The masked threshold to noise ratio in brainstem electric response audiometry: assessment of the conductive loss component by bone-conducted masking.

The aim of this study was to assess the conductive loss component (CLC) by brainstem electric response audiometry. A bone-conducted noise was used to mask out the response to a conventional air-conducted click stimulus. The difference between the levels of the click and the noise is defined as the masked threshold to noise ratio (MTNR). This MTNR was determined for 21 normal ears (MTNR = -13 +/- 5 dB). The increase in MTNR compared to this normative value is a measure of the CLC. For 10 ears with an artificially induced purely conductive loss, the increase in MTNR is in good agreement with the results of conventional pure-tone and brainstem electric response audiometry.