Emergence of speech sounds between 7 and 24 months of cochlear implant use

Prelinguistic Consonant Production and the Influence of Mouthing Before and After Cochlear Implantation

OBJECTIVES

The goal of the study was to investigate prelinguistic consonant production and the influence of vocalizations that co-occurred with object mouthing on consonant production in infants with profound sensorineural hearing loss before and after cochlear implantation to advance knowledge of early speech development in infants with profound hearing loss.

DESIGN

Participants were 43 infants, 16 infants with profound sensorineural hearing loss and 27 hearing infants. In the mixed longitudinal and cross-sectional design, infants with profound hearing loss and age-matched hearing infants participated before cochlear implantation, at an average age of 9.9 mo, and/or after cochlear implantation, at an average age of 17.8 mo. Mean age at cochlear implantation for infants with profound hearing loss was 12.4 mo; mean duration of cochlear implant use at time of testing was 4.2 mo.

RESULTS

Before and after cochlear implantation, infants with profound hearing loss produced significantly fewer supraglottal consonants per consonant-vowel vocalization than hearing peers and had smaller overall consonant inventories. Before, but not after cochlear implantation, infants with profound hearing loss produced proportionally more vocalizations, supraglottal consonant-vowel vocalizations, and different supraglottal consonants in vocalizations during mouthing than did hearing infants.

CONCLUSIONS

The results document consonant production before cochlear implantation in a larger group of infants with profound hearing loss than previously examined. The results also extend evidence of early delays in consonant production to infants who received cochlear implants at 12 mo of age, and show that they likely miss the potential benefits of auditory-motor feedback in vocalization-mouthing combinations that occur before they have access to sound through cochlear implants.

Consonant and vowel production in the spontaneous speech productions of children with auditory brainstem implants

Auditory brainstem implantation provides hearing sensations in children and adults with anomalies of the auditory nerves. In children, perceptual benefits have been established, and research already demonstrated (limited) effects on children's speech production. The current study extends the literature by scrutinizing the phonological development of three children with ABI. Spontaneous speech samples were used to establish their phonemic inventories of vowels, word-initial consonants and word-final consonants, both independently of the target phoneme and relative to the target phoneme. The three children produced all vowels with longer device use and larger vocabulary size. Word-initial and word-final consonants appeared in the three children's spontaneous productions. However, the segmental accuracy was only moderate in the children's productions.

Glendonald Auditory Screening Procedure (GASP): clinical markers of the development of auditory recognition and comprehension abilities in children using cochlear implants

PURPOSE

To verify the influence of the age of implantation in the development of closed-set auditory recognition and auditory comprehension abilities in children using unilateral cochlear implants (CI), comparing distinct groups and determining clinical markers.

METHODS

Participants were 180 children operated and activated until 36 months of age and who used a CI for at least 60 months. Abilities of auditory recognition in closed-set and auditory comprehension were analyzed through the GASP Tests 5 and 6. The influence of age of implantation was investigated with three groups of children: implanted before 18 months (G1), between 19 and 24 months (G2) and between 25 and 36 months of age (G3).

RESULTS

There was no statistically significant difference when comparing the three groups. Children progressively developed auditory abilities, presenting auditory recognition ability together at approximately 41±4 months of CI use and auditory comprehension at 53±4 months.

CONCLUSION

There was no correlation between hearing performance and age of implantation for children implanted before 36 months of age. For the abilities of auditory recognition and comprehension, the clinical marker was 41±4 and 53±4 months of auditory age, respectively. Therefore, it is expected that, around 60 months of CI use, children implanted during the sensitive period can understand speech without the aid of orofacial reading, reaching the most complex hearing abilities.

Perception-Production Links in Children's Speech

Purpose Child phonologists have long been interested in how tightly speech input constrains the speech production capacities of young children, and the question acquires clinical significance when children with hearing loss are considered. Children with sensorineural hearing loss often show differences in the spectral and temporal structures of their speech production, compared to children with normal hearing. The current study was designed to investigate the extent to which this problem can be explained by signal degradation. Method Ten 5-year-olds with normal hearing were recorded imitating 120 three-syllable nonwords presented in unprocessed form and as noise-vocoded signals. Target segments consisted of fricatives, stops, and vowels. Several measures were made: 2 duration measures (voice onset time and fricative length) and 4 spectral measures involving 2 segments (1st and 3rd moments of fricatives and 1st and 2nd formant frequencies for the point vowels). Results All spectral measures were affected by signal degradation, with vowel production showing the largest effects. Although a change in voice onset time was observed with vocoded signals for /d/, voicing category was not affected. Fricative duration remained constant. Conclusions Results support the hypothesis that quality of the input signal constrains the speech production capacities of young children. Consequently, it can be concluded that the production problems of children with hearing loss-including those with cochlear implants-can be explained to some extent by the degradation in the signal they hear. However, experience with both speech perception and production likely plays a role as well.

Consonant Acquisition in Young Cochlear Implant Recipients and Their Typically Developing Peers

PURPOSE

Consonant acquisition was examined in 13 young cochlear implant (CI) recipients and 11 typically developing (TD) children.

METHOD

A longitudinal research design was implemented to determine the rate and nature of consonant acquisition during the first 2 years of robust hearing experience. Twenty-minute adult-child (typically a parent) interactions were video and audio recorded at 3-month intervals following implantation until 24 months of robust hearing experience was achieved. TD children were similarly recorded between 6 and 24 months of age. Consonants that were produced twice within a 50-utterance sample were considered "established" within a child's consonant inventory.

RESULTS

Although the groups showed similar trajectories, the CI group produced larger consonant inventories than the TD group at each interval except for 21 and 24 months. A majority of children with CIs also showed more rapid acquisition of consonants and more diverse consonant inventories than TD children.

CONCLUSIONS

These results suggest that early auditory deprivation does not significantly affect consonant acquisition for most CI recipients. Tracking early consonant development appears to be a useful way to assess the effectiveness of cochlear implantation in young recipients.

Word initial fricative production in children with cochlear implants and their normally hearing peers matched on lexicon size

Fricative production is affected in children with cochlear implants (CI) as compared to age-matched normally hearing (NH) children. However, the phonological development of children with CI is rarely compared to that of NH peers matched on lexicon size. We compare the early word initial fricative development of 10 children with CI and 30 NH children matched on lexicon size and on chronological age. Children with CI are expected to differ from their NH peers when they are matched on chronological age. But, are lexical development and phonological development commensurate in children with CI as they have been shown to be in NH children? Results show that fricative production in children with CI deviates from that of age-matched NH peers. The differences between both groups disappear when they were matched on lexicon size. Thus, phonological development in children with CI is similar to that of their NH peers with comparable lexicon sizes.