Maureen B. Higgins

Longitudinal changes in children's speech and voice physiology after cochlear implantation.

Objectives The purposes of this investigation were 1) to describe speech/voice physiological characteristics of prelingually deafened children before and after cochlear implantation and determine whether they fall into a range that would be considered deviant, 2) to determine whether selected deviant articulatory and phonatory behaviors of children with cochlear implants persist despite long-term cochlear implant use and continued participation in aural rehabilitation services, and 3) to determine whether further development of deviant articulatory and phonatory behaviors occurs postimplantation. Design Seven prelingually deafened children who received cochlear implants after 5 yr of age were followed from shortly before implantation until 5 to 6 yr postimplantation. These children received their early education in a Total Communication environment and used the Nucleus 22-electrode cochlear implant. All of them initially used the MPEAK speech processing strategy, and five of them eventually upgraded to the SPEAK speech processing strategy. Speech/voice physiological measurements that were obtained periodically from the children included intraoral air pressure (Po), nasal and phonatory air flow, voice onset time (VOT), and fundamental frequency (Fo). Data from the deaf children were compared with a database from 56 children with normal hearing to determine when the deaf children exhibited “deviant” speech/voice behaviors. Speech/voice behaviors were considered “deviant” if they never occurred for children with normal hearing or were associated with z-scores that were outside the range of ±2.0. Results The deaf children showed a wide range of deviant speech and voice behaviors both pre- and post-cochlear implant. The most frequently occurring atypical behaviors were use of negative Po, high Po for [b, m], long and short VOT for [p], and high Fo. Some deviant behaviors improved post-cochlear implant. However, deviant behaviors often persisted for several years post-cochlear implant. There was considerable evidence of further development of deviant behaviors post-cochlear implant. All of the deaf children demonstrated deviancy on at least two of our measures at the last data collection interval (5 to 6 yr post-cochlear implant). Conclusions Children who received cochlear implants after 5 yr of age and who were educated in a Total Communication setting showed persistence and further development of deviant speech/voice behaviors for several years post-cochlear implant. Although our findings cannot be generalized to other populations of children with cochlear implants (i.e., those who were implanted earlier, those educated in auditory-oral programs), it seems wisest at the present time not to assume that children’s deviant speech/voice behaviors will remit spontaneously with continued cochlear implant use. Our data provide an important comparative database for future investigations of pediatric cochlear implant users who have had shorter periods of auditory deprivation and who have received cochlear implants with more current technological features. Longitudinal Changes in Children’s Speech and Voice Physiology after Cochlear Implantation

Speech and voice physiology of children who are hard of hearing

Objective: The purpose of this investigation was to examine the nature and frequency of deviant speech and voice physiology in children who are hard of hearing (HH). Design: Ten HH children (age, 5 to 15 yrs) participated. Their hearing losses ranged in severity from moderate to severe. The following speech/voice physiological measures were examined: frequency of occurrence of negative intraoral air pressure (−Po), magnitude of Po, phonatory air flow, nasal air flow, voice onset time (VOT), and fundamental frequency (F0). Findings were compared with data previously collected from 56 children with normal hearing and 7 children with cochlear implants (Higgins, McCleary, Carney, & Schulte, 2003). Results: Five of the 10 HH children exhibited deviant speech/voice behaviors. Only one showed deviancy on more than one measure. In addition, 8 HH children had some borderline-deviant speech behavior. The frequency and degree of speech/voice deviancy for the children in the present study was far less than what we previously had observed for children who underwent cochlear implantation after 5 yrs of age (Higgins et al., 2003). This was the case even for a child with a cochlear implant from our earlier study who eventually achieved speech perception scores that were as good as or better than some of the HH children in the present investigation. Conclusions: Deviant speech/voice physiology occurs to a limited extent for some HH children. Of the measures that we examined, those related to vocal fold tension and vocal fold articulation appeared to be most sensitive to the effects of diminished auditory input and feedback that occurs for HH children. Data from this and other studies suggest that abnormally high F0 occurs for about 20% of HH children and may be associated with poor speech perception skills. Future studies should examine whether earlier implantation can help deaf children to produce speech that is at least as normal as that of HH children.

