volume is up and down

Special Interest Groups Audio Processing
1

Hi newbie here

I have an track in audacity which is vocal only, not singing just speaking. The problem is that the volume seems to be going up and down as if the person is moving to and from the mic. Any suggestions how I can fix this?

thanks
David

2

Is it something you have recorded yourself? The most likely reason reason is “enhancements” like “echo cancellation” in the sound card - turn them off in the sound card control panel.

Also try updating the drivers of the sound device you are using. Update the device so that it has the latest drivers specific to your operating system and your particular computer model, as supplied by the device or motherboard manufacturer. See:
http://wiki.audacityteam.org/index.php?title=Updating_Sound_Device_Drivers


Gale

3

It was recorded using H2 Zoom but with a radio mic. If I pick out the quiet bits and amplifiy them it makes it a little better as it’s not so up and down then. Problem is, it’s 35 mins long so it’s taking me ages to go through it and I have another 6 others to do.

Is there an auto way I can do this?

Thanks

4

Try the Compressor effect. Choose a short portion of the recording where the audio changes volume, and try different settings until you get something that works. Undo that then apply the Compressor with those settings to the entire track.

http://manual.audacityteam.org/index.php?title=Compressor

– Bill

5

There is another dynamics compressor that is available as an Audacity plug-in from here: http://pdf23ds.net/software/dynamic-compressor/
This plug-in can (probably) give better results for this type of task than the built-in Audacity compressor effect.

How to install plug-ins: http://audacityteam.org/download/plugins
(Chris’s dynamic compressor is a “Nyquist Plug-in”)

6

I’ll give it a try and post how I get on.

Thanks guys

7

the volume seems to be going up and down as if the person is moving to and from the mic

Were they? You can get a huge change in signal volume if the person is too close to the microphone and likes to weave around and get expressive. Back off. There is a trick they use in recording studios called the pop and blast filter…

It’s express purpose is to get rid of popping “P” sounds, and it does that, but it also serves to keep lipstick from the microphone.

If you’re recording a dramatic performance, those can be killer as the performers reach for the last balcony.

“I’ll whisper the secret in your ear” (in a voice that be heard in the next time zone).

Koz

8

I’ve downloaded the compressor plugin above but I still can’t get my audio to sound good. If anybody fancies having a crack at it then please feel free and let me know what you did.

I have attached a segment of my original file. By the way it’s in Welsh just in case you are wondering what on earth the person is talking about.

Or in context the files can be see here:

http://www.eglwysefengylaiddaberystwyth.co.uk/?p=77

Thanks
David

9

Try Effect > Compressor with these settings:
Threshold -18
Noise Floor -80
Ratio 6:1
Attack Time 0.1
Decay Time 1.0
Make-up gain for 0dB after compressing - checked
Compress based on peaks - checked

You have other problems besides the change in volume. When the volume goes down the frequency response also changes - it gets a bit “tinny”. You say you used a radio mic and a Zoom recorder? Sounds like the automatic gain control or protection limiter was cutting in, either in the Zoom or the radio mic.

– Bill