Research Doctorate - Doctor of Philosophy (PhD) / Sound field distribution is becoming increasingly known as a method to overcome problems associated with noise, distance, and reverberation in classrooms. No robust research on this intervention has been conducted in the New Zealand context. Changing pedagogies in the education of New Zealand children and young people have been observed particularly since the 1970’s, resulting in noisier classrooms (Wilson, 2000). Acoustic standards for New Zealand classrooms that were adopted in 2003 apply only to new or renovated classrooms, and not to the majority of existing classrooms (Ministry of Education, 2003a). This study investigated: (a) the efficacy of sound field distribution in 30 New Zealand classrooms from five schools and compared outcome measures with a representative control group; (b) the variations of benefit for groups from specific populations, in particular children from five different socio-economic backgrounds and those with histories of middle ear dysfunction; and (c) the effects on teachers who use this equipment. Data were collected from standardized objective measurement tools and from the teachers and students who were participating in the study. Results revealed that sound field distribution, with the equipment configuration of boom microphones and four speakers, can enhance the listening and learning environment resulting in significant positive benefits in raising the achievement levels of children and young people. These results were observed in listening comprehension, which has a flow-on effect on the overall scholastic achievement of all students. Evidence of improved outcomes in areas with a strong link to mastery of literacy were significant, in particular in the areas of phonologic skills, reading comprehension, and reading vocabulary. Results of the study strongly support the use of sound field distribution in all mainstream school settings irrespective of whether the children and young people belong to a particular ethnic group, have had a history of middle ear dysfunction, or attend schools of a particular socio-economic status. Classroom sound field distribution seemingly benefits all children and young people. As a result of the positive results of this study and given the stated goals for education by the New Zealand Ministry of Education (Ministry of Education, 2003b), sound field distribution needs to be considered at a policy level as an intervention to assist in reducing disparity and to improve learning outcomes for all young New Zealanders in mainstream school settings.

ABSTRACT Thus far, literature is scant in assessing the ability of children with conductive hearing impairment to understand everyday speech. This assessment is important in determining the functional ability of children with conductive hearing impairment. In order to identify the hearing ability of children with conductive hearing impairment, many assessments to date have used speech stimuli, such as syllables, words and sentences, to measure how well children perform. In general, these tests are useful in measuring speech recognition ability, but are not adequate in measuring the functional ability of children to understand the conversations they encounter in their daily lives. In addition, many of these tests are not designed to be interesting or engage the children whom they are assessing. The University of Queensland Understanding of Everyday Speech (UQUEST) Test was developed to address the above issues by providing a stimulating speech perception assessment for children aged 5 to 10 years. This overall objectives of this thesis were to: (1) determine the applicability of a computer-based, self-driven assessment of speech comprehension, the UQUEST, (2) establish normative UQUEST data for school children, (3) compare the UQUEST results in children with and without histories of otitis media in understanding everyday speech, and (4) measure speech understanding in noise by children with minimal conductive hearing impairment. A total of 1094 children were assessed using the UQUEST. All children were native speakers of English and attended schools in the Brisbane Metropolitan and Sunshine Coast regions within the state of Queensland, Australia. All children were firstly assessed using otoscopic examination, pure tone audiometry testing and tympanometry. Children with sensorineural hearing impairment were excluded from the study. Following the initial audiological assessments, the UQUEST was administered to all participants. Three experiments were performed on three cohorts of children selected from the pool of 1094 children. Experiment 1 aimed to assess whether the UQUEST is a feasible speech perception assessment tool for school children and to establish normative data in a sample of normally hearing children. ix In this experiment, participants were a total of 99 children (55 boys / 44 girls), attending Grade 3 and grade 4 (41/58, mean age = 8.3 yr, range = 7 – 10 yr, SD = 0.7). The results showed that the UQUEST is a feasible test of speech understanding in children aged 7 to 10 years. In general, the UQUEST scores decreased as the signal-to-noise-ratio (SNR) decreased from 10 to 0 dB. Normative data based on the scores of six passages of equal difficulty were established for the 0 dB and 5 dB SNR conditions. In addition, the children appeared to be captivated with the UQUEST task and the attention of all the children was sustained throughout the duration of the test. Experiment 2 determined whether children with histories of otitis media (experimental group) performed worse on the UQUEST in comparison to those children without histories of otitis media (OM). A total of 484 children (246 boys / 238 girls), attending Grade 3 (272, mean age = 8.25 yr, SD = 0.43) and Grade 4 (212, mean age = 9.28 yr, SD = 0.41), were assessed. Children were grouped according to the number of episodes of otitis media as per parental report (control: < 4 episodes; mild history group: 4-9 episodes; and moderate history group: > 9 episodes OM). All children had normal hearing as determined by otoscopy, pure tone audiometry screening and tympanometry results. Results showed no significant difference in UQUEST scores between the control group in comparison to the experimental groups. However, children with a history of OM demonstrated varying speech comprehension abilities. Some children had severe difficulty with the speech comprehension task, suggesting that in cases with extensively reported episodes of OM, performance on the UQUEST was compromised. Experiment 3 determined the prevalence of conductive hearing loss in the Australian primary school population and investigated the ability of school children with minimal conductive hearing loss to understand everyday speech under noisy conditions. Based on a sample of 1071 children (mean age = 7.7 yr; range = 5.3 - 11.7 yr), 10.2% of children were found to have conductive hearing loss in one or both ears. To evaluate the binaural speech comprehension ability of children, a sample of 542 children were divided into four groups according to their audiological assessment results: Group 1: 63 children (34 boys, 29 girls, mean age = 7.7 yr, SD = 1.5) who failed the pure tone audiometry and tympanometry tests in both ears; Group 2: 38 children (17 x boys, 21 girls, mean age = 7.5 yr, SD = 1.2) who passed pure tone audiometry and tympanometry in one ear but failed both tests in the other ear; Group 3 (control group): 357 children (187 boys, 170 girls, mean age = 7.8 yr, SD = 1.3) who passed pure tone audiometry and tympanometry in both ears; Group 4: 84 children (41 boys, 43 girls, mean age = 7.2 yr, SD = 1.3) who passed pure tone audiometry in both ears, but failed tympanometry in one or both ears. The results showed that Group 1 had the lowest mean scores of 60.8% - 69.3% obtained under noise conditions. Their scores were significantly lower than the corresponding scores of 69.3% - 75.3% obtained by children in Group 4; 70.5% - 76.5% obtained by children with unilateral conductive hearing loss (Group 2); and 72.0% - 80.3% obtained by their normally hearing peers (Group 3). This study confirmed that young children, who are known to have poorer speech understanding in noise than adults, show further disadvantage when a bilateral conductive hearing loss is present In summary, the UQUEST has been found to be a useful tool to measure children‟s understanding of everyday speech. This test could be successfully used as a measure of speech comprehension in background noise in children. The UQUEST met expectations of being an interesting and engaging test for children aged 5-10 years. In addition, the UQUEST scores showed that children performed worse when challenged by the more difficult noise conditions incorporated in the test design. The findings from this thesis demonstrated that, at the group level, children with histories of OM did not perform any differently from those without significant histories of OM. However, at the individual level, children with significant OM histories had degraded functional performance with low UQUEST scores. Lastly, this thesis provided much needed speech comprehension data obtained from children with minimal conductive hearing impairment and provided evidence that young children were more affected by the co-occurrence of environmental noise and bilateral conductive hearing loss than their normally hearing peers in understanding everyday speech.