility of lower volume
>> noises in general. We are using PCMU direct from the agent's mic to
>> through Asterisk to PRIs, so we don't "suffer" from compression
>> artifacts. The down side, is that you can make out even very quiet
>> conversations in the background (like 3 agents to one side.)
>>
>> How have people handled this? I'm experimenting with a noise gate  
>> that
>> will lower the volume when the agent isn't talking, but that won't  
>> help
>> when the agent is talking.
>
> Nah, there's nothing really.
>
> The noise gate is your best bet.  I would assume that while an  
> agent is
> talking the customer will be listening to the agent, so the background
> noise will hardly be noticeable.
>
> The issue is, while two people are talking its pretty hard to remove
> just one of them from a wave file.
>
> Try the noise gate and see how you go.
>
> Oh, you might want to try a downwards expander instead (a noise  
> gate but
> with ratio as well as threshold).
>
>
We have an IP600 located in our colo, a very noisy environment. For a  
spooky experience make a phone call and pass the call through a  
Ditech audio processor in the path of the PRIs. You will hear no  
background noise. You can even use the speakerphone. Even Polycom to  
Polycom is not too bad. But an all IP path to anything else and you  
cant hardly hear the other person.