Frequency change detection and speech perception in cochlear implant users

Digits in noise testing in a multilingual sample of Asian adults

OBJECTIVE

Appropriate speech-in noise assessment is challenging in multilingual populations. This study aimed to assess whether first preferred language affected performance on an English Digits-in-noise (DIN) test in the local Asian multilingual population, controlling for hearing threshold, age, sex, English fluency and educational status. A secondary aim was to determine the association between DIN test scores and hearing thresholds.

DESIGN

English digit-triplets in noise testing and pure-tone audiometry were conducted. Multiple regression analysis was performed with DIN scores and hearing thresholds as dependent variables. Correlation analysis was performed between DIN-SRT and hearing thresholds.

STUDY SAMPLE

165 subjects from the Singapore Longitudinal Ageing Study, a population-based longitudinal study of community-dwellers over 55 years of age.

RESULTS

Mean DIN speech reception threshold (DIN-SRT) was -5.7 dB SNR (SD 3.6; range 6.7 to -11.2). Better ear pure tone average and English fluency were significantly associated with DIN-SRT.

CONCLUSIONS

DIN performance was independent of first preferred language in a multilingual ageing Singaporean population after adjusting for age, gender and education. Those with poorer English fluency had a significantly lower DIN-SRT score. The DIN test has the potential to provide a quick, uniform method of testing speech in noise in this multilingual population.

Validation of the acoustic change complex (ACC) prediction model to predict speech perception in noise in adult patients with hearing loss: a study protocol

BACKGROUND

Speech perception tests are essential to measure the functional use of hearing and to determine the effectiveness of hearing aids and implantable auditory devices. However, these language-based tests require active participation and are influenced by linguistic and neurocognitive skills limiting their use in patients with insufficient language proficiency, cognitive impairment, or in children. We recently developed a non-attentive and objective speech perception prediction model: the Acoustic Change Complex (ACC) prediction model. The ACC prediction model uses electroencephalography to measure alterations in cortical auditory activity caused by frequency changes. The aim is to validate this model in a large-scale external validation study in adult patients with varying degrees of sensorineural hearing loss (SNHL) to confirm the high predictive value of the ACC model and to assess its test-retest reliability.

METHODS

A total of 80 participants, aged 18-65 years, will be enrolled in the study. The categories of severity of hearing loss will be used as a blocking factor to establish an equal distribution of patients with various degrees of sensorineural hearing loss. During the first visit, pure tone audiometry, speech in noise tests, a phoneme discrimination test, and the first ACC measurement will be performed. During the second visit (after 1-4 weeks), the same ACC measurement will be performed to assess the test-retest reliability. The acoustic change stimuli for ACC measurements consist of a reference tone with a base frequency of 1000, 2000, or 4000 Hz with a duration of 3000 ms, gliding to a 300-ms target tone with a frequency that is 12% higher than the base frequency. The primary outcome measures are (1) the level of agreement between the predicted speech reception threshold (SRT) and the behavioral SRT, and (2) the level of agreement between the SRT calculated by the first ACC measurement and the SRT of the second ACC measurement. Level of agreement will be assessed with Bland-Altman plots.

DISCUSSION

Previous studies by our group have shown the high predictive value of the ACC model. The successful validation of this model as an effective and reliable biomarker of speech perception will directly benefit the general population, as it will increase the accuracy of hearing evaluations and improve access to adequate hearing rehabilitation.

Frequency detection, frequency discrimination, and spectro-temporal pattern perception in older and younger typically hearing adults

