Dissertations / Theses on the topic 'Pitch discrimination'

The purpose of this study was to determine whether the ability to perceive pitch direction across a variety of melodic contours differs across grade levels. In addition, differences between responses to ascending versus descending patterns and between responses to two- versus three- versus four-note patterns were examined.
The main study involved two experiments; Experiment 1 examined children's ability to identify pitch direction using a visual aid; Experiment 2 examined children's spontaneous notations of the same melodic contours.
The results showed a subsequent increase in mean scores from grades 1 to 6 across both tests. The clearest increase in ability occurred within the first three grades with a plateau reached by grade four. Same-pitch patterns received the highest overall means. The ability to identify direction using a visual aid was easier for children than to write spontaneous notations. Melodic contours with larger intervals were more easily perceived.

Objective: The current research indicates that those with autism have an excellent memory for pitch. Persons with autism have better pitch discrimination and memory for individual notes. The purpose of this study was extend this research in school aged children, comparing pitch discrimination and melodic memory of children with autism to that of typically developing children.
Method: Twenty-five children with autism between the ages of 8-12 and 25 typically developing children within the same age range participated in the study. Children completed pitch discrimination tasks in two differing contexts. In one context, children were asked to indicate whether two pitches were the same or different when the two pitches were either the same or one note of the pair had been altered so that it was 25, 35, or 45-cents sharp or flat. In the other context, children were asked to discriminate whether two melodies were the same or different when the leading tone of each melody was either the same or had been altered so that it was 25, 35, or 45-cents sharp or flat. In addition, children were also asked to recall melodies one week after they were paired with pictures during a familiarization task. All the tasks in the study were formatted on computer.
Results: Children with autism outperformed typically developing children in both pitch discrimination contexts. Children with autism were superior to typically developing children when remembering melodies one week after they had been paired with animal pictures.
Conclusion: Children with autism demonstrated better pitch discrimination and melodic memory than typically developing children. These abilities may be genetic, as the majority of the participants in the study had limited music training. Alternatively, these abilities could be reflective of a different developmental process in the auditory modality of children with autism whereby developmental differences in auditory perceptions may be adaptive in some musical contexts.
Objectif: Les recherches actuelles démontrent que les personnes autistiques discernent mieux la hauteur des sons et ont une meilleure mémoire des sons individuels. La présente étude vise à étendre la recherche aux enfants d'âge scolaire en comparant, chez les enfants autistiques par rapport aux enfants qui se développent normalement, le discernement de la hauteur des sons et la mémoire mélodique.
Méthodologie: Vingt-cinq enfants autistiques ainsi que 25 enfants ayant un développement normal, tous âgés de 8 à 12 ans, ont participé à l'étude. Placés dans deux contextes différents, les enfants ont effectué des tâches faisant appel à leur capacité de discerner la hauteur des sons. Dans le premier contexte, les enfants devaient indiquer si deux sons étaient semblables ou différents lorsque les deux sons étaient les mêmes ou lorsque l'un d'eux avait été modifié pour être plus aigu ou plus bas de 25, 35, ou 45-cents. Dans l'autre contexte, les enfants devaient dire si deux sons mélodies étaient les memes ou si elles étaient différentes lorsque chacune des melodies étaient la mêmes ou si elles étaient différentes lorsque la sensible de chacune des melodies étaient soit la même, soit qu'elle avait été modifiée pour être plus aigue ou plus basse de 25, 35, ou 45-cents. En outre, les enfants devaient aussi se remémorer des mélodies qui, la semaine précédente, avaient été associées à des images d'animaux au cours d'une tâche de familiarsation. Toutes les tâches accomplies par les enfants au cours de l'étude ont été effectuées sur ordinateur.
Résultats: Les enfants autistiques ont mieux réussis que les enfants ayant un développement normal et, cela, dans les deux contextes de discernment de la hauteur des sons. Ils ont aussi été supérieurs lorsqu'il a fallu se remémorer des melodies une semaine après qu'elles eurent été associés à des images d'animaux.
Conclusions: Les enfants autistiques ont démontré que leur jugement de la hauteur des sons et et leur mémoire mélodique étaient meilleurs que ceux des enfants ayant un développement normal. Ces habiletés pourraient être innées étant donné que la majorité des participants á l'étude avaient une formation musicale limitée. Par ailleurs, ces habiletés pourraient être le signe d'un processus développemental different des attributs auditifs des enfants autistiques, ces différences développementales des perceptions auditives pouvent comporter une capacité d'adaptation à certains contextes musicaux.