Articulatory changes with short-term deactivation of the cochlear implants of two prelingually deafened children.

Objective The purpose of this investigation was to determine how suddenly diminished auditory feedback affects articulatory behaviors for prelingually deafened children with cochlear implants (CIs). Design Two 6-yr-old children served as participants. Considering their level of hearing impairment, one child had above average speech perception and production skills while the other child had e-ceptionally good speech perception and production abilities. Baseline data were collected four times over the course of 2 days with the children wearing their CIs. For three additional days, data were collected while the children wore their CIs (ON condition) and then again after their CIs had been deactivated for 1 hr (OFF condition). Variables assessed included amount of jaw opening, F1, F2, nasal air flow, voice onset time (VOT), voicing duration, and the magnitude and duration of intraoral air pressure (Po). Findings were related to each other and to previously reported phonatory findings from the same two children (Higgins, McCleary, & Schulte, 1999) to determine whether changes in articulatory variables in the OFF condition were consistent with a direct effect of diminished auditory feedback or an indirect influence of suprasegmental parameters. Results Both children e-hibited consistent and significant changes in articulatory parameters in the absence of auditory feedback. Such changes occurred more often for the child who had especially proficient speech perception and production skills. Some changes (i.e., reduced Po for [p] and reduced nasal air flow for [m]) appeared related to the influence of suprasegmental parameters, in particular, reduced subglottal air pressure. Other effects (i.e., increased F2 for [|g] and reduced VOT for [p]) were suggestive of changes in the children’s abilities to maintain appropriate articulatory placements and timing. Finally, a few changes (reduced jaw opening for [i] and increased Po duration for [p]) may have reflected compensatory strategies to maintain correct tongue placement and enhance temporal distinctions in the absence of auditory feedback. Conclusions Based on the data of our two participants, it appears that some prelingually deafened children with CIs and good speech perception/production skills rely on auditory feedback to maintain articulatory precision. In the absence of auditory feedback, such children may demonstrate changes in articulatory placement and timing. In addition, data from one of our participants are consistent with the idea that some children may be aware that their articulatory control is compromised in the absence of auditory feedback and attempt to compensate by altering articulatory durations or the range of associated articulatory movements.

Altered phonatory physiology with short-term deactivation of children's cochlear implants.

OBJECTIVES The purposes of this investigation were 1) to determine whether short-term auditory deprivation results in systematic phonatory changes for prelingually deafened children who use cochlear implants (CIs) and 2) to determine whether such changes are similar to those that have been reported for postlingually deafened adults. DESIGN Participants were two 6-yr-old children with CIs. Both children had been prelingually deafened, had good to excellent speech production and speech perception skills, and had been using their CIs for 2.5 yr. A single-subject design was used. Intraoral air pressure (Po), phonatory air flow (Vl), electroglottograph (EGG) cycle width, fundamental frequency (F0), and intensity were measured during syllable production over two baseline days and three experimental days. Data were collected twice on each baseline day while the children wore their CIs, with a 1 hr break between data collection sessions. On experimental days, data were collected while the children wore their CIs (ON condition) and after their CIs had been removed for 1 hr (OFF condition). RESULTS Both children demonstrated highly variable phonatory behaviors in baseline. The child with the more proficient speech production and perception skills showed consistent and significant reductions in Po, F0, and intensity in the OFF condition. These findings were dissimilar to those that occurred with repeated testing in the baseline condition and so were attributed to the sudden loss of auditory feedback. The other child showed a consistent and significant increase in mean Vl in the OFF condition. However, this child exhibited a similar finding with repeated testing in the baseline condition. Therefore, increased Vl in the OFF condition may have represented a practice effect. She also showed a small and consistent decrease in F0 in the OFF condition when F0 was derived from acoustic data, but this effect was not reliable in another data set when F0 was derived from the EGG signal. Our results with prelingually deafened children were inconsistent with reports of increased intensity and F0 in the absence of auditory feedback for postlingually deafened adults with CIs. CONCLUSIONS Some prelingually deafened children who are successful CI users appear to use auditory feedback to self-monitor phonation. We suggest that the participant in our investigation who showed systematic phonatory changes in response to diminished auditory feedback was using auditory feedback primarily to stabilize her phonatory behaviors. She may not have had adequate experience with auditory feedback or adequate flexibility in her use of feedback mechanisms to implement the phonatory compensations that late-deafened adults use when auditory feedback suddenly is diminished. We further suggest that the phonatory changes that she exhibited during short-term auditory deprivation reflected disruption of her typical speaking strategies or apprehension about speaking when her ability to self-monitor auditorily was compromised.

