The relation between the degree of de-efferentation in the inner hair cell area and loss of afferent synapses (A) or ABR Wave 1 amplitude (B) is similar whether the de-efferentation is caused by OC lesion or by chronic conductive hearing loss.

<p>Data include all frequency regions from 8 to 45 kHz. Data are normalized to the mean value for age-matched controls at the appropriate frequency region. Wave 1 amplitudes (B) are extracted for stimulus levels from 60–80 dB SPL, as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0142341#pone.0142341.g003" target="_blank">Fig 3</a>. Data are not shown for <i>TMx ipsi</i> and <i>OM ipsi</i> groups since conductive hearing loss, <i>per se</i> profoundly decreases ABR amplitudes. Groups and group sizes are as defined in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0142341#pone.0142341.g002" target="_blank">Fig 2</a>. Key in A also applies to B.