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Re: Dear auditory list,
Dead regions in the cochlea have received a lot of attention in the last few years. The concept has been described extensively by Moore (e.g. Moore, 2001; Moore & Alcantara, 2001; Moore, 2004; Cairns, Frith, Munro, & Moore, 2007) and researched by Moore and others (e.g. Cairns et al, 2007; Scollie & Glista, 2007; Summers et al., 2003). A dead region refers to an area in the cochlea where the inner hair cells (IHCs) and/or neurons do not function (Moore & Alcantara, 2001). One phenomenon that has been associated with cochlear dead regions is off-frequency listening (Moore, 2001). Off-frequency listening has direct implications for conventional pure tone audiometry. If a tone is presented at a high enough intensity, the subject will respond that they heard it. This will result in false thresholds and, possibly, high amounts of gain in frequencies where dead regions are present. In order to identify the presence of dead regions, Moore developed the Threshold-Equalizing Noise (TEN) test. This test, calibrated in 2004 to dB HL, includes two steps. The first step involves finding the subject?s thresholds at from 250 to 4000 Hz using tones recorded on a CD (Moore, 2004). Following this, the clinician presents broadband TEN (HL) noise from the CD to the subject?s same ear and finds the masked threshold (Moore, 2004). The noise is presented at a constant level for all frequencies. The TEN (HL) noise is a kind of masking noise specially designed to prevent the upward and downward spread of activation of the basilar membrane that occurs when a high intensity tone is presented (Scollie & Glista, 2007). Essentially, the filtered noise occupies the area around the portion of the basilar membrane that the tone is activating, preventing the subject from engaging in off-frequency listening. If any masked threshold differs from the level of the noise by 10dB HL or more, a dead region is likely to be present. For a more comprehensive discussion of TEN (HL) test interpretation, please refer to Moore, B., Glasberg, B., & Stone, M. (2004). New version of the TEN test with calibrations in dB HL. Ear and Hearing, 25 (5), 478-487.
Navid Shahnaz, Ph.D., Aud. (C)
School of Audiology & Speech Sciences
Faculty of Medicine
University of British Columbia
5804 Fairview Ave., J. Mather Building
Vancouver, BC Canada V6T 1Z3
Tel. 604- 822-5953
From: AUDITORY - Research in Auditory Perception on behalf of lakshmi suresh
Sent: Wed 8/6/2008 4:01 AM
Subject: Dear auditory list,
I would be thankful if i could get information on TEN (threshold equalisation in noise) test and its clinical implications...
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