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

The purpose of the present study was to tease apart the paralinguistic from the linguistic aspects of infants' perception of infant-directed (ID) speech. Several studies have shown that infants beginning at a few days after birth discriminate native from nonnative speech and can discriminate specific contours (rising, falling, rising-falling) in ID speech. Some studies have also indicated that infants at 4.5 months of age prefer their own name over other names but at 6 months of age, fail to prefer a sentence with their own name embedded in it. Using a discrimination procedure, the current study investigated whether 6-month-old infants could detect a change in contour and/or a change in words when listening to ID utterances. Results indicated that 6-month-old infants detected both a contour and a word change. From these results, it is argued that as has been shown in other exper- iments, infants are extremely sensitive to subtle changes in speech. Furthermore, ID speech appears to facilitate infants' ability to discriminate small changes in ID speech (both linguistic and paralinguistic). It is suggested that future studies investigate more discrete changes in speech samples and a replication of this research with adult-directed (AD) speech.
Master of Science

The P300 complex has been dissociated into a parietally maximal P3b and a more anteriorly distributed P3a in auditory, visual and somatosensory modalities. The seven experiments reported in this thesis investigate the variables affecting the elicitation of the P3a. The Knight et al. (1989) paradigm was used which involves the presentation of frequent, rare target and rare nontarget auditory stimuli. Experiment 1 showed that the P3a was elicited by novel sounds (environmental noises) when presented as rare nontargets in a sequence of frequent and target tones. When the rare nontarget novel sounds were presented in a sequence of other novel sounds the P3a was not elicited (Experiment 2). Experiment 3 showed that making the rare novel sound a target abolished the P3a, as did omitting the frequent stimuli from the sequence (Experiment 4). In the experiments in which the P3a was abolished, the novel sounds were found to elicit a P300 deflection with a parietally maximal scalp distribution (P3b). Other experiments showed no indication of habituation of the P3a over subsequent stimulus presentations (experiment 6) but did show that the amplitude of the P3a was larger when preceded by several stimuli different to the eliciting novel sound, than when immediately preceded by the identical sound (experiment 7). In contrast to novel sounds, tones did not elicit a P3a, even when presented as rare nontargets among frequent and target novel sounds (experiment 5). The findings were related to a recent model of auditory attention (Naatanen, 1990). The P3a was interpreted as reflecting a process related to the orienting of attention resulting from the detection of a mismatch between present and previous stimuli.

Cochlear Implants (Cis) are surgically implanted devices that can provide access to the hearing world for individuals with bilateral ‘severe to profound’ hearing loss who do not gain benefit from conventional hearing aids. However, some patients who have received Cis derive more benefit from them than others. There is a relative paucity of work involving those individuals who have had poor outcomes and are performing (with regard to speech understanding) below the level expected for them pre-operatively. The aim of this thesis was to identify potentially remedial factors that contribute to poor performance with a CI, in an attempt to develop practical clinical protocols for the management of ‘poor performers’. Hypotheses: la. The ability to discriminate pitch reliably across the electrode array predicts overall speech discrimination levels in Cochlear Implant users. lb. Using pitch discrimination findings as a ‘site-selection strategy’ would lead to improvements in speech understanding in poor performers. 2. Areas of poor pitch discrimination may correlate with specific electrode position within the cochlea measured by post-operative computerised tomography imaging.

