Speech and Electrophysiological outcomes.

<p>Speech and Electrophysiological outcomes.</p

Difference analyses and correlations with speech-scores.

<p>Difference analyses and correlations with speech-scores.</p

Schematic representation of the electrical interaction assessment method by eABR.

<p>Left: low-interaction case. The sum of the four eABR measures obtained from individual stimulations (red) equals the eABR obtained with the multi-electrode stimulation (blue), the MIC value tends to 1. Right: high-interaction case: the eABR amplitude obtained from the multi-electrode stimulation tends to equal that of one eABR measure in the individual recording, the MIC tends to rise and constitutes a metric of the electrical interaction.</p

Grand-averaged eABRs obtained in the multi- and individual-electrode conditions.

<p>Red: grand-averaged eABR (N = 16) obtained by summing the traces from the individual-electrodes recordings. Blue: grand-averaged eABR (N = 16) obtained from the same pulse-train, multi-electrodes stimulation. III: peak of wave-III. V: peak of wave-V.</p

Prognostic model of the speech recognition performance as a function of the electrical interaction measured by EABR.

<p>Individually calculated MIC values compared to VCV scores. Triangles: the eight low speech performing patients (VCV score < 40%). Circles the eight best performing patients (VCV scores > 40%). Orange curve: the decreasing exponential non-linear regression matching the data and following equation: <i>MIC</i> = 1 + 2.8<i>e</i>^{−0.04(<i>VCVscore</i>−6.25)}.</p

Subject demographics.

<p>Subject demographics.</p

Binaural Diplacusis and Its Relationship with Hearing-Threshold Asymmetry

<div><p>Binaural pitch diplacusis refers to a perceptual anomaly whereby the same sound is perceived as having a different pitch depending on whether it is presented in the left or the right ear. Results in the literature suggest that this phenomenon is more prevalent, and larger, in individuals with asymmetric hearing loss than in individuals with symmetric hearing. However, because studies devoted to this effect have thus far involved small samples, the prevalence of the effect, and its relationship with interaural asymmetries in hearing thresholds, remain unclear. In this study, psychometric functions for interaural pitch comparisons were measured in 55 subjects, including 12 normal-hearing and 43 hearing-impaired participants. Statistically significant pitch differences between the left and right ears were observed in normal-hearing participants, but the effect was usually small (less than 1.5/16 octave, or about 7%). For the hearing-impaired participants, statistically significant interaural pitch differences were found in about three-quarters of the cases. Moreover, for about half of these participants, the difference exceeded 1.5/16 octaves and, in some participants, was as large as or larger than 1/4 octave. This was the case even for the lowest frequency tested, 500 Hz. The pitch differences were weakly, but significantly, correlated with the difference in hearing thresholds between the two ears, such that larger threshold asymmetries were statistically associated with larger pitch differences. For the vast majority of the hearing-impaired participants, the direction of the pitch differences was such that pitch was perceived as higher on the side with the higher (i.e., ‘worse’) hearing thresholds than on the opposite side. These findings are difficult to reconcile with purely temporal models of pitch perception, but may be accounted for by place-based or spectrotemporal models.</p></div

Mean hearing loss as a function of frequency for the HI participants.

<p>Green: mean hearing loss for the ‘better’ ear; purple: mean pure-tone thresholds for the contralateral ear. Error bars show +/- 1 standard deviation (SD).</p

Example psychometric function fitted to data from one NH participant.

<p>For this example, the PSE shift was approximately equal to -1.7/16 octave (approximately 7.64%).</p

Mean PSE shifts for the NH group.

<p>Red: right ear; blue: left ear. Test frequencies are listed on the abscissa.</p