Auto-Tune and Pitch-Correcting Plug-In:
http://www.antarestech.com/products/auto-tune5.shtml
For correcting pitch in general, see Pitch correction.
"Pitch correction - Wikipedia":
http://en.wikipedia.org/wiki/Pitch_correction
For automated optimization software, see Self-tuning.
"Self-tuning - Wikipedia":
http://en.wikipedia.org/wiki/Self-tuning
"Auto tune - Wikipedia":
http://en.wikipedia.org/wiki/Auto_tune
Adobe Audition 3.0 Pitch Correction effect:
The Time And Pitch > Pitch Correction effect provides two ways to adjust the pitch adjustments of vocals or solo instruments. Automatic mode analyzes the audio content and automatically corrects the pitch based on the key you define, without making you analyze each note. Manual mode creates a pitch profile that you can adjust note‑by‑note. You can even over‑correct vocals to create robotic‑sounding effects.
The Pitch Correction effect detects the pitch of the source audio and measures the periodic cycle of the waveform to determine its pitch. The effect is most effective with audio that contains a periodic signal - that is, audio with one note at a time, such as saxophone, violin, or vocal parts. Nonperiodic audio, or any audio with a high noise floor, can disrupt the effect’s ability to detect the incoming pitch, resulting in incomplete pitch correction.
Cheers ebs