Confusion with "Trim" behavior

I’m splitting up a larger Audacity project into small segments for easier editing. Here’s the workflow I’m trying to follow:

  • Select a (time) region in the file (often by using a label track)
  • Click on each audio track to make sure it’s included in the selection (now I have a vertical selection across all tracks for a time-interval)
  • Use Edit->Remove Audio->Trim to delete sound clips not in the selection
  • Close audio tracks which have no audio within the selection
  • Timeshift the selection to the beginning
  • Save under a new project name with appropriate metadata

Theoretically, I should be able to repeat this and split up the project into several smaller ones.

But I’ve noticed that the behavior with “Trim” is inconsistant and doesn’t always do “the right thing” (or what I want anyway).

First of all, if a track has no audio clips within the selection, then only clips after the selection are deleted (but ones before it left in place). This isn’t too serious, because I can just delete those tracks entirely.

BUT, this alternate behavior sometimes happens even for tracks which DO have audio clips in the selection. I have no idea why they are not being trimmed normally. They are definitely selected. And the trim does delete clips which occur after the selection (i.e. at later playback times or to the right of the selection on screen).

All of these tracks are sparse: They have just a few clips of audio spread out over a large period (they’re dialog lines or sound effects).

It is possible to delete the remaining clips (the ones before the selection on the left). I just have to select them and use “Split Delete” or “Delete” on them (I currently have my preferences set so that deleting a clip does not timeshift the clips after it in the same track). So I can work around this problem, but I’d like to understand what’s going on!

  • What is the formal reason for having this alternate behavior in the first place?
  • What factors determine which behavior is followed?

I’m using Audacity 2.0.0 – the stock package from Debian GNU/Linux “Wheezy”.


The apparent variation in behaviour is to allow an individual audio clip to be trimmed.
If the selection starts inside an audio clip, then previous audio clips are not affected.
If the selection ends inside an audio clip, then later audio clips are not affected.
If the audio clip is entirely inside the selection, then Audacity assumes that you want to trim the track rather than just the clip.

In your case, to get consistent behaviour, join the clips together (with silence) before you trim.

  1. Ctrl+A (Select All)
  2. Ctrl+J (Join)

Now you have one audio clip per track.
If you want to split them up again after trimming, use Alt+Ctrl+J
(these functions are also available in the Edit menu, but the shortcuts are quicker and not hard to remember)

A quicker way:

  1. Make the selection in one track.
  2. “Edit > Select > In A;; Tracks” (Ctrl+shift+K)