Elderly adults often experience difficulties in speech understanding, possibly due to age-related deficits in frequency perception. It is unclear whether age-related deficits in frequency perception differ between the apical or basal regions of the cochlea. It is also unclear how aging might differently affect frequency discrimination or detection of a change in frequency within a stimulus. In the present study, pure-tone frequency thresholds were measured in 19 older (61-74 years) and 20 younger (22-28 years) typically hearing adults. Participants were asked to discriminate between reference and probe frequencies or to detect changes in frequency within a probe stimulus. Broadband spectro-temporal pattern perception was also measured using the spectro-temporal modulated ripple test (SMRT). Frequency thresholds were significantly poorer in the basal than in the apical region of the cochlea; the deficit in the basal region was 2 times larger for the older than for the younger group. Frequency thresholds were significantly poorer in the older group, especially in the basal region where frequency detection thresholds were 3.9 times poorer for the older than for the younger group. SMRT thresholds were 1.5 times better for the younger than for the older group. Significant age effects were observed for SMRT thresholds and for frequency thresholds only in the basal region. SMRT thresholds were significantly correlated with frequency thresholds only in the older group. The poorer frequency and spectro-temporal pattern perception may contribute to age-related deficits in speech perception, even when audiometric thresholds are nearly normal.

Adult Cochlear Implant Users Versus Typical Hearing Persons: An Automatic Analysis of Acoustic-Prosodic Parameters

PURPOSE

The aim of this study was to investigate the speech prosody of postlingually deaf cochlear implant (CI) users compared with control speakers without hearing or speech impairment.

METHOD

Speech recordings of 74 CI users (37 males and 37 females) and 72 age-balanced control speakers (36 males and 36 females) are considered. All participants are German native speakers and read Der Nordwind und die Sonne (The North Wind and the Sun), a standard text in pathological speech analysis and phonetic transcriptions. Automatic acoustic analysis is performed considering pitch, loudness, and duration features, including speech rate and rhythm.

RESULTS

In general, duration and rhythm features differ between CI users and control speakers. CI users read slower and have a lower voiced segment ratio compared with control speakers. A lower voiced ratio goes along with a prolongation of the voiced segments' duration in male and with a prolongation of pauses in female CI users. Rhythm features in CI users have higher variability in the duration of vowels and consonants than in control speakers. The use of bilateral CIs showed no advantages concerning speech prosody features in comparison to unilateral use of CI.

CONCLUSIONS

Even after cochlear implantation and rehabilitation, the speech of postlingually deaf adults deviates from the speech of control speakers, which might be due to changed auditory feedback. We suggest considering changes in temporal aspects of speech in future rehabilitation strategies.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.21579171.

Differential auditory cortical development in left and right cochlear implanted children

Unilateral aural stimulation has been shown to cause massive cortical reorganization in brain with congenital deafness, particularly during the sensitive period of brain development. However, it is unclear which side of stimulation provides most advantages for auditory development. The left hemisphere dominance of speech and linguistic processing in normal hearing adult brain has led to the assumption of functional and developmental advantages of right over left implantation, but existing evidence is controversial. To test this assumption and provide evidence for clinical choice, we examined 34 prelingually deaf children with unilateral cochlear implants using near-infrared spectroscopy. While controlling for age of implantation, residual hearing, and dominant hand, cortical processing of speech showed neither developmental progress nor influence of implantation side weeks to months after implant activation. In sharp contrast, for nonspeech (music signal vs. noise) processing, left implantation showed functional advantages over right implantation that were not yet discernable using clinical, questionnaire-based outcome measures. These findings support the notion that the right hemisphere develops earlier and is better preserved from adverse environmental influences than its left counterpart. This study thus provides, to our knowledge, the first evidence for differential influences of left and right auditory peripheral stimulation on early cortical development of the human brain.

The Acoustic Change Complex Compared to Hearing Performance in Unilaterally and Bilaterally Deaf Cochlear Implant Users

OBJECTIVES

Clinical measures evaluating hearing performance in cochlear implant (CI) users depend on attention and linguistic skills, which limits the evaluation of auditory perception in some patients. The acoustic change complex (ACC), a cortical auditory evoked potential to a sound change, might yield useful objective measures to assess hearing performance and could provide insight in cortical auditory processing. The aim of this study is to examine the ACC in response to frequency changes as an objective measure for hearing performance in CI users.

