Related Clues:

• Sing like a mountaineer
• Serenade Heidi, maybe
• 42-down, at higher altitudes
• Sing Swiss-style
• Swiss trill
• Higher calling?
• Tyrolean's tune
• Tyrolean trill
• Alpine echo
• Song sung on 57 Down
• Alpine air?
• Call in the Alps
• Tune involving intermittent falsetto
• Feature of bluegrass singing
• Long-distance call?