The hearing range of the human ear is:

CONCEPT

Frequency is the number of vibrations per second and is measured in hertz (Hz). A hearing range is described by the lowest and highest frequencies that an ear can ordinarily detect at sufficient sound intensity.

The conventional reference limits for a healthy young human are about 20 Hz and 20 kHz; sensitivity near these limits varies with age, hearing health, and sound level.

APPLICATION

1. Convert the upper limit to the unit used in the choices: 20 kHz = 20 × 1,000 Hz = 20,000 Hz.

2. Therefore, the interval formed by the conventional lower and upper limits is 20 Hz to 20,000 Hz.

CONTRAST

• Frequencies below 20 Hz are called infrasound, so they describe a region below the lower limit rather than the full interval.

• Frequencies above 20,000 Hz are called ultrasound, so they describe a region above the upper limit rather than the full interval.

• Only one listed interval uses both conventional limits, so the statement “More than one of the above” does not apply.

• A matching interval is listed, so the statement “None of the above” does not apply.

CROSS-CHECK

The lower boundary separates audible sound from infrasound, and the upper boundary separates audible sound from ultrasound. Thus both boundary checks give the same interval.

Result: 20 Hz to 20,000 Hz.