Thesis (Ph.D.)--Kent State University, 2007. / Title from PDF t.p. (viewed Mar. 31, 2008). Advisor: Linda B. Walker. Keywords: music, hearing, band directors, teachers, audiology, spl, musicians. Includes survery instrument. Includes bibliographical references (p. 171-182).

Thesis (DPhil(Communication Pathology))--University of Pretoria, 2004. / Includes bibliographical references.

Thesis (M. Communication Pathology)--University of Pretoria, 2004. / Includes bibliographical references.

A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in ful lment of the requirements for the degree of Master of Science in Engineering, Johannesburg, September 2019 / The objective of this research was to develop an integrated Port Hamiltonian model of the human outer, middle and inner ear. The developed Port Hamiltonian model of the human ear is based on the Dirac structure. The outer, middle and inner ear are developed in segments, tested and validated prior to the system being coupled. The outer, middle and inner ear are validated against existing literature and the results are found to be comparable. The application of the developed Port Hamiltonian model is illustrated using a developed feedback based noise policy management model for mine workers. This feedback based measurement system can be used to monitor mine workers in the mines hence provide the mine administrators with the current state of hearing of the individual worker. The information obtained from the system may be used by the administration to provide an early intervention and as a result the mine workers are protected from experiencing signi cant hearing threshold shifts. A control engineering approach is then used to formulate the mining noise occupational policies as a control law. Both social and measurements aspects of this system are explored. The International Standard Organization guide ISO:1999 is used to generate data and develop a basic feedback model. The basic feedback model is further re ned into a dynamic model which includes a Port Hamiltonian integrated ear model and the mining policies. The feedback based noise policy management model is validated using real data from the mine documented in open source literature. The models are implemented using MATLAB as a modelling platform and the results are generated using the Simulink model. This research work has been given an ethical clearance certi cate by the Human Research Ethics Committee (Medical), therefore, allowing for the ndings of the investigations to be published. In conclusion,to be developed is an integrated Port Hamiltonian model of the Human outer, middle and inner ear to be used for estimation of Noise induced hearing loss. The use of this model is then illustrated using a feedback based noise policy monitoring system for mine workers. / PH2020

No description available.

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

Thesis (M. Sc. (Nursing Science)) --University of Limpopo, 2017. / Refer to the document

Thesis (M.S.)--University of Michigan, 1991.

Thesis (M.S.)--University of Michigan, 1991.

