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<p class="MsoNormal">Dear list<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">We have obtained an odd asymmetric auditory ERP. Does anyone have an explanation? Any suggestions would be welcome.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">We recorded ERPs to pure tone beeps of 500 and 3000 Hz at 3 intensity levels. Tones were randomised and played separately to left and right ears, with responses recorded at Cz with a nose tip reference using a Neuroscan system. Insert headphones
were calibrated before testing and re-checked after; left and right headphones provide identical levels of output. Participants were 58 older people (mean age 70 years) with age-related hearing loss (Mean HL of 45 dB at 2kHz). Selection criteria included symmetrical
hearing (not greater than 15dB difference at any frequency), and overall mean HL is symmetrical.
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Grand mean ERPs are higher in amplitude for tones played to left ear compared to right ear (by about ~1uV for N1 and ~.5uV for P2), and this is a consistent pattern among participants. Latencies are similar. I would have thought amplitudes
should also be very similar between left and right ear. What is happening here?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thanks for your help<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:navy">Piers Dawes PhD<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:navy">Audiology and Deafness Research Group<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:navy">School of Psychological Sciences<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:navy">Ellen Wilkinson Building<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:navy">University of Manchester<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:navy">Manchester M13 9PL<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:navy">Tel: +44 (0)161 30 61758</span><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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