Speech perception with F0mod,a cochlear implant pitch coding strategy

Objective: The fundamental frequency modulation (F0mod) sound processing strategy was developed to improve pitch perception with cochlear implants. In previous work it has been shown to improve performance in a number of pitch-related tasks such as pitch ranking, familiar melody identification, and Mandarin Chinese tone identification. The objective of the current study was to compare speech perception with F0mod and the standard clinical advanced combination encoder (ACE) strategy. Study sample: Seven cochlear-implant listeners were recruited from the clinical population of the University Hospital Leuven. Design: F0mod was implemented on a real-time system. Speech recognition in quiet and noise was measured for seven cochlear-implant listeners, comparing F0mod with ACE, using three different Dutch-language speech materials. Additionally the F0 estimator used was evaluated physically, and pitch ranking performance was compared between F0mod and ACE. Results: Immediately after switch-on of the F0mod strategy, speech recognition in quiet and noise were similar for ACE and F0mod, for four out of seven listeners. The remaining three listeners were subjected to a short training protocol with F0mod, after which their performance was reassessed, and a significant improvement was found. Conclusions: As F0mod improves pitch perception, for the seven subjects tested it did not interfere with speech recognition in quiet and noise, and has a low computational complexity, it seems promising for implementation in a clinical sound processor.     

The long-term results of speech perception in elderly cochlear implant users

Objectives: To evaluate the speech discrimination performance of elderly post-lingually deafened cochlear implant (CI) users and the stability of performance over time relative to a control group of younger CI users.

Methods: The study group consisted of 20 native Dutch speaking, post-lingually deafened CI users, aged 70 or older at the time of implantation. Controls were patients aged 40–60 years at implantation and included according to the same inclusion criteria (except age). Linear mixed models assessed speech recognition scores between groups, the variability of their performance, and stability over time.

Results: 20 elderly and 37 controls were included. The mean follow-up was 4.4 and 5.3 years for elderly and controls, respectively. There was no significant difference in average speech discrimination between both groups. The elderly group had a larger intra-subject variability over time. There was no significant effect of follow-up on the speech discrimination, indicating a stable performance over time.

Discussion: This study has a longer follow-up than methodologically comparable previous studies. We found no difference in speech discrimination between elderly patients and controls and no deterioration of performance over time. The subjects in the elderly group exhibit a larger variability around their mean performance.

Conclusion: Speech recognition in both elderly and younger adult CI users is stable over time and is not significantly related to the age of implantation.     

Audiovisual speech perception in elderly cochlear implant recipients

OBJECTIVES/HYPOTHESIS: This study examined the speech perception skills of a younger and older group of cochlear implant recipients to determine the benefit that auditory and visual information provides for speech understanding. STUDY DESIGN: Retrospective review. METHODS: Pre- and postimplantation speech perception scores from the Consonant-Nucleus-Consonant (CNC), the Hearing In Noise sentence Test (HINT), and the City University of New York (CUNY) tests were analyzed for 34 postlingually deafened adult cochlear implant recipients. Half were elderly (i.e., >65 y old) and other half were middle aged (i.e., 39-53 y old). The CNC and HINT tests were administered using auditory-only presentation; the CUNY test was administered using auditory-only, vision-only, and audiovisual presentation conditions RESULTS: No differences were observed between the two age groups on the CNC and HINT tests. For a subset of individuals tested with the CUNY sentences, we found that the preimplantation speechreading scores of the younger group correlated negatively with auditory-only postimplant performance. Additionally, older individuals demonstrated a greater reliance on the integration of auditory and visual information to understand sentences than did the younger group CONCLUSIONS: On average, the auditory-only speech perception performance of older cochlear implant recipients was similar to the performance of younger adults. However, variability in speech perception abilities was observed within and between both age groups. Differences in speechreading skills between the younger and older individuals suggest that visual speech information is processed in a different manner for elderly individuals than it is for younger adult cochlear implant recipients.     

Reverberation negatively impacts musical sound quality for cochlear implant users

Abstract

Objective

Satisfactory musical sound quality remains a challenge for many cochlear implant (CI) users. In particular, questionnaires completed by CI users suggest that reverberation due to room acoustics can negatively impact their music listening experience. The objective of this study was to more specifically characterize of the effect of reverberation on musical sound quality in CI users, normal hearing (NH) non-musicians, and NH musicians using a previously designed assessment method, called Cochlear Implant-MUltiple Stimulus with Hidden Reference and Anchor (CI-MUSHRA).

