Previous research has demonstrated the negligible impact of harmonicity on English speech perception for normal hearing (NH) listeners inquiet environments. This study aims to bridge the gap in understanding the role of harmonicity in Mandarin speech perception for cochlear implant (CI) users. Speech perception inquiet was tested in both CI simulation group and actual CI user group using harmonic and inharmonic Mandarin speech. Furthermore, speech-on-speech perception was tested in NH, CI simulation, and actual CI user groups. For speech perception in quiet, results show that, compared to harmonic speech, inharmonic speech decreased the mean recognition rate for both actual CI user and CI simulation groups by about 10 percentage points. For speech-on-speech perception, all groups (i.e., NH, CI simulation, and actual CI user) performed worse with inharmonic stimuli compared to harmonic stimuli. The findings of this study, along with previous studies in NH listeners, indicate that harmonicity aids target speech recognition for NH listeners in speech-on-speech conditions but not speech perception inquiet. In contrast, harmonicity plays an important role in CI users' Mandarin speech recognition in both quiet and speech-on-speech conditions. However, under speech-on-speech conditions, CI users could only understand target speech at positive SNRs (often > 5 dB), suggesting that their performance depends on the intelligibility of the target speech. The contribution of harmonicity to masking release in CI users remains unclear.

Cochlear implant (CI) recipients face great challenges in speech-in-noise recognition, partially due to the fact that only temporal envelopes from a limited number of bands are preserved in most CI signal processing strategies. In "n-of -m " strategies (e.g., the Advanced Combinational Encoder, ACE), the number of maxima (nmax) and elec-trical dynamic range (EDR) are two essential parameters that may affect the envelope representation and further influence speech perception. Speech recognition can be improved by optimizing parameter settings in CI pro-gramming. To investigate the effects of nmax and EDR on speech-in-noise perception, Mandarin speech reception thresholds (SRTs) in babble noise were measured in CI recipients using ACE. The nmax was set to 2, 4, 6, 8, and 16. The EDR was set to the base EDR (i.e., participants' clinical EDR) and 50 % EDR (i.e., 50 %-compressed base EDR). Results showed that: 1) there was no significant interaction effect between nmax and EDR, 2) SRTs with nmax = 2, 4, and 16 were significantly higher (or worse) than those with moderate nmax (6-8), 3) narrower EDRs significantly lead to higher SRTs. Simulation experiments using a Gaussian-Enveloped Tones Vocoder in normal -hearing listeners were also conducted and provided both supportive and additional observations to the CI results. This study suggests that, in CI programming, nmax and EDR are two independent influencing factors. Large nmax (e.g., 16) is not recommended as it may harm speech intelligibility in noisy environments, and inaccurate EDR measurements should be avoided.

Perception with electric neuroprostheses is sometimes expected to be simulated using properly designed physical stimuli. Here, we examined a new acoustic vocoder model for electric hearing with cochlear implants (CIs) and hypothesized that comparable speech encoding can lead to comparable perceptual patterns for CI and normal hearing (NH) listeners. Speech signals were encoded using FFT-based signal processing stages including band-pass filtering, temporal envelope extraction, maxima selection, and amplitude compression and quantization. These stages were specifically implemented in the same manner by an Advanced Combination Encoder (ACE) strategy in CI processors and Gaussian-enveloped Tones (GET) or Noise (GEN) vocoders for NH. Adaptive speech reception thresholds (SRTs) in noise were measured using four Mandarin sentence corpora. Initial consonant (11 monosyllables) and final vowel (20 monosyllables) recognition were also measured. NaÏve NH listeners were tested using vocoded speech with the proposed GET/GEN vocoders as well as conventional vocoders (controls). Experienced CI listeners were tested using their daily-used processors. Results showed that: 1) there was a significant training effect on GET vocoded speech perception; 2) the GEN vocoded scores (SRTs with four corpora and consonant and vowel recognition scores) as well as the phoneme-level confusion pattern matched with the CI scores better than controls. The findings suggest that the same signal encoding implementations may lead to similar perceptual patterns simultaneously in multiple perception tasks. This study highlights the importance of faithfully replicating all signal processing stages in the modeling of perceptual patterns in sensory neuroprostheses. This approach has the potential to enhance our understanding of CI perception and accelerate the engineering of prosthetic interventions. The GET/GEN MATLAB program is freely available athttps://github.com/BetterCI/GETVocoder.

Modern cochlear implants (CIs) generate electric current pulsatile stimuli from real-time incoming to stimulate residual auditory nerves of deaf ears. In this unique way, deaf people can (re)gain a sense of hearing and consequent speech communication abilities. The electric hearing mimics the normal acoustic hearing (NH), but with a different physical interface to the neural system, which limits the performance of CI devices. Simulating the electric hearing process of CI users through NH listeners is an important step in CI research and development. Many acoustic modelling methods have been developed for simulation purposes, e.g., to predict the performance of a novel sound coding strategy. Channel vocoders with noise or sine-wave carriers are mostly popular among the methods. The simulation works have accelerated the procedures of re-engineering and understanding of the electric hearing. This paper presents an overview of the literature on channel-vocoder simulation methods. Strengths, limitations, applications, and future works about acoustic vocoder simulation methods are introduced and discussed.

