Measurement of the Electrically Evoked Stapedial Reflex Response with Wideband Acoustic Reflectance Measurement.

BACKGROUND: The electrically evoked stapedial reflex threshold (ESRT) has been shown to be a good predictor of upper stimulation level for cochlear implant recipients. Previous research has shown that the ESRT may be recorded at lower stimulation levels and with a higher incidence of success with the use of higher frequency probe tones (e.g., 678 and 1000 Hz) relative to the use of the conventional 226-Hz probe tone. Research has also shown that the acoustic reflex may be recorded at lower stimulus levels with the use of wideband reflectance when compared to the acoustic reflex threshold recorded with a conventional acoustic immittance measurement. PURPOSE: The objective of this study was to compare the ESRT recorded with acoustic immittance and wideband reflectance measurements. RESEARCH DESIGN: A repeated measures design was used to evaluate potential differences in ESRTs with stimulation at an apical, middle, and basal electrode contact with the use of two different techniques, acoustic immittance measurement and wideband reflectance. STUDY SAMPLE: Twelve users of Cochlear Nucleus cochlear implants were included in the study. DATA COLLECTION AND ANALYSIS: Participants' ESRTs were evaluated in response to simulation at three different electrode contact sites (i.e., an apical, middle, and basal electrode contact) with the use of two different middle ear measurement techniques, acoustic immittance with the use of a 226-Hz probe tone and wideband reflectance with the use of a chirp stimulus. RESULTS: The mean ESRT recorded with wideband reflectance measurement was significantly lower when compared to the ESRT recorded with acoustic immittance. For one participant, the ESRT was not recorded with acoustic immittance before reaching the participant's loudness discomfort threshold, but it was successfully recorded with the use of wideband reflectance. CONCLUSIONS: The ESRT may potentially be recorded at lower presentation levels with the use of wideband reflectance measures relative to the use of acoustic immittance with a 226-Hz probe tone. This may allow for the ESRT to be obtained at levels that are more comfortable for the cochlear implant recipient, which may also allow for a higher incidence in the successful recording of the ESRT.

Voice gender and the segregation of competing talkers: Perceptual learning in cochlear implant simulations.

Two experiments explored the role of differences in voice gender in the recognition of speech masked by a competing talker in cochlear implant simulations. Experiment 1 confirmed that listeners with normal hearing receive little benefit from differences in voice gender between a target and masker sentence in four- and eight-channel simulations, consistent with previous findings that cochlear implants deliver an impoverished representation of the cues for voice gender. However, gender differences led to small but significant improvements in word recognition with 16 and 32 channels. Experiment 2 assessed the benefits of perceptual training on the use of voice gender cues in an eight-channel simulation. Listeners were assigned to one of four groups: (1) word recognition training with target and masker differing in gender; (2) word recognition training with same-gender target and masker; (3) gender recognition training; or (4) control with no training. Significant improvements in word recognition were observed from pre- to post-test sessions for all three training groups compared to the control group. These improvements were maintained at the late session (one week following the last training session) for all three groups. There was an overall improvement in masked word recognition performance provided by gender mismatch following training, but the amount of benefit did not differ as a function of the type of training. The training effects observed here are consistent with a form of rapid perceptual learning that contributes to the segregation of competing voices but does not specifically enhance the benefits provided by voice gender cues.

Potential Benefits of an Integrated Electric-Acoustic Sound Processor with Children: A Preliminary Report.

