Noise Reduction Introducing Artefacts

[MikeS]

Using spectral subtraction on recordings to remove hiss, hiss removal is effective. However additional sounds seem to be added. The sound a bit like crinkling of silver paper, or birds twittering, and seem to follow on from transients like a foot fall frome somebody walking accross the floor, or from a sudden sound from an instrument like a violin. Additionally using Multiband Noise Gating removes these effects, but even with the settings set to remove noise only at a very low background level eg noise gate level -90db, the sound can be ruined. An example of this is a violin start to play a string. The initial start of the sound is eliminated, and the violin sound begins late and at relively high level.

 

I have now tried to use these techniques os several recordings, but the result is always the same. The recordings become unusable, and the recording with the initial background noise is always preferable. If the spectral subtraction did not introduce the new effects, there would be no problem. By the way, I have always used the smallest sample possible for sampling the noise to be remove, minimising the effects from noises additional to the background hiss.

 

Has anybody got any suggestions?