Amy S. Martinez

Speech recognition with reduced spectral cues as a function of age

Adult listeners are able to recognize speech even under conditions of severe spectral degradation. To assess the developmental time course of this robust pattern recognition, speech recognition was measured in two groups of children (5-7 and 10-12 years of age) as a function of the degree of spectral resolution. Results were compared to recognition performance of adults listening to the same materials and conditions. The spectral detail was systematically manipulated using a noise-band vocoder in which filtered noise bands were modulated by the amplitude envelope from the same spectral bands in speech. Performance scores between adults and older children did not differ statistically, whereas scores by younger children were significantly lower; they required more spectral resolution to perform at the same level as adults and older children. Part of the deficit in younger children was due to their inability to utilize fully the sensory information, and part was due to their incomplete linguistic/cognitive development. The fact that young children cannot recognize spectrally degraded speech as well as adults suggests that a long learning period is required for robust acoustic pattern recognition. These findings have implications for the application of auditory sensory devices for young children with early-onset hearing loss.

Speech Recognition at 1-Year Follow-Up in the Childhood Development after Cochlear Implantation Study: Methods and Preliminary Findings

The Childhood Development after Cochlear Implantation (CDaCI) study is a longitudinal multicenter investigation designed to identify factors influencing spoken language in young deaf children with cochlear implants. Normal-hearing peers serve as controls. As part of a comprehensive evaluation battery, a speech recognition hierarchy was designed to assess how well these children recognize speech stimuli across developmental stages. Data were analyzed for the earliest measures in 42 pairs of children reaching 1 year of follow-up. A number of children in the cochlear implant group who met criteria for testing approached levels of performance similar to the normal-hearing controls, and some could identify sentences in competition. These results demonstrate the responsiveness of the speech recognition hierarchy in tracking emergent skills from a sample of the CDaCI cohort.

Spoken word recognition development in children with residual hearing using cochlear implants and hearing AIDS in opposite ears.

Objective: With broadening candidacy criteria for cochlear implantation, a greater number of pediatric candidates have usable residual hearing in their nonimplanted ears. This population potentially stands to benefit from continued use of conventional amplification in their nonimplanted ears. The purposes of this investigation were to evaluate whether children with residual hearing in their nonimplanted ears benefit from bilateral use of cochlear implants and hearing aids and to investigate the time course of adaptation to combined use of the devices together. Design: Pediatric cochlear implant recipients with severe sensorineural hearing loss in their nonimplanted ears served as participants. Ten children continued to use hearing aids in their nonimplanted ears after cochlear implantation; 12 children used their cochlear implants exclusively. Participants were tested longitudinally on spoken word recognition measures at 6-month intervals. The children who continued wearing hearing aids were tested in three sensory aid conditions: cochlear implants alone, hearing aids alone, and cochlear implants in conjunction with hearing aids. The children who did not continue hearing aid use were tested after surgery in their only aided condition, cochlear implant alone. Results: The results suggest that children with severe hearing loss who continued using hearing aids in their nonimplanted ears benefited from combining the acoustic input received from a hearing aid with the input received from a cochlear implant, particularly in background noise. However, this benefit emerged with experience. Conclusions: Our findings suggest that it is appropriate to encourage pediatric cochlear implant recipients with severe hearing loss to continue wearing an appropriately fitted hearing aid in the nonimplanted ear to maximally benefit from bilateral stimulation.

Comprehensive Evaluation of a Child With an Auditory Brainstem Implant

Objective: We had an opportunity to evaluate an American child whose family traveled to Italy to receive an auditory brainstem implant (ABI). The goal of this evaluation was to obtain insight into possible benefits derived from the ABI and to begin developing assessment protocols for pediatric clinical trials. Study Design: Case study. Setting: Tertiary referral center. Patient: Pediatric ABI Patient 1 was born with auditory nerve agenesis. Auditory brainstem implant surgery was performed in December, 2005, in Verona, Italy. The child was assessed at the House Ear Institute, Los Angeles, in July 2006 at the age of 3 years 11 months. Follow-up assessment has continued at the HEAR Center in Birmingham, Alabama. Intervention: Auditory brainstem implant. Main Outcome Measures: Performance was assessed for the domains of audition, speech and language, intelligence and behavior, quality of life, and parental factors. Results: Patient 1 demonstrated detection of sound, speech pattern perception with visual cues, and inconsistent auditory-only vowel discrimination. Language age with signs was approximately 2 years, and vocalizations were increasing. Of normal intelligence, he exhibited attention deficits with difficulty completing structured tasks. Twelve months later, this child was able to identify speech patterns consistently; closed-set word identification was emerging. These results were within the range of performance for a small sample of similarly aged pediatric cochlear implant users. Conclusion: Pediatric ABI assessment with a group of well-selected children is needed to examine risk versus benefit in this population and to analyze whether open-set speech recognition is achievable.

