Diagnosis and testing

An audiologist carries out a range of tests on adults and children to determine the presence, nature and extent of hearing loss and balance disorders, enabling accurate clinical diagnosis in a range of hearing related conditions. They quantify and qualify hearing in terms of the degree, the type and the configuration of the hearing loss.

Patients referred for evaluation, diagnosis and/or treatment receive a test battery that includes pure tone audiometry and/or immittance testing. When diagnostically indicated, further testing could include stapedial reflex thresholds and decay, speech audiometry and otoacoustic emissions. The extent of hearing loss and psychosocial disposition will determine further habilitation options (eg referral for hearing therapy).

Anatomy of the ear

Pure tone audiometry (PTA)

This test assesses your hearing sensitivity across a range of frequencies (pitches), which are involved in speech perception. It involves listening to sounds via headphones and responding by pressing a button every time a sound is heard. It usually takes approximately 20 minutes to complete. Audiologists quantify and qualify hearing in terms of the degree of hearing loss, the type of hearing loss and the configuration of the hearing loss.

With regard to degree of hearing loss, the audiologist is looking for quantitative information. Hearing levels are expressed in decibels (dB) based on the pure tone average for the frequencies 250 to 8000 Hz and discussed using descriptors related to severity:

  • normal hearing (up to 20 dB HL)
  • mild hearing loss (21 to 40 dB HL)
  • moderate hearing loss (41 to 70 dB HL)
  • severe hearing loss (71 to 95 dB HL)
  • profound hearing loss (95 dB HL or greater).

With regard to the configuration of the hearing loss, the audiologist is looking at qualitative attributes such as:

  • bilateral (both ears) versus unilateral (one ear)hearing loss
  • symmetrical (same level/severity of hearing loss in both ears) versus asymmetrical hearing loss (different levels/severity of hearing loss in each ear)
  • high-frequency/pitched versus low frequency/pitched hearing loss
  • progressive versus sudden hearing loss
  • stable versus fluctuating hearing loss.

After assessment/diagnostic procedures are complete, the option of hearing aid amplification is discussed with the patient if necessary. The final decision as to the type of hearing aid fitted is based on an audiological assessment of the patient’s individual suitability.

Tympanometry and stapedial reflexes (immitance testing)

This is a quick objective test used to assess middle ear function. It involves placing small plugs in the ears which record middle ear pressure. This may include listening to some loud noises for a few minutes in order to measure the reflex of the muscles in the middle ear.

Speech audiometry

This is a diagnostic test that assesses speech discrimination using single words. It involves listening to words and repeating what was heard to the audiologist who records the results. It takes approximately 30 minutes to complete.

Types of Hearing Loss

With regard to the type of hearing loss, the audiologist is looking for information that suggests the point in the auditory system where the loss is occurring (the origin/source of the problem). The loss may be:


A conductive hearing loss is one that affects the structures that conduct the sound to the inner ear – this includes both the middle and outer ear. Common causes of conductive hearing loss are, wax build up, fluid or infection in the middle ear, ruptured/perforated eardrum or damage to the middle ear bones. Many cases of conductive hearing loss are treated by ENT consultants. Wax and fluid build-up are easily removed, an infection can be treated with antibiotics, a ruptured eardrum can be patched and damaged middle ear bones can be replaced or reconstructed in surgical procedures.

Sensori-neural (SNHL)

This type of hearing loss is due to damage to the pathway that sound impulses take from the hair cells of the inner ear to the auditory nerve and the brain. Possible causes of SNHL are:

  • Age-related hearing loss (presbycusis). This is the natural decline in hearing that many people experience as they get older. It’s partly due to the loss of hair cells in the cochlea (hearing organ in the inner ear).
  • Acoustic trauma (injury caused by loud noise) can damage hair cells.
  • Certain viral or bacterial infections such as mumps or meningitis can lead to loss of hair cells or other damage to the auditory nerve.
  • Menière’s disease, which causes dizziness, tinnitus, and hearing loss.
  • Certain drugs, such as some powerful antibiotics, can cause permanent hearing loss. At high doses, aspirin is thought to cause temporary tinnitus – a ringing in the ears. The antimalarial drug quinine can also cause tinnitus, but it’s not thought to cause permanent damage.
  • Acoustic neuroma. This is a benign (non-cancerous) tumour that can compress the auditory nerve. It needs to be observed by an ENT consultant and is sometimes treated with surgery.
  • Other neurological (affecting the brain or nervous system) conditions such as multiple sclerosis, stroke, or a brain tumour
Mixed hearing loss

The term mixed hearing loss is used to describe a hearing loss that is a combination of conductive and sensori-neural loss – in other words affecting both the outer/middle and inner ear.

Sensory versus neural hearing loss

Sensory hearing loss originates in the inner ear and neural hearing loss originates from structures or systems beyond the inner ear (eg the auditory nerve or the central nervous system).