The purpose of this study was to examine the effectiveness of the Yamaha Junior Music Programme in developing pitch discrimination and rhythm performance skills in five- and six-year old children over a six month period. Specifically, it aimed to measure improvements in the ability to distinguish between high and low-pitched tones, the ability to identify the pitch of tones, the ability to imitate rhythms, and the ability to beat in time to music in four groups of ten subjects. Two groups (Y1 and Y2) had been involved in the Yamaha music programme, which aimed to improve the skills mentioned above. The other two groups (K1 and K2) had attended Kindergarten but had not been involved in any formal music programmes. Two of these groups (Y1 and K1) participated in pre-tests and post-tests. The other two groups (Y2 and K2) had participated in the post-tests only. The two groups which were taught via the Yamaha method consisted of ten students (male and female). The two other groups consisted of ten students in each group. These groups comprised students randomly selected from two Kindergarten classes at Fraser Primary school in the A.C.T. All students were presented with three tests: one pitch test, and two rhythm performance tests. Each test contained ten items. The three tests were trialled in a pilot study, with only minimum changes to procedure being required. The Yamaha groups were also given a pitch identification test at the conclusion of the six-month period. Each student's performance in the ten trials of the three tests was recorded on audio tape. Three judges used these recorded responses to grade each student's performance. The trials were also recorded digitally on an Apple II Computer using a sequencing software package. Detailed statistical analysis was carried out on both subjective and digital scores. The experimental design used in this research was the "Solomon's Four" design, which was ideal in controlling for internal sources of invalidity. A series of comparisons were drawn between the various groups involved, and it was concluded that the six-month Yamaha aural training programme led to the following outcomes: * improvements in the ability of Yamaha students to determine pitch height. * a higher incidence of improvement for the experimental group in the pitch pairs test (to determine pitch height) than for the control group. * improvements in the ability of Yamaha students to identify the pitch of notes. * no statistically significant improvements for Yamaha students at the end of six months for rhythm test A (rhythm imitation). * no statistically significant improvements in the performance of Yamaha students at the end of six months for rhythm test B (beating in time to music). * no statistically significant improvements in the performance of the Kindergarten groups at the end of six months for rhythm test A. * no statistically significant improvements in the performance of the Kindergarten groups at the end of six months for rhythm test B. A number of explanations were offered for the absence of improvement in the two rhythm tests and recommendations were made for future research.

The purpose of the present study was to investigate the role of pitch contours in directing infant attention to adult speech. Several studies have shown that infants from a few days old to 9 months of age prefer infant-directed (ID) over adult-directed (AD) speech. Moreover, 4-month-olds have been shown to prefer pitch contours that simulate ID speech, suggesting that the exaggerated pitch contours are necessary for infant attention. The current study investigated this attentional preference utilizing ID and AD pitch contours in a fixation-based preference procedure. Results from the first experiment failed to show a similar preference for the ID pitch contours. Because a lack of preference could have been due to a failure to discriminate, a habituation study was also conducted. The results from the second experiment showed that 4-month-olds can discriminate the ID and AD pitch contours. From these results, it is argued that the pitch contour may be but one of many possible prosodic characteristics that attract infant attention and this attention may occur only within a language context. It is suggested that future studies investigate ID speech using a more context-dependent procedure, where natural or more complete speech samples are utilized.
Master of Science

