Karyn L. Galvin

Perceptual Benefit and Functional Outcomes for Children Using Sequential Bilateral Cochlear Implants

Objective: To evaluate the additional perceptual benefit provided to children through the use of two cochlear implants in comparison to one after 6 to 13 mo experience with sequential bilateral implants. Design: A second cochlear implant was received by 11 children. The principal selection criteria were being age 4 to 15 yr with a bilateral profound hearing loss and being a consistent user of a first implant with a commitment to use of a second implant. Horizontal localization was assessed by using pink noise bursts presented from a 180°, eight-loudspeaker array. Speech perception was assessed by using a four-alternative forced-choice spondee test, with speech presented from in front and adaptive background noise presented from 90° to the left or right. Both tests were completed in the first implant alone and bilateral conditions. A questionnaire measured the pre- to postoperative change in the parent’s ratings of the child’s performance in specific listening situations. Items were related to speech perception, spatial hearing, or other qualities of hearing. Regular parental reports of device use, attitude and performance were collected. Most subjects were assessed at 6 mo after surgery, with two assessed at 13 mo. Results: The 11 subjects demonstrated a great range of outcomes. For one subject, only anecdotal data were collected. Speech perception testing indicated that when noise was presented ipsilateral to the first implant, 8 of 10 subjects showed a benefit in the bilateral condition. None of the nine subjects tested showed a benefit when noise was contralateral to the first implant. Generally, there was no benefit to localization in the bilateral condition. For eight subjects, postoperative performance ratings were generally higher than preoperative ratings, particularly in the spatial hearing section. Anecdotal reports indicated that most subjects had a negative attitude toward, and gained limited experience with, the second implant alone. The subjects developed a range of speech perception skills, from detection to conversation level. Regarding the use of bilateral implants, attitudes were more positive and device use was consistent for eight subjects, and six parents reported some evidence of improved performance in daily life. Conclusions: Children over age 4 yr may gain significant additional benefit from a second implant, including improved speech perception in some noise contexts and functional advantages in daily life. There is, however, no evidence from this study to suggest that binaural listening skills, including localization, will develop during the first 6 mo. Furthermore, some children who may be committed users of a first implant may not adapt to or benefit from a second implant during the first 6 mo of device use. Although the factors influencing benefit cannot be clearly identified, limited preoperative auditory experience with the second ear, a delay of years between implants, relatively advanced age, and lack of second-implant-alone experience do not preclude benefit. Continued evaluation of these and additional subjects will clarify the factors that do contribute to benefit. Such information will be vital in helping families of implanted children to make an informed decision regarding a second implant.

Speech Perception Benefit for Children with a Cochlear Implant and a Hearing Aid in Opposite Ears and Children with Bilateral Cochlear Implants.

The aims of the present study are to investigate: (1) the effect of using a hearing aid (HA) or a second cochlear implant (2nd CI) on speech recognition in noise for children; (2) the ability to perceive phoneme groups of different frequencies when using a CI and an HA in opposite ears (bimodal fitting) and when using a CI in each ear (bilateral implant fitting), and (3) the relationship between aided thresholds in the HA ear and bimodal advantage. Thirteen school-age children who consistently used a bimodal or bilateral implant fitting participated. Perception was evaluated using consonant-nucleus-consonantwords presented from in front with noise from either side. Significant bimodal or bilateral CI advantage in speech perception was demonstrated by most subjects in at least 1 noise condition. Comparisons indicated that the bimodal advantage obtained by the bimodal subjects was greater than the bilateral CI advantage obtained by the bilateral-implant subjects in the noise front condition, but also suggested that the 2nd CI may provide more functional advantage in real life. The mechanisms underlying the advantage provided by the second device appear to be different in the bimodal and bilateral groups. Information transmission analysis did not show a clear difference between the groups in the pattern of advantage across phoneme groups. For the bimodal subjects, those with better aided thresholds at low frequencies and poorer aided thresholds at 4 kHz demonstrated greater bimodal advantage. Overall, these findings encourage the use of bimodal and bilateral implant fittings for children, provide insight into the individual variability in bimodal outcome, and enhance understanding of the differences between an HA and a 2nd CI when used together with an implant in the opposite ear.

