Diagnosis of Hearing loss
The ENT specialist will record the patient’s medical history, examine their ears using an otoscope or microscope (removing any wax, if necessary) and perform a hearing test.
The hearing test includes subjective and objective tests which provide data as to whether or not the patient has impaired hearing; if there is hearing loss, it also indicates what type, to what degree and the type of treatment required.
Tests used to diagnose Hearing loss
Subjective tests
These tests depend on the patient’s collaboration and the examiner’s expertise. They are used more than others because of the amount and quality of the information they provide.
Acoumetry. A set of tests and instruments used to examine hearing without the need for any electronic equipment. They are usually conducted with tuning forks. The most used tests are:
- Rinne test. This consists of comparing the patient’s perception of sound transmitted by air or bone conduction. On one hand, a tuning fork is vibrated and placed firmly on the patient’s mastoid bone (bone conduction). On the other hand, the ends of the tuning fork are then placed in the entrance of the external ear canal (air conduction). A comparison of the results from both conduction routes can identify the location of the lesion causing the hearing loss.
- Weber test. The Weber test is a quick hearing test used to detect unilateral conductive hearing loss (middle ear hearing loss) and unilateral sensorineural hearing loss (inner ear hearing loss). It is carried out by placing a tuning fork in front of the patient who must then state on which side they hear the sound.
Audiometry. Audiometry refers to hearing examination systems that use electronic devices. The instrument used in these tests is called an audiometer. It is basically a device that can emit the sounds required to study a person’s hearing.
- Pure tone audiometry. This test is used to measure the patient’s auditory acuity and locate the lesion. The patient’s hearing threshold (the volume at which they start hearing sounds) is detected at different frequencies (deep, intermediate and high-pitched tones), by means of both air (transmitting sounds along the external ear canal using earphones) and bone conduction (transmitting sounds through the mastoid using a bone vibrator). Each of these thresholds is recorded with a series of internationally recognised signs, giving rise to a graphic record called an audiogram.
- Speech audiometry. Speech audiometry uses lists of two syllable words instead of pure tones to assess the quality of the patient’s residual hearing.
Objective tests
These tests do not require the patient’s collaboration, so they can be carried out on babies:
- Otoacoustic emissions
- Impedancemetry
- Brainstem auditory evoked potentials
- Auditory steady-state evoked potentials
What is an audiometry?
Pure tone audiometry evaluates how well a patient’s hearing system functions and identifies if the section involving sound transmission is damaged or if the loss is related to the nervous system. This information helps determine the appropriate treatment.
Pure tone audiometry is carried out in an audiometric booth and with the aid of an audiometer. The audiometer emits acoustic signals at different sound pressure levels (volumes) and frequencies. The patient must press a button or lift their hand to tell the technician when they can hear the signal.
The test data are transferred to the audiogram. An audiogram is a graphic reproduction of the results from the pure tone audiometry test; it displays the patient’s hearing thresholds (the levels at which they start to hear the sounds). A pure tone audiometer expresses hearing thresholds in decibels hearing loss (dB HL) and uses a normal hearing threshold curve for reference (0 dB). An individual with thresholds above 20 dB has some degree of hearing loss or hypoacusis.
This test is usually carried out in two different ways: using air conduction, with the aid of earphones, or via bone conduction, by placing a bone vibrator behind the ear.
A comparison of the two means of conduction reveals more information about which part of the ear is responsible for the hearing loss (conductive, sensorineural or mixed hearing loss).
Speech audiometry tests are similar to pure tone audiometry, but the patient must listen and then repeat different words rather than listening to tones.
This test measures the patient’s speech perception threshold, which is an indication of their ability to hear and understand normal conversations.
Substantiated information by:
Published: 18 May 2018
Updated: 18 May 2018
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