Noise Reduction Q

Hey guys,

I am using Audacity on osx 10.5.8.

I have an audio recording on my phone of a talk I attended. The audio has a verity of different background noises in it including passing cars/street noise (when the door opened) and pops & clicks from moving objects on the table. There is also quite a constant ‘room’ noise throughout the whole recording.

Which tools in audacity would I use to clean this up best I can? I have experimented with Noise Reduction feature… will this feature be able to delete a certain noise from the whole audio track or just a section of the audio when no one is speaking?

many thanks,

If the constant “room noise” is reasonably low level then the “Noise Removal” effect should work reasonably well on that.
Sounds such as cars passing do not count as “noise”, they are “performers” in your show and will probably need to be edited (cut/deleted) from the show to remove them (which of course will also remove all other sound that is occurring at that time).

Ok thanks… Problem is, my recorder was at the back of the room (speaker at the front) and the level of the room noise is quite high throughout, in relation to the speakers voice. Is this just the same problem as having loud cars in the background, even though it is one constant sound?

It means that Noise Removal will be less effective.
Noise removal works best on low level constant noise. Give it go, but don’t try to totally eliminate the noise or the remaining sound will be horribly bubbly and metallic, just try to reduce it to an acceptable level.

There’s a useful article about removing noise on the Audacity wiki:

Noise Reduction only works on one constant sound. It works in two steps. The Profile step is where you point the tool to a segment of the show with noise only, no performance so the tool can “learn” what the noise is. Step two is where you apply the tool to actually reduce the noise in the rest of the show.

Only if the noise is constant over the whole show does Noise Reduction do anything useful.

You are the poster child for why people can’t record performances like that. Most if not all of the trash is permanent. The video people get burned with this constantly. You can’t “zoom in” the microphone.