Speech detection and localization results and clinical outcomes for children receiving sequential bilateral cochlear implants before four years of age

The aim of this study was to describe the adaptation to bilateral cochlear implant use and the perceptual benefits demonstrated by 10 children who were successful users of a first implant when a second was received before four years of age. Although one subject rejected the second implant at switch-on, the nine subjects who accepted the device adapted easily to bilateral implant use and developed useful listening skills with the second implant. Tests of localization (left versus right) and speech detection in noise were administered in the unilateral and bilateral conditions, usually after six months experience. All subjects demonstrated some bilateral benefit on speech detection testing (mostly due to a headshadow effect), and the majority localized left versus right. Results suggested that outcomes may be negatively impacted by increased age at the time of second implant switch-on. The majority of the subjects adapted well to bilateral implant use within six months and demonstrated some perceptual benefit and, according to subjective parent reports, improved daily functioning; however, device rejection must be discussed pre-operatively as a possibility.

Spatial Unmasking and Binaural Advantage for Children with Normal Hearing, a Cochlear Implant and a Hearing Aid, and Bilateral Implants

The aims of this study were to: (1) determine if spatial unmasking existed and differed for children with normal hearing, a hearing aid and a cochlear implant (CIHA), and bilateral implants (BICI); (2) determine if binaural advantage and headshadow effect differed between children with CIHA and BICI. Results indicated that most of the CIHA and BICI children demonstrated spatial unmasking, though to a lesser degree than children with normal hearing. Results also indicated that the children with BICI demonstrated greater headshadow effect than those with CIHA. The CIHA and BICI children also differed in binaural advantage, which could be due to the differences in headshadow effect and in detection abilities with the hearing aid versus the second implant.

Can adolescents and young adults with prelingual hearing loss benefit from a second, sequential cochlear implant?

Abstract This study aimed to determine if adolescents/young adults gained additional perceptual benefit from sequential bilateral cochlear implants within 12 months, and to document adaptation to the second implant. Assessments comprised a pediatric version of The Speech, Spatial and Qualities of Hearing Scale (SSQ), anecdotal reports of device use and daily listening, and the Adaptive Spondee Discrimination Test (AdSpon). All nine participants achieved full-time use of, a preference for, and superior daily listening with, bilateral implants. Eight participants were comfortable using the second implant alone, and two achieved similar daily listening with either implant alone. SSQ ratings were higher post-operatively for the majority of participants. AdSpon performance was superior bilaterally for five participants with noise ipsilateral to the first implant, but not contralateral. Unilateral performance with either implant was similar for one participant. A second implant may provide additional benefit up to 19 years of age, even with congenital hearing loss and >16 years between implants. Families and clinicians should understand the aspects of second-implant candidacy and post-operative use that are unique to adolescents/young adults. Sumario El objetivo del estudio fue determinar si los adolescentes y adultos jóvenes obtenían un beneficio adicional con implantes cocleares bilaterales secuenciales en un periodo de 12 meses, y documentar la adaptación al segundo implante. La evaluación comprendió una versión pediátrica de la Escala para el Lenguaje, la Audición Espacial y las Cualidades Auditivas (SSQ), reportes anecdóticos de uso de dispositivos y escucha cotidiana; y la Prueba Adaptativa de Discriminación de Espondaicas (AdSpon). Los nueve participantes lograron el uso por tiempo completo, la preferencia por, y la escucha superior cotidiana con los implantes bilaterales. Ocho participantes se sintieron a gusto con el segundo implante solamente y dos lograron condiciones de escucha similares con cualquiera de los implantes individualmente. Las puntuaciones de SSQ fueron más altas en el postoperatorio para la mayoría de los participantes. Para seis participantes, el desempeño en la AdSpon fue superior en la condición bilateral con ruido ipsilateral en el primer implante, pero no en el contralateral. El desempeño unilateral con cualquiera de los implantes fue similar para un participante. Un segundo implante puede proporcionar beneficio adicional hasta los 19 años de edad, aun en el caso de hipoacusia congénita y más de 16 años entre implantes. Las familias y los clínicos deben entender los aspectos para la candidatura de un segundo implante y su uso postoperatorio que son singulares para los adolescentes y los adultos jóvenes.

