Aligning multiple recordings of the same piece

I am using Debian 10 (buster), with Audacity 2.2.2 from the distribution’s package.

I have three recordings of the same track, taken from multiple copies of the same record, currently in individual Audacity projects, and am trying to make the best possible recording of the track by, if necessary, taking sections from the different recordings, or possibly averages of them.

Is there anything in Audacity to help me align the three recordings together to make this easier? The track is in stereo, if that makes any difference to the process.

Time Shift Tool: Time Shift Tool - Audacity Manual

Zoom: Zooming Overview - Audacity Manual

Move the tracks roughly in line, then zoom in and adjust the positions a bit more accurately, zoom in closer … repeat as necessary to achieve the required precision.

A problem that you may encounter is that the recording may not all be at exactly the same speed. If that’s the case, then even when you have the start of the tracks accurately aligned, the tracks may drift slightly apart. If this happens, you could use the “Change Speed” effect to stretch the tracks as necessary. (Change Speed and Pitch - Audacity Manual)

Aligning tracks manually is something I often do. It can be difficult to do by visual inspection if the sound files differ substantially, say, if one is a filtered version of the other.

One way to automate this process would be to calculate the cross correlation between the two tracks at various lags. The lag that yields the highest cross correlation indicates how much one of the tracks should be time shifted. If someone would like to implement this, my suggestion would be that the user first manually aligns the tracks roughly as they should be, then one calculates the cross correlation up to some maximum time lag and one of the tracks is delayed by the appropriate amount.

Just to say I’m getting on quite well with this. I have the three recordings in, with a noticeable “phasing” effect if copies 2 and 3 are on together (with or without copy 1). I’m going to experiment with aligning those to see if I can shift that effect.

There is a program called [u]VocALign[/u]. But It’s not free (there is a free trial) and there is no Linux version.