Related Clues:

• Lip-___ (not really sing)
• Put in harmony
• Harmonization, for short
• Simultaneity
• Match, informally
• Good thing to be in
• Lip-__
• Fit the sound to the action, e.g.
• Fit sound to action, e.g.
• Lip ---
• Harmonization
• In __ (harmonized)
• Coordinate, digitally
• Pop music's 'N __
• Cause to coincide