[linux-audio-user] Re: Removing AC hum after the fact.

Curtis Sloan curtis.sloan at shaw.ca
Mon May 29 14:22:32 EDT 2006


On Monday 29 May 2006 11:16, Alex Polite wrote:
> Thanks for all the input.
>
> I did some experimentation with jamin. Cutting of everything below 300
> Hz sure helped alot. But the  harmonics went right through the speech
> spectrum so canceling them all out pretty much meant canceling the
> speech out as well.
>
> I found freqtweak and hooked that up. It did  produce a very beautiful
> spectrogram but it didn't solve my problem.
>
> I need something smarter. Something that will  1) take a few seconds
> of audio when there's no speech (only hum) and treat that as a
> baseline. 2) Reduce the frequencies all over by that baseline.
>
> In effect analyzing the tool would look at the hum and create a filter
> that matches it exactly. I guess there's a word for that?

Yes, I think it's gnomewavecleaner (http://gwc.sourceforge.net/).

Seriously, though, it sounds like you want a 
de-hiss/hum/noise/snap/crackle/pop (okay maybe not so serious) utility which 
would take a lot of the manual labour out of it.  I don't think there's any 
magic solution, but maybe GWC would help.  There's others as well (e.g. 
http://home.snafu.de/wahlm/dl8hbs/declick.html -- kind of old and sketchy but 
easy to use).

HTH,
Curtis S.


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