Noise Reduction
Acoustica provides tools for removal of stationary noise.
An exact definition of stationary signals is beyond the
scope of this help, but the
frequency spectrum
of stationary signals remain pretty constant over time.
In other words, tape hiss, humming or other constant
disturbances are removable using the Acoustica noise
reduction system.
The noise reduction is based upon the spectral subtraction
technique. This means that a spectrum of the noise present
in the recording is needed. The spectrum of the noise
can be obtained in the two following ways.
Removing Noise with Noise Footprint
If your recording contains pauses with pure noise without
any other signal, this sections can be used to create
a footprint automatically. Select Enhancement | Noise Analysis
after marking a section containing noise only. After the
analysis phase, select Enhancement | Noise Reduction | Based
on Noise Analysis. Choose the reduction level and press
ok.
Removing Noise with Drawn Noise Profile
If no pauses are available for noise analysis you can draw
a noise profile by hand. Select Enhancement | Noise Reduction
| Based on User Profile. A curve editor shows up where you
can manually enter a noise profile. For tape hiss this method
works quite well. The tape noise is more or less evenly
distributed in the spectrum, thus a flat line should to
the job. Finding the right threshold can be tricky, but
after a bit of try and fail, good sounding settings should
be possible to find.