Welch Allyn Audioscope 3 Portable Screening Audiometer - User Manual - Manual (Page 7)

5
AudioScope 3 –
Intr
oduction
TRADITIONAL HEARING TESTING
Tuning forks were one of the first methods used to determine the
type of hearing loss. They may still be used by some to differenti-
ate between conductive and sensorineural losses. However, they
have in great part been replaced by the audiometer.
Traditional audiometers produce pure tones of varying frequency
and intensity. Frequency is measured in Hertz (Hz) or cycles per
second, and is perceived as pitch. Human hearing ranges from
approximately 20 to 20,000 Hz. Intensity is measured in decibels
(dB) and is perceived as loudness.
Most often, hearing is measured by specialists in terms of thresh-
old, or the faintest sound which an average listener can just hear in
the quiet. Thresholds are measured at various frequencies, usually
in the speech range (500 Hz to 4000 Hz) and just beyond (125 Hz
to 8000 Hz).
The magnitude or degree of loss is recorded on a form called an
audiogram shown on Table 1 (p. 6).
Measurements are made by air conduction, where the sound is
introduced through a headphone into the ear. Measurements may
also be made by bone conduction, where the sound is introduced
through a vibrator which is placed on the mastoid bone behind the
ear. By comparing these two measurements, the type of loss (con-
ductive, sensorineural or mixed), can be determined.
WANM-3999-COL AudioScope3 3/11/97 1:23 PM Page 5