The everyday speech environments of preschoolers with and without cochlear implants.

Children who receive cochlear implants develop spoken language on a protracted timescale. The home environment facilitates speech-language development, yet it is relatively unknown how the environment differs between children with cochlear implants and typical hearing. We matched eighteen preschoolers with implants (31-65 months) to two groups of children with typical hearing: by chronological age and hearing age. Each child completed a long-form, naturalistic audio recording of their home environment (appx. 16 hours/child; >730 hours of observation) to measure adult speech input, child vocal productivity, and caregiver-child interaction. Results showed that children with cochlear implants and typical hearing were exposed to and engaged in similar amounts of spoken language with caregivers. However, the home environment did not reflect developmental stages as closely for children with implants, or predict their speech outcomes as strongly. Home-based speech-language interventions should focus on the unique input-outcome relationships for this group of children with hearing loss.

Preschoolers rely on rich speech representations to process variable speech.

To learn language, children must map variable input to categories such as phones and words. How do children process variation and distinguish between variable pronunciations ("shoup" for soup) versus new words? The unique sensory experience of children with cochlear implants, who learn speech through their device's degraded signal, lends new insight into this question. In a mispronunciation sensitivity eyetracking task, children with implants (N = 33), and typical hearing (N = 24; 36-66 months; 36F, 19M; all non-Hispanic white), with larger vocabularies processed known words faster. But children with implants were less sensitive to mispronunciations than typical hearing controls. Thus, children of all hearing experiences use lexical knowledge to process familiar words but require detailed speech representations to process variable speech in real time.

Acoustic-Lexical Characteristics of Child-Directed Speech Between 7 and 24 Months and Their Impact on Toddlers' Phonological Processing.

Speech-language input from adult caregivers is a strong predictor of children's developmental outcomes. But the properties of this child-directed speech are not static over the first months or years of a child's life. This study assesses a large cohort of children and caregivers (n = 84) at 7, 10, 18, and 24 months to document (1) how a battery of phonetic, phonological, and lexical characteristics of child-directed speech changes in the first 2 years of life and (2) how input at these different stages predicts toddlers' phonological processing and vocabulary size at 2 years. Results show that most measures of child-directed speech do change as children age, and certain characteristics, like hyperarticulation, actually peak at 24 months. For language outcomes, children's phonological processing benefited from exposure to longer (in phonemes) words, more diverse word types, and enhanced coarticulation in their input. It is proposed that longer words in the input may stimulate children's phonological working memory development, while heightened coarticulation simultaneously introduces important sublexical cues and exposes them to challenging, naturalistic speech, leading to overall stronger phonological processing outcomes.

Auditory feedback experience in the development of phonetic production: Evidence from preschoolers with cochlear implants and their normal-hearing peers.

Previous work has found that preschoolers with greater phonological awareness and larger lexicons, who speak more throughout the day, exhibit less intra-syllabic coarticulation in controlled speech production tasks. These findings suggest that both linguistic experience and speech-motor control are important predictors of spoken phonetic development. Still, it remains unclear how preschoolers' speech practice when they talk drives the development of coarticulation because children who talk more are likely to have both increased fine motor control and increased auditory feedback experience. Here, the potential effect of auditory feedback is studied by examining a population-children with cochlear implants (CIs)-which is naturally differing in auditory experience. The results show that (1) developmentally appropriate coarticulation improves with an increased hearing age but not chronological age; (2) children with CIs pattern coarticulatorily closer to their younger, hearing age-matched peers than chronological age-matched peers; and (3) the effects of speech practice on coarticulation, measured using naturalistic, at-home recordings of the children's speech production, only appear in the children with CIs after several years of hearing experience. Together, these results indicate a strong role of auditory feedback experience on coarticulation and suggest that parent-child communicative exchanges could stimulate children's own vocal output, which drives speech development.

Practice and experience predict coarticulation in child speech.

