A pure tone is the sound of a single frequency. An audiometer is a device that generates pure tones and its frequency can be increased or decreased by 5Hz.
The threshold for air conduction (AC) of sound frequencies from 125-8000 Hz and the threshold for bone conduction (BC) of sound frequencies from 250-4000 Hz is measured and the result is plotted on an audiogram.
Normal thresholds:
For AC: 15dB
For BC: 25 dB
Uses of PTA:
-Confirms the type of hearing loss
-The exact degree of hearing loss can be measured and a record can be kept permanently
-It helps to measure the degree of handicap for medico-legal purposes
-It is used for the prescription of hearing aid
-It helps to predict speech reception threshold