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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Probe-Signal Investigation of an Attentional Filter for Fundamental Frequency

Peddie, Rachel January 2014 (has links)
When listeners are detecting tones of a given frequency in noise, they operate with a narrowband attentional filter which is tuned to the frequency of the attended tone. This means that tones with frequencies which match that which is being attended to, will be detected, whereas tones with frequencies outside the filter will be detected at chance levels. In the current study, attentional filters were measured on two auditory dimensions. The first experiment employed a modified version of the methods of previous studies to measure attentional filters in the frequency dimension (Greenberg & Larkin, 1968). The mean results replicated those of previous experiments, revealing an attentional filter for frequency. In the second experiment, the methods of the first experiment were used to investigate whether there is an attentional filter in the fundamental frequency (f0) dimension. To test this, sentences with a given f0 were presented in noise. Infrequently, sentences were presented with f0s which the listeners were not attending to. The changes in f0 (∆f0) tested were ± 5 Hz and ±10 Hz, with respect to the expected 220 Hz f0. The effect of ∆f0 was investigated using sentence identification scores. Mean results indicated that listeners were best at identifying the sentences with an expected f0, and sentences with ∆f0s of 10 Hz from the expected f0. Sentences with ∆f0s of 5 Hz from the expected f0, on the other hand, were more poorly detected. This could be due to the presence of an attentional filter for f0, which has a narrow bandwidth, ranging between 10 and 20 Hz. An attentional filter for f0 may have different properties than those for attentional filters for frequency. The complex nature of sentence materials might change the way that attention is allocated across the f0 distribution, so that greater changes in f0 may be enough to switch the listeners’ attention to that f0. Overall, the results did not approximate the typical attentional filter shape which was found for frequency. Therefore, the results cannot be used to demonstrate the existence of attentional filters for f0. The presence of an attentional filter for f0, however, cannot be ruled out. Further research is needed, using a greater variety of ∆f0s to confirm and further investigate the presence, and properties of an attentional filter for f0.
2

Auditory Attention to Fundamental Frequency of Pure Tones

Suckling, Anna Louise January 2014 (has links)
Two experiments were conducted. The first was a control condition and used the probe signal method similar to Greenberg and Larkin (1968) to see if a filter-like attentional mechanism was acting when listeners were presented with pure tone stimuli in the presence of background noise. The second experiment also used the probe signal method of Greenberg and Larkin (1968) to investigate the extent to which listeners direct their attention to a particular fundamental frequency (f0) when detecting complex tones masked by noise. Twenty adult listeners ranging from 23 years to 54 years with a median age of 28 years participated in both experiments. Of the 20 listeners, 8 were male and 14 were female. Both experiments used a Two Interval Forced Choice (2IFC) procedure. There were two types of trials, the target signal trial and the probe signal trial. The target frequency was presented on 71% of trials, and the probe frequencies on the remaining 29%. The results of Experiment 1 were similar to those obtained in Greenberg and Larkin’s (1968) pioneering study. The 1000 Hz target tone was detected at a significantly higher proportion than probe signals differing in frequency (p < 0.05). Detection scores were observed to be higher when probe signals had a frequency close to the 1000 Hz signal compared to when they had a frequency positioned further from the 1000 Hz target tone. Experiment 2 using complex target tones with f0 of 115 Hz (part 1) and 220 Hz (part 2) revealed a similar pattern to Experiment 1. Listener’s detection scores decreased the further the f0 of probe tones were positioned from the f0 of the target tone, revealing the shape of a band-pass filter. This pattern is consistent with the presence of an auditory attentional filter in the f0 domain for complex tones
3

Vocal Sounds of the Chinchilla

Hunyady, Heather 13 May 2008 (has links)
No description available.
4

Novel Pitch Detection Algorithm With Application to Speech Coding

Kura, Vijay 19 December 2003 (has links)
This thesis introduces a novel method for accurate pitch detection and speech segmentation, named Multi-feature, Autocorrelation (ACR) and Wavelet Technique (MAWT). MAWT uses feature extraction, and ACR applied on Linear Predictive Coding (LPC) residuals, with a wavelet-based refinement step. MAWT opens the way for a unique approach to modeling: although speech is divided into segments, the success of voicing decisions is not crucial. Experiments demonstrate the superiority of MAWT in pitch period detection accuracy over existing methods, and illustrate its advantages for speech segmentation. These advantages are more pronounced for gain-varying and transitional speech, and under noisy conditions.
5

On Inverse Problems for a Beam with Attachments

Mir Hosseini, Farhad 05 December 2013 (has links)
The problem of determining the eigenvalues of a vibrational system having multiple lumped attachments has been investigated extensively. However, most of the research conducted in this field focuses on determining the natural frequencies of the combined system assuming that the characteristics of the combined vibrational system are known (forward problem). A problem of great interest from the point of view of engineering design is the ability to impose certain frequencies on the vibrational system or to avoid certain frequencies by modifying the characteristics of the vibrational system (inverse problem). In this thesis, the effects of adding lumped masses to an Euler-Bernoulli beam on its frequencies and their corresponding mode shapes are investigated for simply-supported as well as fixed-free boundary conditions. This investigation paves the way for proposing a method to impose two frequencies on a system consisting of a beam and a lumped mass by determining the magnitude of the mass as well as its position along the beam.
6

