[shabble]

Yes, the FFT/STFT[1] is generally invertible, potentially subject to knowing the parameters it was generated with, or finding some reference markers in the original input you could use to derive them.

There's also the possibility the spectrographic image itself might be a lossy representation of the actual frequency domain data, in which case you won't get a perfect result back out. Probably recognisable though.

If I had time I'd do some flubbing with octave/scipy and demonstrate it, but alas, the margins of this weekend are too small, etc, etc.

[1] https://en.wikipedia.org/wiki/Short-time_Fourier_transform#I...