Noise Reduction

Acoustica provides tools for removal of both stationary noise (hiss and hum) and impulsive noise (clicks, pops and crackle). 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.

Removing Clicks and Crackle in Audio Recordings

New in version 2.2 of Acoustica is a declicking algorithm specilized on removing impulsive noise such as clicks, pops and crackle. The click filter can be found in the Enhancement Menu and has two parameters: Optionally, clicks may be removed manually by selecting one single click and using the Interpolate command in the Enhancement menu.