Condition · Central / brainstem

Hyperacusis

Reduced loudness tolerance — reflexes typically present, sometimes at lower levels

A problem of loudness tolerance

Hyperacusis is reduced tolerance to ordinary environmental sound, often with normal pure-tone thresholds. The acoustic reflex is generally present; some patients show reflex thresholds at the lower end of, or slightly below, the normal range, in keeping with altered central loudness processing.

The reflex signature

Stim. Right
Stim. Left
Probe Right
Present
75 dB HL
Present
80 dB HL
Probe Left
Present
80 dB HL
Present
75 dB HL
The characteristic four-cell grid for this condition.

A normal grid, with thresholds toward the lower end of the normal band in some patients.

Reflex decay

0s2s4s6s8s10s0%50%100%50% criterion
Negative (normal) decay — amplitude is well maintained across the 10-second hold. Decay is normal; hyperacusis is a disorder of loudness perception rather than of reflex sustainability.

Pure-tone audiogram

0204060801002505001k2k4k8kFrequency (Hz)Hearing level (dB HL)
○ Right ear✕ Left ear
Pure-tone hearing is characteristically normal — the difficulty is loudness tolerance, not sensitivity.

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

References for this page

  1. Baguley DM (2003). Hyperacusis. Journal of the Royal Society of Medicine, 96(12), 582–585.
  2. Borg E (1973). On the neuronal organization of the acoustic middle ear reflex. A physiological and anatomical study. Brain Research, 49(1), 101–123.
  3. Katz J (Ed.) (2015). Handbook of Clinical Audiology (7th ed.). Wolters Kluwer, Philadelphia.
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