Related Clues:

• Perfect accord
• High-toned, in a manner of speaking
• Tiny Tim sang in it
• Simultaneity
• What some singers sing in
• Certain doo-wopper
• People often sing in it
• A choir may sing in it
• Coincidence in pitch
• Yodeler's range
• High voice
• Unnaturally high voice
• Homophony
• Tandem
• Concert