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Steeply sloping high-frequency hearing loss is often associated with cochlear dead regions. These can be identified by measuring pure-tone thresholds in quiet and in Threshold-Equalising Noise (TEN). However, many patients cannot be adequately tested because the low frequencies in the TEN lead to uncomfortable loudness. We investigated the effect of high-pass filtering on the TEN-test results and the loudness of the TEN. Twenty-four normally hearing subjects and 35 subjects with steeply sloping high-frequency hearing loss were tested, using the standard TEN (TENs), and TEN high-pass filtered at 0.5 kHz (TEN0.5) or 1 kHz (TEN1). For both groups, masked thresholds did not differ across noise types for frequencies above 1 kHz. Over 50% of the hearing-impaired ears tested met the criteria for a dead region at 4 kHz, using all three noise types. However, masked thresholds and the prevalence of positive TEN-test results at 1 kHz were both lower with the TEN1. The TEN1 was judged the most comfortable noise by 68% of the hearing-impaired subjects. We conclude that high-pass filtering would allow testing at higher TEN levels for patients with steeply sloping hearing loss. © 2006 British Society of Audiology, International Society of Audiology, and Nordic Audiological Society., SCOPUS: ar.j, info:eu-repo/semantics/published

Click-evoked otoacoustic emissions (CEOAEs) may be reduced in amplitude by the presentation of “suppressor” clicks that either closely lead or follow the stimulus (“test”) clicks. This “click suppression” represents nonlinear temporal interaction between the test and suppressor clicks and/or the CEOAEs they evoke. Such suppression has not previously been studied in detail and the mechanisms giving rise to it are not understood. In particular, it is unclear whether click suppression may simply reflect the compressive nonlinearity of the CEOAE level function. It is also unclear whether the larger magnitude “rate suppression” observed in CEOAEs measured using streams of clicks at very high rates may be explained by a simple additive accumulation of click suppression. The present study addresses these questions by detailed measurement of this suppression phenomenon in 20 normal adult ears, and establishes that: 1. Maximum suppression is generally obtained for suppressors presented up to 4 ms in advance of test clicks, contrary to expectation. 2. Suppression by suppressors that lead test clicks does not simply reflect CEOAE level function nonlinearity. It may, instead, arise from disturbance of the generator elements from their resting state prior to generation of the CEOAE. 3. Suppression by following suppressors behaves markedly differently from that by leading suppressors, and appears more closely related to level function nonlinearity. 4. Contrary to previous suggestions, suppression for both leading and following suppressors is insensitive to polarities of test and suppressor clicks. 5. Suppression does not accumulate in a simple, additive manner as has previously been suggested. Consequently, a more complex mechanism underpins the greater magnitude of rate suppression. The parametric characterisation of click suppression presented may

Click-evoked otoacoustic emissions (CEOAEs) may be reduced in amplitude by the presentation of “suppressor” clicks that either closely lead or follow the stimulus (“test”) clicks. This “click suppression” represents nonlinear temporal interaction between the test and suppressor clicks and/or the CEOAEs they evoke. Such suppression has not previously been studied in detail and the mechanisms giving rise to it are not understood. In particular, it is unclear whether click suppression may simply reflect the compressive nonlinearity of the CEOAE level function. It is also unclear whether the larger magnitude “rate suppression” observed in CEOAEs measured using streams of clicks at very high rates may be explained by a simple additive accumulation of click suppression. The present study addresses these questions by detailed measurement of this suppression phenomenon in 20 normal adult ears, and establishes that: 1. Maximum suppression is generally obtained for suppressors presented up to 4 ms in advance of test clicks, contrary to expectation. 2. Suppression by suppressors that lead test clicks does not simply reflect CEOAE level function nonlinearity. It may, instead, arise from disturbance of the generator elements from their resting state prior to generation of the CEOAE. 3. Suppression by following suppressors behaves markedly differently from that by leading suppressors, and appears more closely related to level function nonlinearity. 4. Contrary to previous suggestions, suppression for both leading and following suppressors is insensitive to polarities of test and suppressor clicks. 5. Suppression does not accumulate in a simple, additive manner as has previously been suggested. Consequently, a more complex mechanism underpins the greater magnitude of rate suppression. The parametric characterisation of click suppression presented may