BACKGROUND: A number of published studies have demonstrated the benefits of electric-acoustic stimulation (EAS) over conventional electric stimulation for adults with functional low-frequency acoustic hearing and severe-to-profound high-frequency hearing loss. These benefits potentially include better speech recognition in quiet and in noise, better localization, improvements in sound quality, better music appreciation and aptitude, and better pitch recognition. There is, however, a paucity of published reports describing the potential benefits and limitations of EAS for children with functional low-frequency acoustic hearing and severe-to-profound high-frequency hearing loss. PURPOSE: The objective of this study was to explore the potential benefits of EAS for children. RESEARCH DESIGN: A repeated measures design was used to evaluate performance differences obtained with EAS stimulation versus acoustic- and electric-only stimulation. STUDY SAMPLE: Seven users of Cochlear Nucleus Hybrid, Nucleus 24 Freedom, CI512, and CI422 implants were included in the study. DATA COLLECTION AND ANALYSIS: Sentence recognition (assayed using the pediatric version of the AzBio sentence recognition test) was evaluated in quiet and at three fixed signal-to-noise ratios (SNR) (0, +5, and +10 dB). Functional hearing performance was also evaluated with the use of questionnaires, including the comparative version of the Speech, Spatial, and Qualities, the Listening Inventory for Education Revised, and the Children's Home Inventory for Listening Difficulties. RESULTS: Speech recognition in noise was typically better with EAS compared to participants' performance with acoustic- and electric-only stimulation, particularly when evaluated at the less favorable SNR. Additionally, in real-world situations, children generally preferred to use EAS compared to electric-only stimulation. Also, the participants' classroom teachers observed better hearing performance in the classroom with the use of EAS. CONCLUSIONS: Use of EAS provided better speech recognition in quiet and in noise when compared to performance obtained with use of acoustic- and electric-only stimulation, and children responded favorably to the use of EAS implemented in an integrated sound processor for real-world use.

Assistive technology evaluations: Remote-microphone technology for children with Autism Spectrum Disorder.

The goal of this study was to conduct assistive technology evaluations on 12 children diagnosed with Autism Spectrum Disorder (ASD) to evaluate the potential benefits of remote-microphone (RM) technology. A single group, within-subjects design was utilized to explore individual and group data from functional questionnaires and behavioral test measures administered, designed to assess school- and home-based listening abilities, once with and once without RM technology. Because some of the children were unable to complete the behavioral test measures, particular focus was given to the functional questionnaires completed by primary teachers, participants, and parents. Behavioral test measures with and without the RM technology included speech recognition in noise, auditory comprehension, and acceptable noise levels. The individual and group teacher (n=8-9), parent (n=8-9), and participant (n=9) questionnaire ratings revealed substantially less listening difficulty when RM technology was used compared to the no-device ratings. On the behavioral measures, individual data revealed varied findings, which will be discussed in detail in the results section. However, on average, the use of the RM technology resulted in improvements in speech recognition in noise (4.6dB improvement) in eight children, higher auditory working memory and comprehension scores (12-13 point improvement) in seven children, and acceptance of poorer signal-to-noise ratios (8.6dB improvement) in five children. The individual and group data from this study suggest that RM technology may improve auditory function in children with ASD in the classroom, at home, and in social situations. However, variability in the data and the inability of some children to complete the behavioral measures indicates that individualized assistive technology evaluations including functional questionnaires will be necessary to determine if the RM technology will be of benefit to a particular child who has ASD.

Electromagnetic versus electrical coupling of personal frequency modulation (FM) receivers to cochlear implant sound processors.

