Adobe AUDITION 1.5 - Manual (Page 136)

CHAPTER 5 128
Enhancing and Restoring Audio
For more information, search for “Hiss Reduction options” in Help.
Using the Noise Reduction effect (Edit View only)
The Noise Reduction effect dramatically reduces background and broadband noise with a
minimal reduction in signal quality. This effect can remove a wide range of noise,
including tape hiss, microphone background noise, 60-cycle hum, or any noise that is
constant throughout a waveform.
The proper amount of noise reduction depends upon the type of background noise and
the acceptable loss in quality for the remaining signal. In general, you can increase the
signal-to-noise ratio by 5 to 20 dB and retain high audio quality.
To achieve the best results with the Noise Reduction effect, apply it to 16- or 32-bit audio
with no DC offset. With 8-bit audio, this effect cannot reduce noise below –45 dB, which
is very audible. (To achieve a lower noise floor with 8-bit audio, upsample the file to 16
bits, apply the Noise Reduction effect, and downsample the file back to 8 bits.) With a DC
offset, this effect may introduce clicks in quiet passages. (To remove a DC offset, select the
Center Wave preset provided by the Amplify/Fade effect.)
Adjusting frequency-specific settings with the Noise Reduction graphs:
A. Noise floor B. Reduction graph C. Original audio D. Processed audio
To reduce noise added by a sound card during recording, start the recording with a
second of silence. After recording is complete, use that silence as the Noise Reduction
Profile, and then remove it from the complete recording. In some cases, this process can
increase dynamic range by 10 dB.
C
D
A
B
ug.book Page 128 Tuesday, March 16, 2004 1:29 PM