In impedance audiometry, acoustic reflex decay (ARD) test is performed at 500 Hz and 1000 Hz. A positive ARD test (decay >50% within 10 seconds at 10 dB above reflex threshold) is most consistent with:

• A Otosclerosis affecting the stapes footplate
• B Retrocochlear pathology (acoustic neuroma or CN VIII lesion) ✓
• C Cochlear sensorineural hearing loss with recruitment
• D Secretory otitis media with effusion

Explanation

Acoustic reflex decay occurs when the reflex amplitude declines by more than 50% in 10 seconds at a tone presented 10 dB above reflex threshold at 500 Hz or 1000 Hz. This adaptation failure indicates retrocochlear (VIII nerve or auditory brainstem) pathology such as acoustic neuroma or demyelinating lesions. Cochlear SNHL shows absence of decay. Otosclerosis and middle ear effusion affect the reflex threshold or cause absence of reflexes but not decay.

Reference: Dhingra Diseases of Ear, Nose and Throat, 7th ed.

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Written and medically reviewed by the StethoPrep medical team.