Measuring listening effort expended by adolescents and young adults with unilateral or bilateral cochlear implants or normal hearing

Abstract Objectives To compare the listening effort expended by adolescents and young adults using implants versus their peers with normal hearing when these two groups are achieving similar speech perception scores. The study also aimed to compare listening effort expended by adolescents and young adults with bilateral cochlear implants when using two implants versus one. Methods Eight participants with bilateral cochlear implants and eight with normal hearing aged 10–22 years were included. Using a dual-task paradigm, participants repeated consonant–nucleus–consonant (CNC) words presented in noise and performed a visual matching task. Signal-to-noise ratios were set individually to ensure the word perception task was challenging but manageable for all. Reduced performance on the visual task in the dual-task condition relative to the single-task condition was indicative of the effort expended on the listening task. Results The cochlear implant group, when using bilateral implants, expended similar levels of listening effort to the normal hearing group when the two groups were achieving similar speech perception scores. For three individuals with cochlear implants, and the group, listening effort was significantly reduced with bilateral compared to unilateral implants. Discussion The similar amount of listening effort expended by the two groups indicated that a higher signal-to-noise ratio overcame limitations in the auditory information received or processed by the participants with implants. This study is the first to objectively compare listening effort using two versus one cochlear implant. The results provide objective evidence that reduced listening effort is a benefit that some individuals gain from bilateral cochlear implants.

An investigation of input level range for the nucleus 24 cochlear implant system: speech perception performance, program preference, and loudness comfort ratings.

Objective Cochlear implant recipients often have limited access to lower level speech sounds. In this study we evaluated the effects of varying the input range characteristics of the Nucleus 24 cochlear implant system on recognition of vowels, consonants, and sentences in noise and on listening in everyday life. Design Twelve subjects participated in the study that was divided into two parts. In Part 1 subjects used speech processor (Nucleus 24 SPrint™) programs adjusted for three input sensitivity settings: a standard or default microphone sensitivity setting (MS 8), a setting that increased the input sensitivity by 10.5 dB (MS 15), and the same setting that increased input sensitivity but also incorporated the automatic sensitivity control (ASC; i.e., MS 15A) that is designed to reduce the loudness of noise. The default instantaneous input dynamic range (IIDR) of 30 dB was used in these programs (i.e., base level of 4; BL 4). Subjects were tested using each sensitivity program with vowels and consonants presented at very low to casual conversational levels of 40 dB SPL and 55 dB SPL, respectively. They were also tested with sentences presented at a raised level of 65 dB SPL in multi-talker babble at individually determined signal to noise ratios. In addition, subjects were given experience outside of the laboratory for several weeks. They were asked to complete a questionnaire where they compared the programs in different listening situations as well as the loudness of environmental sounds, and state the setting they preferred overall. In Part 2 of the study, subjects used two programs. The first program was their preferred sensitivity program from Part 1 that had an IIDR of 30 dB (BL 4). Seven subjects used MS 8 and four used MS 15, and one used the noise reduction program MS 15A. The second program used the same microphone sensitivity but had the IIDR extended by an additional 8 to 10 dB (BL 1/0). These two programs were evaluated similarly in the speech laboratory and with take-home experience as in Part 1. Results Part 1 Increasing the microphone input sensitivity by 10.5 dB (from MS 8 to MS 15) significantly improved the perception of vowels and consonants at 40 and 55 dB SPL. The group mean improvement in vowel scores was 25 percentage points at 40 dB SPL and 4 percentage points at 55 dB SPL. The group mean improvement for consonants was 23 percentage points at 40 dB SPL and 11 percentage points at 55 dB SPL. Increased input sensitivity did not significantly reduce the perception of sentences presented at 65 dB SPL in babble despite the fact that speech peaks were then within the compressed range above the SPrint processors automatic gain control (AGC) knee-point. Although there was a demonstrable advantage for perception of low-level speech with the higher input sensitivity (MS 15 and 15A), seven of the 12 subjects preferred MS 8, four preferred MS 15 or 15A, and one had no preference overall. Approximately half the subjects preferred MS 8 across the 18 listening situations, whereas an average of two subjects preferred MS 15 or 15A. The increased microphone sensitivity of MS 15 substantially increased the loudness of environmental sounds. However, use of the ASC noise reduction setting with MS 15 reduced the loudness of environmental sounds to equal or below that for MS 8. Results Part 2 The increased instantaneous input range gave some improvement (8 to 9 percentage points for the 40 dB SPL presentation level) in the perception of consonants. There was no statistically significant increase in vowel scores. Mean scores for sentences presented at 65 dB SPL in babble were significantly lower (5 percentage points) for the increased IIDR setting. Subjects had no preference for the increased IIDR over the default. The IIDR setting had no effect on the loudness of environmental sounds. Conclusions Given the fact that individuals differ in threshold (T) and comfort (C) levels for electrical stimulation, and preferred microphone sensitivity, volume control, and noise-reduction settings, it is essential for the clinician and recipient to determine what combination is best for the individual over several sessions. The results of this study clearly show the advantage of using higher microphone sensitivity settings than the default MS 8 to provide better speech recognition for low-level stimuli. However, it was also necessary to adjust other parameters such as map C levels, automatic sensitivity control and base level, to optimize loudness comfort in the diversity of listening situations an individual encounters in everyday life.