Much research in child speech development suggests that young children coarticulate more than adults. There are multiple, not mutually-exclusive, explanations for this pattern. For example, children may coarticulate more because they are limited by immature motor control. Or they may coarticulate more if they initially represent phonological segments in larger, more holistic units such as syllables or feet. We tested the importance of several different explanations for coarticulation in child speech by evaluating how four-year-olds' language experience, speech practice, and speech planning predicted their coarticulation between adjacent segments in real words and paired nonwords. Children with larger vocabularies coarticulated less, especially in real words, though there were no reliable coarticulatory differences between real words and nonwords after controlling for word duration. Children who vocalized more throughout a daylong audio recording also coarticulated less. Quantity of child vocalizations was more predictive of the degree of children's coarticulation than a measure of receptive language experience, adult word count. Overall, these results suggest strong roles for children's phonological representations and speech practice, as well as their immature fine motor control, for coarticulatory development.

African American English and Early Literacy: A Comparison of Approaches to Quantifying Nonmainstream Dialect Use.

Purpose Many studies have found a correlation between overall usage rates of nonmainstream forms and reading scores, but less is known about which dialect differences are most predictive. Here, we consider different methods of characterizing African American English use from existing assessments and examine which methods best predict literacy achievement. Method Kindergarten and first-grade students who speak African American English received two assessments of dialect use and two assessments of decoding at the beginning and end of the school year. Item-level analyses of the dialect-use assessments were used to compute measures of dialect usage: (a) an overall feature rate measure based on the Diagnostic Evaluation of Language Variation-Screening Test, (b) a subscore analysis of the Diagnostic Evaluation of Language Variation-Screening Test based on items that pattern together, (c) an alternative assessment where children repeat and translate sentences, and (d) "repertoire" measures based on a categorical distinction of whether a child used a particular feature of mainstream American English. Results Models using feature rate measures provided better data-model fit than those with repertoire measures, and baseline performance on a sentence repetition task was a positive predictor of reading score at the end of the school year. For phonological subscores, change from the beginning to end of the school year predicted reading at the end of the school year, whereas baseline scores were most predictive for grammatical subscores. Conclusions The addition of a sentence imitation task is useful for understanding a child's dialect and anticipating potential areas for support in early literacy. We observed some support for the idea that morphological dialect differences (i.e., irregular verb morphology) have a particularly close tie to later literacy, but future work will be necessary to confirm this finding. Supplemental Material https://doi.org/10.23641/asha.13425968.

Relationship between early phonological processing and later phonological awareness: Evidence from nonword repetition.

This study investigated whether individual differences in vocabulary size, speech perception and production, and nonword repetition in 2½ to 3-year-old children predicted phonological awareness two years later. One hundred twenty-two children were tested twice. During the first testing period, we measured children's receptive vocabulary, speech perception, nonword repetition, and articulation. At the second testing period, we measured children's phonological awareness. The best predictors of phonological awareness at age 5 were receptive vocabulary and a measure of phonological processing derived from performance on the nonword repetition task. The results of this study suggest that nonword repetition accuracy can be used to index implicit phonological awareness at an age when children are too young to perform explicit phonological awareness tasks reliably.

Assessing Fine-Grained Speech Discrimination in Young Children With Bilateral Cochlear Implants.

HYPOTHESIS: Children of 2 to 3 years old with cochlear implants can perform consonant discriminations using fine-grained acoustic cues. BACKGROUND: Children born with severe-to-profound deafness are provided with early cochlear implantation (<2 yr) to maximize oral communication outcomes. Little is known regarding their abilities to discriminate consonant contrasts for accurately identifying speech sounds. METHODS: Using a Reaching for Sound paradigm to collect behavioral responses, consonant contrast discrimination was measured in 13 children with bilateral cochlear implants (BiCIs; aged 28-37 mo), and 13 age-matched normal-hearing (NH) children. Four contrast pairs were tested: 1) place + voicing, 2) place, 3) voicing, and 4) reduced voice-onset-time cue. Using standard processing strategies, electrodograms showing pulsatile stimulation patterns were created retrospectively to assess the spectral-temporal cues delivered through the clinical speech processors. RESULTS: As a group, children with BiCIs were able to discriminate all consonant contrasts at a level that was above chance, but their performance was poorer than NH children. Larger individual variability in discrimination performance was found in children with BiCIs. Stepwise regression revealed that, in the place contrast, chronological age was correlated with improved discrimination performance among children with BiCIs. CONCLUSION: Children with BiCIs were able to discriminate consonant contrasts using fine-grained spectral-temporal cues above chance level but more poorly than their NH peers. Electrodogram analysis confirmed the access to spectral-temporal cues in the consonant contrasts through clinical speech processors. However, the cue saliency might not have be enough for children with BiCIs to achieve the same discrimination accuracy as NH children.

