Hi Everybody,
I am working on designing a digital hearing aid as my MSc project but I am
facing severe difficulties in removing noise. Is there anybody to tell me
how to solve this problem or an implementable robust VAD (Voice Activity
Detection) algorithm. There are loads of stuff about VAD on the web, but
all of them just explain the theory.
Plz if someone has the solution, help me because time is running out.

Thanks in advance.

Hi waheed2nice,

Could you be more specific in your question? You need to remove noise
from an observation of noisy speech? What exactly is/are your
problem(s)? We cannot do your thesis for you, of course.

Voice Activity Detection algorithms are means to help estimating speech
and/or noise statistics, for example using the empirical
auto-correlation function estimator. Basically VADs are based on some
sort of thresholding on an observable parameter (energy, periodicity,
zero-crossing, SIR/SNR). Sometimes specific distributions are assumed
for the noise and/or speech signal under consideration.

Maybe you should consider whether you goal is a VAD marking, or noise
reduction. Most noise reduction algorithms relies on estimates of noise
statistics and, as such, just shifts the problem to for example a VAD
marking.

Here is a basic algorithm. You just need to define the vad_parameter
and estimate a threshold.

IF ( vad_parameter <= threshold )
  THEN
    vad_mark = false;
  ELSE
    vad_mark = true;
ENDIF


Good luck,
Martin Hammer


On Tue, 27 Mar 2007 07:47:06 -0500
"waheed2nice" <w...@yahoo.com> wrote:

> Hi Everybody,
> I am working on designing a digital hearing aid as my MSc project but
> I am facing severe difficulties in removing noise. Is there anybody
> to tell me how to solve this problem or an implementable robust VAD
> (Voice Activity Detection) algorithm. There are loads of stuff about
> VAD on the web, but all of them just explain the theory.
> Plz if someone has the solution, help me because time is running out.
> 
> Thanks in advance.
> 
> 


-- 
Martin Hammer
DK-9000, Aalborg
Denmark

m...@kom.aau.dk
http://martinhammer.dk

On Mar 27, 5:47 am, "waheed2nice" <waheed2n...@yahoo.com> wrote:
> Hi Everybody,
> I am working on designing a digital hearing aid as my MSc project but I am
> facing severe difficulties in removing noise. Is there anybody to tell me
> how to solve this problem or an implementable robust VAD (Voice Activity
> Detection) algorithm. There are loads of stuff about VAD on the web, but
> all of them just explain the theory.
> Plz if someone has the solution, help me because time is running out.
>
> Thanks in advance.

You might find the listings at http://www.isca-students.org/freeware
useful.  VAD is in the Qualcomm-ICSI-OGI system and the ETSI Advanced
system.  Noise reduction is in both of those as well as other
resources
linked from that page such as CtuCopy.