A: Why not accompany your cheery chanteuse on improvised office-supply instruments? Or shout out requests? ("Do you know 'The Road to El Dorado?' " "Yes, shall I sing it?" "No — take it.")
Seriously, as the manager, you're in a position to ground this songbird with repeated, increasingly firm reminders to pipe down. You're also in a position to propose adjusting that open-door policy so your workers can shut out — or in — distracting sounds.
Karla L. Miller writes an advice column on navigating the modern workplace. Each week she will answer one or two questions from readers. Miller has written for and edited tax publications for 16 years, most recently for the accounting firm KPMG's Washington National Tax office.