CompHEAR: A Customizable and Scalable Web-Enabled Auditory Performance Evaluation Platform for Cochlear Implant Sound Processing Research.

Objective: Cochlear implants (CIs) are auditory prostheses for individuals with severe to profound hearing loss, offering substantial but incomplete restoration of hearing function by stimulating the auditory nerve using electrodes. However, progress in CI performance and innovation has been constrained by the inability to rapidly test multiple sound processing strategies. Current research interfaces provided by major CI manufacturers have limitations in supporting a wide range of auditory experiments due to portability, programming difficulties, and the lack of direct comparison between sound processing algorithms. To address these limitations, we present the CompHEAR research platform, designed specifically for the Cochlear Implant Hackathon, enabling researchers to conduct diverse auditory experiments on a large scale. Study Design: Quasi-experimental. Setting: Virtual. Methods: CompHEAR is an open-source, user-friendly platform which offers flexibility and ease of customization, allowing researchers to set up a broad set of auditory experiments. CompHEAR employs a vocoder to simulate novel sound coding strategies for CIs. It facilitates even distribution of listening tasks among participants and delivers real-time metrics for evaluation. The software architecture underlies the platform's flexibility in experimental design and its wide range of applications in sound processing research. Results: Performance testing of the CompHEAR platform ensured that it could support at least 10,000 concurrent users. The CompHEAR platform was successfully implemented during the COVID-19 pandemic and enabled global collaboration for the CI Hackathon (www.cihackathon.com). Conclusion: The CompHEAR platform is a useful research tool that permits comparing diverse signal processing strategies across a variety of auditory tasks with crowdsourced judging. Its versatility, scalability, and ease of use can enable further research with the goal of promoting advancements in cochlear implant performance and improved patient outcomes.

Development and Validation of the Spanish AzBio Sentence Corpus.

OBJECTIVE: To create and validate a Spanish sentence test for evaluation of speech understanding of Spanish-speaking listeners with hearing loss or cochlear implants (CI). STUDY DESIGN: Two thousand sentences were recorded from two male and two female speakers. The average intelligibility of each sentence was estimated as the mean score achieved by five listeners presented with a five-channel cochlear implant simulation. The mean scores of each sentence were used to construct 42 lists of 20 sentences with similar mean scores. List equivalency was then validated by presenting all lists to 10 CI users and in a 2-list comparison in a clinical setting to 38 CI patients. SETTING: Tertiary referral center. PATIENTS: Normal-hearing listeners (n = 5), CI users in a research study (n = 10), and CI patients (n = 38) in routine clinical follow-up. INTERVENTION: Multiple sentence lists from a newly minted speech perception test. MAIN OUTCOME MEASURES: List intelligibility and equivalence across sentence lists. RESULTS: Forty-two lists of sentences were equivalent when all lists were presented in random order to 10 adult CI recipients. The variability of scores observed on lists presented to the same listener in the same condition was captured using a binomial distribution model based on a 40-item list for 38 adult implant recipients. CONCLUSION: The Spanish AzBio Sentence Test includes 42 lists of 20 sentences. These sentences are roughly equivalent in terms of overall difficulty and confidence limits have been provided to assess the significance of variability in list scores observed within or across conditions. These materials will be of benefit when assessing native Spanish speakers in both research and clinical settings.

Participant-generated Cochlear Implant Programs: Speech Recognition, Sound Quality, and Satisfaction.

