I would doubt that a spectral analysis would be revealing, or indeed, of any use whatsoever. After all, such an analysis would vary from performance to performa

I would doubt that a spectral analysis would be revealing, or indeed, of any use whatsoever. After all, such an analysis would vary from performance to performance, or even between recordings of the same performance. It would seem more likely that the musical contents would somehow be the relevant factor, although this is speculative, of course.