Apple Logic Express 8 - Manual (Page 637)

Chapter 27 Bouncing Your Project 637
Bouncing and POW-r Dithering
Logic Express provides you with the professional POW-r dither algorithm, designed to
convert 24 bit recordings to 16 bit files—as required for CD burning, for example.
POW-r (Psychoacoustically Optimized Wordlength Reduction) is licensed from the
development team of the POW-r Consortium LLC.
POW-r dithering can be applied when:
 Bouncing audio files to disk
 Exporting OMF files (see “
Exporting OMF Files ” on page 660).
POW-r offers three distinct dithering modes.
 None No dithering is applied.
 POW-r #1: Uses a special dithering curve to minimize quantization noise.
 POW-r #2: (Noise Shaping): Uses additional noise shaping over a wide frequency
range, which can extend the dynamic range of the bounced file by 5 to 10 dB.
 POW-r #3: (Noise Shaping): Uses additional, optimized noise shaping, which can
extend the dynamic range by 20 dB within the 2 to 4 kHz range—the range the
human ear is most sensitive to.
Note: Noise Shaping minimizes the side effects caused by bit reduction. It does this by
moving the quantization noise spectrum to the frequency range above 10 kHz—the
range the human ear is least sensitive to. Technically, this process is known as spectral
displacement.
The dithering mode which will sound best to you is primarily dependent on the audio
material, and your personal taste. Audition the audio material with each of the
dithering modes to determine the right setting. In some cases, you may find that the
best results are achieved by using no dithering at all!
Important: Dithering the same audio signal multiple times should be avoided.