Sound is described in terms of
frequency and intensity. Your hearing threshold is how loud the sound of a
certain frequency must be for you to hear it.
Frequency, or pitch (whether a sound is low or
high), is measured in vibrations per second, or hertz (Hz). The human ear can
normally hear frequencies from a very low rumble of 16 Hz to a high-pitched
whine of 20,000 Hz. The frequencies of normal conversations in a quiet place
are 500 Hz to 2,000 Hz.
Intensity, or loudness, is measured in
decibels (dB). The normal range (threshold or lower limit) of hearing is 0 dB to
25 dB. For children, the normal range is 0 dB to 15 dB. Normal results show that
you hear within these ranges in both ears.
The following table relates how loud a sound must be for a
person to hear it (hearing thresholds) to the degree of hearing loss for
Hearing loss table
Hearing threshold in
Degree of hearing
Ability to hear
Difficulty with faint or
Difficulty with conversational
Speech must be loud;
difficulty with group conversation
Difficulty with loud speech;
understands only shouted or amplified speech
May not understand amplified
What Affects the Test
Reasons you may not be able to
have the test or why the results may not be helpful include:
Being unable to cooperate, follow directions,
and understand speech well enough to respond during most tests. It may be
difficult to conduct hearing tests on young children or on people who have
physical or mental disabilities.
Equipment problems, such as
cracked or poorly fitting headphones or an uncalibrated audiometer, or
Difficulty speaking or understanding the language
of the tester.
A recent cold or ear infection.
around loud noises within 16 hours before the test.
What To Think About
Other types of tests may be used to evaluate
hearing. These tests include:
Acoustic immittance testing (tympanometry
and acoustic reflex testing). This 2- to 3-minute test measures how well
the eardrum moves in response to sound. The soft tip of a small instrument is inserted
into the ear canal and adjusted to achieve a tight seal. Sound and air pressure
are then directed toward the eardrum. The test is not painful, but slight
changes in pressure may be felt or the tone may be
Vestibular tests (falling and past-pointing tests). These
tests can detect problems with areas of the inner ear that help control balance
and coordination. During these tests, the person tries to maintain balance and
coordination while moving the arms and legs in certain ways, standing on one
foot, standing heel-to-toe, and performing other maneuvers with the eyes open
and closed. The health professional will protect the person from falling, and
no special preparation is needed.