Audiology and hearing-test interpretation

Overview & Definition

Picture the two-week-old baby who referred on the newborn hearing screen and has just arrived at the clinic, or the three-year-old whose nursery teacher worries he is not turning when his name is called. In both, the question is whether this child can hear well enough to acquire speech — and the audiological tests answer it by interrogating different parts of the hearing mechanism in turn. That is the territory this page owns. [1]

Audiology is the measurement of hearing, and in children it has to match the test to the age and to the part of the pathway in question. The pure-tone audiogram measures the softest sound the cochlea can detect at each frequency and gives the degree and type of loss. Tympanometry measures how the eardrum and middle ear move in response to a pressure change and tells you whether the middle ear is aerated, fluid-filled, or under negative pressure. Otoacoustic emissions (OAE) are the faint sounds generated by the cochlear outer hair cells that leak back out into the ear canal; they test the cochlea. The auditory brainstem response (ABR) is the electrical signature the auditory nerve and brainstem produce a few milliseconds after a click or tone, and it tests the whole pathway from cochlea to brainstem. [1] [5]

What makes paediatric audiology distinct from adult audiology is that the child usually cannot raise a hand to signal a threshold, so the tests divide into physiological measures that need no cooperation (OAE, ABR, tympanometry — used in newborns and infants) and behavioural measures that build cooperation by age (behavioural observation, visual reinforcement audiometry, play audiometry, then conventional pure-tone testing). The fellowship skill being tested is choosing the right test for the age, reading the pattern the tests produce together, and never being reassured by a single test that does not answer the whole question — above all, never accepting an OAE pass as proof of hearing in a child at risk of auditory neuropathy. [1] [11]