1.   The sound is inaudible to the human ear.

2.   Those they use for navigation are so high-pitched that they are ultrasonic, far beyond the range of any human ear.

3.   Ultrasonic waves are at a higher pitch than the human ear can hear.

4.   Her voice kept rising,as if working its way out of the range of the human ear.

5.   So, the meter response to pressure change is just like a human ear?

6.   In other words the meter tries to reproduce the sort of listening qualities that a human ear would.

7.   Although some studies have suggested that shorter tubing may transmit better quality sound, the difference between the models is inaudible to the human ear, Ms. Penner said.

8.   And it is analog circuitry in the CD player that turns the digital code back into an electronic speaker signal that a human ear can hear.

9.   A certain degree of tonal anchoring was inevitable because the human ear demanded it.

10.   A microphone in the Pacific Ocean near Wake Island recorded a low, two-minute-long roar, too faint to be heard by human ears.