Apple Logic Pro 8 - Manual (Page 508)

508 Chapter 21 Editing Audio in the Sample Editor
Length in SMPTE
Displays the length of the selected area in SMPTE time format.
Length in Bars
Displays the length of the selected area in musical values (bars, beats, divisions, and
ticks). If you have already adjusted the project tempo to match the region that you’re
about to edit, the original value will automatically be set correctly. If not, you need to
manually enter the original length here.
Pitch Parameters
You use the pitch parameters to determine the amount of transposition in cents, and
also the strength of harmonic correction, if used.
Transposition (Cent)
Transposition of the sound material in 1/100th semitone units (cents). A value of 100
will result in an upwards transposition by one semitone. A value of –1200 will result in
the audio material being transposed down an octave.
Harmonic Correction
The entire spectral structure is shifted when audio is transposed. During this process,
not only is the fundamental pitch transposed, but all of the resonances (formants) are
shifted as well—as though the whole instrument or singer is being reduced or
enlarged. This, of course, is not natural. Voices transposed up will sound like Mickey
Mouse, or like Darth Vader if transposed down.
You can use the Harmonic Correction feature of the Time and Pitch Machine to correct
this unnatural spectral shifting of formants.
Turn on the Harmonic Correction checkbox to correct the formants that define the
timbre (sonic character). In other words, the formants in the transposed material are
not changed.
This means that the original timbre (or the physical size of the resonance body) is
maintained, resulting in a more natural sounding transposition. The only trade-off is
that calculation takes more time.
Note: The quality of Harmonic Correction is heavily dependent on the source material,
because the algorithm has to make intelligent decisions between tonal and atonal
components of the recording, and handle them separately. This is not an exact science,
and is more accurate on monophonic material than complex stereo material, but you
can certainly use it on a complete mix. The phase correlation of stereo recordings is
maintained.