There was some discussion awhile back about whether, and which, rock bands played to a click track, ie used a metronome to keep their drummer precisely in time. Post-recording quantization is also used, and, like pitch correction, has percolated down to consumer software such as Garage Band. I thought it would be interesting to use the same software to see how steady my beat is. Here's the version I used, which allows you to upload your own track for analysis. (Or, if you just want to look at tracks found online, this is slightly more advanced.)
This is a plot of the tempo during the rehearsal last night. Our maestro picked a rather bright pace, compared to previous rehearsals, perhaps because we had only a couple minutes of rehearsal time left. To be honest, it felt a little too fast to be in control for me, although on an absolute scale it's a reasonable speed. There's some wandering up and down, but it ends up about where it started. After the rehearsal I was guessing the speed at 116, but in fact it averages more like 106, which is around where I'm aiming. When you're working with the software, you can have it play sections, and watch the marker move on the plot, so you can see and hear how the tempo change affects the music.
For comparison, here's a plot of Dag Jensen's recording. It's much faster overall, around 120 average, and steadier, with certain large deviations for effect.
Finally, here's the recording itself. I'm not happy with it, but being pseudonymous is what lets me post stuff like this. And while I did screw various things up, the final show is probably going to sound a lot like this, so I can consider it a preview.
Mozart Rehearsal 2011-05-03 by TFox17