Spectral Moment Analysis has helped further our understanding of the spectral properties of obstruent speech production; however, the physiologic correlates of these spectral measures are not well understood. The aim of the present study was to examine the possible correlations between the linguapalatal contact patterns used to produce the fricatives /s/ and /ʃ/ and the resulting spectral characteristics. Using spectral moment analysis and electropalatography (EPG), the real-word productions of eight speakers of American English were investigated. The spectral measures for the fricative tokens in the present study were found to be similar to data reported in previous research with adult speakers. Although the majority of the correlations examined in this study were found to be statistically significant, none of the correlations accounted for a large proportion of the variance in the data. Generally the strongest correlations were found between the spectral mean and the symmetry of the contact pattern in the anterior region of the hard palate and the width of the contact pattern in the medial region of the palate. These findings may indicate that although the width and symmetry of linguapalatal contact contributes to the spectral signature /s/ and /ʃ/ fricatives, they are likely only part of a much more complex process that may involve other mechanisms such as lip rounding, tongue groove depth and shape, aerodynamic factors, and the shape of the vocal tract in other regions.

Spectral moment analysis has helped further our understanding of the spectral properties of obstruent speech production; however, the physiologic correlates of these spectral measures are not well understood. The aim of the present study was to examine the possible correlations between the linguapalatal contact patterns used to produce the stops /t/ and /k/ and the resulting spectral characteristics. Using spectral moment analysis and electropalatography, the real-word productions of eight speakers of American English were investigated. The spectral measures for the stop consonant tokens in the present study were found to be similar to data reported in previous research with adult speakers. The majority of the correlations examined in this study were found to be statistically insignificant, although significant correlations were found between the anterior vertical and posterior vertical indices with spectral variance and spectral skewness, respectively. Despite the significance of these correlations, this did not account for a large proportion of variance in the data. Further analysis using curve estimates revealed significant curvilinear relationships among the data. These findings may indicate that although the anterior-posterior tongue placement and symmetry of linguapalatal contact contribute to the spectral signature of /t/ and /k/ stop consonants, this articulatory movement is only part of a more complex process that may involve aerodynamic factors and the overall shape of the vocal tract.

<p>Humans have the ability to recognize other humans by voice alone. This is important both socially and for the robustness of speech perception. This Thesis contains a set of eight studies that investigates how different factors impact on speaker recognition and how these factors can help explain how listeners perceive and evaluate speaker identity. The first study is a review paper overviewing emotion decoding and encoding research. The second study compares the relative importance of the emotional tone in the voice and the emotional content of the message. A mismatch between these was shown to impact upon decoding speed. The third study investigates the factor dialect in speaker recognition and shows, using a bidialectal speaker as the target voice to control all other variables, that the dominance of dialect cannot be overcome. The fourth paper investigates if imitated stage dialects are as perceptually dominant as natural dialects. It was found that a professional actor could disguise his voice successfully by imitating a dialect, yet that a listener's proficiency in a language or accent can reduce susceptibility to a dialect imitation. Papers five to seven focus on automatic techniques for speaker separation. Paper five shows that a method developed for Australian English diphthongs produced comparable results with a Swedish glide + vowel transition. The sixth and seventh papers investigate a speaker separation technique developed for American English. It was found that the technique could be used to separate Swedish speakers and that it is robust against professional imitations. Paper eight investigates how age and hearing impact upon earwitness reliability. This study shows that a senior citizen with corrected hearing can be as reliable an earwitness as a younger adult with no hearing problem, but suggests that a witness' general cognitive skill deterioration needs to be considered when assessing a senior citizen's earwitness evidence. On the basis of the studies a model of speaker recognition is presented, based on the face recognition model by V. Bruce and Young (1986; British Journal of Psychology, 77, pp. 305 - 327) and the voice recognition model by Belin, Fecteau and Bédard (2004; TRENDS in Cognitive Science, 8, pp. 129 - 134). The merged and modified model handles both familiar and unfamiliar voices. The findings presented in this Thesis, in particular the findings of the individual papers in Part II, have implications for criminal cases in which speaker recognition forms a part. The findings feed directly into the growing body of forensic phonetic and forensic linguistic research.</p>

Humans have the ability to recognize other humans by voice alone. This is important both socially and for the robustness of speech perception. This Thesis contains a set of eight studies that investigates how different factors impact on speaker recognition and how these factors can help explain how listeners perceive and evaluate speaker identity. The first study is a review paper overviewing emotion decoding and encoding research. The second study compares the relative importance of the emotional tone in the voice and the emotional content of the message. A mismatch between these was shown to impact upon decoding speed. The third study investigates the factor dialect in speaker recognition and shows, using a bidialectal speaker as the target voice to control all other variables, that the dominance of dialect cannot be overcome. The fourth paper investigates if imitated stage dialects are as perceptually dominant as natural dialects. It was found that a professional actor could disguise his voice successfully by imitating a dialect, yet that a listener's proficiency in a language or accent can reduce susceptibility to a dialect imitation. Papers five to seven focus on automatic techniques for speaker separation. Paper five shows that a method developed for Australian English diphthongs produced comparable results with a Swedish glide + vowel transition. The sixth and seventh papers investigate a speaker separation technique developed for American English. It was found that the technique could be used to separate Swedish speakers and that it is robust against professional imitations. Paper eight investigates how age and hearing impact upon earwitness reliability. This study shows that a senior citizen with corrected hearing can be as reliable an earwitness as a younger adult with no hearing problem, but suggests that a witness' general cognitive skill deterioration needs to be considered when assessing a senior citizen's earwitness evidence. On the basis of the studies a model of speaker recognition is presented, based on the face recognition model by V. Bruce and Young (1986; British Journal of Psychology, 77, pp. 305 - 327) and the voice recognition model by Belin, Fecteau and Bédard (2004; TRENDS in Cognitive Science, 8, pp. 129 - 134). The merged and modified model handles both familiar and unfamiliar voices. The findings presented in this Thesis, in particular the findings of the individual papers in Part II, have implications for criminal cases in which speaker recognition forms a part. The findings feed directly into the growing body of forensic phonetic and forensic linguistic research.