Persons with Autism Spectrum Disorders (ASD) display enhanced and diminished processing across low-level visual and auditory tasks. In vision, Bertone, Mottron, Jelenic, and Faubert (2005) found evidence that enhanced and diminished visual processing is linked to the level of neural complexity required to process stimuli, as proposed in the neural complexity hypothesis. Based on these findings, Samson, Mottron, Jemel, Belin, and Cioccia (2006) proposed to extend the neural complexity hypothesis to the auditory modality. They hypothesized that persons with ASD should display enhanced auditory sensitivity for simple tones that are processed in primary auditory cortical regions (i.e., A1), but diminished sensitivity for complex tones that require additional processing in associative auditory regions (i.e., A2), in comparison to typically developing individuals. To assess this hypothesis, four adaptive-staircase discrimination experiments were designed targeting pitch, non-vocal and vocal timbre, and loudness. Stimuli consisted of tones varying along spectral and temporal axes of complexity. The participants were individuals with autism, Asperger syndrome, and typical developmental histories, all with IQs in the normal range. Consistent with the neural complexity hypothesis and with the enhanced perceptual functioning model of autism (Mottron & Burack, 2001; Mottron, Dawson, Soulières, Hubert, & Burack, 2006), the participants with autism group displayed enhanced pitch discrimination for simple tones. However, this was not the case for those with Asperger syndrome. Moreover, no differences in auditory discrimination abilities were found between the participants with ASD and those with typical developmental histories across spectrally and temporally complex conditions. These findings indicate that enhanced pure-tone frequency discrimination may be a cognitive correlate of speech-delay among persons with ASD.
Le phénotype autistique est caractérisé par des performances supérieures et inférieures dans des tâches de perception visuelle et auditive. En vision, les résultats d'une étude menée par Bertone, Mottron, Jelenic, et Faubert (2005) suggèrent que la dissociation observée entre un traitement visuel à la fois supérieur et inférieur pourrait s'expliquer par la complexité neuronale requise pour traiter les stimuli, tel que proposé dans l'hypothèse de la complexité neuronale. Suite à ces résultats, Samson, Mottron, Jemel, Belin, et Cioccia (2006) ont proposé d'appliquer cette hypothèse dans la sphère auditive. Selon cette hypothèse, les personnes autistes devraient obtenir de meilleurs seuils de discrimination auditive que les personnes non-autistes pour les sons simples, puisque le traitement de ces derniers s'effectue au niveau des aires corticales auditives primaires A1, et de moins bons seuils de discrimination auditive pour les sons complexes dont le traitement requiert l'intégration entre les régions corticales auditives primaires et non-primaires (A2). Afin d'évaluer cette hypothèse, quatre tâches de discrimination ont été conçues ciblant la hauteur, le timbre de stimuli non-vocaux et vocaux, et l'intensité. Les stimuli consistaient en un ensemble de sons purs et complexes variant sur l'axe spectro-temporal, présentés sous forme statique ou modulée. Les seuils de discrimination auditive de participants autistes, de sujets Asperger et de participants neurotypiques, appariés au niveau du QI global et de l'âge chronologique, ont été estimés via une procédure adaptative. Tel que prédit par l'hypothèse de la complexité neuronale et par le modèle EPF (enhanced perceptual functioning model: Mottron & Burack, 2001; Mottron, Dawson, Soulières, Hubert, & Burack, 2006), les participants autistes ont obtenu des seuils inférieurs pour la discrimination des sons purs statiques, reflétant une capacité de discrimination supérieure pour ce type de sons, une supériorité qui ne se retrouvait pas chez les sujets Asperger. Contrairement à nos prédictions, les seuils de discrimination auditive des sujets autistes et Asperger étaient équivalents à ceux des sujets "neurotypiques" dans les conditions spectro-temporalement complexes. Ces résultats suggèrent que la discrimination de la hauteur de sons purs pourrait représenter un corrélat cognitif de la présence d'un retard de langage chez les personnes autistes.

Musicians represent an ideal model for understanding experience-driven neuroplasticity in the human brain, especially in auditory and motor domains. Musicians exert intensive and durable practice of various multimodal skills (e.g., motor, auditory, visual and memory). It has been reported that certain regions of the adult musicians' brains are structurally larger than non- musicians. Also musicians demonstrate more sensitive pitch discrimination abilities compared to non-musicians because pitch labelling plays an important role in music. Music is made of a highly structured and complex succession of tones that arranged in a specific rhythm and played at specific pitch. In this thesis I aimed to; (1) Explore the influence of musical proficiency on pitch discrimination ability with investigating the laterality pitch discrimination ability and exploring some factors that could affect pitch discrimination ability such as aging, type of musical instrument and duration of musical proficiency. (2) Investigate anatomical plasticity of selected brain structures in musicians with exploring musical proficiency and the instrument type effect on sulcal and gyral topography. (3) Study the correlations between pitch discrimination performance and some cortical features of selected brain structures. (4) Investigate tonotopic mapping in the human auditory cortex using functional magnetic resonance imaging and (fMRI) and magneto encephalography (MEG). (5) Examine the influence of musical proficiency expertise on frequency organization and cortical activation of the human auditory cortex. Different structural methods were implemented to study differences between musicians and non-musicians in some structural features. FMRI and MEG were used to study tonotopic mapping in the human auditory cortex. During pitch discrimination tasks, musicians demonstrated more sensitivity than non-musicians. Musicians also showed significantly larger volume in various brain regions and shape differences in sulcal and gyral anatomy and the right hippocampus. Additionally, there were significant correlations between pitch discrimination performance and different structural measurements. Musicians had stronger BOLD fMRI in the medial and lateral part of the left HG. ANOVA tests of the amplitude of neuromagnetic N100 component showed a group effect of borderline significance. Results clearly show behavioural, structural and functional differences between these two groups. These results indicate that the morphology and neurophysiology of various brain regions and the pitch labelling have an essential role in musical proficiency.

