A brief overview of the workings of the human auditory system is followed by a review of literature concerning both the theories and experimental investigations of human pitch perception. The application of these theories to the inharmonic complex tones produced by bells is discussed, and further experiments using bell sounds are reviewed. A methodology for psychoacoustic experiments with specific reference to those investigating pitch perception of inharmonic complex tones is presented. This methodology is then implemented in an experimental investigation of pitch perception of ringing and chiming bell sounds. A pitch matching experiment using ringing and chiming sounds from four bells aimed to determine perceived pitch differences between ringing and chiming bells. This experiment was inconclusive because insufficient data was collected. Known experimental results, such as the inability of non-musicians to match the pitches of sounds with different timbres were confirmed. Spectral analyses of the stimuli were performed. The presentation of stimuli at a low level of sensation is questioned, as this might have prevented pseudo high frequency noise resulting from stronger upper partials in the ringing sound from being audible, and hence the pitch differences between ringing and chiming bells would not be observed.

This thesis investigates the psychological implications of prolongation, a structural phenomenon of tonal music, which is described in the musicological literature as an elaborative process in which some pitch events - such as chords and notes - remain as if they were sounding even though they are not physically present.

Speech signal processing for voice communications can be characterised in terms of silence compression, noise reduction, and speech compression. The limit in the channel bandwidth of voice communication systems requires efficient compression of speech and silence signals while retaining the voice quality. Silence compression by means of both voice activity detection (VAD) and comfort noise generation could present transparent speech-quality while substantially lowering the transmission bit-rate, since pause regions between talk spurts do not include any voice information. Thus, this thesis proposes smoothed likelihood ratio-based VAD, designed on the basis of a behavioural analysis and improvement of a statistical model-based voice activity detector. Input speech could exhibit noisy signals, which could make the voice communication fatiguing and less intelligible. This task can be alleviated by noise reduction as a preprocessor for speech coding. Noise characteristics in speech enhancement are adapted typically during the pause regions classified by a voice activity detector. However, VAD errors could lead to over- or under- estimation of the noise statistics. Thus, this thesis proposes mixed decision-based noise adaptation based on a integration of soft and hard decision-based methods, defined with the speech presence uncertainty and VAD result, respectively. At low bit-rate speech coding, the sinusoidal model has been widely applied because of its good nature exploiting the phase redundancy of speech signals. Its performance, however, can be severely smeared by mis-estimation of the pitch. Thus, this thesis proposes a robust pitch estimation technique based on the autocorrelation of spectral amplitudes. Another important parameter in sinusoidal speech coding is the spectral magnitude of the LP-residual signal. It is, however, not easy to directly quantise the magnitudes because the dimensions of the spectral vectors are variable from frame to frame depending on the pitch. To alleviate this problem, this thesis proposes mel-scale-based dimension conversion, which converts the spectral vectors to a fixed dimension based on mel-scale warping. A predictive coding scheme is also employed in order to exploit the inter-frame redundancy between the spectral vectors. Experimental results show that each proposed technique is suitable for enhancing speech quality for voice communications. Furthermore, an improved speech coder incorporating the proposed techniques is developed. The vocoder gives speech quality comparable to TIA/EIA IS-127 for noisy speech whilst operating at lower than half the bit-rate of the reference coder. Key words: voice activity detection, speech enhancement, pitch, spectral magnitude quantisation, low bit-rate coding.

This thesis examines an African American woman’s narrative about the day that her daughter was shot. Like many personal narratives of “frightening experiences,” the speaker in this narrative highlights the peak of her story, making sure her point is salient. In earlier analyses, it has been shown that evaluation tends to cluster around the peak of the narrative. In “The day my daughter got shot” we see that this event-filled narrative is not evaluated as predicted as there is no increased usage of evaluative devices at one single point in the narrative. Instead, it is a change in patterning of a number of linguistic and paralinguistic devices that conspire to bring special attention to the peak of the narrative. By examining multiple devices at once, it is seen that they create a cumulative effect that makes the story interesting and exciting, resulting in a successful narrative.

