[audacity4blind] Re: Reducing hum with audacity.

  • From: "jean parker" <disabilityradio@xxxxxxxxxxx>
  • To: <audacity4blind@xxxxxxxxxxxxx>
  • Date: Tue, 27 Jun 2006 22:48:03 +0530

Dear David:

I am also in need of this notch filter. However, when I tried to open it from your attachment windows said there was no program associated with it. What to do please?

You know, it's just the way things go. I saw the notch filter earlier in my email and I thought, oh cool I need one of those too. Then I made a voiceover recording this evening of something I need to submit asap and sure enough, it has a 50 cycle humm that I couldn't chase down. Tried everything, it's probably the tube light above my desk. But you know these sighted people get pissed when you start turning out lights.

Anyway, advise please?

Many thanks,


----- Original Message ----- From: "David R. Sky" <davidsky@xxxxxxxxxxxxxx>
To: <audacity4blind@xxxxxxxxxxxxx>
Sent: Tuesday, June 27, 2006 10:55 AM
Subject: [audacity4blind] Re: Reducing hum with audacity.

Hi Anders,

To remove one specific frequency, don't use the lowpass or highpass
filters, use the notch filter I've attached, called notch50.ny - the
default frequency it will remove is fifty hertz.

Three edit fields: remove 60hz, remove 50hz, or remove frequency of your
choice. Default is remove 50hz.

Next edit field: if you've chosen to remove another frequency, enter it
into this field.

Third edit field: what's known as 'q' or 'quality' of filtering. A lower
value removes a wider range of frequencies centered around the notch
frequency you chose.


On Tue, 27 Jun 2006, Anders Holmberg wrote:

I am about to reduce hom or try to remove it with audacity.
Its from a radio show which i recorded from my stereo receiver.
I didn't realize there was a grounding problem.
Its a 50HZ hum which is really annoying to listen to.
Can anybody here recomend which filter i should use to reduce this hum?
And which cutoff frequency would be the best to use?
I have tried to use lowpass filter from 40 hz and highpass filter from 70 hz.
But i am no mathematics which now seem to be abit frustrating to me.
I am no good in counting so i hope someone can clear out this for me.
Thanks in advance.
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