For cochlear implant (CI) listeners, poorer than normal speech recognition abilities are typically attributed to degraded spectral acuity. However, estimates of spectral acuity have most often been obtained using simple (tonal) stimuli, presented directly to the implanted electrodes, rather than through the speech processor as occurs in everyday listening. Further, little is known about spectral acuity for dynamic stimuli, as compared to static stimuli, even though the perception of dynamic spectral cues is important for speech perception. The primary goal of the current study was to examine spectral acuity in CI listeners, and a comparison group of normal hearing (NH) listeners, for both static and dynamic stimuli presented through the speech processor. In addition to measuring static and dynamic spectral acuity for simple stimuli (pure tones) in Experiment 1, spectral acuity was measured for complex stimuli (synthetic vowels) in Experiment 2, because measures obtained with speech-like stimuli are more likely to reflect listeners’ ability to make use of spectral cues in naturally-produced speech. Sixteen postlingually-deaf, adult CI users and sixteen NH listeners served as subjects in both experiments. In Experiment 1, frequency discrimination limens (FDLs) were obtained for 1.5 kHz reference tones, and frequency glide discrimination limens (FGDLs) were obtained for pure-tone frequency glides centered on 1.5 kHz. Glide direction identification thresholds (GDITs) were also measured, in order to determine the amount of frequency change required to identify glide direction. All three measures were obtained for stimuli having both longer (150 ms) and shorter (50 ms) durations. Spectral acuity for dynamic stimuli (FGDLs, GDITs) was poorer than spectral acuity for static stimuli (FDLs) for both listener groups at both stimulus durations. Stimulus duration had a significant effect on thresholds in NH listeners, for all three measures, but had no significant effect on thresholds in CI listeners for any measure. Regression analyses revealed no systematic relationship between FDLs and FGDLs in NH listeners at either stimulus duration. For CI listeners, the relationship between FDLs and FGDLs was significant at both stimulus durations, suggesting that, for tonal signals, the factors that determine spectral acuity for static stimuli also largely determine spectral acuity for dynamic stimuli. In Experiment 2, estimates of static and dynamic spectral acuity were obtained using three-formant synthetic vowels, modeled after the vowel /^/. Formant discrimination thresholds (FDTs) were measured for changes in static F2 frequency, whereas formant transition discrimination thresholds (FTDTs) were measured for stimuli that varied in the extent of F2 frequency change. FDTs were measured with 150-ms stimuli, and FTDTs were measured with both 150-ms and 50-ms stimuli. For both listener groups, FTDTs were similar for the longer and shorter stimulus durations, and FTDTs were larger than FDTs at the common duration of 150 ms. Measures from Experiment 2 were compared to analogous measures from Experiment 1 in order to examine the effect of stimulus context (simple versus complex) on estimates of spectral acuity. For NH listeners, measures obtained with complex stimuli (FDTs, FTDTs) were consistently larger than the corresponding measures obtained with simple stimuli (FDLs, FGDLs). For CI listeners, the relationship between simple and complex measures differed across two subgroups of subjects. For one subgroup, thresholds obtained with complex stimuli were smaller than those obtained with simple stimuli; for another subgroup the pattern was reversed. On the basis of these findings, it was concluded that estimates of spectral acuity obtained with simple stimuli cannot accurately predict estimates of spectral acuity obtained with complex (speech-like) stimuli in CI listeners. However, a significant relationship was observed between FDTs and FTDTs. Thus, similar to the measures obtained with pure-tone stimuli in Experiment 1 (FDLs and FGDLs), estimates of static spectral acuity (FDTs) appear to predict estimates of dynamic spectral acuity (FTDTs) when both measures are obtained with stimuli of similar complexity in CI listeners. Taken together, findings from Experiments 1 and 2 support the following conclusions: (1) Dynamic spectral acuity is poorer than static spectral acuity for both simple and complex stimuli. This outcome was true for both NH and CI listeners, despite the fact that absolute thresholds were substantially larger, on average, for the CI group. (2) For stimuli having the same level of complexity (i.e., tonal or speech-like), dynamic spectral acuity in CI listeners appears to be determined by the same factors that determine spectral acuity for static stimuli. (3) For CI listeners, no systematic relationship was observed between analogous measures of spectral acuity obtained with simple, as compared to complex, stimuli. (4) It is expected that measures of spectral acuity based on complex stimuli would provide a better indication of CI users’ ability to make use of spectral cues in speech; therefore, it may be advisable for studies attempting to examine the relationship between spectral acuity and speech perception in this population to measure spectral acuity using complex, rather than simple, stimuli. (5) Findings from the current study are consistent with recent vowel identification studies suggesting that some poorer-performing CI users have little or no access to dynamic spectral cues, while access to such cues may be relatively good in some better-performing CI users. However, additional research is needed to examine relationship between estimates of spectral acuity obtained here for speech-like stimuli (FDTs, FTDTs) and individual CI users’ perception of static and dynamic spectral cues in naturally-produced speech.

