Possible Clues:

• 'Uh ... excuse me'
• 'Um, I'm trying to talk here ...'
• Faux cough
• ''Um, excuse me . . .''
• 'By the sound of it, a clearance for a border (4)'
• ''May I speak?''
• Throaty "beg pardon . . ."
• Sound of a clearance for a border
• ''Um . . . excuse me''
• Throaty cousin of "psst!"