12-month post-operative results for older children using sequential bilateral implants.

Within a long-term project investigating the perceptual benefits of bilateral implants, six children aged 5 to 15 yr received a second implant. Parent reports of functional performance were collected, and localization and spondee discrimination in noise was assessed. Outcomes varied from no benefit to significant benefit, although no improvement in localization was demonstrated. A major proportion of the benefit was likely due to headshadow effect. Success did not correlate with hearing aid use, age, time between implants, or second implant experience.

Cochlear implants for congenitally deaf adolescents: is open-set speech perception a realistic expectation?

The prognosis for benefit from use of cochlear implants in congenitally deaf adolescents, who have a long duration of profound deafness prior to implantation, has typically been low. Speech perception results for two congenitally deaf patients implanted as adolescents at the University of Melbourne/Royal Victorian Eye and Ear Hospital Clinic show that, after 12 months of experience, both patients had significant open-set speech discrimination scores without lipreading. These results suggest that although benefits may in general be low for congenitally deaf adolescents, individuals may attain significant benefits to speech perception after a short period of experience. Prospective patients from this group should therefore be considered on an individual basis with regard to prognosis for benefit from cochlear implantation.

Perception of sentences, words, and speech features by profoundly hearing‐impaired children using a multichannel electrotactile speech processor

Fourteen prelinguistically profoundly hearing-impaired children were fitted with the multichannel electrotactile speech processor (Tickle Talker) developed by Cochlear Pty. Ltd. and the University of Melbourne. Each child participated in an ongoing training and evaluation program, which included measures of speech perception and production. Results of speech perception testing demonstrate clear benefits for children fitted with the device. Thresholds for detection of pure tones were lower for the Tickle Talker than for hearing aids across the frequency range 250-4000 Hz, with the greatest tactual advantage in the high-frequency consonant range (above 2000 Hz). Individual and mean speech detection thresholds for the Ling 5-sound test confirmed that speech sounds were detected by the electrotactile device at levels consistent with normal conversational speech. Results for three speech feature tests showed significant improvement when the Tickle Talker was used in combination with hearing aids (TA) as compared with hearing aids along (A). Mean scores in the TA condition increased by 11% for vowel duration, 20% for vowel formant, and 25% for consonant manner as compared with hearing aids alone. Mean TA score on a closed-set word test (WIPI) was 48%, as compared with 32% for hearing aids alone. Similarly, mean WIPI score for the combination of Tickle Talker, lipreading, and hearing aids (TLA) increased by 6% as compared with combined lipreading and hearing aid (LA) scores. Mean scores on open-set sentences (BKB) showed a significant increase of 21% for the tactually aided condition (TLA) as compared with unaided (LA). These results indicate that, given sufficient training, children can utilize speech feature information provided through the Tickle Talker to improve discrimination of words and sentences. These results indicate that, given sufficient training, children can utilize speech feature information provided through the Tickle Talker to improve discrimination of words and sentences. These results are consistent with improvement in speech discrimination previously reported for normally hearing and hearing-impaired adults using the device. Anecdotal evidence also indicates some improvements in speech production for children fitted with the Tickle Talker.