Methods

In this method, listeners were randomly presented with an anechoic musical segment and five-versions of this segment in which increasing amounts of reverberation were artificially added. Participants listened to the six reverberation versions and provided sound quality ratings between 0 (very poor) and 100 (excellent).

Results

Results demonstrated that on average CI users and NH non-musicians preferred the sound quality of anechoic versions to more reverberant versions. In comparison, NH musicians could be delineated into those who preferred the sound quality of anechoic pieces and those who preferred pieces with some reverberation.

Discussion/Conclusion

This is the first study, to our knowledge, to objectively compare the effects of reverberation on musical sound quality ratings in CI users. These results suggest that musical sound quality for CI users can be improved by non-reverberant listening conditions and musical stimuli in which reverberation is removed.     

Open-set speech perception in adult cochlear implant users with ossified cochleae

Abstract

This study describes open-set speech recognition in cochlear implant subjects with ossified cochleae and compares it to a control group with open cochleae. Twenty-one postlingually deafened adults with a Med-El Combi 40/40+GB splitelectrode implant were matched to patients using a Med-El cochlear implant with a standard electrode. Speech recognition was assessed over an 18-month period. Splitelectrode patients improved significantly over time, but their scores were significantly lower and increased significantly slower than those of controls. Of 14 patients with a duration of deafness less than 20 years, average sentence test scores were 50%, and average monosyllabic word test scores were 31%. This study provides evidence that cochlear implantation is beneficial to patients with ossified cochleae, but early implantation is advisable.     

Speech perception and auditory performance in Finnish adult cochlear implant users

Abstract

Objective This study aimed at investigating the association between speech perception and categories of auditory performance (mCAP) in everyday life for adult cochlear implant users.

Design A prospective repeated measures design over a two-year follow-up period was used.

Methods The speech perception and auditory performance of 19 Finnish-speaking adults were assessed before implantation and 1, 3, 6, 12 and 24 months after switching on the implant. Spearman's rank order correlation coefficients (r_s) were calculated between mCAP and sentence, word, syllable, vowel and consonant recognition. Pearson's product moment correlation coefficients (r) were calculated among the speech perception results.

Results The correlation between mCAP and the speech perception results was high and statistically significant (r_s = 0.81?0.85, p 0.0001), as well as the correlation among the speech perception tests (r = 0.79?0.92, p 0.0001).

Conclusions The speech perception tests used may be considered as good describers of everyday performance of the subjects of this investigation.     

Effects of residual speech and auditory deprivation on speech perception of adult cochlear implant recipients

Objective

Possible predictive factors of cochlear implant (CI) outcomes have been extensively reported in literature for different user groups such as prelingual pediatric or postlingual adult users. However, there remains unexplained outcome variability among adult CI users; therefore, research concerning these patients continues and many different variables have been reported. This study aimed at evaluating the relationship between preoperative speech reception capacity, residual hearing, duration of deafness, age of implantation, and postoperative monosyllabic word recognition scores (WRSs) in postlingual CI users.

Preoperative functional assessment of auditory cortex in adult cochlear implant users

OBJECTIVES: To explore functional neuroanatomical responses to auditory stimulation before and after implantation. STUDY DESIGN: A prospective study of three cochlear implant candidates (pure-tone averages of 90 dB HL or greater bilaterally and hearing in noise test [HINT] performances of <40%) in which regional cerebral blood flow (rCBF) was assessed using single photon emission computed tomography (SPECT). METHODS: Candidates watched a 15-minute videotaped story under four conditions: audio presented monaurally in the right and left ears (aided), audio presented binaurally (aided), and visual-only presentation of the story. Five minutes into each story, 20 to 25 mCi of technetium 99m (99mTc) hexamethyl-propyleneamine-oxime (HMPAO) (Ceratec; Nycomed Amersham, Princeton, NJ, U.SA) was injected over a 30-second period to ensure that subjects were unaware of tracer administration. Subjects were scanned for 20 minutes using a PRISM 3000 gamma camera (Picker International, Cleveland, OH, U.S.A.). Data were normalized and co-registered, and subtraction images were compiled. Subtraction images contrasted activation patterns generated under the visual-only control condition to the auditory activation states acquired monaurally and binaurally. RESULTS: Right and left ear monaural stimulation in normal hearing subjects resulted in significant bilateral activation of Brodmann areas 41, 42, 21, 22, and 38. Although substantial intersubject response variability was noted, subjects generally failed to bilaterally activate these areas under monaural hearing aid presentations; however, bilateral activation of areas 41 and 22 was noted under binaural presentations. CONCLUSIONS: Despite relatively similar hearing losses in each ear, significant differences in preoperative auditory cortex activation were observed between ears. These data suggest that functional brain imaging provides a useful tool for exploring the responsiveness of the auditory cortex in cochlear implant candidates.     