Cochlear implant (CI) devices afford many profoundly deaf individuals worldwide partially restored hearing ability. Although CI users achieve remarkable speech perception with contemporary multichannel CI devices, their music perception ability is generally unsatisfactory. Improved CI-mediated music perception ability requires that the underlying constraints hindering processing of music-relevant information need to be identified and understood. This study puts forward a systematic approach, informed by the neurocognitive mechanisms underlying music perception in normal hearing (NH), for investigating implant-mediated music perception. Psychoacoustical experiments were used to explore the extent to which music-relevant information delivered to the central auditory system following peripheral electrical stimulation supports music perception. Task-specific stimuli and test procedures were developed to assess perception of pitch, rhythm and loudness information, both as separate and in combined form, in sound-field listening conditions. CI users’ unsuccessful judgement of the musical character of short, novel single-voice melodies suggests that insufficient information reaches the central auditory processing system to effect a unified musical percept. This is despite sound field frequency discrimination behaviour being better than had been expected and rhythm perception ability with regard to short tone sequences of varying pitch and rhythmic complexity being comparable to that of NH listeners. CI listeners also performed similarly to NH listeners during pitch-dependent loudness perception tasks. Within the framework of a hierarchical, modular processing system underlying music perception, it appears that early pitch processing deficits propagate throughout the music processing system to exert an overriding inhibitory perceptual effect. The outcomes of this study not only underline the importance of delivering sufficient pitch information to the electrically stimulated auditory system but also show that music perception in CI-mediated hearing should be investigated and understood as the outcome of an integrated perceptual system.
Thesis (PhD)--University of Pretoria, 2013.
Electrical, Electronic and Computer Engineering
Unrestricted