Meine Dissertation behandelt verschiedene neue rauschinduzierte Phänomene in anregbaren Neuronenmodellen, insbesondere solche mit FitzHugh-Nagumo Dynamik. Ich beschreibe das Auftreten von vibronischer Resonanz in anregbaren Systemen. Sowohl in einer anregbaren elektronischen Schaltung als auch im FitzHugh-Nagumo Modell zeige ich, daß eine optimale Amplitude einer hochfrequenten externen Kraft die Signalantwort bezüglich eines niederfrequenten Signals verbessert. Weiterhin wird der Einfluß von additivem Rauschen auf das Zusammenwirken von stochastischer und vibronischer Resonanz untersucht. Weiterhin untersuche ich Systeme, die sowohl oszillierende als auch anregbare Eigenschaften beinhalten und dadurch zwei interne Frequenzen aufweisen. Ich zeige, daß in solchen Systemen der Effekt der stochastischen Resonanz deutlich erhöht werden kann, wenn eine zusätzliche hochfrequente Kraft in Resonanz mit den kleinen Oszillationen unterhalb der Anregungsschwelle hinzugenommen wird. Es ist beachtenswert, daß diese Verstärkung der stochastischen Resonanz eine geringere Rauschintensität zum Erreichen des Optimums benötigt als die standartmäßige stochastische Resonanz in anregbaren Systemen. Ich untersuche Frequenzselektivität bei der rauschinduzierten Signalverarbeitung von Signalen unterhalb der Anregungsschwelle in Systemen mit vielen rauschunterstützten stochastischen Attraktoren. Diese neuen Attraktoren mit abweichenden gemittelten Perioden weisen auch unterschiedliche Phasenbeziehungen zwischen den einzelnen Elementen auf. Ich zeige, daß die Signalantwort des gekoppelten Systems unter verschiedenen Rauscheinwirkungen deutlich verbessert oder auch reduziert werden kann durch das Treiben einzelner Elemente in Resonanz mit diesen neuen Resonanzfrequenzen, die mit passenden Phasenbeziehungen korrespondieren. Weiterhin konnte ich einen rauschinduzierten Phasenübergang von einem selbstoszillierenden System zu einem anregbaren System nachweisen. Dieser Übergang erfolgt durch eine rauschinduzierte Stabilisierung eines deterministisch instabilen Fixpunktes der lokalen Dynamik, während die gesamte Phasenraumstruktur des Systems erhalten bleibt. Die gemeinsame Wirkung von Kopplung und Rauschen führt zu einem neuen Typ von Phasenübergängen und bewirkt eine Stabilisierung des Systems. Das sich daraus ergebende rauschinduziert anregbare Regime zeigt charakteristische Eigenschaften von klassisch anregbaren Systemen, wie stochastische Resonanz und Wellenausbreitung. Dieser rauschinduzierte Phasenübergang ermöglicht dadurch die Übertragung von Signalen durch ansonsten global oszillierende Systeme und die Kontrolle der Signalübertragung durch Veränderung der Rauschintensität. Insbesondere eröffnen diese theoretischen Ergebnisse einen möglichen Mechanismus zur Unterdrückung unerwünschter globaler Oszillationen in neuronalen Netzwerken, welche charakteristisch für abnorme medizinische Zustände, wie z.B. bei der Parkinson′schen Krankheit oder Epilepsie, sind. Die Wirkung von Rauschen würde dann wieder die Anregbarkeit herstellen, die den normalen Zustand der erkrankten Neuronen darstellt. / My thesis is concerned with several new noise-induced phenomena in excitable neural models, especially those with FitzHugh-Nagumo dynamics. In these effects the fluctuations intrinsically present in any complex neural network play a constructive role and improve functionality. I report the occurrence of Vibrational Resonance in excitable systems. Both in an excitable electronic circuit and in the FitzHugh-Nagumo model, I show that an optimal amplitude of high-frequency driving enhances the response of an excitable system to a low-frequency signal. Additionally, the influence of additive noise and the interplay between Stochastic and Vibrational Resonance is analyzed. Further, I study systems which combine both oscillatory and excitable properties, and hence intrinsically possess two internal frequencies. I show that in such a system the effect of Stochastic Resonance can be amplified by an additional high-frequency signal which is in resonance with the oscillatory frequency. This amplification needs much lower noise intensities than for conventional Stochastic Resonance in excitable systems. I study frequency selectivity in noise-induced subthreshold signal processing in a system with many noise-supported stochastic attractors. I show that the response of the coupled elements at different noise levels can be significantly enhanced or reduced by forcing some elements into resonance with these new frequencies which correspond to appropriate phase-relations. A noise-induced phase transition to excitability is reported in oscillatory media with FitzHugh-Nagumo dynamics. This transition takes place via noise-induced stabilization of a deterministically unstable fixed point of the local dynamics, while the overall phase-space structure of the system is maintained. The joint action of coupling and noise leads to a different type of phase transition and results in a stabilization of the system. The resulting noise-induced regime is shown to display properties characteristic of excitable media, such as Stochastic Resonance and wave propagation. This effect thus allows the transmission of signals through an otherwise globally oscillating medium. In particular, these theoretical findings suggest a possible mechanism for suppressing undesirable global oscillations in neural networks (which are usually characteristic of abnormal medical conditions such as Parkinson′s disease or epilepsy), using the action of noise to restore excitability, which is the normal state of neuronal ensembles.