# spectral subtraction for stationary noise

my recording was suffering from stationary background noise. I used spectral subtraction to remove it. the noise is reduced in loudness but not eliminated completely. before: http://vocaroo.com/i/s18FtoUwSah4 after: http://vocaroo.com/i/s12U4feLs6iu

is spectral subtraction working?What can I do to further improve my results.

What you can try is tweak the parameters. The most obvious parameter to tune is the (over)-subtraction factor, which determines how much of the estimated noise is subtracted from the noisy spectrum. It is not uncommon to have over-subtraction factors of around $2.0$ or $2.5$. Of course you have to make sure that the resulting estimated speech (magnitude or power) spectrum remains non-negative.