Gender differences in vocal fold contact computed from electroglottographic signals: The influence of measurement criteria

EGGW is a phonatory parameter that can be derived from electroglottographic (EGG) signals and used to infer the relative degree of vocal fold contact. Vocal fold models predict that men will exhibit medial bulging of their vocal folds during phonation but women will not. These models lead us to expect gender differences in the magnitude of EGGW. Nevertheless, significant gender differences in EGGW for adults with normal voices have not been documented in previous studies when EGGW was computed from criterion lines placed at 25%-40% of the amplitude of the uninverted EGG wave form. We hypothesized that EGGW would better reflect gender differences in vocal fold adductory patterns if EGGW was computed from portions of the wave form that were associated with more vocal fold contact. EGGW was measured for seven men and seven women with normal voices. When EGGW was computed from segments of the wave form that were associated with relatively greater vocal fold contact (i.e., using criterion levels of > or = 55%), findings were consistent with the gender-specific adductory patterns that have been proposed from vocal fold models. Guidelines for appropriate placement of criterion lines when computing EGGW are discussed.

Use of Visual Feedback to Treat Negative Intraoral Air Pressures of Preschoolers With Cochlear Implants

The primary purpose of this study was to determine if negative intraoral air pressures (−Po) produced by young deaf children can be treated effectively with visual feedback. We used two forms of vi...

Acoustics of clear speech from children with normal hearing and cochlear implants

It is common among clinicians to ask children to produce their best speech during intervention. However, it is unclear whether children know how to respond to these directions and whether any contingent changes in their production actually result in better speech. Normal and best speech for children with normal hearing (NH) and cochlear implants (CI) were compared on a variety of acoustic measures. The children (7 to 14 years of age) were asked to read ten simple sentences to train up a fictional automatic speech recognizer for children. They subsequently produced the same sentences with their best and then very best, very clearest speech (ostensibly to test the recognizer). Sentence, pause, and vowel duration were calculated for all sentences as well as vowel intensity and fundamental frequency. Additionally, phonetic distinctiveness was evaluated through vowel space size and voice onset time differences between voiced and voiceless stops. NH children demonstrated patterns of best speech that resemble ad...

Strategies used to increase speech clarity by normal‐hearing children

It is common among clinicians to ask children to produce their best speech during intervention. However, it is unclear whether children know how to make their speech clearer. The strategies used by children with and without hearing loss have implications for maximizing intelligibility and for understanding the development of communication competency. As a first step toward this understanding, children (7 to 12 years of age) with normal hearing were asked to read ten simple sentences. They were told that they were testing a new computer program designed to recognize speech. There was, in fact, no recognition program and each child received the same output feedback. After providing normal speech to allow the program to get used to their voices, they subsequently produced their best and then very best, very clearest speech in order to see how accurate the recognition program could be. Acoustic analyses (intensity, fundamental and first two formant frequencies for all vowels, as well as sentence, vowel, and V...

Intelligibility and clarity of clear and conversational speech by children with implants and hearing aids

Studies of clear versus conversational speech have shown perceptual and acoustic differences. The basic premise is that the speaker understands the direction to speak more clearly, and translates the direction to speech motor acts. Children with hearing losses receive intervention during which they are instructed to use their best speech. The purpose of this study was to determine: (1) whether hearing‐impaired children’s intelligibility changed with directions to use better speech, and (2) whether these children’s speech was judged to be clearer when they had intended to produce clear speech. There were two groups of speakers: 14 deaf children with cochlear implants and 7 hard‐of‐hearing children with hearing aids. Each produced ten short sentences using typical speech, better speech, and best speech. All sentences were presented to a total of 189 adult listeners with normal hearing who wrote down what they heard. Hard‐of‐hearing children had average speech intelligibility of 98%; those with implants aver...