Spectral and temporal measures of coarticulation in child speech.

Speech produced by children is characterized by a high fundamental frequency which complicates measurement of vocal tract resonances, and hence coarticulation. Here two whole-spectrum measures of coarticulation are validated, one temporal and one spectral, that are less sensitive to these challenges. Using these measures, consonant-vowel coarticulation is calculated in the speech of a large sample of 4-year-old children. The measurements replicate known lingual coarticulatory findings from the literature, demonstrating the utility of these acoustic measures of coarticulation in speakers of all ages.

Quantifying robustness of the /t/-/k/ contrast using a single, static spectral feature.

Dynamic spectral shape features accurately classify /t/ and /k/ productions across speakers and contexts. This paper shows that word-initial /t/ and /k/ tokens produced by 21 adults can be differentiated using a single, static spectral feature when spectral energy concentration is considered relative to expectations within a given speaker and vowel context. Centroid and peak frequency-calculated from both acoustic and psychoacoustic spectra-were compared to determine whether one feature could reliably differentiate /t/ and /k/, and, if so, which feature best differentiated them. Centroid frequency from both acoustic and psychoacoustic spectra accurately classified productions of /t/ and /k/.

The Acoustics of Word-Initial Fricatives and Their Effect on Word-Level Intelligibility in Children With Bilateral Cochlear Implants.

OBJECTIVES: Previous research has found that relative to their peers with normal hearing (NH), children with cochlear implants (CIs) produce the sibilant fricatives /s/ and /∫/ less accurately and with less subphonemic acoustic contrast. The present study sought to further investigate these differences across groups in two ways. First, subphonemic acoustic properties were investigated in terms of dynamic acoustic features that indexed more than just the contrast between /s/ and /∫/. Second, the authors investigated whether such differences in subphonemic acoustic contrast between sibilant fricatives affected the intelligibility of sibilant-initial single word productions by children with CIs and their peers with NH. DESIGN: In experiment 1, productions of /s/ and /∫/ in word-initial prevocalic contexts were elicited from 22 children with bilateral CIs (aged 4 to 7 years) who had at least 2 years of CI experience and from 22 chronological age-matched peers with NH. Acoustic features were measured from 17 points across the fricatives: peak frequency was measured to index the place of articulation contrast; spectral variance and amplitude drop were measured to index the degree of sibilance. These acoustic trajectories were fitted with growth-curve models to analyze time-varying spectral change. In experiment 2, phonemically accurate word productions that were elicited in experiment 1 were embedded within four-talker babble and played to 80 adult listeners with NH. Listeners were asked to repeat the words, and their accuracy rate was used as a measure of the intelligibility of the word productions. Regression analyses were run to test which acoustic properties measured in experiment 1 predicted the intelligibility scores from experiment 2. RESULTS: The peak frequency trajectories indicated that the children with CIs produced less acoustic contrast between /s/ and /∫/. Group differences were observed in terms of the dynamic aspects (i.e., the trajectory shapes) of the acoustic properties. In the productions by children with CIs, the peak frequency and the amplitude drop trajectories were shallower, and the spectral variance trajectories were more asymmetric, exhibiting greater increases in variance (i.e., reduced sibilance) near the fricative-vowel boundary. The listeners' responses to the word productions indicated that when produced by children with CIs, /∫/-initial words were significantly more intelligible than /s/-initial words. However, when produced by children with NH, /s/-initial words and /∫/-initial words were equally intelligible. Intelligibility was partially predicted from the acoustic properties (Cox & Snell pseudo-R > 0.190), and the significant predictors were predominantly dynamic, rather than static, ones. CONCLUSIONS: Productions from children with CIs differed from those produced by age-matched NH controls in terms of their subphonemic acoustic properties. The intelligibility of sibilant-initial single-word productions by children with CIs is sensitive to the place of articulation of the initial consonant (/∫/-initial words were more intelligible than /s/-initial words), but productions by children with NH were equally intelligible across both places of articulation. Therefore, children with CIs still exhibit differential production abilities for sibilant fricatives at an age when their NH peers do not.

A Prekindergarten Curriculum Supplement for Enhancing Mainstream American English Knowledge in Nonmainstream American English Speakers.

