What is an acoustic reflex measurement?
Just like tympanometry measurements, a probe is inserted into the ear canal. While playing a continues probe tone, short test signals (e.g. 0.5, 1 or 2kHz) are presented at levels of 70 - 100dB, triggering the stapes muscle to contract.
Through this contraction, the ossicular chain and ear drum stiffens as well, leading to a measurable decrease of compliance in the ear canal. The acoustic reflex is measurable in both ears (ipsilateral and contralateral).
Why measure acoustic reflexes?
Acoustic reflexes are regularly used in audiological testing and measure the stapedius and the tensor tympani reflex generated eardrum movement in response to intense sound. Acoustic reflex measurements provide feedback on:
- Type and degree of hearing loss (conductive, sensory, neural)
- Injury of the facial nerve or vestibulocochlear nerve
- Otosclerosis
What is a tympanometer?
A tympanometer is an instrument that measures the pathology of the middle ear, including the ear drum. It is often referred to as a middle ear analyser, impedance or admittance meter, as the so-called tympanometry measurement is only one part of the entire middle ear assessment. Further tests include measurement of the interaural muscles (acoustic reflex, decay and latency tests) as well as eustachian tube tests.