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

On Mon, 29 May 2006 09:08:58 +0100
Gordon JC Pearce <wsynth@email-addr-hidden> wrote:

> On Mon, 2006-05-29 at 10:05 +0200, Alex Polite wrote:
> > Hi there.
> >
> > I have an interview with a lot of AC hum. I'd like to remove as much
> > of the hum as possible. This is not for broadcasting. I just want to
> > be able to hear what the persons on the recording are saying.
> >
> > I've looked at the sound in a frequency spectrum analyzer[1]. The hum
> > looks just as consistent as it sounds so I guess there must be a way
> > to filter it out. I just don't know which linux tool will do it for
> > me.
>
> Very sharp notch filter?
>
> Gordon.

If it's just for speech then you don't need a notch filter at all, just
kill everything below 300Hz. A simple graphic equaliser should be able
to do a reasonable job of this. Giving a small boost at around 4kHz can
also help improve clarity.

-- 
F