Dissertation (MMus (Performing Art))--University of Pretoria, 2002. / Music / unrestricted

A great deal of evidence suggests that parental communication and involvement are essential for the development of language in young children. However, hearing parents of deaf children face unique challenges in providing appropriate stimulation and language input to their deaf children. To date, few studies have determined which types of input are best. This study utilized data collected from the largest, youngest, nationally representative sample of deaf children receiving cochlear implants. The purpose of this study was to identify the facilitative language techniques that are most effective in facilitating receptive and expressive language development in young deaf children. Ninety-three deaf children, ages 2 years and under were enrolled at six implant centers. Deaf children were assessed prior to implantation and then followed for three years post-implantation. At each assessment, parent-child interactions were videotaped in an unstructured Free Play and structured Art Gallery task. All parent and child speech, vocalizations, and sign language were transcribed from the 10 minute videotaped parent-child interactions and coded using the Parenting Strategies for Communication coding system. Results revealed that the most frequently used lower-level strategies used by parents were directives, comments, and close-ended questions. The most frequently used higher-level strategies were parallel talk, open-ended questions, and recast. In addition, the Art Gallery task facilitated more parent utterances and longer mean length of utterances compared to Free Play, but the frequency of facilitative language techniques was not different. Using bivariate latent difference score modeling, higher-level strategies predicted growth in expressive language scores across three years post-implantation. Further, higher-level strategies had a delayed effect on receptive language, with techniques used at 24 months post-implantation predicting growth in receptive language at 36 months post-implantation. These results suggested that parent's play an active role in facilitating their child's language development. Interventions for parents should be developed using a coaching model, where parents receive hands-on training and practice using these effective facilitative language techniques. Future studies should evaluate the effectiveness of this intervention, as well as the effectives of these language techniques in children implanted after 2 years of age.

The audiological characteristics of the Monge family of Costa Rica were investigated in a sample of fifty-two affected members and twelve unaffected members. Through laboratory analysis by staff personnel from the University of Costa Rica and audiological test results obtained in the present investigation, it was concluded that affected Monge members demonstrate a slowly progressive low frequency sensorineural hearing loss of autosomal dominant transmission. The initial site of lesion appears to be the apical portion of the cochlea, with significant onset occurring during early childhood following normal speech and language acquisition. The rate at which the hearing loss progresses and the frequency regions affected are contingent upon chronological age, culminating in a flat profound hearing impairment by age thirty for all affected members.

