Possible Clues:

• They help one speak one's mind
• What every singer needs -- a clue to what the guitarist may be playing!
• They help to produce speech, possibly providing collections of notes
• 90% discount on opening of neighbourhood business — approach succeeded — they make some noise
• Singer's "pipes"
• Membranes that vibrate
• Anatomical pipes
• Thyroid-cartilage attachments
• Coloratura's assets
• Singing pair