DESIGN

Thirteen bilaterally deaf and six single-sided deaf subjects were included, all having used a unilateral CI for at least 1 year. Speech perception was tested with a consonant-vowel-consonant test (+10 dB signal-to-noise ratio) and a digits-in-noise test. Frequency discrimination thresholds were measured at two reference frequencies, using a 3-interval, 2-alternative forced-choice, adaptive staircase procedure. The two reference frequencies were selected using each participant's frequency allocation table and were centered in the frequency band of an electrode that included 500 or 2000 Hz, corresponding to the apical electrode or the middle electrode, respectively. The ACC was evoked with pure tones of the same two reference frequencies with varying frequency increases: within the frequency band of the middle or the apical electrode (+0.25 electrode step), and steps to the center frequency of the first (+1), second (+2), and third (+3) adjacent electrodes.

RESULTS

Reproducible ACCs were recorded in 17 out of 19 subjects. Most successful recordings were obtained with the largest frequency change (+3 electrode step). Larger frequency changes resulted in shorter N1 latencies and larger N1-P2 amplitudes. In both unilaterally and bilaterally deaf subjects, the N1 latency and N1-P2 amplitude of the CI ears correlated to speech perception as well as frequency discrimination, that is, short latencies and large amplitudes were indicative of better speech perception and better frequency discrimination. No significant differences in ACC latencies or amplitudes were found between the CI ears of the unilaterally and bilaterally deaf subjects, but the CI ears of the unilaterally deaf subjects showed substantially longer latencies and smaller amplitudes than their contralateral normal-hearing ears.

CONCLUSIONS

The ACC latency and amplitude evoked by tone frequency changes correlate well to frequency discrimination and speech perception capabilities of CI users. For patients unable to reliably perform behavioral tasks, the ACC could be of added value in assessing hearing performance.

Relationship Between the Ability to Detect Frequency Changes or Temporal Gaps and Speech Perception Performance in Post-lingual Cochlear Implant Users

Previous studies, using modulation stimuli, on the relative effects of frequency resolution and time resolution on CI users’ speech perception failed to reach a consistent conclusion. In this study, frequency change detection and temporal gap detection were used to investigate the frequency resolution and time resolution of CI users, respectively. Psychophysical and neurophysiological methods were used to simultaneously investigate the effects of frequency and time resolution on speech perception in post-lingual cochlear implant (CI) users. We investigated the effects of psychophysical results [frequency change detection threshold (FCDT), gap detection threshold (GDT)], and acoustic change complex (ACC) responses (evoked threshold, latency, or amplitude of ACC induced by frequency change or temporal gap) on speech perception [recognition rate of monosyllabic words, disyllabic words, sentences in quiet, and sentence recognition threshold (SRT) in noise]. Thirty-one adult post-lingual CI users of Mandarin Chinese were enrolled in the study. The stimuli used to induce ACCs to frequency changes were 800-ms pure tones (fundamental frequency was 1,000 Hz); the frequency change occurred at the midpoint of the tones, with six percentages of frequency changes (0, 2, 5, 10, 20, and 50%). Temporal silences with different durations (0, 5, 10, 20, 50, and 100 ms) were inserted in the middle of the 800-ms white noise to induce ACCs evoked by temporal gaps. The FCDT and GDT were obtained by two 2-alternative forced-choice procedures. The results showed no significant correlation between the CI hearing threshold and speech perception in the study participants. In the multiple regression analysis of the influence of simultaneous psychophysical measures and ACC responses on speech perception, GDT significantly predicted every speech perception index, and the ACC amplitude evoked by the temporal gap significantly predicted the recognition of disyllabic words in quiet and SRT in noise. We conclude that when the ability to detect frequency changes and the temporal gap is considered simultaneously, the ability to detect frequency changes may have no significant effect on speech perception, but the ability to detect temporal gaps could significantly predict speech perception.