Despite pitch being considered the primary cue for discriminating lexical tones, there are secondary cues such as loudness contour and duration, which may allow some cochlear implant (CI) tone discrimination even with severely degraded pitch cues. To isolate pitch cues from other cues, we developed a new disyllabic word stimulus set (Di) whose primary (pitch) and secondary (loudness) cue varied independently. This Di set consists of 270 disyllabic words, each having a distinct meaning depending on the perceived tone. Thus, listeners who hear the primary pitch cue clearly may hear a different meaning from listeners who struggle with the pitch cue and must rely on the secondary loudness contour. A lexical tone recognition experiment was conducted, which compared Di with a monosyllabic set of natural recordings. Seventeen CI users and eight normal-hearing (NH) listeners took part in the experiment. Results showed that CI users had poorer pitch cues encoding and their tone recognition performance was significantly influenced by the “missing” or “confusing” secondary cues with the Di corpus. The pitch-contour-based tone recognition is still far from satisfactory for CI users compared to NH listeners, even if some appear to integrate multiple cues to achieve high scores. This disyllabic corpus could be used to examine the performance of pitch recognition of CI users and the effectiveness of pitch cue enhancement based Mandarin tone enhancement strategies. The Di corpus is freely available online: https://github.com/BetterCI/DiTone.

Traditional face-to-face subjective listening test has become a challenge due to the COVID-19 pandemic. We developed a remote assessment system with Tencent Meeting, a video conferencing application, to address this issue. This paper presents our work on evaluating the reliability of the remote assessment system. Two speech reception threshold (SRT) experiments were conducted to study the effects of noise suppression and maxima selection number on cochlear implant (CI) hearing. Both experiments were conducted locally and remotely, the correlations between the respective results were analyzed. Results showed that remote tests replicated the differences among testing conditions observed in local tests, but the absolute SRT values for individual conditions varied significantly between the two modes. The variations could be attributed to multiple reasons, such as online data transmission issues, audio playback devices, environmental conditions, and the training of participants. In conclusion, the relative variation of SRTs for CIs can be measured reliably, but the absolute SRT values should be carefully compared and explained according to objective and subjective experimental conditions.

The aim of this study is to evaluate the effects of pulse rate (i.e., stimulation rate) on Mandarin tone recognition by cochlear implant users. Mandarin tone recognition was measured by using monosyllabic and disyllabic tone data-bases at three pulse rates in cochlear implant users. The three pulse rates included each participant's clinical default pulse rate (i.e., 900 or 1200 pulses per second (pps) for each electrode), 400 pps, and 200 pps. A real-time research speech processor, CCi-Mobile, was used to implement the signal processing strategies. Although the results are variable among participants, there was a trend that the recognition rates of both monosyllabic and disyllabic databases decreased with lower pulse rates, indicating that low pulse rates degrade acoustic cues, like periodicity, for Mandarin tone perception. This study also provided preliminary data for evaluating the CCi-Mobile research processor for the first time in China. The processor could be used for signal processing algorithm development and psychophysical experiments in the future.

Objective:To analysis the long-term outcomes of ossicular chain reconstruction using the malleostapedotomy（MT）. Method:A total of 11 patients（12 ears） underwent MT and their hearing levels were measured prior to surgery, 1 week and more than 1 year after surgery. The indications of MT were discussed and its safety and efficacy were evaluated in terms of the intra-operative findings, post-operative hearing and complications. Result:Among 11 patients（12 ears）, there were 1 patient（1 ear） with tympanosclerosis, 3 patients（4 ears） with ossicular chain deformity, 5 patients（5 ears） with otosclerosis and 2 patients（2 ears） with localized cholesteatoma of the middle ear. No cases of bone conduction hearing loss（more than 10 dB） were observed within 2 weeks after surgery while four patients suffered from short-term vertigo with an average remission duration of 3 days. And no recurrence was found in the two patients with cholesteatoma. After a follow-up of 1-6 years, we found a remarkable improvement of air conduction without bone conduction loss in all patients and there was a significant difference between preoperative and post-operative air-bone gap（P<0.05）. Conclusion:With a strict selection according to the indications, MT showes safe and effective long-term outcomes and is proved to be applicable in ossicular chain reconstruction in the cases of fixation of the stapes footplate accompanied with malleus/incus mobility disorder by various causes.

Objectives To evaluate the safety and feasibility of cochlear implantation (CI) in irradiated ears of nasopharyngeal carcinoma (NPC) patients. Study Design A retrospective study. Methods From 2008 to 2017, 10 adults with binaural severe or profound sensorineural hearing loss subsequent to radiotherapy for NPC underwent CI in our center. The mean follow-up was 63.2 months. Hearing and speech performance were evaluated pre- and postoperatively with audiometric and speech discrimination testing, Category of Auditory Performance, Speech Intelligibility Rating, and Chinese version of Nijmegen Cochlear Implant Questionnaire. Results According to the severity of radioactive osteomyelitis of temporal bone, patients were classified into three categories: mild, moderate, and severe. Patients in mild category underwent routine CI. Patients in moderate category underwent extended radical mastoidectomy and CI simultaneously. Patients in severe category underwent subtotal temporal bone resection, external auditory canal elimination, and CI simultaneously or by stage. There was no massive hemorrhage, facial paralysis, or nonunion of incision after operation. One suffered from radiation encephalopathy 13 months postoperatively; since then, the cochlear implant has been idle. The other nine patients demonstrated encouraging results of hearing and speech performance. Conclusion CI for postirradiated ears of NPC is safe and feasible. Strict control of operative indications and extra care during surgery are required. Individual surgical plan should be made according to the severity of radioactive osteomyelitis. Choose one-stage surgery as much as possible in severe cases to avoid the risk of difficulty in locating round window in second-stage surgery. Level of Evidence 4Laryngoscope, 2020