deleting defined sections of audio

I have done some field recordings. I have large spaces of ambient noise that I’m trying to get rid of - I’m recording conversations I have with people in Chinese, but between the conversations, there is street noise.

Usually, the conversatiosn are louder than the noise. So I’m wondering if there is a way to delete audio in this long recording which is below a certain decibel level. Or if there is a better way to do this, please let me know.


There is a Noise Gate plugin. Its job is to suppress quiet noises. (4.13 KB)

Thanks very much. And I am running 2.0.5 on trusty.

While this Noise Gate is quite useful, it will not perform the function I need. I am hoping that there is something that will delete quiet audio between high-amplitude audio - in other words, it will delete the parts of the recording which are obviously noise. Is something like this available?

There is noise removal , but that is only effective on constant monotonous background noise like an electric-fan humming.
If the parts which are “obviously noise” are not constant* throughout the recording then Audacity’s Noise-removal isn’t going to help.

[ * street-noise of vehicles and people talking in the background isn’t monotonous-type constant , which is the only type of noise that Audacity’s Noise_Removal can reduce ]

I’m surprised there is nothing that could simply measure the amplitude of the recording and delete audio which fails to exceed a threshold. Seems simple, but then again I don’t know much about audacity.

There is Truncate Silence. It detects audio that is below the threshold for at least the specified time, and can truncate it to 0 seconds, thereby deleting that audio. So it will make the recording shorter. It can’t isolate the audio that is quieter and only delete that, leaving the length the same.


There is. As koz has already written, it’s called a “gate” or “noise gate”.
There is one available on the Audacity wiki: Missing features - Audacity Support
Instructions for installing: Missing features - Audacity Support

That’s a normal noise gate effect, you can find one on the Nyquist effects page of the Audacity Wiki.

There is a lot of confusion in this topic. Noise Gate reduces the level of noise that has higher level audio before and after it (as you look at the Timeline). The higher level audio is not affected. The track remains the same length as before, so no audio is deleted.

Truncate Silence deletes the quieter audio (such as noise), changing the length of the track.


That is correct.
So it depends on whether hiddenharmonies wants to
A) silence the low level audio, in which case use a Noise Gate,
B)delete the audio (including the space that the low level audio occupied, in which case use “Truncate Silence”.

There is one other possibility, which is to
C) delete the low level audio completely, leaving “empty” space (white-space) between separate clips of the remaining audio, in which case, use a noise gate (such as the one that I previously linked to) and gate the low level noise to absolute silence, then use “Edit > Clip Boundaries > Detach at Silences”

Here is a comparison of A, B and C:

If you do “A”, then the exported file would start with the silence or low level noise to left of the first actual audio content.

If you do “C”, then the exported file would start with the first actual audio content, then would have silence between each subsequent section of content.