acoustic reflex
Involuntary middle ear muscle contraction in response to loud sounds, measured during impedance testing.
Full Definition
The acoustic reflex is a protective mechanism where the stapedius muscle contracts bilaterally when exposed to sounds typically above 70-90 dB HL, stiffening the middle ear system to reduce sound transmission. This reflex can be measured ipsilaterally (same ear) or contralaterally (opposite ear) during tympanometry testing. Acoustic reflex thresholds and decay patterns provide diagnostic information about retrocochlear pathology, facial nerve function, and middle ear disorders. Absent or elevated acoustic reflexes may indicate sensorineural hearing loss, middle ear pathology, or neurological conditions affecting the brainstem reflex arc.
Usage
Usage note: Do not confuse with 'acoustic reflex threshold' or 'acoustic reflex decay' - these are specific measurements of the reflex.
In Context
- "Acoustic reflex testing showed absent responses bilaterally, suggesting significant hearing loss." — Audiological evaluation report
- "Positive acoustic reflex decay indicates possible retrocochlear pathology requiring further investigation." — Diagnostic interpretation guidelines