Apple Using WaveBurner Pro 1.0 (with Logic Pro) - Manual (Page 32)

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Denoiser
Using the Denoiser, you can eliminate or reduce many kinds of low-level noise (noise
floor) from an audio signal. The main parameters of the Denoiser are Threshold, Reduce,
and Noise Type. The Threshold parameter sets how high the noise floor is for the audio
signal. The recommended method for setting the Threshold is to find a passage where
you hear only noise, then set the Threshold so that signals at this volume level are
filtered out.
The Reduce parameter sets the level to which amount the noise floor is reduced. You
use the Noise Type parameter to set the type of noise that the Denoiser reduces. There
are three choices of noise type:
• Setting the Noise Type to 0 (zero) causes the Denoiser to reduce “white noise” (all
frequencies reduced equally).
• Setting the Noise Type to a positive value causes the Denoiser to reduce “pink noise”
(harmonic noise; greater bass response).
• Setting the Noise Type to a negative value causes the Denoiser to reduce “blue noise”
(hiss, sibilants, tape noise).
The Denoiser recognizes frequency bands with a lower volume and less complex
harmonic structure, and then reduces them to the desired dB value. This method is not
completely precise, and neighboring frequencies are also reduced. Using the Denoiser
at too-high settings can produce the “glass-noise” effect, which is usually less desirable
than the existing noise.
There are three smoothing parameters that you can use to minimize the “glass-noise”
effect: Frequency smoothing, Time smoothing, and Level smoothing. Raising the
Frequency smoothing slider results in a smoother transition of denoising to the
neighboring frequencies. When the Denoiser recognizes that only noise is present in a
certain frequency band, the higher the Frequency smoothing parameter is set, the
more it will also change the neighboring frequency bands to avoid glass noise.