Magister Legum - LLM / An understanding of the structure, function and performance relationships in different sports, including softball, allows for improved coaching approaches, development of sport specific fitness and skills training programmes, team selections and talent identification in young players. Despite the fact that fast pitch softball is an established sport with a long history, it has received little scientific attention. It does for example, not have a specific battery of softball specific fitness tests and relies on the tests and norms of baseball. The specific morphological and fitness demands of the sport are therefore not fully understood. The purpose of this study was to establish whether morphological and fitness characteristics are related to skill and performance measures in men's fast pitch softball players and to determine what the strengths of any such relationships are. The sample was purposively selected and consisted of 15 Provincial and 15 club male fast pitch softball players. All participants were members of the provincial Softball Federation. Anthropometric, fitness and skills test and measurements were conducted at the training sites over a number of weeks because it coincided with team training. Anthropometric measurements included height, weight, skinfolds, and were done in accordance with ISAK specifications. Derived anthropometric variables included BMI and body fat percentage. The following physical fitness tests were conducted: vertical jump test, standing broad jump and the Illinois agility run while the skills tests conducted were the softball throw for distance, the two base sprint test, the batting tests and the fielding test. Match statistics were easier to obtain since records were available in printed form from the Provincial softball federation for the Provincial players and from the club for its members. The data obtained were analysed and interpreted both collectively as a group of thirty and then separately as provincial and club teams for the purpose of comparison. Since the data were not normally distributed, the Spearman's rank Correlation was used to test for associations between variables. Comparisons of the squads were done using the nonparametric Wilcoxon Rank Sum test. The results of the study identified a number of strong significant relationships between the different variables tested. Height and percent body fat, amongst others were found to be the two anthropometric variables which significantly interacted with two key performance areas of fast pitch softball i.e. batting and fielding. Percent body fat also negatively correlated with the vertical jump test which highlights the general negative impact of excess fat on performance. The relationships established in this research strongly suggest that coaches include fitness, morphological and skills tests in their coaching and fitness programmes and they should further be used in team selections processes as they are strong indicators for success and will make the selection process more objective.

Four functional magnetic resonance imaging (fMRI) studies of pitch processing in auditory cortex were designed to reduce the impact of a number of methodological issues that have hitherto limited previous research findings. Due to adaptation effects, it is necessary to repeatedly present short stimulus bursts rather than long-duration stimuli. Thus, conventionally, in neuroimaging studies of pitch perception, a number of short bursts of the pitch stimulus, separated by silent intervals, are compared to a Gaussian noise presented in the same way. The results of the first experiment indicate that replacing the silent intervals with an energetically matched noise context increases the pitch-specific response by removing the 'energy-onset response' that saturates the overall response if silent intervals are used. In the second experiment, a particular pitch-evoking stimulus, iterated ripple noise (IRN), which is commonly used in neuroimaging studies of pitch perception, was examined. Hall and Plack (Cerebral Cortex 2009;19:576-585) showed that IRN contains slowly varying spectro-temporal features unrelated to pitch, and suggested that these features could account for at least some of the cortical activation produced by IRN. The results support this hypothesis, but also suggest that there is an additional pitch-dependent effect in the same region of auditory cortex.The third experiment assessed the effect of using a different control stimulus to the usual Gaussian noise. The new matched controls were a pulse train with randomly jittered inter-pulse intervals and a random-phase unresolved harmonic complex tone. These low-pitch-salience controls were compared to a regular interval pulse train, which is identical to a cosine-phase unresolved harmonic complex tone. The third experiment did not provide evidence for sensitivity to pitch-salience in pitch-responsive regions of auditory cortex. The fourth and final experiment was a factorial design seeking to answer two main questions: 1) Is the pitch-sensitive region of auditory cortex responsive to the salience of other sound features (e.g. modulation)? 2) Are the responses to pitch and to modulation within this region co-located? Two different pitch-evoking stimuli with different levels of pitch salience were used, presented in a noise context. Results indicate that the pitch-sensitive region contains representations for both pitch and modulation. Furthermore, there was no evidence for an interaction between pitch and modulation, suggesting that the two responses are independent. Overall, the results suggest that careful stimulus design, and appropriate experimental control, is necessary to obtain reliable information on the cortical response to pitch. In addition, the results have shed further light on the likely neural substrates of pitch processing in the cortex.