Home-Based Speech Perception Monitoring for Clinical Use With Cochlear Implant Users

Speech-perception testing is essential for monitoring outcomes with a hearing aid or cochlear implant (CI). However, clinical care is time-consuming and often challenging with an increasing number of clients. A potential approach to alleviating some clinical care and possibly making room for other outcome measures is to employ technologies that assess performance in the home environment. In this study, we investigate 3 different speech perception indices in the same 40 CI users: phoneme identification (vowels and consonants), digits in noise (DiN) and sentence recognition in noise (SiN). The first two tasks were implemented on a tablet and performed multiple times by each client in their home environment, while the sentence task was administered at the clinic. Speech perception outcomes in the same forty CI users showed that DiN assessed at home can serve as an alternative to SiN assessed at the clinic. DiN scores are in line with the SiN ones by 3–4 dB improvement and are useful to monitor performance at regular intervals and to detect changes in auditory performance. Phoneme identification in quiet also explains a significant part of speech perception in noise, and provides additional information on the detectability and discriminability of speech cues. The added benefit of the phoneme identification task, which also proved to be easy to administer at home, is the information transmission analysis in addition to the summary score. Performance changes for the different indices can be interpreted by comparing against measurement error and help to target personalized rehabilitation. Altogether, home-based speech testing is reliable and proves powerful to complement care in the clinic for CI users.

The Acoustic Change Complex in Response to Frequency Changes and Its Correlation to Cochlear Implant Speech Outcomes

One of the biggest challenges that face cochlear implant (CI) users is the highly variable hearing outcomes of implantation across patients. Since speech perception requires the detection of various dynamic changes in acoustic features (e.g., frequency, intensity, timing) in speech sounds, it is critical to examine the ability to detect the within-stimulus acoustic changes in CI users. The primary objective of this study was to examine the auditory event-related potential (ERP) evoked by the within-stimulus frequency changes (F-changes), one type of the acoustic change complex (ACC), in adult CI users, and its correlation to speech outcomes. Twenty-one adult CI users (29 individual CI ears) were tested with psychoacoustic frequency change detection tasks, speech tests including the Consonant-Nucleus-Consonant (CNC) word recognition, Arizona Biomedical Sentence Recognition in quiet and noise (AzBio-Q and AzBio-N), and the Digit-in-Noise (DIN) tests, and electroencephalographic (EEG) recordings. The stimuli for the psychoacoustic tests and EEG recordings were pure tones at three different base frequencies (0.25, 1, and 4 kHz) that contained a F-change at the midpoint of the tone. Results showed that the frequency change detection threshold (FCDT), ACC N1' latency, and P2' latency did not differ across frequencies (p > 0.05). ACC N1'-P2 amplitude was significantly larger for 0.25 kHz than for other base frequencies (p < 0.05). The mean N1' latency across three base frequencies was negatively correlated with CNC word recognition (r = -0.40, p < 0.05) and CNC phoneme (r = -0.40, p < 0.05), and positively correlated with mean FCDT (r = 0.46, p < 0.05). The P2' latency was positively correlated with DIN (r = 0.47, p < 0.05) and mean FCDT (r = 0.47, p < 0.05). There was no statistically significant correlation between N1'-P2' amplitude and speech outcomes (all ps > 0.05). Results of this study indicated that variability in CI speech outcomes assessed with the CNC, AzBio-Q, and DIN tests can be partially explained (approximately 16-21%) by the variability of cortical sensory encoding of F-changes reflected by the ACC.

Psychosocial Impact of Assistive Devices and Other Technologies on Deaf and Hard of Hearing People

Deaf and hard of hearing people use a variety of assistive devices and technologies as a strategy to mitigate, counter or compensate for life difficulties resulting from hearing loss. Although outcome measures are commonly used with hearing aids, few studies have explored the perceived psychosocial impact of other assistive devices and technologies or the factors leading to their abandonment or lack of use. Therefore, the main aim of this study was to assess the psychosocial impact of different assistive devices on deaf and hard of hearing people using the Psychosocial Impact of Assistive Devices Scale. The sample was made up of 291 individuals, 176 women and 115 men, with an average age of 56.12 years (standard deviation (SD) = 25.11), who were all users of different assistive devices. Overall, the results of the study showed that the use of assistive devices had a positive psychosocial impact, although this impact varied slightly depending on the specific type of device. Moreover, a relationship was identified between the psychosocial impact and the probability of future abandonment of a hearing aid or a cochlear implant. The results point to the importance of considering the psychosocial impact derived from the use of a device as a relevant variable in the adoption process of assistive technologies for deaf and hard of hearing people.

