Electric noise on audio recording

[steve]

As all sockets in my room are not correctly grounded I ask:
Is there some kind of device or filter that could remove this buzzing noise ?

You can remove buzz by using a series of notch filters: http://manual.audacityteam.org/o/man/notch_filter.html

"Plot Spectrum" can indicate the frequencies of the buzz: http://manual.audacityteam.org/o/man/plot_spectrum.html

Typically the buzz will occur at exact multiples of the AC power frequency, so in the US, if you analyse a quiet section of the recording where there is only the buzz, you are likely to see spikes in the spectrum at 60, 120, 180.... Hz. In the UK and much of Europe where the AC power frequency is 50 Hz, the spikes are likely to be at 50, 100, 150, 200... Hz.

Note that notching out the buzz will remove all sound in that frequency range. Making the notch narrow will minimise the damage to the recorded audio, but the best solution is to avoid the noise in the first place by using correctly grounded equipment. Also, much electrical equipment should be correctly grounded for safety reasons.

[kozikowski]

I know that I can use Audacity noise removal feature...

You should stop knowing that. Audacity Noise Removal is very difficult to use and frequently damages the show it's trying to help. You really need to solve this problem before Audacity gets to it. Once you burn buzz into the show, it's like a very difficult disease.

You can send Audacity into monitor mode and listen in real time while you take steps to help.

Audacity Preferences > Recording > [X] Playthrough (select).
Right click or Control Click on the red recording meters > Start Monitoring.

Listen in headphones and turn up the volume so you can hear the buzz. Keep doing that as you change your system to figure out what's causing the problem. You don't have to make a recording and play it back each time.

Koz