So the idea would be to reconstruct the low frequency components from whatever upper harmonics are left in the recording? If you know the instruments and posit

So the idea would be to reconstruct the low frequency components from whatever upper harmonics are left in the recording? If you know the instruments and positioning of the recording device and something of its(the instruments, recorder, environment, etc.) characteristics, it might be possible to solve that using classic methods. There would be huge numbers of parameters, it is an interesting thought. Is there a large easily/freely available corpus of those recordings?