I. Behavioural tests
a) Pure-tone audiometry: This test measures the sensitivity of hearing. During the test, the participant will listen to a range of pure tones of different frequencies and gives behavioural response such as pressing a button or raising his/her hand. Hearing thresholds will then be plotted on a graph called audiogram (a graph showing intensity as a function of frequency).
b) Speech audiometry: This test uses speech instead of pure tones as stimuli. During the test, the participant will listen to speech material such as monosyllabic words, short phrases or sentences and repeats the stimuli as accurately as possible. Speech material in the test will be given at different volume to measure the participant’s speech recognition threshold (SRT). This test provides information on how well one recognises speech.
II. Non-behavioural / objective or physiological tests
a) Immittance Audiometry:
i) Tympanometry: This test is used to inspect middle-ear functioning including the mobility of the eardrum and the conduction of middle-ear ossicles (bones in the middle ear). During the test, an earplug will be placed into the participant’s ear. The device will change the air pressure in the ear canal and thus measure the energy transmission through the middle ear.
ii) Acoustic reflex test: When presented with a high-intensity sound stimulus, the stapedius and tensor tympani muscles of the ossicles in the middle ear contract. This is an involuntary muscle contraction that occurs in the middle ear in response to high-intensity sound stimuli. This test evaluates the middle ear function.
c) Otoacoustic emission test: Otoacoustic emissions refer to the low-intensity sound produced by the cochlea. This test examines cochlear status in the inner ear, specifically, the outer hair cell function.
d) Evoked auditory potentials: This test measures the brain wave activity that occurs in response to sound. The response is collected through electrodes placed on the participant’s scalp and earlobes. This test helps diagnose nervous system problems and hearing loss.