Where did this bizarre background noise come from?

[KayDenmark]

I've been happily editing several .wav files, but now for some reason an extremely loud background noise has been added to them. I assume I hit some kind of button or changed some kind of setting, but I can't figure out what it is. Any wise words from the community?

[EuanWilliamson]

Hi Kay,

I took a look and a listen.

The original recording level was quite low, about -18db

Is this the usual level you record at? A higher recording level will help the signal to noise level

ie how loud the voice is compared to background noise.

In the image above I've normalised the audio to -1db and then selected the noise in the gaps

between words.

You can see in both the spectral frequency display and the frequency analysis window the nature of the noise.

It's sitting here ( after normalisation ) at roughly -55db

It's uniform across the spectrum 10hz - 20khz and beyond.  This is classic white noise.

As to causes, it's not likely that you have "hit a button".

More likely it will help to record at a higher volume.

It's possible that an audio lead in your setup could cause this if it's starting to go faulty or perhaps you

have moved your recording setup to a more noisy location either audible or electrical.

If you don't have a way to re record this, it should be possible to remove it.

[SteveG_AudioMasters_]

Actually I don't think that the record level is the problem at all. When I opened the file, it says that it's 8-bit mono. Any 8-bit file cannot have a dynamic range of more than 48dB, and that's exactly where your noise floor is. If your original file was 16-bit, then that's what you should continue to save as. You can work out where the noise floor is going to be for any file by multiplying the number of bits it is stored at by 6.02 - which gives you a noise floor of half the 16-bit one - about the same as an old cassette recording. I hope you've still got your original file, because once the noise floor has been raised like that, you can't get it back down again - that noise is printed into the 8-bit file.

[EuanWilliamson]

Thank you @SteveG_AudioMasters_ 

You are correct as always 🙂

(That'll teach me to have my file browser window so narrow and not see all the tech columns)

My apologies @KayDenmark that I missed the obvious.

[KayDenmark]

Thank you, gentleman.

However, I don't think we've solved the problem. 

It seems to be related to the saving process.

See the screen shots below for how it all seems to go south when the recording (which is a .wav) is saved again as a new .wav.

1) A nice healthy file.

2) I highlight and copy the soundwaves.

3) I create a new file.

4) New file looks good!

5) I paste the soundwaves in the new file. Looks good. I check it for sound - sounds good.

6) I save the new file, then close.

7) I open up the new file and it's a mess. 

FWIW, this doesn't happen with AIFF saves. I can save and close an AIFF file, open it up again with no problems. Only .wav to .wav. 

[SteveG_AudioMasters_]

See your other thread. We have solved your problem - you just haven't implemented the solution yet.