The sound sensation of a pure tone in cochlear implant recipients with single-sided deafness

Abstract

Ten cochlear implant (CI) users with single-sided deafness were asked to vary the parameters of an acoustic sound played to their contralateral ear to characterize the perception evoked by a pure tone played through the direct audio input of their CI. Two frequencies, centered on an apical and a medial electrode, were tested. In six subjects, the electrode positions were estimated on CT scans. The study was divided in 3 experiments in which the parameters of the acoustic sound varied. The listeners had to vary the frequency of a pure tone (Exp.1), the center frequency and the bandwidth of a filter applied to a harmonic complex sound (Exp.2), and the frequency of the components and the inharmonicity factor of a complex sound (Exp.3). Two testing sessions were performed at 3 and 12 months after activation. The mean results of Exp. 1 showed that the frequency of the matched tone was significantly lower for the apical than for the medial stimulus. In Exp.2, the mean center frequencies of the filters were also significantly lower for the apical than for the medial stimulus. As this parameter modifies the energy ratio between the high and low-frequency components, this result suggests that the medial stimulus was perceived with a brighter timbre than the apical stimulus. In Exp.3, the mean frequencies of the components were not significantly different between the sounds resulting from the stimulation of the two electrodes, but were significantly lower at the12-month session compared to the 3-month visit. These results suggest that a change in place of excitation may be perceived as a change in timbre rather than a change in pitch, and that an effect of adaptation can be observed.

Interaural Place-of-Stimulation Mismatch Estimates Using CT Scans and Binaural Perception, But Not Pitch, Are Consistent in Cochlear-Implant Users

“…The literature is mixed regarding the question of CI pitch plasticity. Some studies have shown pitch perception to shift toward the sound-processor frequency allocation (Reiss et al, 2014;Hu and Dietz, 2015;Tan et al, 2017), and others have not (Schatzer et al, 2014;Aronoff et al, 2016;Marozeau et al, 2020). One possible reason for the disparate results is that the procedures (Jensen et al, 2021) and stimuli (Adel et al, 2019) used have a large impact on the observed results, questioning whether these measurements reflect place of stimulation.…”

Interaural place-of-stimulation mismatch estimates using CT scans and binaural perception, but not pitch, are consistent in cochlear-implant users

“…Some studies have shown plasticity toward clinical CFs (Reiss et al, 2014;Hu and Dietz, 2015;Tan et al, 2017) while others have shown little such evidence. For example, Aronoff et al (2016) found that BI-CI pitch matches often deviate from numbermatched electrodes, while Schatzer et al (2014) and Marozeau et al (2020) found that SSD-CI pitch matches align more closely with radiographic estimates of electrode position than with clinical CFs.…”

Temporal Cues in the Judgment of Music Emotion for Normal and Cochlear Implant Listeners

“…A speech vocoder is a valuable tool for studying speech perception in CI listeners as it simulates speech performance of CI listeners with NH listeners. Although there is a common misconception that listening through a vocoder is equivalent to listening through a CI, several studies have shown that this is not the case ( Karoui et al, 2019 ; Marozeau et al, 2020 ).…”