Condition · Cochlear

Cochlear Hearing Loss

Sensorineural loss with recruitment — reflex at reduced sensation level

The reflex survives a surprising amount of loss

For cochlear losses up to roughly 50 dB HL, the acoustic reflex threshold stays within normal limits. As the loss grows beyond this, reflex thresholds elevate and eventually become absent — typically once the loss exceeds about 80 dB HL.

Recruitment and the Metz test

The Metz test compares the reflex threshold to the pure-tone threshold. When the reflex appears within 60 dB of the pure-tone threshold (a reduced sensation level), recruitment is implied, supporting a cochlear site of lesion.

The reflex signature

Stim. Right
Stim. Left
Probe Right
Present
95 dB HL
Present
90 dB HL
Probe Left
Present
100 dB HL
Present
100 dB HL
The characteristic four-cell grid for this condition.

Reflexes are present but the sensation level is reduced — the reflex appears close to the raised pure-tone threshold, a positive Metz sign.

Reflex decay

0s2s4s6s8s10s0%50%100%50% criterion
Negative (normal) decay — amplitude is well maintained across the 10-second hold. Reflex decay is normal (absent) in pure cochlear loss; abnormal decay points away from a cochlear site.

Pure-tone audiogram

0204060801002505001k2k4k8kFrequency (Hz)Hearing level (dB HL)
○ Right ear✕ Left ear
Symmetric mild-to-moderate sloping sensorineural loss with no air–bone gap.

Frequencies plotted: 250, 500, 1k, 2k, 4k, 8k Hz.

References for this page

  1. Silman S, Gelfand SA (1981). The relationship between magnitude of hearing loss and acoustic reflex threshold levels. Journal of Speech and Hearing Disorders, 46(3), 312–316.
  2. Gelfand SA, Schwander T, Silman S (1990). Acoustic reflex thresholds in normal and cochlear-impaired ears: Effects of no-response rates on 90th percentiles in a large sample. Journal of Speech and Hearing Disorders, 55(2), 198–205.
  3. Metz O (1952). Threshold of reflex contractions of muscles of middle ear and recruitment of loudness. Archives of Otolaryngology, 55(5), 536–543.
  4. Katz J (Ed.) (2015). Handbook of Clinical Audiology (7th ed.). Wolters Kluwer, Philadelphia.
Want to contrast this with another condition? The comparison tool places any two reflex signatures side by side.