21.   The voice was audible to the increasingly drowsy reporters listening to Selig and Fehr drone on.

22.   The anti-burglary system transmits ultrasonic waves, not audible to human ear, to detect the movement of an object.

23.   The signal is so high-pitched it is not audible to humans.

24.   The system tranmits ultrasonic waves, not audible to the human ear, to detect the movement of an object.

25.   Saudia has said the instructions of Indian air traffic controllers to its jumbo to maintain a particular altitude had not been audible to the pilots of the Boeing.

26.   She said the office of the French advisor in the camp was close enough that the screams would have been audible to him.

27.   The exchange, not clearly audible to most people in the room, was at first greeted with amusement.

28.   The exchange, not clearly audible to most people in the room, was greeted with amusement.