Historical clue formulations

• Vibrating effect — 2012-10-01
• Mandolin effect — 2010-03-20
• Voice lesson topic — 2006-11-25
• Singing effect — 2005-01-14
• Vibrating effect — 2004-03-09
• Relative of vibrato — 2002-11-17
• Organ device — 2001-09-08
• Organ effect — 1998-09-04
• Diva's device — 1997-04-24
• Vibrating effect — 1997-03-23
• Warbling — 1996-07-21
• Rapid repeat, in music — 1995-07-28