Related Clues:

• Off-peak calls?
• Is in peak singing condition?
• Alpine songs
• Peak performances?
• Some country music effects
• Mountain airs
• Sings at a high level?
• Warbles
• Sings Swiss-style
• Sings in peak form?
• Displays peak singing condition?
• Serenades Heidi, maybe
• Falsetto songs
• Alpine refrains
• Mountain airs?