Mixing stereo to mono in tracks menu raises pitch

Importing audio tracks into my virtual choir project in Audacity 2.4.2, on a Windows 10 laptop, some are mono and some are stereo. Normally, I just use the Tracks menu to mix the stereo tracks to mono. Just recently however, every time I do this the mono track is raised in pitch by about a semitone. How can I prevent this occurring?

It’s probably unrelated to mono/stereo -

First. make sure you’re not mixing-and-matching sample rates. The difference between 44.1kHz and 48kHz is close to one semitone. The software & drivers are supposed to automatically take care of any necessary re-sampling so that doesn’t usually cause problems but occasionally something “goes wrong”.

Or sometimes “cheap consumer soundcards” can have an inaccurate sample rate clock… No clock is perfect but some are off by enough to cause problems. In that case the problem doesn’t show-up unless you record and play-back on a different soundcard/device. It can happen if two or more people are working on a project, each using their own computer or it can happen if you record with a USB microphone (or USB audio interface) and then play-back on your regular soundcard.

You can try Tracks > Resample

It’s a bug in Audacity 2.4.2. It is fixed in the current version of Audacity (3.0.2).

Note that Audacity 3.x has a different project format to previous versions, so if you’re in the middle of a project I’d recommend that you complete the project before updating.

More information about:

Audacity 3.0.0 (read first): https://www.audacityteam.org/audacity-3-0-0-released/

Audacity 3.0.2 (current version): https://www.audacityteam.org/audacity-3-0-2-released/

Download current version: https://www.audacityteam.org/download/