Pitches are important precursors for carbon materials. They are usually obtained by thermal treatment of petroleum and coal fractions. Pitches have higher carbon content and are capable of developing into graphitisable carbons upon heat treatment. Petroleum pitches are generally less aromatic than coal tar pitches. Medium-temperature gasifier pitch (MTP), from Sasol’s Lurgi process, is a potential precursor for graphitisable carbon. MTP showed a high degree of solubility in several organic solvents, namely dimethylformamide, quinoline, tetrahydrofuran, pyridine, morpholine, benzene, toluene, xylene and acetone. It was virtually insoluble in n-hexane, cyclohexane, cyclohexanol, acetonitrile and formamide. MTP pitch was partially soluble in methanol and had a solubility limit of 40 g/l at ambient temperature. MTP samples were spiked with boron to make 1000 ppm B-containing samples. The boron distribution coefficient was defined as the ratio of the boron contents of the insoluble pitch residue to the methanol-soluble pitch extracts, using a mass balance. This justified the decision to define the apparent boron partition coefficients based on the boron content of the recovered pitch residues. 4-(dibenzofuranyl) boronic acid (DBA), 2 phenoxyphenyl boronic acid (PBA), p-tolylboronic acid (TBA) and phenylboronic acid (PLA) were retained the most in the residues after methanol extraction. Over 500 ppm of PBA, TBA and PLA were retained in the pitch residues following methanol extraction. The results showed that methanol extracted substituted boron acid model compounds. Methanol dissolved mostly low molecular mass/aliphatic species, which are not important for graphitisation. The thermomechanical analysis (TMA) results showed that MTP has a low softening point compared with the methanol-insoluble (MI) fractions. The attenuated total reflectance (ATR) results showed that the benzene-insoluble (BI), toluene-insoluble (TI) and MI fractions had more intense aromatic C–H stretching peaks than their corresponding soluble fractions. Elemental analysis and the solid-state 13C nuclear magnetic resonance (NMR) results revealed that the benzene-, toluene- and methanol-insoluble fractions are more aromatic than their corresponding soluble fractions. The order of the aromaticity index for the insoluble fractions was as follows: MTP<MI<TI<BI. Matrix-assisted laser desorption (MALDI) analysis of the mass distribution revealed that the majority of compounds in MTP and its soluble and insoluble fractions were in the low molecular mass range, i.e. 190–388 atomic mass units. The thermal analysis results showed that the benzene-, toluene- and methanol-insoluble fractions were thermally stable and had higher carbon yields than their corresponding soluble fractions. MTP was thermally more stable than the methanol-, toluene- and benzene-soluble fractions. Evaluation of the polycyclic aromatic hydrocarbons (PAHs) by gas chromatography-mass spectrometry (GC-MS) showed that the methanol-insoluble fractions had lower PAH contents than MTP and MI.   Copyright / Dissertation (MSc)--University of Pretoria, 2012. / Chemistry / unrestricted

The formation and development of mesophase from different pitches under carbonisation conditions was investigated. Members of the pyrolysis series were prepared from four pitches. A temperature range between 380 and 500°C was used to follow mesophase development for each pitch. As-received pitches and their green cokes were characterised by thermomechanical analysis (glass transition temperature and softening point temperature), elemental analysis, Fourier transform infrared spectroscopy, thermogravimetry or differential thermogravimetry, and optical microscopy (mesophase content). Additional data about the evolution of different volatile products and about possible chemical reactions occurring during thermal decomposition were obtained from thermogravimetric mass spectrometric analysis. The effect of heating rate on the behaviour and carbon yield was also studied. The results showed that the two anthracene oil pitches do not develop mesophase, whereas the medium-temperature and high-temperature pitches do. However, their textures are completely different. The medium-temperature pitch shows an improvement in texture from the mosaic to the coarse domain at 500°C, whereas the high-temperature pitch shows flow domains. It was further shown that the process of preparing mesophase, i.e. the heat-treatment process, increases the aromaticity and carbon yield. Thermogravimetric mass spectrometric analysis showed that the dominant reaction for all the pitches is the condensation reaction, which is accompanied by the evolution of H2 and CO. The heating rate affects the behaviour of the pyrolysing pitches in that a lower heating rate lowers the carbon yield. This study gave insight into the influence of the nature and composition of the precursor on the formation of mesophase. / Dissertation (MSc)--University of Pretoria, 2009. / Chemistry / unrestricted

