Remove silence in Audacity

Truncate Silence, step by step

1. Select the audio you want to clean. Select all to clean the whole track.
2. Choose Effect > Special > Truncate Silence. Older versions list it directly under Effect.
3. Set Threshold, the level below which audio counts as silence (−20 to −80 dB), and Duration, the shortest gap to treat as silence.
4. Choose Truncate Detected Silence and a Truncate to length, or Compress Excess Silence to shorten gaps by a percentage.
5. Apply, listen, and export.

Choosing the numbers

Start the threshold a few decibels above the room noise, which you can read from a quiet stretch with the meter. A Truncate to of 0.3 to 0.5 seconds keeps speech natural.

No install?

The free tool on this site does the same cut in the browser and shows every gap before you download.

Sources: Audacity manual.