Related Clues:

• Waits at Christmas, for example, for some birds
• They might be heard in the police station or on the radio
• Voices below altos
• Glee club members
• Opera heroes, typically
• No rest at sea for the singers
• Notes, we hear, for singers
• Domingo, Carrera, and Pavarotti, famously
• Caruso and Domingo
• Group of like voices
• Some singers at the Met
• Notes we hear from singers in famous trio
• Wagner's Tristan and Parsifal, e.g
• Singers with a number of alternatives?
• Barbershop voices