Neural encoding of spectro-temporal cues at slow and near speech-rate in cochlear implant users

The ability to process rapid modulations in the spectro-temporal structure of sounds is critical for speech comprehension. For users of cochlear implants (CIs), spectral cues in speech are conveyed by differential stimulation of electrode contacts along the cochlea, and temporal cues in terms of the amplitude of stimulating electrical pulses, which track the amplitude-modulated (AM'ed) envelope of speech sounds. Whilst survival of inner-ear neurons and spread of electrical current are known factors that limit the representation of speech information in CI listeners, limitations in the neural representation of dynamic spectro-temporal cues common to speech are also likely to play a role. We assessed the ability of CI listeners to process spectro-temporal cues varying at rates typically present in human speech. Employing an auditory change complex (ACC) paradigm, and a slow (0.5Hz) alternating rate between stimulating electrodes, or different AM frequencies, to evoke a transient cortical ACC, we demonstrate that CI listeners-like normal-hearing listeners-are sensitive to transitions in the spectral- and temporal-domain. However, CI listeners showed impaired cortical responses when either spectral or temporal cues were alternated at faster, speech-like (6-7Hz), rates. Specifically, auditory change following responses-reliably obtained in normal-hearing listeners-were small or absent in CI users, indicating that cortical adaptation to alternating cues at speech-like rates is stronger under electrical stimulation. In CI listeners, temporal processing was also influenced by the polarity-behaviourally-and rate of presentation of electrical pulses-both neurally and behaviorally. Limitations in the ability to process dynamic spectro-temporal cues will likely impact speech comprehension in CI users.

Cortical potentials evoked by tone frequency changes compared to frequency discrimination and speech perception: Thresholds in normal-hearing and hearing-impaired subjects

Frequency discrimination ability varies within the normal hearing population, partially explained by factors such as musical training and age, and it deteriorates with hearing loss. Frequency discrimination, while essential for several auditory tasks, is not routinely measured in clinical setting. This study investigates cortical auditory evoked potentials in response to frequency changes, known as acoustic change complexes (ACCs), and explores their value as a clinically applicable objective measurement of frequency discrimination. In 12 normal-hearing and 13 age-matched hearing-impaired subjects, ACC thresholds were recorded at 4 base frequencies (0.5, 1, 2, 4 kHz) and compared to psychophysically assessed frequency discrimination thresholds. ACC thresholds had a moderate to strong correlation to psychophysical frequency discrimination thresholds. In addition, ACC thresholds increased with hearing loss and higher ACC thresholds were associated with poorer speech perception in noise. The ACC threshold in response to a frequency change therefore holds promise as an objective clinical measurement in hearing impairment, indicative of frequency discrimination ability and related to speech perception. However, recordings as conducted in the current study are relatively time consuming. The current clinical application would be most relevant in cases where behavioral testing is unreliable.

Cortical processing of location and frequency changes of sounds in normal hearing listeners