A systematic review of the impact of adjusting input dynamic range (IDR), electrical threshold (T) level and rate of stimulation on speech perception ability in cochlear implant users

Objective: To systematically review the evidence of how adjustments of the electrical threshold (T) level, input dynamic range (IDR) and electrical stimulation rate impact on speech perception for cochlear implant (CI) users.

Design: Systematic review.

Study sample: A search of two electronic data sources yielded 32 studies, which met the inclusion criteria. A quality assessment and two evidence-based practice (EBP) review rating schemes were used to grade studies.

Results: Due to the heterogeneity of speech perception measures, CI device type and study design, comparisons were made by structured review.

Conclusion: The quality of studies was found to be moderate to poor. Increasing T levels above behavioural threshold, or as a proportion of electrical dynamic range (EDR), has been demonstrated to improve perception of monosyllables in quiet and sentences in both quiet and in noise. Specific IIDR and IDR setting may improve perception of monosyllables in quiet and sentences in noise. However, no recommendation could be determined for setting rate of stimulation as speech perception varied significantly across rates examined. To optimise speech perception, a bespoke approach to parameter setting providing an individualised CI fitting is recommended; however, detail of how to optimise settings and the interactions between parameters is as yet unknown.     

Speech perception in cochlear implant users with the HiRes 120 strategy: a systematic review

Despite technological advances employed in signal processing strategies, one of the remaining obstacles are spectral gap details on the information transmitted. Considering its importance in speech perception, researchers have investigated mechanisms to optimize spectral details through virtual spectral channels. The clinical application of this technique resulted in a new approach to signal processing - the HiRes 120.ObjectiveTo assess the auditory performance of cochlear implant users with the HiRes 120 strategy.MethodologyThe literature review was conducted in an electronic database, with standard bibliographic search in the year 2011, using specific keywords. In order to select and evaluate the scientific studies found in the search, we setup search containing the following aspects: type of study, subjects, intervention used and evaluation of the results.ConclusionScientific evidence points to an improvement in hearing performance in noisy environments with the HiRes 120 strategy, but this does not occur in quiet situations. The optimization of speech perception with this strategy is closely related to the cochlear implant user's age, to the time of sensory deprivation and the acclimatization time required to use the strategy's spectral information.     

The role of speech rate for Italian-speaking cochlear implant users: insights for everyday speech perception

Abstract

This study investigated the effect of speech rate for Italian-speaking cochlear implant (CI) users with the aim of gaining insight into everyday listening situations where speaker’s rate may vary considerably together with speech level in fluctuating background noise. The test material was prepared by processing the Italian STARR test with temporal compression of sentence material. Twelve adult CI users were divided into two subgroups based on their STARR performance: good and poor performers. The effect of varying speech rate was remarkable for both subgroups. Good performers showed significant performance deterioration for the faster speech rate, whereas outcomes for poor performers improved significantly for the slower speech rate. Background noise is inevitable during daily life and CI users face a variety of speakers, so must cope with changes in both speech level and rate. Traditional tests with a single talker speaking very clearly while using a moderate to low speech rate may overestimate everyday speech perception for CI users. The use of tests that mimic everyday perception is of great importance and should become a routine part of audiometric measures for hearing impaired people.     

Effect of input compression and input frequency response on music perception in cochlear implant users

Objective: A study was conducted to determine whether modifications to input compression and input frequency response characteristics can improve music-listening satisfaction in cochlear implant users. Design: Experiment 1 compared three pre-processed versions of music and speech stimuli in a laboratory setting: original, compressed, and flattened frequency response. Music excerpts comprised three music genres (classical, country, and jazz), and a running speech excerpt was compared. Experiment 2 implemented a flattened input frequency response in the speech processor program. In a take-home trial, participants compared unaltered and flattened frequency responses. Study sample: Ten and twelve adult Nucleus Freedom cochlear implant users participated in Experiments 1 and 2, respectively. Results: Experiment 1 revealed a significant preference for music stimuli with a flattened frequency response compared to both original and compressed stimuli, whereas there was a significant preference for the original (rising) frequency response for speech stimuli. Experiment 2 revealed no significant mean preference for the flattened frequency response, with 9 of 11 subjects preferring the rising frequency response. Conclusions: Input compression did not alter music enjoyment. Comparison of the two experiments indicated that individual frequency response preferences may depend on the genre or familiarity, and particularly whether the music contained lyrics.     

