Possible Clues:

• White sounds
• Plunk/thunk
• Sound as if one is in what 10 across are in
• One is in the snouts, or so one hears
• They break the silence
• 116-Across and others
• 15-Across ingredients
• By the sound of them, I may be found in what are to be found on the face of it
• One is in them on the face of it, by the sound of them
• Hiss and hum