Clinical Case · Clinician

A surprising low-frequency response at very high intensity

Vignette

During ASSR testing of a child with a profound loss, an apparent response is detected at 500 Hz at 115 dB HL, while no response is seen at 2000 or 4000 Hz at any tested level. The clinician repeats the 500 Hz measurement with alternating stimulus polarity, and the response disappears.

Audiogram

-10020406080100120500 Hz1k Hz2k Hz4k HzHearing level (dB HL)
O Right earX Left ear
Estimated thresholds by ear. O = right, X = left.

ASSR finding

An apparent 500 Hz response at very high intensity that vanishes when stimulus polarity is alternated, with no responses at the higher carriers.

Diagnostic question

How should the original 500 Hz 'response' be interpreted?