Deficits in auditory frequency discrimination and speech recognition in cochlear implant users

Abstract

Objectives

Speech recognition varies considerably following cochlear implantation for reasons that are still poorly understood. Considering the role of frequency discrimination in normal speech recognition, the aim of this study was to investigate the association between deficits in auditory frequency discrimination and speech recognition in cochlear implant users.

Methods

Frequency discrimination thresholds and speech recognition were assessed in a group of 20 cochlear implant users and 16 normally hearing controls.

Results

Based on their results on the speech recognition task, the cochlear implant users were categorized either as proficient (n = 10) or non-proficient users (n = 10). The non-proficient cochlear implant users had poorer auditory frequency discrimination compared to the normal hearing participants and proficient cochlear implant users (both P < 0.05). No significant difference was found between the proficient cochlear implant users and the normally hearing group (P > 0.05). Furthermore, a bivariate correlation analysis revealed a relationship between speech recognition and frequency discrimination.

Conclusions

The present findings suggest an association between auditory frequency discrimination and speech recognition proficiency in cochlear implant users. Although no causal link can be drawn from these data, possible reasons for this association are discussed.     

Effect of deep insertion of the cochlear implant electrode array on pitch estimation and speech perception

Conclusion. Deeply inserted electrodes offer the possibility that apical stimulation may improve speech performances. Therefore, deep insertion is reasonable and should be performed in patients with profound or total hearing loss. Objectives. To evaluate the importance of insertion depth beyond 25 mm in a group of cochlear implant patients with deeply inserted electrodes up to 32 mm. Patients and methods. In the first part of the study patients were asked to perform a pitch estimation for channels across the whole length of the electrode array. We evaluated whether pitch discrimination was possible along the whole cochlea and especially in its apical part. Then, the audiological performances of 10 patients were tested in 5 conditions, in which we artificially varied the insertion depth in each patient by activating and deactivating channels. The patients were tested immediately in the new condition to avoid adaptation. Results. The results showed that activating the electrodes in the uppermost region of the cochlea improves speech perception significantly. Furthermore it could be demonstrated that the pitch perceived in the cochlea with electrical stimulation decreases with increasing insertion depth along the whole length of deeply inserted electrode arrays.     

Cortical auditory evoked potentials in cochlear implant listeners via single electrode stimulation in relation to speech perception

Abstract

The objectives of this study were to investigate the effects of place of stimulation on cortical auditory evoked potentials in relation to speech performance in cochlear implant listeners. It was designed that cortical responses were recorded for single-electrode bursts at apical, medial and basal portions of the electrode array with varying inter-stimulus intervals ranging from 300?ms to 5?s. Latency and amplitude of N1 and P2 peaks were analysed in relation to monosyllabic word scores. The study sample was 44 adult cochlear implant users ranging in age from 28 to 86?years. N1, P2 and N1–P2 amplitudes declined significantly from apical to basal electrodes. The most robust and pronounced responses were recorded for slower stimulation rates (5?s). Speech recognition correlated positively with N1 and N1–P2 amplitudes at the medial electrode. P2 latency showed a significant negative correlation with speech performance at the apical electrode. At last, cortical responses varied significantly depending on the stimulation site and rate. We can objectively quantify speech performance with the N1, N1–P2 amplitude and P2 latency in cochlear implant users. Deafness-related neural degeneration persists even after the cochlear implantation and is more distinct at the base than the apex of the cochlea.     

Effect of spatial separation and noise type on sentence recognition by Mandarin-speaking cochlear implant users

Objectives: To investigate the effects of spatial separation and noise type on sentence recognition by unilateral Mandarin-speaking cochlear implant (CI) users and normal-hearing (NH) listeners.

Method: Twenty-two unilateral Mandarin-speaking CI users and six NH listeners participated in this study. Speech reception thresholds were measured for three noise types (steady state noise, speech babble, and music). Sentences from the Mandarin Speech Perception test were presented directly in front of the listener (0°). Noise was presented from one of the five speaker locations: ?90°, ?45°, 0°,?+45°, and?+90°.