Experimental phonetic research on speech rhythm seems to have reached an impasse. Recently, this research field has tended to investigate produced (rather than perceived) rhythm, focussing on timing, i.e. duration as an acoustic cue, and has not considered that rhythm perception might be influenced by native language. Yet evidence from other areas of phonetics, and other disciplines, suggests that an investigation of rhythm is needed which (i) focuses on listeners' perception, (ii) acknowledges the role of several acoustic cues, and (iii) explores whether the relative significance of these cues differs between languages. This thesis, the originality of which derives from its adoption of these three perspectives combined, indicates new directions for progress. A series of perceptual experiments investigated the interaction of duration and f0 as perceptual cues to prosody in languages with different prosodic structures - Swiss German, Swiss French, and French (i.e. from France). The first experiment demonstrated that a dynamic f0 increases perceived syllable duration in contextually isolated pairs of monosyllables, for all three language groups. The second experiment found that dynamic f0 and increased duration interact as cues to rhythmic groups in series of monosyllabic digits and letters; the two cues were significantly more effective than one when heard simultaneously, but significantly less effective than one when heard in conflicting positions around the rhythmic-group boundary location, and native language influenced whether f0 or duration was the more effective cue. These two experiments laid the basis for the third, which directly addressed rhythm. Listeners were asked to judge the rhythmicality of sentences with systematic duration and f0 manipulations; the results provide evidence that duration and f0 are interdependent cues in rhythm perception, and that the weighting of each cue varies in different languages. A fourth experiment applied the perceptual results to production data, to develop a rhythm metric which captures the multi-dimensional and language-specific nature of perceived rhythm in speech production. These findings have the important implication that if future phonetic research on rhythm follows these new perspectives, it may circumvent the impasse and advance our knowledge and model of speech rhythm.

This study investigated relationships between 36 predictor variables and ensemble pitch and rhythm error discrimination ability. Precollege musical background and other demographic data were collected by means of the Musical Background Questionnaire. Musical achievement was measured by the Aliferis-Stecklein Music Achievement Test, College Midpoint Level. Undergraduate musical coursework data were obtained from transcripts. The criterion variables were measured by the Ramsey-Vincent Test of Instrumental Error Detection; a test of aural-visual pitch and rhythm error discrimination for full-score band music of medium difficulty. All three instruments were administered to 82 undergraduate music students. Subjects represented three Canadian universities and two community colleges. Pearson product-moment correlation tests were used to identify variables significantly related to musical ensemble error discrimination at the .10 level of significance. Eighteen variables were found to be significantly related to ensemble pitch error discrimination. Fourteen variables were found to be significantly related to ensemble rhythm error discrimination. Regression procedures were performed for each of the significant variables. These variables were then organized into blocks representing precollege musical background, other demographic variables, musical achievement, and undergraduate coursework. Regressions were performed for each of the blocks. Musical achievement, precollege musical background, demographic, and undergraduate coursework blocks of variables accounted for 5, 15, 35, and 21 percent of the variance in ensemble pitch error discrimination scores respectively. Musical achievement, precollege musical background, demographic, and undergraduate coursework blocks of variables accounted for 21, 16, 19, and 12 percent of the variance in ensemble rhythm error discrimination scores respectively. Combinations of variables from these blocks produced a linear model comprised of five demographic variables plus precollege choral experience that accounted for 42 percent of the variance in ensemble pitch error discrimination scores. Combinations of variables from the four blocks produced a linear model of ensemble rhythm error discrimination comprised of rhythmic discrimination, choice of a band instrument as one's major performance medium, composition as one's program major, and precollege band or orchestral experience. These four variables accounted for 32 percent of the variance in ensemble rhythm error discrimination scores. The variables selected for use in this study accounted for a substantial portion of the variance in error discrimination scores. To improve the predictive power of future studies, other variables need to be identified and included in the model. Ten conclusions were made regarding the prediction of ensemble error prediction ability. Three recommendations were made for improving error discrimination training and seven recommendations were made for future research in ensemble error discrimination. / Education, Faculty of / Graduate