Sounds we hear in our daily life contain changes in the acoustic features (e.g., frequency, intensity, and duration or "what" information) and/or changes in location ("where" information). The purpose of this study was to examine the cortical auditory evoked potentials (CAEPs) to the change within a stimulus, the acoustic change complex (ACC), in frequency (F) and location (L) of the sound in normal hearing listeners. Fifteen right-handed young normal hearing listeners participated in the electroencephalographic (EEG) recordings. The acoustic stimuli were pure tones (base frequency at 250 Hz) of 1 s, with a perceivable change either in location (L, 180°), frequency (F, 5% and 50%), or both location and frequency (L+F) in the middle of the tone. Additionally, the 250 Hz tone of 1 sec without any change was used as a reference. The participants were asked to listen passively to the stimuli and not to move their heads during the testing. Compared to the reference tone, by which only the onset-CAEP was elicited, the tones containing changes (L, F, or L+F) elicited both onset-CAEP and the ACC. The waveform analysis of ACCs from the vertex electrode (electrode Cz) showed that, larger sound changes evoked larger peak amplitudes [e.g., (L+50%F)- > L-change; (L+50%F)- > 5%F-change] and shorter the peak latencies ([(L+5%F)- < 5%F-change; 50%F- < 5%F-change; (L+50%F)- < 5%F-change] . The current density patterns for the ACC N1' peak displayed some differences between L-change vs. F-change, supporting different cortical processing for "where" and "what" information of the sound; regardless of the nature of the sound change, larger changes evoked a stronger activation than smaller changes [e.g., L- > 5%F-change; (L+5%F)- > 5%F-change; 50%F- > 5%F-change] in frontal lobe regions including the cingulate gyrus, medial frontal gyrus (MFG), superior frontal gyrus (SFG), the limbic lobe cingulate gyrus, and the parietal lobe postcentral gyrus. The results suggested that sound change-detection involves memory-based acoustic comparison (the neural encoding for the sound change vs. neural encoding for the pre-change stimulus stored in memory) and involuntary attention switch.

Speech intelligibility and auditory perception of pre-school children with Hearing Aid, cochlear implant and Typical Hearing

Purpose

There is a growing interest in speech intelligibility and auditory perception of deaf children. The aim of the present study was to compare speech intelligibility and auditory perception of pre-school children with Hearing Aid (HA), Cochlear Implant (CI), and Typical Hearing (TH).

Methods

The research design was descriptive-analytic and comparative. The participants comprised 75 male pre-school children aged 4–6 years in the 2017–2018 from Tehran, Iran. The participants were divided into three groups, and each group consisted of 25 children. The first and second groups were respectively selected from pre-school children with HA and CI using the convenience sampling method, while the third group was selected from pre-school children with TH by random sampling method. All children completed Speech Intelligibility Rating and Categories of Auditory Performance Questionnaires.

Results

The findings indicated that the mean scores of speech intelligibility and auditory perception of the group with TH were significantly higher than those of the other groups (P < 0.0001). The mean scores of speech intelligibility in the group with CI did not significantly differ from those of the group with HA (P < 0.38). Also, the mean scores of auditory perception in the group with CI were significantly higher than those of the group with HA (P < 0.002).

Conclusion

The results showed that auditory perception in children with CI was significantly higher than children with HA. This finding highlights the importance of cochlear implantation at a younger age and its significant impact on auditory perception in deaf children.

The Effect of Side of Implantation on the Cortical Processing of Frequency Changes in Adult Cochlear Implant Users

Cochlear implants (CI) are widely used in children and adults to restore hearing function. However, CI outcomes are vary widely. The affected factors have not been well understood. It is well known that the right and left hemispheres play different roles in auditory perception in adult normal hearing listeners. It is unknown how the implantation side may affect the outcomes of CIs. In this study, the effect of the implantation side on how the brain processes frequency changes within a sound was examined in 12 right-handed adult CI users. The outcomes of CIs were assessed with behaviorally measured frequency change detection threshold (FCDT), which has been reported to significantly affect CI speech performance. The brain activation and regions were also examined using acoustic change complex (ACC, a type of cortical potential evoked by acoustic changes within a stimulus), on which the waveform analysis and the standardized low-resolution brain electromagnetic tomography (sLORETA) were performed. CI users showed activation in the temporal lobe and non-temporal areas, such as the frontal lobe. Right-ear CIs could more efficiently activate the contralateral hemisphere compared to left-ear CIs. For right-ear CIs, the increased activation in the contralateral temporal lobe together with the decreased activation in the contralateral frontal lobe was correlated with good performance of frequency change detection (lower FCDTs). Such a trend was not found in left-ear CIs. These results suggest that the implantation side may significantly affect neuroplasticity patterns in adults.

