Possible Clues:

• Cheap trill
• Vibrating vocal effect
• Two-note keyboard effect
• In strictly mistaken terminology blamed on Leo Fender, a guitar’s ____ arm is called a whammy bar
• Vocalist's vibration
• Lot more played for musical effect
• Effect of quavers on the score
• Unevenness in pitch? English right back has second look
• Quivering, let room in error
• Keeping activity under lids, to behold fluttering effect