The purpose of the study was to investigate the effect of 10 minutes of daily exposure for 10 weeks to a Chinese Music Curriculum and its effect on generating positive cultural attitudes towards the Chinese people, improving tonal discrimination skills, singing accuracy of tonal patterns, and accuracy of singing Chinese lyrics for third-, fourth-, and fifth-grade students, compared to a comparison group not receiving the Chinese Music Curriculum. In an elementary school in Miami-Dade County, Florida, 6 third-, fourth-, and fifth-grade classes were chosen and randomly assigned to either an intervention or a comparison group. A Chinese Music Curriculum was developed for the intervention group and implemented by classroom teachers. Meanwhile, the comparison group received normal academic instruction and a weekly music class by a music specialist. Pre- and post-tests were administered to both the intervention and comparison groups: (1) Children's Attitudes toward Chinese (CATC), (2) Intermediate Measures of Music Audiation-Tonal (IMMA, Gordon, 1982), and (3) Tonal Pattern Performance Measure (TPPM). The Chinese Song Performance Measure (CSPM) was administered to the intervention group only in order to measure students' abilities for accurately singing the Chinese lyrics of a simple Chinese song, "Little Rat." Data were subjected to a mixed Multivariate Analysis of Variance (MANOVA) statistical analysis, item analysis, and Pearson Product-Moment correlation. The results demonstrated that the CATC survey was a reliable and valid measure to assess children's attitudes toward Chinese people. The overall effect of the Chinese Music Curriculum was significant in combination of the three outcome measures: CATC, IMMA, and TPPM. The follow-up individual examination revealed that children's attitudes toward Chinese people and tonal pattern singing accuracy were significantly improved, but tonal discrimination skills did not improve. Grade was found to influence children's singing accuracy of tonal patterns with fifth graders outperforming the third and fourth graders. All participants in the intervention group were able to sing a Chinese song with over 70% accuracy of the Chinese lyrics.

Auditory filters were derived in 20 normal-hearing human listeners at center frequencies (CFs) of 913, 1095, 3651, and 4382 Hz using the roex (p,r) method. Comparisons were made between slopes of the filters' skirts at the neighboring CFs with filter output levels of 45 and 70 dB. The same comparisons were made with regard to filter equivalent rectangular bandwidth (ERB). In the 1000-Hz region, the low-frequency slopes (Pl) of filters centered at 913 and 1095 Hz were significantly correlated at both stimulus levels, while the high-frequency slopes (Pu) were similar only at the high test level. In the 4000-Hz region, for sinusoids of 3651 and 4382 Hz, the level effect was clearer as both Pu and Pl values diverged at the low level but were related at high levels. The ERBs centered at the same CFs displayed a similar level dependence. At the stimulus level most likely to be affected by an active feedback mechanism, auditory filters centered at nearly the same frequency displayed quite distinct frequency selectivity, and this trend was stronger in the 4000-Hz region than the 1000-Hz region. The findings suggest that a saturating, active cochlear mechanism may not be distributed evenly, or contribute to peripheral tuning with equal effectiveness throughout the length of the partition.