A Preliminary Study of the Effects of Attentive Music Listening on Cochlear Implant Users' Speech Perception, Quality of Life, and Behavioral and Objective Measures of Frequency Change Detection

Introduction

Most cochlear implant (CI) users have difficulty in listening tasks that rely strongly on perception of frequency changes (e.g., speech perception in noise, musical melody perception, etc.). Some previous studies using behavioral or subjective assessments have shown that short-term music training can benefit CI users’ perception of music and speech. Electroencephalographic (EEG) recordings may reveal the neural basis for music training benefits in CI users.

Objective

To examine the effects of short-term music training on CI hearing outcomes using a comprehensive test battery of subjective evaluation, behavioral tests, and EEG measures.

Design

Twelve adult CI users were recruited for a home-based music training program that focused on attentive listening to music genres and materials that have an emphasis on melody. The participants used a music streaming program (i.e., Pandora) downloaded onto personal electronic devices for training. The participants attentively listened to music through a direct audio cable or through Bluetooth streaming. The training schedule was 40 min/session/day, 5 days/week, for either 4 or 8 weeks. The pre-training and post-training tests included: hearing thresholds, Speech, Spatial and Qualities of Hearing Scale (SSQ12) questionnaire, psychoacoustic tests of frequency change detection threshold (FCDT), speech recognition tests (CNC words, AzBio sentences, and QuickSIN), and EEG responses to tones that contained different magnitudes of frequency changes.

Results

All participants except one finished the 4- or 8-week training, resulting in a dropout rate of 8.33%. Eleven participants performed all tests except for two who did not participate in EEG tests. Results showed a significant improvement in the FCDTs as well as performance on CNC and QuickSIN after training (p < 0.05), but no significant improvement in SSQ scores (p > 0.05). Results of the EEG tests showed larger post-training cortical auditory evoked potentials (CAEPs) in seven of the nine participants, suggesting a better cortical processing of both stimulus onset and within-stimulus frequency changes.

Conclusion

These preliminary data suggest that extensive, focused music listening can improve frequency perception and speech perception in CI users. Further studies that include a larger sample size and control groups are warranted to determine the efficacy of short-term music training in CI users.

Musical Sound Quality as a Function of the Number of Channels in Modern Cochlear Implant Recipients

Objectives

This study examined musical sound quality (SQ) in adult cochlear implant (CI) recipients. The study goals were to determine: the number of channels needed for high levels of musical SQ overall and by musical genre; the impact of device and patient factors on musical SQ ratings; and the relationship between musical SQ, speech recognition, and speech SQ to relate these findings to measures frequently used in clinical protocols.

Methods

Twenty-one post-lingually deafened adult CI recipients participated in this study. Electrode placement, including scalar location, average electrode-to-modiolus distance (M¯), and angular insertion depth were determined by CT imaging using validated CI position analysis algorithms (e.g., Noble et al., 2013; Zhao et al., 2018, 2019). CI programs were created using 4–22 electrodes with equal spatial distribution of active electrodes across the array. Speech recognition, speech SQ, music perception via a frequency discrimination task, and musical SQ were acutely assessed for all electrode conditions. Musical SQ was assessed using pre-selected musical excerpts from a variety of musical genres.

Results

CI recipients demonstrated continuous improvement in qualitative judgments of musical SQ with up to 10 active electrodes. Participants with straight electrodes placed in scala tympani (ST) and pre-curved electrodes with higher M¯ variance reported higher levels of musical SQ; however, this relationship is believed to be driven by levels of musical experience as well as the potential for preoperative bias in device selection. Participants reported significant increases in musical SQ beyond four channels for all musical genres examined in the current study except for Hip Hop/Rap. After musical experience outliers were removed, there was no relationship between musical experience or frequency discrimination ability and musical SQ ratings. There was a weak, but significant correlation between qualitative ratings for speech stimuli presented in quiet and in noise and musical SQ.

Conclusion

Modern CI recipients may need more channels for musical SQ than even required for asymptotic speech recognition or speech SQ. These findings may be used to provide clinical guidance for personalized expectations management of music appreciation depending on individual device and patient factors.