10.6

Table Of Contents
138Logic Pro Effects
The audio signal arriving at the analysis input passes through the analysis filter bank,
where it is divided into bands.
An envelope follower is coupled to each filter band. The envelope follower of each band
tracks, or follows, volume changes in the audio source—or, more specifically, the portion
of the audio that has been allowed to pass by the associated bandpass filter. In this way,
the envelope follower of each band generates dynamic control signals.
These control signals are then sent to the synthesis filter bank—where they control the
levels of the corresponding synthesis filter bands. This is done with voltage-controlled
amplifiers (VCAs) in analog vocoders. Volume changes to the bands in the analysis filter
bank are imposed on the matching bands in the synthesis filter bank. These filter level
changes are heard as a synthetic reproduction of the original input signal—or a mix of
the two filter bank signals.
Logic Pro EVOC 20 TrackOscillator interface
EVOC 20 TrackOscillator is divided into a number of parameter sections.
Analysis In parameters: Determine how the input signal is analyzed and used by the
analysis filter bank. See Logic Pro
EVOC 20 TrackOscillator analysis in controls.
U/V Detection parameters: Detect the unvoiced portions of the sound in the analysis
signal, improving speech intelligibility. See Logic Pro
EVOC 20 TrackOscillator U/V
detection controls.
Synthesis In parameters: Determine how the input signal is used by the synthesis filter
bank. See Logic Pro
EVOC 20 TrackOscillator Synthesis in controls.
Tracking Oscillator parameters: Determine how the analysis input signal is used by
the oscillator. See Logic Pro EVOC 20 TrackOscillator oscillator controls.
Formant Filter parameters: Configure the analysis and synthesis filter banks. See
Logic Pro
EVOC 20 TrackOscillator formant filter.
LFO parameters: Modulate either the oscillator pitch or the Formant Shift parameter.
See Logic Pro
EVOC 20 TrackOscillator modulation.
Output parameters: Configure the output signal of the EVOC 20 TrackOscillator. See
Logic Pro EVOC 20 TrackOscillator output controls.