Audacity Forum

I have this song I am trying to edit and want to take the end of it and slow it down gradually, making it get slower and slower overtime. I only see the option to change the whole section to one slower tempo. I have a friend who uses Bias Peak Pro. They have an effect called "change duration (variable)". It takes the selected section and has a chart where you can plot the gradual change in tempo. Is there a plug in I don't know about for an effect like this in audacity? I've been looking around but haven't seemed to find anything as of yet.

I have no practictical experience of tis , but I seem to remeber from reading earlier postings that you can do this in Audacity by adding a Time Track to your recording Tracks > Add New > Time Track.

Sorry I can't actually advise how to manipulate it - try searching the forum and theWiki for "Time Track"

WC

waxcylinder wrote:I have no practictical experience of tis , but I seem to remeber from reading earlier postings that you can do this in Audacity by adding a Time Track to your recording Tracks > Add New > Time Track.

Yes indeed - and it is very easy to use. When you create a time track, there is a horizontal blue line that you can manipulate with the "envelope tool". Making the line go up will speed up playback and moving the line down will slow down playback.
Click on the track name (Time Track) for a menu option for the maximum and minimum range for the speed variation.

Note that this effect changes the playback speed, so the pitch will change as well as the tempo.

Is there any way to alter the tempo without altering the pitch?

Audacity does not have a way to gradually change tempo (and not pitch), but having tried that in other audio programs, it tends to sound rather unnatural anyway. The way to achieve the effect is a little more time consuming, but produces pretty good results.

I'll use some convenient times and tempos as an example:
Let's say that our original tempo is 120 bpm, and we want to slow the tempo down by around 20% over the last 4 bars in 4/4 time - that's an average of around 5% slower per bar. However the tempo change will probably sound better is we do not slow it down quite evenly. For example, of our final 4 bars, we may decide to slow the firs bar down by 5%, the second bar by a further 3%, the third by a further 3%, the first 2 beats of the final bar by another 4%, and the final 2 beats by 5%.

We select the final 4 bars (16 beats - 16 seconds), or just a fraction more, and from the Effects menu select "Change Tempo" and adjust the tempo by 5%. We then select the last 3 bars, and apply the effect again to reduce the tempo by a further 3%, then again for the last 2 bars (this time we can use Ctrl+R to repeat the last effect rather than having to select "Change Tempo" from the Effects menu), Then the last bar by a further 4%, and finally the last couple of notes by 5%.

A couple of things to note: Ctrl+R repeats the last used effect with whatever settings it had, and, if you try to change the tempo too much, the sound quality will begin to suffer and start sounding wobbly and generally not very good.