Double-click the Acid desktop icon to open the program. It may take a few seconds for the program to fully launch. Depending on how you have Acid configured, it will either open the last edited session or a blank session. To call up the relevant session, click "File," "Open Recent" and select the song from the drop-down menu.
Click "Tools," "Plugins" and select "Auto-Tune" from the drop-down menu.
Click on the channel containing the audio to be Auto-Tuned; for example "Lead Vocal 1." This assigns subsequent edits to that audio channel.
Click the "Input Type" tab and select the register that most closely matches the register of the audio. For example, "Alto" or "Tenor."
Click on "Key" and enter the key of the song, for example "C."
Adjust the "Retune Speed" dial. For a natural-sounding effect, set it to around halfway. The re-tune speed determines how quickly Auto-Tune corrects your out-of-tune notes.
Adjust the "Tracking" setting. This governs the pitch range inside which Auto-Tune corrects the notes. The extremes of this parameter are called "Relaxed" and "Choosy." For a natural, corrective sound, set the virtual dial nearer to Relaxed than Choosy. The Relaxed setting corrects only very out-of-tune notes.
Click "Save" and close the Auto-Tune window to return to the Acid interface.
Click "Input Type" and select the option that least matches the register of the input notes. For example, if the vocal is in the bass register, select "Soprano." This effectively "tricks" Auto-Tune into correcting out-of-tune notes by pitching them in a different register. This creates a distinct jump from one note to another.
Set the "Re-tune Speed" to zero. This creates a robotic, glitch sound. There is no transition between the out-of-tune note and the corrected note; it is an instant switch.
Set "Tracking" to Choosy. This sets the effect to correct any note that is even a tiny amount out-of-tune.
Click "Save" and close the Auto-Tune window to return to the Acid interface.