Relationships between speech perception abilities and spoken language skills in young children with hearing loss

The goal of this study was to examine the relationships between scores obtained from measures of speech perception and language in a group of young children with hearing loss (HL). Eighteen children (mean age = 4.3 years) and their mothers participated in this study. Speech perception was measured using the online imitative test of speech pattern contrast perception (OLIMSPAC). Standardized language age equivalent scores were obtained using the Reynell developmental language scales-III. Number of word tokens, word types, and mean length of utterance (MLU) were extracted from the childrens spontaneous language samples. Significant positive relationships were observed between childrens OLIMSPAC scores and both standardized language scores (r ranging from 0.60 to 0.69; p <0.01) and all measures derived from childrens spontaneous language samples (r ranging from 0.80 to 0.86; p<0.01). After controlling for child age, OLIMSPAC scores explained 34.1% of the variance in childrens MLU. Using a new speech perception measure with reduced language demands, strong positive correlations were evident between speech perception and language skills for a young group of children with HL.

Improvements in visual attention in deaf infants and toddlers after cochlear implantation

The aims of this study were to examine the development of visual attention in deaf and hearing infants and toddlers, and assess whether improvements in visual attention were observed in the deaf sample after 12 months of cochlear implantation. A novel puppet task, based on a measure of attention developed with normally hearing infants, was administered to 88 deaf and 42 normal-hearing children at three time points: baseline, six and 12 months post-implantation for the deaf sample. At baseline, deaf children demonstrated significantly more inattentive looks during the puppet skits than hearing children, and these looks were of longer duration, confirming the results of prior studies which have documented deficits in visual attention in deaf children. Longitudinal analyses showed significant decreases in the frequency of inattentive looks for both groups, with a significant decrease in the duration of inattentive looks only for the cochlear implant group. The largest decrease in duration of off-task looks occurred at six months post-implantation, indicating that improvements occurred rapidly after restoration of auditory input. These results provided support for the ‘division of labor’ hypothesis which suggests that deaf children with no access or limited access to sound must monitor their environment visually, making it difficult for them to focus and attend to specific tasks. Cochlear implantation appeared to alter the developmental trajectory of visual attention in a positive manner. The clinical implications of visual attention for the development of early language, reading and social skills are discussed.

Clinical Performance of Children Following Revision Surgery for a Cochlear Implant

OBJECTIVES: The purpose of this study was to describe the causes for revision surgery and to compare clinical performance before and after surgery in children who required electrode reinsertion. STUDY DESIGN AND SETTINGS: Soundfield thresholds and speech recognition scores were compared before device failure and following electrode reinsertion. Temporal bones from a deceased adult implant user who underwent bilateral revision implantation were analyzed. RESULTS: Histopathology in the adult temporal bones revealed new bone formation in the scala tympani and substantially reduced spiral ganglion counts, with open-set speech recognition realized. Of 28 children undergoing revision surgery, 18 required electrode reinsertion. With the exception of 1 patient with severe cochlear malformation, new electrode arrays were fully inserted without difficulty. Clinical outcomes between pre-device failure and post-electrode reinsertion did not differ statistically. CONCLUSION AND SIGNIFICANCE: Electrode reinsertion is technically feasible in the pediatric population. The majority of children recover their prerevision clinical performance.

Studies in Pediatric Hearing Loss at the House Research Institute

Three clinical research projects are described that are relevant to pediatric hearing loss. The three projects fall into two distinct areas. The first area emphasizes clinical studies that track developmental outcomes in children with hearing loss; one project is specific to cochlear implants and the other to hearing aids. The second area addresses speech perception test development for very young children with hearing loss. Although these two lines of research are treated as separate areas, they begin to merge as new behavioral tests become useful in developing protocols for contemporary studies that address longitudinal follow-up of children with hearing loss.

Establishing new criteria in selecting children for a cochlear implant: performance of "platinum" hearing aid users.

The Figure, B, shows a similar depiction of speech perception and intelligibility scores for the children using simultaneous communication. Note the greater variation in performance of the group: some children have high speech intelligibility and speech perception scores, while other children have limited intelligibility and speech perception abilities. Also note that at least 1 child has very good speech perception scores with only limited speech intelligibility.

Electric charge requirements of pediatric cochlear implant recipients enrolled in the childhood development after cochlear implantation study

Objective: To evaluate mapping characteristics of children with cochlear implants who are enrolled in the Childhood Development After Cochlear Implantation (CDACI) multicenter study. Study Design: Longitudinal evaluation during 24 months of speech processor maps of children with cochlear implants prospectively enrolled in the study. Setting: Six tertiary referral centers. Subjects: One hundred eighty-eight children enrolled in the CDACI study who were 5 years old or younger at the time of enrollment. Of these children, 184 received unilateral implants, and 4 received simultaneous bilateral implants. Intervention: Children attended regular mapping sessions at their implant clinic as part of the study protocol. Maps were examined for each subject at 4 different time intervals: at device activation and 6, 12, and 24 months postactivation. Main Outcome Measures: Mean C/M levels (in charge per phase) were compared for 4 different time intervals, for 3 different devices, for 6 different implant centers, and for children with normal and abnormal cochleae. Results: All 3 types of implant devices demonstrate significant increases in C/M levels between device activation and the 24-month appointment. Significant differences in mean C/M levels were noted between devices. Children with cochlear anomalies demonstrate significantly greater C/M levels than children with normal cochleae. Conclusion: The CDACI study has enabled us to evaluate the mapping characteristics of pediatric patients who use 3 different devices and were implanted at a variety of implant centers. Analysis of such data enables us to better understand the mapping characteristics of children with cochlear implants.