How the ATR-1a corrects pitch
The ATR-1a works by continuously tracking the pitch of an input sound and comparing it to a user-defined scale. The scale tone closest to the input is continuously identified. If the input pitch exactly matches the scale tone, no correction is applied. If the input pitch varies from the desired scale pitch, an output pitch is generated which is closer to the scale tone than the input pitch. (The exact amount of correction is controlled by the Speed parameter, described below and in Chapter 4.)
Scales
The heart of the ATR-1a’s pitch correction is the Scale. The ATR-1a allows you to program 50 different Scales. For each Scale you can define which notes will sound and which won’t. And for each note that will sound, you can decide whether the ATR-1a will apply pitch correction to input pitches near that note or leave those pitches uncorrected.
Speed
You also have control over how rapidly, in time, the pitch adjustment is made toward the scale tone. This is set with the SPEED control (see Chapter 4 for more details).
•Fast SPEED settings are more appropriate for short duration notes and for mechanical instruments, like an oboe or clarinet, whose pitch typically changes almost instantly. A fast enough setting will also minimize or completely remove a vibrato.
•Slow SPEED settings, on the other hand, are appropriate for longer notes where you want expressive pitch gestures (like vibrato) to come through at the output and for vocal and instrumental styles that are typified by gradual slides (portamento) between pitches. An appropri- ately selected slow setting can leave a vibrato unmodified while the average pitch is accurately adjusted to be in-tune.
Vibrato
The ATR-1a can also apply a vibrato to the input sound. You can program the vibrato depth, vibrato rate and the onset delay of the vibrato (or even control it in real time via MIDI). You can also choose the shape of the pitch variation in the vibrato (sine, ramp or square). By combining a fast Speed setting with the ATR-1a Vibrato settings, you can even remove a performer’s own vibrato and replace it with the ATR-1a’s programmed vibrato, all in real time. Also, unusual combinations of Vibrato Waveform, Rate and Depth settings can be used for some interesting special effects.
