[speex-dev] speex preprocess redux

[Tom Harper]

Steve,

The main problem I am having with the system is clipping off the start
of someone's speech when they first start talking- the ends of the sentences
seem to be handled properly.  I am wondering whether this is the fault of the
audio playback system or whether this is a speex issue-

I also get the musical artifacts problem with the denoiser.  This seems to
be more of a problem on open air mics/speaker combinations.  However,
this and the issues you pointed out are a minor deal in comparison with the
clipping problem.

Tom

<p><p>At 03:40 PM 5/17/2004, Steve Kann wrote:
>Tom Harper wrote:
>
>>Hi All & Jean Marc,
>>
>>Once again I find myself delving into the pre-processing code to fiddle
>>with the VAD, AGC and denoising code.
>>
>>Where i am at is that I have implemented all of Steve Kann's mods, and
>>they are 90% of the way there in terms of working, except that I am still
>>having issues denoising open air mics.  But that is tangential to my 
>>question-
>>
>>I was wondering what the following function is supposed to be used for:
>>speex_preprocess_estimate_update(....)
>>
>>I couldn't find anywhere in the code that references it- it appears to update
>>the noise estimate without denoising anything- ?  If so, does this need to
>>be called for AGC to work, or?
>
>
>Beats me :)
>
>I've found the denoiser to work very well on open-air microphones.
>
>
>One thing I've found in using the preprocessor that I need to find a 
>solution for is that sometimes the denoiser is incorrectly detecting 
>speech as noise.  This happens when a speaker speaks for a while, and the 
>denoiser tries to remove their intonation (i.e. the sound of their 
>voicebox; the vowels).  The result is that towards the ends of sentences, 
>their voice gets "thinned" out.
>
>I'd like to find out how to "slow down" the rate of adaptation within the 
>denoiser to make this less likely to happen.  I assume that the tradeoff 
>is that it will adapt more slowly to changing noise patterns (or initial 
>noise).  I'm just not sure where to do that; maybe if I had the "Cohen 
>Paper" it would help :)
>
>-SteveK
>
>>
>>Thanks,
>>Tom
>>
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-- 

Tom Harper - tharper at sightspeed.com
Lead Software Engineer
SightSpeed - A Roda Group Affiliated Company

918 Parker St, Suite A14
Berkeley, CA 94710

Phone: 510.665.2920
Cell: 415.378.3779

http://www.sightspeed.com

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