L’amusie congénitale est un trouble neuro-développemental qui s’exprime par un déficit de discrimination tonale fine. Le cerveau des amusiques ne répond pas aux petites différences de hauteur, tel que révélé par l’absence de la composante de potentiel évoqué P3b, qui est associée aux processus de discrimination tonale tardifs et conscients. Peu d’études se sont penchées sur les mécanismes précoces et préconscients de discrimination tonale chez les amusiques, qui peuvent être étudiés par l’entremise d’une composante de potentiel évoqué appelée la négativité de discordance (MMN). Certaines études ont démontré qu’il est possible d’enregistrer la MMN pendant la présentation d’un film avec la trame sonore en simultané aux sons visant à évoquer la composante. Toutefois, une étude a démontré que la présentation de la trame sonore réduisait l’amplitude de la MMN, sans néanmoins clarifier la nature de l’effet d’interférence en cause. Les objectifs du présent projet sont d’abord, d’investiguer les effets à l’origine de la réduction d’amplitude de la MMN observée lors de la présentation d’un film avec la trame sonore, puis d’évaluer cette même composante chez les amusiques. La première étude visait à déterminer si un effet d’interférence attentionnelle ou acoustique était en cause dans la réduction d’amplitude observée sur la MMN lors de la présentation de la trame sonore d’un film. Les résultats ont montré qu’un effet de masquage acoustique, attribuable à la trame sonore, était responsable de la réduction d’amplitude de la MMN, cette dernière augmentant au fur et à mesure que l’intensité sonore de la trame du film était réduite. La seconde étude a été conduite dans le but d’investiguer la MMN chez les amusiques et de vérifier si le complexe d’ondes anormales N2b-P3b, observé en réponse aux grandes différences tonales chez les amusiques, pouvait être attribuable à un effet de saillance des stimuli. Dans un premier temps, nous avons comparé la MMN des amusiques à celle des contrôles, puis nous avons modifié le paradigme expérimental visant à évoquer la N2b-P3b en ajustant les probabilités d’occurrence des sons présentés aux contrôles en fonction des sons perçus par les amusiques. Les résultats ont montré que le cerveau des amusiques parvient à discriminer les différences de hauteur à un niveau précoce et préconscient, tel que révélé par une MMN normale, mais que les réponses cérébrales plus tardives, associées au processus de discrimination des hauteurs conscient, sont anormales chez les amusiques, et ce, uniquement pour les petites différences de hauteur, tel que révélé par l’absence de la P3b. En conclusion, ces résultats démontrent que l’amplitude de la MMN est affectée de manière significative par la présentation de la trame sonore d’un film et que cela est attribuable à un effet d’interférence acoustique. Dans un deuxième temps, nous avons démontré que les mécanismes précoces et préconscients de discrimination tonale sont préservés chez les amusiques, et que le déficit sous-jacent à l’amusie congénitale est attribuable à une atteinte du processus de discrimination tonale fine associé à un niveau de traitement cérébral tardif et conscient, le complexe d’ondes anormales N2b-P3b étant pour sa part attribuable à un effet de saillance des stimuli.
Congenital amusia is a neurodevelopmental disorder which is characterized by a deficit in fine-grained pitch discrimination. In fact, the amusic brain does not respond to small pitch changes, such as reflected by the absence of the event-related (ERP) component P3b, which is associated to late and conscious pitch discrimination processes. Until now, very few studies focused on early preconscious levels of processing in amusia, which can be studied through an ERP component called the mismatch negativity (MMN). Some studies have demonstrated that the MMN can be recorded while playing the soundtrack of a movie in concurrence with the MMN-critical tones. However, one study demonstrated that playing the movie soundtrack reduced MMN amplitude, but did not investigate the origin of this effect. The main goals of this project are, first, to investigate the nature of the effect responsible for the MMN reduction observed when playing a movie soundtrack, and secondly, to evaluate the MMN in congenital amusia. The first study aimed to investigate if an attentionnal or acoustical interference effect could account for the reduction in MMN amplitude observed when playing the movie soundtrack. The results showed that an acoustical masking effect of the movie soundtrack was responsible for the reduction in MMN amplitude. In fact, MMN amplitude increased as the intensity level of the movie soundtrack decreased. The goal of the second study was to investigate the MMN in congenital amusia, but also to explore if the abnormal N2b-P3b complex observed in amusics in a previous study could be accounted for by an effect of salience of the stimuli. Thus, we first compared the MMN results between amusics and controls, and then, we modified the experimental paradigm meant to evoke the N2b-P3b by adjusting the probabilities of occurrence of the sounds presented to the controls as a function of the sounds perceived by their matched amusics. The results showed that the amusic brain can detect all pitch changes at an early and preconscious level of processing, such as demonstrated by a normal MMN in both groups. Furthermore, our results showed that the amusic brain does not respond normally solely to small pitch changes at a later conscious level of processing, such as revealed by the absence of the P3b, thus showing that the abnormal N2b-P3b complex of ERP components observed in a previous study is better explained by a saliency effect of the stimuli and does not represent an electrophysiological anomaly specific to congenital amusia. In conclusion, our results have first shown that MMN amplitude is decreased by presenting a movie soundtrack and this is due to a masking effect at the acoustical level of the soundtrack over the MMN-critical tones. Finally, our second study showed that the early preconscious mechanisms of pitch discrimination are preserved in congenital amusia, and that the pitch deficit underlying congenital amusia is limited to an anomaly in the late and conscious processing of small pitch changes, the abnormal N2b-P3b complex being rather explained by an effect of salience of the stimuli.