BACKGROUND: Previous research has suggested that electrically coupled frequency modulation (FM) systems substantially improved speech-recognition performance in noise in individuals with cochlear implants (CIs). However, there is limited evidence to support the use of electromagnetically coupled (neck loop) FM receivers with contemporary CI sound processors containing telecoils. PURPOSE: The primary goal of this study was to compare speech-recognition performance in noise and subjective ratings of adolescents and adults using one of three contemporary CI sound processors coupled to electromagnetically and electrically coupled FM receivers from Oticon. RESEARCH DESIGN: A repeated-measures design was used to compare speech-recognition performance in noise and subjective ratings without and with the FM systems across three test sessions (Experiment 1) and to compare performance at different FM-gain settings (Experiment 2). Descriptive statistics were used in Experiment 3 to describe output differences measured through a CI sound processor. STUDY SAMPLE: Experiment 1 included nine adolescents or adults with unilateral or bilateral Advanced Bionics Harmony (n = 3), Cochlear Nucleus 5 (n = 3), and MED-EL OPUS 2 (n = 3) CI sound processors. In Experiment 2, seven of the original nine participants were tested. In Experiment 3, electroacoustic output was measured from a Nucleus 5 sound processor when coupled to the electromagnetically coupled Oticon Arc neck loop and electrically coupled Oticon R2. DATA COLLECTION AND ANALYSIS: In Experiment 1, participants completed a field trial with each FM receiver and three test sessions that included speech-recognition performance in noise and a subjective rating scale. In Experiment 2, participants were tested in three receiver-gain conditions. Results in both experiments were analyzed using repeated-measures analysis of variance. Experiment 3 involved electroacoustic-test measures to determine the monitor-earphone output of the CI alone and CI coupled to the two FM receivers. RESULTS: The results in Experiment 1 suggested that both FM receivers provided significantly better speech-recognition performance in noise than the CI alone; however, the electromagnetically coupled receiver provided significantly better speech-recognition performance in noise and better ratings in some situations than the electrically coupled receiver when set to the same gain. In Experiment 2, the primary analysis suggested significantly better speech-recognition performance in noise for the neck-loop versus electrically coupled receiver, but a second analysis, using the best performance across gain settings for each device, revealed no significant differences between the two FM receivers. Experiment 3 revealed monitor-earphone output differences in the Nucleus 5 sound processor for the two FM receivers when set to the +8 setting used in Experiment 1 but equal output when the electrically coupled device was set to a +16 gain setting and the electromagnetically coupled device was set to the +8 gain setting. CONCLUSIONS: Individuals with contemporary sound processors may show more favorable speech-recognition performance in noise electromagnetically coupled FM systems (i.e., Oticon Arc), which is most likely related to the input processing and signal processing pathway within the CI sound processor for direct input versus telecoil input. Further research is warranted to replicate these findings with a larger sample size and to develop and validate a more objective approach to fitting FM systems to CI sound processors.

Benefit of a commercially available cochlear implant processor with dual-microphone beamforming: a multi-center study.

OBJECTIVE: Previous research shows that cochlear implant users experience significant difficulty with speech perception in noisy listening situations. There is a paucity of research evaluating the potential improvement in speech recognition in noise provided by a dual-microphone directional system in a commercial implant sound processor. The primary objective of this study was to compare speech recognition in quiet and in noise for the Nucleus Freedom and Nucleus 5 CP810 sound processors set to the manufacturer's default user programs for quiet and noisy environments. RESEARCH DESIGN: Crossover with repeated-measures design. SETTING: This multi-center study was conducted across four cochlear implant clinics in the United States. PATIENTS: Thirty-five adults with unilateral Nucleus Freedom cochlear implants. All subjects had used their cochlear implant for at least 6 months and had substantial open-set word recognition as evidenced by a score of at least 40% correct on the Consonant-Nucleus-Consonant (CNC) monosyllabic word recognition test in quiet. INTERVENTION: All subjects (previous users of the Nucleus Freedom sound processor) were fitted with the Nucleus 5 sound processor. Performance was assessed while these subjects used each sound processor in the default user program the manufacturer recommends for quiet and noisy conditions. MAIN OUTCOME MEASURES: Speech recognition was assessed with CNC monosyllabic words in quiet and sentences in noise from the BKB-SIN (Bamford-Kowal-Bench Sentences in Noise) test. The data were analyzed with descriptive statistics and performance with each processor in each listening condition was compared using a repeated-measures analysis of variance. RESULTS: Word recognition in quiet was significantly better with the Nucleus 5 sound processor when compared to performance with the Nucleus Freedom processor. In noise, the Nucleus 5 sound processor also provided a significant improvement in speech recognition relative to the performance with the Nucleus Freedom. CONCLUSION: The results of the study suggest that the Nucleus 5 sound processor provides significantly better speech recognition in quiet and in noise when compared with performance with the Nucleus Freedom processor.

Long-term effects of non-linear frequency compression for children with moderate hearing loss.

