Tympanometry is a non-invasive hearing test that assesses the health and function of the middle ear. It involves a small probe placed in the ear canal, which varies air pressure to measure how effective sound energy is transmitted via the middle ear into the cochlea. This helps identify issues like fluid behind the eardrum or problems with the ossicles. Tympanometry is crucial in diagnosing various ear conditions and guiding appropriate treatment.

The acoustic reflex is an involuntary contraction of the stapedial muscle in response to loud sounds. When the stapedial muscle contracts, it stiffens the ossicles and tympanic membrane decreasing admittance, or the absorption of sound. This stiffening can be measured in the same way as during tympanometry. During ART testing, loud sounds (70 – 115 dB), typically presented at 500, 1000, 2000, and at times 4000 Hz are introduced into the ear alongside a constant probe tone. These loud sounds induce the acoustic reflex while the probe tone detects the contraction.

Acoustic reflex decay testing is performed nearly identically to acoustic reflex threshold testing but evaluates the maintenance of the reflex contraction over time. ARD testing is useful in differentiating between cochlear and retrocochlear losses, as the reflex will often weaken during continuous stimulation in retrocochlear pathologies. During ARD testing, a tone is presented typically at 500 and 1000 Hz above the patient’s threshold at that frequency. The tone is presented for 10 seconds as the reflex contraction is measured.