Low variable rate stimulation strategy for cochlear implants using temporal cues and electrophysiological factors

Article type: Research Article

Authors: Zarei, Elham^a | Sadjedi, Hamed^{b; *} | Farhadi, Mohammad^c

Affiliations: [a] Department of Biomedical Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran | [b] Engineering Faculty, Shahed University, Tehran, Iran | [c] ENT and Head & Neck Research Center and Department, Hazrat Rasoul Akram Hospital, Iran University of Medical Sciences, Tehran, Iran

Correspondence: [*] Corresponding author: Hamed Sadjedi, Engineering Faculty, Shahed University, Persian Gulf Highway, Tehran, Iran. Tel.: +98 215121 2048; E-mail: [email protected].

Abstract: BACKGROUND: The performance of a cochlear implant (CI), especially in conveying pitch depends on its electrical stimulation strategy. OBJECTIVE: The present study proposes a variable-rate stimulation algorithm which improves speech emotion perception by using temporal fine-structure cues and electrophysiological parameters of the patient. METHODS: This method is based on the coding of the phase information at the peak time intervals of the band-passed signals. The stimulation pulse is generated at the time of peak occurrence, which is able to excite the number of fibers with a discharge probability above a threshold. Calculating the discharge probability is based on the excitable fiber model and taking into account the biological characteristics of the patient, such as the fiber threshold and the distribution of remaining intact fibers. RESULTS: The results of the emotion detection test on selective reconstructed sentences from the Persian emotional speech database (Persian ESD) indicated that the listeners have been able to detect the emotion by an average of 83.82% using the proposed stimulation algorithm while it was 75% and 48.03% for the zero-crossing and the continuous interleaved sampling (CIS), respectively. Furthermore, the number of pulses compared to the zero-crossing and the CIS has decreased by 76.3% and 75.4%, respectively. CONCLUSIONS: In this paper, a stimulation method was proposed for cochlear implants by considering the patient’s biological parameters. It has been successful in transmitting speech emotion despite the reduction of stimulating pulses. This has some advantages such as reducing the interaction of current fields between electrodes during stimulation and reducing battery usage.

Keywords: Cochlear implant, electrical stimulation, excitable nerve fiber, voice pitch frequency, emotion detection

DOI: 10.3233/THC-171154

Journal: Technology and Health Care, vol. 26, no. 6, pp. 879-888, 2018