Related Clues:

• Fail to modulate
• Harp sound
• Borrrring voice
• Queen's attendant
• Monotonous tone
• Bee in a hive
• Remote-controlled craft
• Sing sans melody
• Plane sans pilot
• Go on (and on, and on ...)
• Queen's mate
• Unchanging intonation
• Pluck guitar strings idly
• Play banjo idly
• Ambient sound