Related Clues:

• Warning to a chatty theatergoer
• 'Be quiet ...'
• Not the kind of money that talks?
• "Not a sound!"
• Sound of ''Silence!''
• 'Too loud!'
• Quiet son taking a couple of horses across America
• "Be still!"
• 'Keep quiet!'
• Where work piles up ... with a hint to this puzzle's theme
• Theatregoer's reproof
• 'Lower your voice!'
• "Lower your voice!"
• Hospital reminder, perhaps
• Stereotypical librarian admonition