OBJECTIVE: To evaluate non-linear frequency compression (NLFC) as a means to improve speech recognition for children with moderate to moderately-severe hearing loss following a six-month acclimatization period. DESIGN: Within subject design with repeated measures across test conditions. STUDY SAMPLE: Fifteen children, ages 5 to 13 years, with moderate to moderately-severe high-frequency sensorineural hearing loss were fitted with Phonak Nios, micro-sized, BTE hearing aids and evaluated after two six-week intervals with and without NLFC and again after a six-month period of consecutive NLFC use. RESULTS: Using repeated measures analyses, the six-month results were compared to data that was collected following six-week trials with and without NLFC hearing aids (Wolfe et al, in press). Improvements seen with NLFC in the initial study (Wolfe et al, in press) were maintained or significantly increased in the present study. When compared to the six-week data, aided non-sense syllable speech recognition thresholds in quiet and speech recognition in noise were significantly better at the six-month interval. CONCLUSIONS: These results suggest that NLFC improves audibility for and recognition of high-frequency speech sounds for children with moderate to moderately-severe hearing loss. In many cases, improvements found with NLFC increased with a longer period of acclimatization to the technology.

The effect of front-end processing on cochlear implant performance of children.

OBJECTIVE: Previous research shows that children using cochlear implants experience significant difficulty with speech perception in noisy listening situations. There are several types of input signal processing available for the cochlear implant sound processor; however, there is a paucity of research to support this technology for children. The primary objective of this study was to examine the potential benefits of 2 types of input signal processing, adaptive dynamic range optimization (ADRO) as compared with autosensitivity (ASC) plus ADRO for children using Cochlear Corporation implants. RESEARCH DESIGN: Cross-sectional repeated-measures design. SETTING: Outpatient nonprofit foundation providing audiology services and auditory-verbal therapy. PATIENTS: Eleven children, aged 4 years 4 months to 12 years, with unilateral or bilateral Cochlear Limited implants. All children used their cochlear implant(s) for at least 1 year, had no additional disabilities, were enrolled in preschool or elementary school, and had age-appropriate receptive and expressive language. INTERVENTION: All children used Cochlear Limited cochlear implants with either the Nucleus Freedom or Nucleus 5 cochlear implant sound processor. Performance was assessed while these children used ADRO-only input processing and ASC+ADRO input processing. MAIN OUTCOME MEASURES: Speech perception of PBK-50 monosyllabic words in quiet and BKB-SIN sentences in noise was measured for each child. In the noise conditions, children were using the ADRO-only or ASC+ADRO input signal processing strategies. The data in quiet were analyzed with descriptive statistics, and the conditions in noise were compared using a 1-way repeated-measures analysis of variance. RESULTS: All children demonstrated word recognition in quiet at or above 90% correct. In noise, sentence-perception performance in the ASC+ADRO condition was significantly better than that in the ADRO-alone condition. CONCLUSION: The results of the study suggest substantial benefit from combining 2 types of input signal processing, ASC and ADRO, for children with unilateral and bilateral cochlear implants. Specifically, signal processing to adjust the sensitivity of the sound processor microphone automatically has substantial positive effects on speech-perception thresholds in noise.

Effects of FM-receiver gain on speech-recognition performance of adults with cochlear implants.

The primary aim of this study was to examine the effects of frequency-modulated (FM) settings on speech-recognition performance in noise of listeners using two different cochlear implant speech processors. Participants included eight users of ESPrit 3G speech processors and nine users of Auria speech processors. A modified adaptive-testing paradigm was used to assess speech recognition in noise with the cochlear implant and FM system at four receiver-gain settings: +6, +10, +14, or +20. In the no-FM condition, performance differences were not detected between the two processor groups. In the FM conditions, significantly better performance was found for participants with the Auria processor compared to those using the ESPrit 3G processor. Increases in receiver gain did not significantly improve speech recognition of participants using ESPrit 3G processors, but did significantly influence performance for those using Auria processors. For Auria users, the +6 setting resulted in significantly poorer performance than all other conditions, and optimal FM performance was found in the +14 and +20 gain settings. Clinical recommendations will be provided according to results of the study.