PURPOSE: The purpose of this study was to evaluate the efficacy of a curriculum supplement designed to enhance awareness of Mainstream American English (MAE) in African American English- (AAE-) speaking prekindergarten children. METHOD: Children in 2 Head Start classrooms participated in the study. The experimental classroom received the Talking and Learning for Kindergarten program (Edwards, Rosin, Gross, & Chen, 2013), which used contrastive analysis to highlight morphological, phonological, and pragmatic differences between MAE and AAE. The control classroom received the Kindness Curriculum (Flook, Goldberg, Pinger, & Davidson, 2014), which was designed to promote mindfulness and emotional self-regulation. The amount of instruction was the same across the 2 programs. Both classrooms participated in pre- and posttest assessments. RESULTS: Children in the experimental classroom, but not the control classroom, showed significant improvement in 3 norm-referenced measures of phonological awareness and in an experimental measure that evaluated comprehension of words that are ambiguous in AAE, but unambiguous in MAE, because of morphological and phonological differences between the 2 dialects. CONCLUSION: Although more research needs to be done on the efficacy of the Talking and Learning for Kindergarten program, these results suggest that it is possible to enhance AAE-speaking children's awareness of MAE prior to kindergarten entry.

Effects of Vocabulary Size on Online Lexical Processing by Preschoolers.

This study was designed to investigate the relationship between vocabulary size and the speed and accuracy of lexical processing in preschoolers between the ages of 30-46 months using an automatic eye tracking task based on the looking-while-listening paradigm (Fernald, Zangl, Portillo, & Marchman, 2008) and mispronunciation paradigm (White & Morgan, 2008). Children's eye gaze patterns were tracked while they looked at two pictures (one familiar object, one unfamiliar object) on a computer screen and simultaneously heard one of three kinds of auditory stimuli: correct pronunciations of the familiar object's name, one-feature mispronunciations of the familiar object's name, or a nonword. The results showed that children with larger expressive vocabularies, relative to children with smaller expressive vocabularies, were more likely to look to a familiar object upon hearing a correct pronunciation and to an unfamiliar object upon hearing a novel word. Results also showed that children with larger expressive vocabularies were more sensitive to mispronunciations; they were more likely to look toward the unfamiliar object rather than the familiar object upon hearing a one-feature mispronunciation of a familiar object-name. These results suggest that children with smaller vocabularies, relative to their larger-vocabulary age peers, are at a disadvantage for learning new words, as well as for processing familiar words.

Impact of dialect use on a basic component of learning to read.

Can some black-white differences in reading achievement be traced to differences in language background? Many African American children speak a dialect that differs from the mainstream dialect emphasized in school. We examined how use of alternative dialects affects decoding, an important component of early reading and marker of reading development. Behavioral data show that use of the alternative pronunciations of words in different dialects affects reading aloud in developing readers, with larger effects for children who use more African American English (AAE). Mechanisms underlying this effect were explored with a computational model, investigating factors affecting reading acquisition. The results indicate that the achievement gap may be due in part to differences in task complexity: children whose home and school dialects differ are at greater risk for reading difficulties because tasks such as learning to decode are more complex for them.

The Impact of Auditory Spectral Resolution on Listening Effort Revealed by Pupil Dilation.

OBJECTIVES: This study measured the impact of auditory spectral resolution on listening effort. Systematic degradation in spectral resolution was hypothesized to elicit corresponding systematic increases in pupil dilation, consistent with the notion of pupil dilation as a marker of cognitive load. DESIGN: Spectral resolution of sentences was varied with two different vocoders: (1) a noise-channel vocoder with a variable number of spectral channels; and (2) a vocoder designed to simulate front-end processing of a cochlear implant, including peak-picking channel selection with variable synthesis filter slopes to simulate spread of neural excitation. Pupil dilation was measured after subject-specific luminance adjustment and trial-specific baseline measures. Mixed-effects growth curve analysis was used to model pupillary responses over time. RESULTS: For both types of vocoder, pupil dilation grew with each successive degradation in spectral resolution. Within each condition, pupillary responses were not related to intelligibility scores, and the effect of spectral resolution on pupil dilation persisted even when only analyzing trials in which responses were 100% correct. CONCLUSIONS: Intelligibility scores alone were not sufficient to quantify the effort required to understand speech with poor resolution. Degraded spectral resolution results in increased effort required to understand speech, even when intelligibility is at 100%. Pupillary responses were a sensitive and highly granular measurement to reveal changes in listening effort. Pupillary responses might potentially reveal the benefits of aural prostheses that are not captured by speech intelligibility performance alone as well as the disadvantages that are overcome by increased listening effort.

