Related Clues:

• You'll hear it again
• Sound reduced by carpeting
• Navigation aid for a bat
• What comes after Delta in the NATO phonetic alphabet
• Parrot's speech offensive to some extent
• Sound effect used by bats
• Rebound, as sound
• Unoriginal voice
• Ring section from multiple choice
• Tail removed from genuine old parrot
• Sign of hollowness
• Copy held in Czech observatory
• Sound in a tunnel
• Bat's navigational signal
• E, to NATO