Just to expand on Bernard's advice, maybe they could first try feeding the 
output from the TV into an audio amplifier with a graphic equalizer; turning 
down all frequencies outside normal speech (beyond 500Hz and above 2Khz or 
so) and then experimenting with the remaining controls to try to filter out 
unwanted sounds? It's worth trying before starting to use digital editing 
techniques on the soundtrack, especially if it's a scratchy old VHS they're 
still using. The technicians in the library or AV labs have probably got 
some really good quality amps sitting around they can finally justify 
spending all that money on. Some amps even have the ability for any sounds 
below a certain volume level to be masked out, which might help.

Obviously, the student should be allowed to try out headphones. If the 
student uses hearing aid(s) with T position setting, maybe using radio 
microphone kit to link directly to the output of the TV or audio amp could 
allow him/her to make better use of any sound cancelling/enhancing features 
of the hearing aid (e.g. RNID sell the Conversor kit with optional SCART 
adapter).

I doubt attempts to improve the quality of the speech element of the 
recording will affect the validity of the test. I suspect the task involves 
understanding native language speakers, rather than a test of hearing range 
and ability on busy streets in Paris, unless perhaps it's a course in being 
a French Traffic Warden ...

The department might need to arrange an alternative to this test. Providing 
a transcript probably defeats the object completely. Re-recording the 
dialogue might not be effective, as the student might normally use 
lip-reading skills (possibly without realising, as many people do) to 
support hearing, so you'd have to be sure the new recording is precisely 
synchronised to the video. I guess it's time for the tutors to start to 
evaluate new AV materials to use on the course that have better quality 
audio recordings.

Just to clarify: EQ isn't normally used to remove vocal tracks from music. 
This is done by inverting the phase of the left or right audio track 
(assuming a stereo recording). The idea is that anything in the centre of 
the mix (usually the vocals) will be cancelled by two equal but inverted 
waves playing at the same time. It doesn't work, but it does sometimes sound 
like they made the vocalist sing into a bucket in the hall outside the 
studio.

Ian




----- Original Message ----- 
From: "A Velarde" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Saturday, February 23, 2008 9:40 AM
Subject: Re: reducing background noise on videos


So Bernard. It is possible but may be not be the entire solution as some 
noises could not be ammelliorated or eliminated completely, right?  Andy
  ----- Original Message ----- 
  From: BERNARD DOHERTY
  To: [log in to unmask]
  Sent: Friday, February 22, 2008 5:35 PM
  Subject: Re: reducing background noise on videos


  Um, I don't think things work quite this way.  What happens is some 
frequencies can be boosted and others lowered.  Various bits of software 
that promise to take out vocals from CDs so that you can sing along work 
this way: they just take out the centre of the recording, including all the 
instruments there.  With a digital recording of the video, the sound track 
could be passed through an equaliser and the top and bottom noise reduced to 
emphasise the vocal, but any other noise at the same frequency will also be 
boosted.

  A better question is what is achieved if the vocal is isolated?  If an 
uncluttered vocalisation is all that is wanted, have a native speaker read a 
transcript.  If that is not acceptable for some reason, then what is being 
tested should be more clearly identified.  It is important to ensure that it 
is a form of testing that a deaf or hearing impaired person could pass.

  Regards, Bernard

  Bernard Doherty
  Assessor
  Cambridge Access Centre

  A Velarde <[log in to unmask]> wrote:
    Just a thought. Maybe someone with  some iT expertise could confirm 
this.  Software that is used to produce music could isolate different type 
of noises ( melodies form different instruments), would such software be 
used to eliminate or ameliorate the background noises digitally? Andy
      ----- Original Message ----- 
      From: Barbara Denton
      To: [log in to unmask]
      Sent: Friday, February 22, 2008 1:16 PM
      Subject: reducing background noise on videos


      We have a student doing a language course, which involves listening to 
a video and writing answers to questions in response. Most of the videos 
have noisy settings e.g. people being interviewed on a Paris street with 
traffic roaring by. The student, who has a hearing impairment, can't hear 
these either in the practice labs (where there is the problem of not 
disturbing other students), or in the assessments (where they can be on 
their own) because of the excessive background noise. The School have 
consulted RNID and tried various solutions, but haven't come up with 
anything that works yet.

      Any ideas?

      Thanks

      Barbara Denton
      IT Disability Support Officer
      Birkbeck College
      020 7079 0717





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