Voiced stop prenasalization in two dialects of Greek.

This study examined the phonetic realization of voiced stops in the Cretan and Thessalonikan dialects of Modern Greek. Six males and six females of each dialect were recorded in a sentence-reading task. Duration and amplitude were measured to compare the degree of nasality of voiced stops to that of nasals in different phonetic contexts. Results showed that amplitude changes during the voicing bar of the voiced stops varied both within and across speakers. In some instances, there was consistently low amplitude throughout the voicing bar (characteristic of voiced stops), whereas in other instances, there was high amplitude at the closure onset followed by decreasing amplitude toward the burst (characteristic of prenasalization). By contrast, nasals had consistently high amplitude throughout the murmur. The mixed-effects models suggest that there were complex and interactive influences of dialect, gender, prosodic position, and stress in realizing prenasality in the voiced stops. In particular, Cretan male speakers showed the least clear tendency of prenasalization consistent with earlier impressionistic studies. Furthermore, productions of Cretan males showed less prenasalization than those of females in both prosodic positions. The procedures in this study can be used to describe prenasalization in other dialects or languages where prenasalization has been observed.

Adapting a receptive vocabulary test for preschool-aged Greek-speaking children.

BACKGROUND: Receptive vocabulary is an important measure for language evaluations. Therefore, norm-referenced receptive vocabulary tests are widely used in several languages. However, a receptive vocabulary test has not yet been normed for Modern Greek. AIMS: To adapt an American English vocabulary test, the Receptive One-Word Picture Vocabulary Test-II (ROWPVT-II), for Modern Greek for use with Greek-speaking preschool children. METHODS & PROCEDURES: The list of 170 English words on ROWPVT-II was adapted by (1) developing two lists (A and B) of Greek words that would match either the target English word or another concept corresponding to one of the pictured objects in the four-picture array; and (2) determining a developmental order for the chosen Greek words for preschool-aged children. For the first task, adult word frequency measures were used to select the words for the Greek wordlist. For the second task, 427 children, 225 boys and 202 girls, ranging in age from 2;0 years to 5;11 years, were recruited from urban and suburban areas of Greece. A pilot study of the two word lists was performed with the aim of comparing an equal number of list A and list B responses for each age group and deriving a new developmental list order. OUTCOMES & RESULTS: The relative difficulty of each Greek word item, that is, its accuracy score, was calculated by taking the average proportion of correct responses across ages for that word. Subsequently, the word accuracy scores in the two lists were compared via regression analysis, which yielded a highly significant relationship (R(2) = 0.97; p < 0.0001) and a few outlier pairs (via residuals). Further analysis used the original relative ranking order along with the derived ranking order from the average accuracy scores of the two lists in order to determine which word item from the two lists was a better fit. Finally, new starting levels (basals) were established for preschool ages. CONCLUSIONS & IMPLICATIONS: The revised word list can serve as the basis for adapting a receptive vocabulary test for Greek preschool-aged children. Further steps need to be taken when testing larger numbers of 2;0 to 5;11-year-old children on the revised word list for determination of norms. This effort will facilitate early identification and remediation of language disorders in Modern Greek-speaking children.

Production of contrast between sibilant fricatives by children with cochlear implants.

Speech production by children with cochlear implants (CIs) is generally less intelligible and less accurate on a phonemic level than that of normally hearing children. Research has reported that children with CIs produce less acoustic contrast between phonemes than normally hearing children, but these studies have included correct and incorrect productions. The present study compared the extent of contrast between correct productions of /s/ and /∫/ by children with CIs and two comparison groups: (1) normally hearing children of the same chronological age as the children with CIs and (2) normally hearing children with the same duration of auditory experience. Spectral peaks and means were calculated from the frication noise of productions of /s/ and /∫/. Results showed that the children with CIs produced less contrast between /s/ and /∫/ than normally hearing children of the same chronological age and normally hearing children with the same duration of auditory experience due to production of /s/ with spectral peaks and means at lower frequencies. The results indicate that there may be differences between the speech sounds produced by children with CIs and their normally hearing peers even for sounds that adults judge as correct.