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Multipulse-excitation has greatly improved the speech quality achievable from linear predictive coders which previously required speech to be classified as voiced or unvoiced for excitation purposes. Multipulse removes the need for voicing classification, improving speech quality by enhancing the excitation and offsetting errors in the vocal tract filter. An investigation of multipulse-excitation applied to a channel vocoder and a formant synthesiser was conducted. The prime objective was to improve the performance of these algorithms and achieve multipulse linear prediction speech quality, our target quality. This dissertation outlines and restates the idea of multipulse-excitation applied to a linear predictive vocoder. We then examine a high quality channel vocoder and formant synthesiser, and the use of multipulse-excitation to improve their performances. In each case time and frequency domain multipulsecalgorithms were used. Various modifications were made to these algorithms in order to accommodate multipulse-excitation and improve the overall speech quality. In the case of the channel vocoder this involved a novel technique, which sacrificed the inherent waveform preserving properties of the multipulse algorithm. Only by increasing both the pulse rate and the number of channels could the multipulse-excited channel vocoder achieve our target quality. With the formant synthesiser it was possible, by variation of the pulse rate alone, to achieve our target quality. Comparisons are drawn between the three multipulse algorithms and reasons given for their differing performance; this is substantiated by experimental results. These results suggested interesting improvements to the multipulse-excited formant synthesiser; and also hinted at a new and novel technique for formant tracking, using multipulse-excitation applied to a formant synthesiser.

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This study investigated the effectiveness of utilizing acoustic measures as an objective tool in monitoring speech errors and providing visual feedback to enhance speech training and aural rehabilitation of children with hearing impairment. The first part of the study included a comprehensive description of the acoustic characteristics related to the speech deficits of a hearing impaired child. Results of a series of t-tests performed on the experimental measures showed that vowel length and the loci of formant frequencies were most relevant in differentiating between correctly and incorrectly produced vowels, while voice onset time along with measures of Moment 1 (mean) and Moment 3 (skewness) obtained from speech moment analysis, were related to consonant accuracy. These findings, especially the finding of an abnormal sound frequency distribution shown in the hearing impaired child's consonant production, suggest a link between perceptual deficits and speech production errors and provide clues to the type of compensatory feedback needed for aural rehabilitation. The second part of the study involved a multiple baseline design across behaviours with replication across three hearing impaired children to assess the efficacy of treatment with acoustic signals as visual feedback. Participants' speech articulations following traditional speech training and training using spectrographic and RMS displays as visual feedback (referred to as 'visual treatment') were compared, with traditional non-visual treatment followed by visual treatment on one or two targets in a time-staggered fashion. Although no statistically significant difference on the experimental measures was found between the two training approaches based on perceptual assessment, some objective acoustic measures revealed more subtle changes toward normal speech patterns with visual treatment as compared to a traditional approach. Further acoustic-perceptual studies with a larger sample size and longer experimental period are needed to better understand the general and long-term effectiveness of visual treatment.

This study examined the effectiveness of the Otago screening protocol in identifying school-aged children with severe speech and language impairments. In order to do so, the results of the Otago screening protocol were compared with those of comprehensive language assessment as determined by best practice protocol (Gillon & Schwarz, 1998, Kennedy, 2002). Following the completion of the screening and the comprehensive assessments, an evaluation of the true positives and false positives was calculated, and an analysis of the false negative outcomes made. Findings indicated that fourteen of the twenty participants were true positives, three were true negatives, three were false positives, and none were false negatives. The Positive Predictive Value and Negative Predictive Value of the screening protocol was 100%. Test Sensitivity and Specificity were very high at 82% and 100%. Inter-rater reliability was very high, generally ranging from 92-100%. Adding a standardised measure of phonological awareness would improve efficiency of the screening protocol. Consideration of alternative screening tools, such as the GAPS test (Gardner et al, 2006) and the CELF-4 screening test (Semel, Secord & Wiig, 2004), should be made. Additional factors which could influence a screening protocol are discussed. The Otago screening protocol is a valid procedure to detect severe speech and language impairments in school-aged students referred to Special Education.

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This study was conducted to explore the influence of architecture on emotions and communication. Correlations were proposed between dimensions of affect (pleasure, arousal, dominance) and communication (formality, warmth, privacy, familiarity, constraint, psychological distance) in interaction environments. Hypotheses also proposed that affective and communicative responses would differ for architectural styles as well as for architects and laypeople. Three contemporary styles of architecture (Modern Traditionalism, Deconstructivism, and Post-Modernism) were depicted in photographs of houses. Using written self-report measures, architects and laypeople rated their affective responses and expectations for communication in stimulus houses. Hypotheses were partially confirmed for correlations between affect and communication dimensions. Results also confirmed that different architectural styles are perceived differently in terms of affect response and expectations for communication. No differences, however, were found between architects' and laypeople's perceptions of architecture. Implications of the findings were discussed concerning the impact of architectural style on human communication and behavior.

The purpose of this study was to determine the effect of utterance length and meaningfulness on the speech initiation times of stuttering and nonstuttering children. Subjects were 36 elementary school students: 18 stutterers and 18 nonstutterers matched by age, grade, and gender. Each child produced 23 each of a short meaningful, long meaningful, and long nonsense utterance in response to a visual cue. Results are consistent with other studies that found stutterers to be slower than nonstutterers when responding verbally to an external cue. It is also apparent that nonstuttering, stuttering-only, and stuttering-plus children are affected differently by utterance length and meaningfulness. This indicates that the three groups may process speech motor events for verbal responses differently.

This study evaluated empirically the Test for Examining Expressive Morphology and the Patterned Elicitation Syntax Test with Morphophonemic Analysis to determine their capacity to aid in answering the following diagnostic questions: (1) "Is there a language impairment" and (2) "What are the specific areas of deficit?" For the first question, a discriminant analysis using 40 preschool children (20 with specific language impairment (SLI), and 20 with normally developing language) revealed 90% sensitivity and 95% specificity for each test. For the second question, an item analysis revealed inconsistent pass/fail rates and low point-to-point agreement for SLI children's performance on items targeting the same morphosyntactic structure across tests. Given their high discriminant capacity, but inconsistent item-level performance, both tests proved appropriate diagnostic tools for question 1 but inappropriate for question 2.

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