Much of speech kinematics research is conducted by attaching a device to the articulators. However very little research has been conducted to determine what influence these devices may have on the perceptual and acoustic characteristics of speech. This study examined the effect of placing a small magnet on the tongue of ten normal adult speakers while reading a sentence containing /s/ and "sh" in initial, medial and final position. Two different placements of 10 and 15 mm from the tip of the tongue were analyzed. Data were taken before magnet placement, immediately after magnet placement, after 5 minutes of conversation, and after an additional 10 minutes of conversation. The acoustic output was analyzed using spectral moments analysis (spectral mean, variance, skewness, and kurtosis). Changes in spectral mean and variance were found for "sh" as a result of magnet placement, which was characterized by an interaction effect between condition and the word position of the target fricative. In addition, significant changes in spectral mean were found for /s/ and "sh" as a result of magnet position. Although results from the present study indicated that there were some acoustic changes in fricative productions with a marker attached at midline, the spectral changes were not consistent or pervasive, and speakers were able to adapt to the presence of the magnet in a relatively short amount of time.

Many studies in speech communication have provided valuable findings concerning the kinematic nature of speech articulation. This type of research often involves introducing an oral device to the vocal tract such as lingual pellets, magnets, and different forms of pseudopalates to track the movement and placement of the articulators. This study examined the effect of an electropalatography (EPG) pseudopalate on the production of five voiceless obstruents (/p, t, k, s/ and /sh/). Acoustic recordings from 20 adult speakers with typical speech production were made during three different speaking conditions: prior to pseudopalate placement, immediately after placement, and following 20 minutes of conversation. The obstruent articulations were examined in terms of four spectral moments (spectral mean, spectral variance, spectral skewness, and spectral kurtosis). The spectral analysis indicated that placement of a pseudopalate resulted in a statistically significant disturbance of the speakers' obstruent productions. After 20 minutes of conversation with the pseudopalate in place, results of the spectral analysis indicated that participants' productions trended back toward a typical pattern of articulation; however their adaptation was not complete and it remains unclear if further practice with the pseudopalate would result in typical speech production.

An optimal solution of vortex-induced vibrations of structures would be a time-domain numerical simulation that simultaneously solves the fluid flow and structural response. Yet, the requirements in terms of computing power remains a major obstacle for implementing such a simulation. On the other hand, lower- or reduced-order models provide an alternative for determining structural response to forcing by fluid flow. The objective of this thesis is to provide a consistent approach for the development of reduced-order models for the lift and drag on oscillating cylinders and the identification of their parameters. Amplitudes and phases of higher-order spectral moments of the lift and drag coefficients data are combined with approximate solutions of the representative models to determine their parameters. The results show that the amplitude and phase of the trispectrum could be used to model the lift on the oscillating cylinder under different excitation conditions. Moreover, the amplitude and phase of the cross-bispectrum could be used to establish the lift-drag relation for oscillating cylinders. A forced van der Pol equation is used to represent the lift on a transversely oscillating cylinder, and a parametrically excited van der Pol equation is used to model the lift coefficient on an inline oscillating cylinder. All cases of excitations lead to close values for the damping and nonlinear parameters in the van der Pol equation. Consequently, and as shown in this thesis, different excitation cases could be used to identify the parameters in the governing equations. Moreover, the results show that the drag coefficient could be derived from the lift coefficient through a square relation that takes into account the effects of the forced motions. / Ph. D.

The purpose of this study was to analyze the phonetic production of fricatives across differing word positions and task types. Further knowledge about the fricative production of second language learners of English would potentially improve the ability to teach correct pronunciation and improve the productivity of second language programs. All participants in this study were native speakers of Mandarin Chinese with English as their second language. A total of 12 subjects participated, all of whom had English proficiency ratings ranging from novice to advanced. The speakers were between 21-51 years of age, with each speaker having between 2 to 6 years of experience learning English in their country of origin. Using acoustic and spectral moment analyses, the acoustic nature of four types of fricative productions (/f/, /θ/, /s/, and /ʃ/) were analyzed as a function of linguistic task type and word position. Although a number of measures were found to differ significantly as a function of word position and task type, the majority of statistical analyses were not found to be significant. This lack of significance may be due to the specific methodology used, the speakers’ atypical voicing patterns, and/or decreased length of sound productions. Findings of this study may indicate that second language learners’ production of fricatives vary minimally across differing word positions and task types.

The purpose of this study was to analyze the phonetic production of fricatives across differing word positions and task types. Further knowledge about the fricative production of second language learners of English would potentially improve the ability to teach correct pronunciation and improve the productivity of second language programs. All participants in this study were native speakers of Mandarin Chinese with English as their second language. A total of 12 subjects participated, all of whom had English proficiency ratings ranging from novice to advanced. The speakers were between 21-51 years of age, with each speaker having between 2 to 6 years of experience learning English in their country of origin. Using acoustic and spectral moment analyses, the acoustic nature of four types of fricative productions (/f/, /θ/, /s/, and /ʃ/) were analyzed as a function of linguistic task type and word position. Although a number of measures were found to differ significantly as a function of word position and task type, the majority of statistical analyses were not found to be significant. This lack of significance may be due to the specific methodology used, the speakers atypical voicing patterns, and/or decreased length of sound productions. Findings of this study may indicate that second language learners production of fricatives vary minimally across differing word positions and task types.

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