Audacity Forum

Hi all, this isn't technically a problem with Audacity so please move or remove this post if it's not appropriate.

I'm using a little consumer-grade Sennheiser PC 8 headset on Mac 10.6.8 and every recording I take has a light (but audible) mosquito hum. I don't hear any hum as I'm recording, but the resulting audio files always have the hum.

I've been using Audacity 2.0.3 (dmg) to remove it, but of course it can't remove it perfectly, and it's an annoying step. I've been adding cheesy background music to my screencasts just to distract people from the noise.

I know the problem is the headset. The hum only affects recordings made with this particular headset, not regular internal mic recordings. The hum happens on different computers located in different rooms (no speakers or humming electronics nearby), and it doesn't matter what program I use to record the audio - Screenflow, Wiretap Studio, whatever: if I use the headset, I get the hum. But this headset is just two weeks old so I'm wondering if there's something obvious I'm doing wrong that will avoid me having to buy another, because I can't find the warranty...

Sample attached. If you turn the volume up you can hear it better. Would be grateful for any ideas! I am a total beginner.

There are a number of things wrong with the recording. Attached is a cleaned up version.

Effect > Noise Reduction: 18, 0, 200, 0
Effect > High Pass Filter: 100Hz 24dB
Effect > Amplify to -1.

So that's how to make what you have into a moderately presentable recording. If you overdo noise removal, it will start messing with your voice.

You're too close to the mic. Back off a little -- swing the boom further from your mouth. I can play your recording on my killer sound system and the thumps scared the cat. If you back away a little, you may not need the High Pass Filter.
It pays handsomely to listen to your work on a very good sound system to catch all the problems before the client hears them.

Now go look for your receipts. It's a sampling error or bad cable shield or something like that. I'm betting it can't be fixed. Are you going through a USB hub by any chance? They will do that.

Koz

Repeated notch filters at 1KHz intervals gets rid of most of it ...

Copy and paste the code below into something called "Nyquist Prompt", which is in the Audacity "Effects" menu.
[ code originally from here ... http://forum.audacityteam.org/viewtopic ... 839#p34839 ]

If you then apply noise reduction, and a noise gate the result isn't too bad ...