Tempo effect on all tracks : unequality

Hi all !

I think there is a problem with the " tempo change" effect. When I select all tracks with ctrl+ A and apply the effect it seems to affect all tracks but unequally.
Ex : track 1 and track 2 starts at the same time. After applying the effect, track 2 starts after track 1 despite being playing faster as well.

I tried affecting one track at a time but it sort of deletes the following tracks and I end up with a mess.

Any idea how to solve this ?

Many thanks,


Windows 7 & Audacity 2.05

There has never been an “Audacity 2.05”. Perhaps you mean Audacity 2.0.5, in which case you are running an old version. The current version is 2.1.1 which is available here: Audacity ® | Free, open source, cross-platform audio software for multi-track recording and editing.
Try the current version, and if you still have the problem we’ll try to work out why it’s not working for you.

My bad, yes it was version 2.0.5 indeed.

Anyway, I downloaded the latest version using your link, I tried againd and I still have the problem. :confused:

Please describe a test case step by step for me to reproduce the issue.


  1. Create 3 tracks, 2 starting ( ie= start to produce music) at the same time, the third starting at some other point in time ( I am editing a four voice vocal canon with each voice being tripled ).

  2. Press ctrl + A for selecting all tracks.

  3. Apply tempo change effect ( faster ) to that selection.

    Many thanks,

I made this following your instructions:

Which gives me this:
The split line in the first track is incorrect (I have logged that as a bug), but otherwise the result appears to be correct.

Here is what I have :

  1. Before applying the tempo change effect

2) and after, notice how the 2nd and 3rd tracks now start after track 1

Forum 2.png

Generate a little silence at the start of the tracks that do not start at time zero.


The problem is that “empty space” before the start of the track does not get stretched, but “silent audio” is stretched just like any other audio.
In order to ensure that all tracks are stretched the same amount, they must all have the same start time. As Gale wrote, the easiest way to do that is to generate a little silence at the beginning of every track.

I notice that track 1 starts before zero, so you will need to either drag all tracks a little to the right, or trim off the audio that is before zero.

Have we got the correct behaviour with time-changing effects, that they don’t stretch the white space before the start of the track? Paul thought they should act on white space before the track start, but then the track starts change.


Possibly not. The implementation is certainly not quite right in the current version because it causes bug 1215. I’ve not tested previous versions to see if it has always been like this.
Do you know why the current behaviour was decided on?