PURE TONE AUDIOMETRY
Definition: This test gives a qualitative and quantitative analysis of patients hearing. The frequency range tested in 125 Hz to 8000 Hz.
Aims of audiometry:
- Analysis of the patients hearing loss. (conductive hearing loss, sensorineural hearing loss or mixed).
- For pre-operative and post-operative evaluation.
- Medico-legal purposes.
- For prescription of hearing aid.
- In malingering patients.
- The intensity of sound raised above the normal level is directly proportional to the degree of hearing loss.
- The bone conduction hearing is indicative of cochlear function.
- The difference between the thresholds of air and bone conduction is a measure of conductive hearing loss.
- The audiometer is calibrated such that a normal person would have an air bone gap within 20db with bone conduction higher than air conduction.
- Sensorineural hearing loss shows reduction in threshold of both bone conduction and air conduction.