Results: Overall, CI performance was significantly poorer than NH performance for all spatial separation and noise type conditions. NH listeners performed best with music and poorest with steady noise. CI users performed best with steady noise, and poorest with babble. Performance was significantly affected by noise location and noise type. There was no significant difference in head shadow effects among the different noise types for CI users.

Conclusions: Performance was much poorer in CI than in NH listeners for all noise types and spatial separations. Noise type differently affected unilateral CI users and NH listeners. The limited spectral resolution in CI users did not appear to affect head shadow.     

语后聋人工耳蜗患者音乐节奏与音色感知能力的评价

目的 评价成人语后聋人工耳蜗使用者感知音乐中节奏和音色的能力.方法 选取年龄与音乐经验相匹配的听力正常受试者与人工耳蜗使用者各12名,均为男5名,女7名.应用人工耳蜗音乐评估软件( Musical Sounds in Cochlear Implants,MuSIC)中的节奏辨别、乐器识别与乐器数辨别测试评价两组受试者的音乐节奏和音色感知能力.结果 12名人工耳蜗受试者平均节奏辨别率为84.4％,与听力正常受试者(85.1％)比较,差异无统计学意义(t=0.116,P＞0.05);人工耳蜗受试者平均乐器识别率为72.3％、乐器数辨别正确率为39.2％,均低于听力正常受试者平均88.3％和73.5％的正确率,差异具有统计学意义(t值分别为2.498和4.673,P值均＜0.05).结论 成人语后聋人工耳蜗使用者的节奏辨别能力与听力正常人相似,但音色感知能力明显差于听力正常人群.     

Value of the promontory stimulation test in predicting speech perception after cochlear implantation

BACKGROUND AND OBJECTIVES: To determine the role of the promontory stimulation test (PST) in cochlear implantation (CI), we evaluated the correlations between PST parameters and the results of speech perception tests after CI. SUBJECTS AND METHOD: With use of a retrospective review of the medical records of 58 patients, the GAP50, GAP100, TDL50, and TDL100 parameters of the PST were compared with the results of speech perception tests at fixed time points after CI. Spearman's rank-order correlation coefficient was used in statistical analyses. RESULTS: GAP100 scores were correlated with all results of speech perception tests at all time points after CI (r = 0.309-0.509, P = .001-0.010), and TDL100 scores were correlated with the results of open set one- and two-syllabic word tests at 1 month after CI (r = 0.288, P = .028); no other significant correlations were found. The GAP100 scores for postlingually deaf patients, especially for gap intervals up to 100 ms, were correlated with all results of speech perception tests after CI. A stepwise multiple regression analysis revealed that the GAP100 score is the only variable that was significantly correlated with the results of speech perception tests. The duration and onset age of deafness did not significantly affect the results. CONCLUSION: The PST may be a useful tool for predicting the prognosis of CI. The GAP100 score, especially for gap intervals up to 100 ms, might be useful in predicting the results of speech perception tests after CI as well as in determining the optimal site for CI in postlingually deaf patients without residual hearing.     

Effects of electrode deactivation on speech recognition in multichannel cochlear implant recipients

Objectives: The objective of the current study is to evaluate how speech recognition performance is affected by the number of active electrodes that are turned off in multichannel cochlear implants. Several recent studies have demonstrated positive effects of deactivating stimulation sites based on an objective measure in cochlear implant processing strategies. Previous studies using an analysis of variance have shown that, on average, cochlear implant listeners’ performance does not improve beyond eight active electrodes. We hypothesized that using a generalized linear mixed model would allow for better examination of this question.

Methods: Seven peri- and post-lingual adult cochlear implant users (eight ears) were tested on speech recognition tasks using experimental MAPs which contained either 8, 12, 16 or 20 active electrodes. Speech recognition tests included CUNY sentences in speech-shaped noise, TIMIT sentences in quiet as well as vowel (CVC) and consonant (CV) stimuli presented in quiet and in signal-to-noise ratios of 0 and +10?dB.

Results: The speech recognition threshold in noise (dB SNR) significantly worsened by approximately 2?dB on average as the number of active electrodes was decreased from 20 to 8. Likewise, sentence recognition scores in quiet significantly decreased by an average of approximately 12%.

Discussion/conclusion: Cochlear implant recipients can utilize and benefit from using more than eight spectral channels when listening to complex sentences or sentences in background noise. The results of the current study suggest a conservative approach for turning off stimulation sites is best when using site-selection procedures.