Historical clue formulations

• Characteristic sound of Yoko Ono? — 2024-03-27
• Vowel sound at the end of 15- and 26-Across — 2022-04-12
• Opening opening? — 2020-12-13
• It appears in droves — 2006-05-11
• Vowel sound in "phone" and "home" — 2006-01-17