[TriLUG] Sound Processing

[jonc]

Brian,

Do you have any idea what is causing the hum? From your descriptions it
sounds like a hardware issue (Microphone with too little resistance?)
Are you applying excessive amplification to the voice?

We use G729 as our primary codec and that removes a *lot* of
environmental noise, since it propagates mainly Voice frequencies.Have
you tried passing the WAV format through various codecs to see if they
can remove the hum?

Good Luck - Jon Carnes


On Tue, 2007-07-10 at 09:48, Brian McCullough wrote:
> I have an issue that has been causing me a great deal of grief over the
> past while.
> 
> I have some sound files ( telephone recordings ) that have a VERY loud
> 60-Hz hum.  They are, at the moment MP3 files, but were WAVs coming out
> of the recorder.
> 
> I am wondering if anybody has and bright ideas for inserting a
> 180 degree out of phase signal to cancel the hum, or any other ideas to
> clean up these files.
> 
> ( The hum seems to be being inserted inside my machine, although I am
> willing to accept suggestions for correcting future meeting recordings,
> as well as correcting the old recordings. )
> 
> 
> Thanks,
> Brian