Related Clues:

• Sound at the door
• Sound of repeated light hitting
• Typist's sound
• Selectric sound
• Repeated knocks make Irish twins retreat
• Typing sound
• 'I'm waiting ... '
• "I'm waiting ... "
• [Is this thing on?]
• [Testing, testing]
• Sound check sound
• Mic check noise
• Mic-testing sound
• [Is this microphone working?]