On Inverse Problems for a Beam with Attachments

Mir Hosseini, Farhad January 2013 (has links)
The problem of determining the eigenvalues of a vibrational system having multiple lumped attachments has been investigated extensively. However, most of the research conducted in this field focuses on determining the natural frequencies of the combined system assuming that the characteristics of the combined vibrational system are known (forward problem). A problem of great interest from the point of view of engineering design is the ability to impose certain frequencies on the vibrational system or to avoid certain frequencies by modifying the characteristics of the vibrational system (inverse problem). In this thesis, the effects of adding lumped masses to an Euler-Bernoulli beam on its frequencies and their corresponding mode shapes are investigated for simply-supported as well as fixed-free boundary conditions. This investigation paves the way for proposing a method to impose two frequencies on a system consisting of a beam and a lumped mass by determining the magnitude of the mass as well as its position along the beam.
7

The Effects of Fundamental Frequency Level on Voice Onset Time in Normal Adult Male Speakers

McCrea, Christopher R., Morris, Richard J. 01 October 2005 (has links)
The purpose of this study was to examine the effect of fundamental frequency (Fo) on stop consonant voice onset time (VOT). VOT was measured from the recordings of 56 young men reading phrases containing all 6 English voiced and voiceless stops in word-initial position across high-, medium-, and low-Fo levels. Separate analyses of variance for the voiced and voiceless stops revealed no significant main effect for Fo for the voiced stops but a significant Fo effect for the voiceless stops. Across the voiceless stops, productions at high Fos displayed significantly shorter VOTs than productions at low or mid F os. The findings indicated that researchers must take into account the Fo level at which voiceless stop VOT is measured.
8

Quantification of Motion and Cry Characteristics of NAS Newborns

Austin, Dexter Cyril 12 September 2017 (has links)
Neonatal abstinence syndrome (NAS) is a condition caused by in-utero exposure to opioids, and its occurrence is increasing nationwide. NAS patients are newborns who can experience withdrawal symptoms including tremors, poor feeding, and respiratory distress. Presently, the Finnegan Scoring System, a subjective rating scale, is commonly used to judge the patient's condition and determine appropriate treatment methods. This project sought to develop a sensor system that is capable of objectively assessing symptoms of withdrawal, including tremors and high pitched cry. The system developed is composed of five wireless accelerometers, for attachment to a subject's limbs and chest, and an external microphone. The sensor system is targeted toward quantifying limb movements of the subject and recording audio information that includes samples of the subject's cry. The sensor system was used as part of a research study, and data was collected from recruited participants. A total of 29 out of 30 desired participants were enrolled and studied as part of the data collection process. Gathered data was analyzed using MATLAB, with motion data being searched for tremor activity in NAS participants, and cry samples searched for unique characteristics. Results generated indicate that detection of tremors was successful, and that the average fundamental frequency of cry differs between the NAS and non-NAS participants. Future considerations for this project include expanding to measure more symptoms, and system refinement to minimize the number of sensors. / Master of Science
9

A Study of Computer Modeling Techniques to Predict the Response of Floor Systems Due to Walking

Perry, Jason Daniel 17 December 2003 (has links)
The possibility of using a commercially available structural analysis program to predict the response of a floor system due to walking excitation as given in AISC Design Guide 11, Floor Vibrations Due to Human Activity (Murray, et al., 1997) was explored. This research included ideal floors that did not have measured values as well as several case study floors that do have measured values for the fundamental frequency. First, multiple model set-ups and loading protocols are applied to the ideal floors and the results compared to results from the Design Guide procedure. A recommendation of the best combination of a model set-up and loading protocol that best matches the Design Guide procedure results is made. Then, case study floors are modeled with the recommended model set-up and loading protocol, and the results compared to the results from the Design Guide procedure and to measured fundamental frequencies. The peak accelerations are also compared to subjective evaluations as to the acceptability of the system. Next, multiple systems were analyzed using five different modeling techniques, including the Design Guide Method, an alteration of the Design Guide Method, the Rayleigh Method, the Analytical Method, and the structural analysis program method, in an attempt to determine the source of discrepancies between the structural analysis program method and the Design Guide method. Finally, conclusions are drawn regarding the structural analysis program procedure as well as possible sources of differences. In general, the structural analysis program procedure reliably predicts the fundamental frequency of a floor system, but does not predict the Design Guide peak acceleration under dynamic loading. The difference in the effective mass of a system between the two methods is a source of discrepancy. / Master of Science
10

An Acoustic and Perceptual Investigation of Contrastive Stress in Children

Dromey, Anita Susan 12 July 2010 (has links) (PDF)
Key aspects of prosody have been studied in adults for a number of years; however, less attention has been paid to the acoustic patterns of prosody in children. Thus, the purpose of the present study was to evaluate how a group of 20 pre-adolescent children use prosody to mark contrastive stress compared to a control group of adult speakers. It was of interest to investigate whether the children's use of prosody differed between boys and girls or the part of speech being emphasized. The prosodic patterns of contrastive stress were evaluated in terms of duration, fundamental frequency, and intensity change relative to a baseline production of the same sentence. In addition, a perceptual experiment was conducted to determine if listeners could reliably identify the gender of the child speakers when listening to sentence length utterances. Statistical analysis indicated that there were some differences in the duration and fundamental frequency change as a function of speaker age and the part of speech being emphasized, with relatively minor differences between genders. However it remains unclear if the acoustic differences found in this study were substantial enough to cause a salient perceptual difference. Although previous studies have identified increases in frequency, intensity, and duration as cues of contrastive stress, the present findings revealed patterns that did not consistently conform to these expectations. Limitations in the task design, individual speaker characteristics, and also the type of acoustic measure used may have contributed to these results.

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