OBJECTIVE: To determine whether patient-derived programming of one's cochlear implant (CI) stimulation levels may affect performance outcomes. BACKGROUND: Increases in patient population, device complexity, outcome expectations, and clinician responsibility have demonstrated the necessity for improved clinical efficiency. METHODS: Eighteen postlingually deafened adult CI recipients (mean = 53 years; range, 24-83 years) participated in a repeated-measures, within-participant study designed to compare their baseline listening program to an experimental program they created. RESULTS: No significant group differences in aided sound-field thresholds, monosyllabic word recognition, speech understanding in quiet, speech understanding in noise, nor spectral modulation detection (SMD) were observed (p > 0.05). Four ears (17%) improved with the experimental program for speech presented at 45 dB SPL and two ears (9%) performed worse. Six ears (27.3%) improved significantly with the self-fit program at +10 dB signal-to-noise ratio (SNR) and four ears (26.6%) improved in speech understanding at +5 dB SNR. No individual scored significantly worse when speech was presented in quiet at 60 dB SPL or in any of the noise conditions tested. All but one participant opted to keep at least one of the self-fitting programs at the completion of this study. Participants viewed the process of creating their program more favorably (t = 2.11, p = 0.012) and thought creating the program was easier than the traditional fitting methodology (t = 2.12, p = 0.003). Average time to create the self-fit program was 10 minutes, 10 seconds (mean = 9:22; range, 4:46-24:40). CONCLUSIONS: Allowing experienced adult CI recipients to set their own stimulation levels without clinical guidance is not detrimental to success.

The use of fundamental frequency for lexical segmentation in listeners with cochlear implants.

Fundamental frequency (F0) variation is one of a number of acoustic cues normal hearing listeners use for guiding lexical segmentation of degraded speech. This study examined whether F0 contour facilitates lexical segmentation by listeners fitted with cochlear implants (CIs). Lexical boundary error patterns elicited under unaltered and flattened F0 conditions were compared across three groups: listeners with conventional CI, listeners with CI and preserved low-frequency acoustic hearing, and normal hearing listeners subjected to CI simulations. Results indicate that all groups attended to syllabic stress cues to guide lexical segmentation, and that F0 contours facilitated performance for listeners with low-frequency hearing.

An electric frequency-to-place map for a cochlear implant patient with hearing in the nonimplanted ear.

The aim of this study was to relate the pitch of high-rate electrical stimulation delivered to individual cochlear implant electrodes to electrode insertion depth and insertion angle. The patient (CH1) was able to provide pitch matches between electric and acoustic stimulation because he had auditory thresholds in his nonimplanted ear ranging between 30 and 60 dB HL over the range, 250 Hz to 8 kHz. Electrode depth and insertion angle were measured from high-resolution computed tomography (CT) scans of the patient's temporal bones. The scans were used to create a 3D image volume reconstruction of the cochlea, which allowed visualization of electrode position within the scala. The method of limits was used to establish pitch matches between acoustic pure tones and electric stimulation (a 1,652-pps, unmodulated, pulse train). The pitch matching data demonstrated that, for insertion angles of greater than 450 degrees or greater than approximately 20 mm insertion depth, pitch saturated at approximately 420 Hz. From 20 to 15 mm insertion depth pitch estimates were about one-half octave lower than the Greenwood function. From 13 to 3 mm insertion depth the pitch estimates were approximately one octave lower than the Greenwood function. The pitch match for an electrode only 3.4 mm into the cochlea was 3,447 Hz. These data are consistent with other reports, e.g., Boëx et al. (2006), of a frequency-to-place map for the electrically stimulated cochlea in which perceived pitches for stimulation on individual electrodes are significantly lower than those predicted by the Greenwood function for stimulation at the level of the hair cell.

The intelligibility of speech with "holes" in the spectrum.

The intelligibility of speech having either a single "hole" in various bands or having two "holes" in disjoint or adjacent bands in the spectrum was assessed with normal-hearing listeners. In experiment 1, the effect of spectral "holes" on vowel and consonant recognition was evaluated using speech processed through six frequency bands, and synthesized as a sum of sine waves. Results showed a modest decrease in vowel and consonant recognition performance when a single hole was introduced in the low- and high-frequency regions of the spectrum, respectively. When two spectral holes were introduced, vowel recognition was sensitive to the location of the holes, while consonant recognition remained constant around 70% correct, even when the middle- and high-frequency speech information was missing. The data from experiment 1 were used in experiment 2 to derive frequency-importance functions based on a least-squares approach. The shapes of the frequency-importance functions were found to be different for consonants and vowels in agreement with the notion that different cues are used by listeners to identify consonants and vowels. For vowels, there was unequal weighting across the various channels, while for consonants the frequency-importance function was relatively flat, suggesting that all bands contributed equally to consonant identification.