This is very difficult at present. Most methods of doing something like this rely upon spectral analysis of the target you wish to remove, and then use FFT deco

This is very difficult at present. Most methods of doing something like this rely upon spectral analysis of the target you wish to remove, and then use FFT decomp/recomp to subtract the result. The results are poor. Someone mentioned the software that can isolate instruments from one another. But the problem is this usually relies upon the instruments or vocals having a different position in a stereo signal, and different frequency ranges, to perform that extraction. This is much easer to do in such cases, especially since the material you are working with is generally clean source material. Here you have a mixed signal, that may or may not contain stereo data, but certainly contains a lot of background noise, as well as other game audio you wish to retain. What is needed is a far more intelligent method of identifying the spectral signature of a known source by matching the target with the source in the time domain, and then using that identified signal in the target itself to cancel itself out. In practice this would mean comparing the amplitude modulation of each spectral band in the source to the target to identify the spectral components that need to be removed, and then using the corresponding "matched" bands, generate a signal, using the source as a guide, from the target audio itself that represents only that portion of the spectral signature that is being matched to the source. This newly generated signal can then be used to remove that audio from the target with 180º phase cancellation. Keep in mind that wherever the spectral bands overlap with other audio content you wish to retain, there will be a lot of artifacting and signal loss or phasing. A second pass would need to use the equivalent of inpainting to reconstruct those missing components. Overall, it's a very hard problem.