Our ability to be active agents in the world depends on our cognitive system to collect complex multisensory information, i.e. information coming from different senses, and integrate it appropriately. One fundamental topic of interest in the study of cognition is to understand the consequences of deafness on the organization of brain functions, specifically when one sensory modality is either lost or the information coming from that sensory modality is limited. In my work I used the spatial cueing paradigm to study how visual attention and selection is affected by diverse grades of congenital or acquired deafness in different life stages. The goal of the first study was to validate an integrated approach of covert and overt orienting to study social and non-social cueing of attention in hearing adults. Specifically, I examined manual and oculomotor performance of hearing observers performing a peripheral discrimination task with uninformative social (gaze cue) and non-social cues (arrow cue). In Experiment 1 the discrimination task was easy and eye movements were not necessary, whereas in Experiment 2 they were instrumental in identifying the target. Validity effects on manual response time (RT) were similar for the two cues in Experiment 1 and in Experiment 2, though in the presence of eye movements, observers were overall slower to respond to the arrow cue compared to the gaze cue. Cue-direction had an effect on saccadic performance before the discrimination was presented and throughout the duration of the trial. Furthermore, I found evidence of a distinct impact of the type of cue on diverse oculomotor components. While saccade latencies were affected by whether the cue was social or not, saccade landing positions were not affected by cue-type. Critically, the manual validity effect was predicted by the landing position of the initial eye movement. This work suggests that the relationship between eye movements and attention is not straightforward. In hearing adults, in the presence of eye movements, saccade latency was related to the overall speed of manual response, while eye movements landing position was closely related to manual performance in response to the validity of the cues. In the second study, I used the above-mentioned approach to investigate the impact of early profound deafness on the oculomotor control and orienting of attention to social and non-social cues. Previous research on covert orienting to the periphery suggests that early deaf adults are less sensitive to uninformative gaze cues, though were equally or more affected by non-social arrow cues. The aim of this second study was to investigate whether spontaneous eye movement behavior helps explain the reduced contribution of this social cue in deaf adults. Twenty-five deaf and twenty-five age-matched hearing observers took part in the experiment. In both groups, the cueing effect on RT was comparable for the gaze- and arrow-cue, although deaf observers responded significantly slower than hearing controls. While deaf and hearing observers responded equally to the cue presented in isolation, deaf participants relied significantly more on eye movements than hearing controls once the discrimination target was presented. Saccade landing position in the deaf group was affected by validity but not by cue type while latency was not modulated by these factors. Saccade landing position was also strongly related to the magnitude of the validity effect on RT, such that the greater the difference in saccade landing position between invalid and valid trials, the greater the difference in manual RT between invalid and valid trials. This work suggests that the contribution of overt selection in central cueing of attention is more prominent in deaf adults and determines the manual performance. The increase in eye movements and overall slower responses in deaf observers may act as an adaptive strategy to balance the need for accuracy in a context where vision and visual attention are used to monitor the surrounding environment in the absence of auditory input. This tendency to emphasize accuracy of response at the cost of responding more slowly seems to allow them to maintain the same level of cue-driven performance as their hearing peers. In the third study I focused on partial hearing loss. Little is known on the consequences of pure presbycusis, which is usually associated with aging (Age-related Hearing Loss, ARHL). In this case, auditory information is still present, although linked to an amount of uncertainty regarding its usefulness. In this study I started to investigate the role of ARHL on cognition considering covert orienting of attention, selective attention and executive control. I compared older adults with and without mild to moderate presbycusis (26-60 dB) performing 1) a spatial cueing task with uninformative central cues (social vs. non-social cues), 2) a flanker task and 3) a neuropsychological assessment of attention. Notably, while hearing impaired individuals responded as equally fast as their normally hearing peers, they were characterized by reduced validity effects on spatial cueing of attention, though no additional group differences were found between the impact of social and non-social cues. Hearing impaired individuals also demonstrated diminished performance on the Montreal Cognitive Assessment (MoCA) and on tasks requiring divided attention and flexibility. Conversely, overall response times and flanker interference effects were comparable across groups. This work indicates that while response speed and response inhibition appear to be preserved following mild to moderate presbycusis, orienting of attention, divided attention and the ability to flexibly allocate attention, are more deteriorated in older adults with ARHL. These findings suggest that presbycusis might exacerbate the detrimental influences of aging on visual attention. Taken together, the findings of my research project highlight the different role hearing loss may play at different life stages. On the one hand, congenital and early deafness seems to induce cognitive and behavioral compensations, which may encompass oculomotor behavior as well; these changes occur progressively during development and may reflect experience-dependent plasticity. On the other hand, late-life compensations in vision and visual attention in older adults with presbycusis may not take place or do not effectively reduce the negative impact of the auditory impairment. Rather, my data suggest that in this population a deficit in audition may consequently lead to a deficit in visual attention. Future lines of research can aim to better characterize other aspects of attention in the aging population with presbycusis, e.g. peripheral visual attention and the relationship between covert and overt attention. Finally, future research may also consider intervention through early diagnosis and treatment by means of hearing aids, which can be beneficial to cognitive functions and might delay or even prevent cognitive decline in this population, in which sensory compensation may not be sufficient.

Background: A review of literature shows that cochlear implant (CI) users face difficulties in terms of music interpretation when compared to regular hearing (RH) counterparts. The electrically pulsing nature of the CI acts differently than sound waves in a normally functioning ear, leading to different interpretations of musical concepts such as pitch or timbre. An exceptional case however has been observed in a university-level violinist with bimodal hearing (congenitally deaf in the right ear, and with very minimal residual hearing in the left; they use one CI and one hearing aid) at the University of Ottawa. Objective: This study will compare the pitch recognition, timbre preference and audiation (linked to pitch and rhythmic perception) abilities between an exceptional CI user and case-control RH violinists. Data has previously been collected on CI users not playing the violin due to CI technology's limitations in pitch processing. Since the violin is considered a pitch-heavy instrument to play, it is expected that the study participant has exceptional pitch recognition skills when compared to other CI users (and perhaps RH peers), while still demonstrating comparable timbre preference and rhythmic audiation abilities to an RH comparison group. Method: Three tests were administered relating to pitch recognition on a violin-like interface, timbre preference between two heard tones, and an Advanced Measures of Music Audiation (AMMA) test for general musical knowledge in pitch and rhythm-based melodic discrimination. Results were compared between the critical case-study with CIs and RH control participants to quantify a basis in pitch perception, timbre preference and melodic audiation (applied to pitch and rhythm) skills. Implications: The study participant demonstrated comparable timbre preference and rhythmic discrimination skills to an RH comparison group. The study participant demonstrated pitch perception skills higher than previously tested CI users, despite being lower than the RH comparison group. The CI-using study participant would have developed these higher-than- average pitch perception skills through rigorous early-age training, and passion and persistence of music training on a pitch-heavy instrument despite known recommendations. This sheds light on the CI's technology not necessarily limiting users' choice of instrument due to its pitch processing, despite previous recommendations.

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