Irritating background hum is bothering me

Post by **philchenevert** » November 12th, 2023, 8:46 pm

Can someone tell me what frequency the background hum is in this sample? https://librivox.org/uploads/philchenevert/sample_to_find_hum_frequency_hopefully.mp3

I can't get close to what frequency to use in a notch filter. It is only under the spoken sections, not the 'silences' between words. Thanks.

lightcrystal · Post by **lightcrystal** » November 13th, 2023, 12:48 am

Microphone is seated properly in the cable or usb cord? The hum sounds similar to when that happened to me last year.

sjmarky · Post by **sjmarky** » November 13th, 2023, 10:53 am

There spikes at 1000Hz and at 22050.

It sounds like RF interference. Maybe you need shielded cables or something.

iBeScotty · Post by **iBeScotty** » November 13th, 2023, 12:22 pm

I don't think that noise/hum/resonance is a narrow frequency that can be notched, unfortunately. It does sound like it is some feedback within the signal chain and you could try replacing pieces one at a time to isolate, i.e. cables and even mic. Or it might be a software processing artifact--do you have the raw, unprocessed recording?

Post by **philchenevert** » November 13th, 2023, 2:09 pm

sjmarky wrote: ↑November 13th, 2023, 10:53 am There spikes at 1000Hz and at 22050.

It sounds like RF interference. Maybe you need shielded cables or something.

Thank you. This is on two tracks only and not on recent ones. I think it might have been with the cables used with my Yeti microphone. I now use a Rode. But shielded cables would probably be a good investment.

Post by **philchenevert** » November 13th, 2023, 2:14 pm

iBeScotty wrote: ↑November 13th, 2023, 12:22 pm I don't think that noise/hum/resonance is a narrow frequency that can be notched, unfortunately. It does sound like it is some feedback within the signal chain and you could try replacing pieces one at a time to isolate, i.e. cables and even mic. Or it might be a software processing artifact--do you have the raw, unprocessed recording?

Sadly, I do not have the raw recordings. There are 10 sections for this project and only two seem to have this nasty 'hum'. It is interesting that noise reduction was originally applied to the entire track and the 'hum' does not appear in the silences, implying that it was probably a cable. Thank you for the feedback. Since recording this I have switched from my good old blue yeti to a Rod NT-1A with a scarlett interface and don't have the problem.

iBeScotty · Post by **iBeScotty** » November 14th, 2023, 3:45 pm

philchenevert wrote: ↑November 13th, 2023, 2:14 pm Since recording this I have switched from my good old blue yeti to a Rod NT-1A with a scarlett interface and don't have the problem.

That's great! I am sure you know this but for any newbies having a similar issue, noise gating can have a similar effect, silencing the relatively low level noise in the quiet parts but leaving it in over the content, which is not very pleasant.

Glad you got it sorted!

Scotty