Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 145 for “"Sound Pressure"”.
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Predicting Axial Flow Fan Sound Pressure Spectrums
Made available in DSpace on 2014-12-11T17:36:09Z (GMT). No. of bitstreams: 1 7524255.pdf: 8339950 bytes, checksum: 096e097bd75d545071c0dfb33a1853d9 (MD5) Previous issue date: 1975
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New empirical equations for calculating sound pressure levels in rooms
… a new empirical room equation to predict the sound pressure distribution in rooms, seventeen rooms whose volumes ranged from 2,671 ft{dollar}\sp3{dollar} to 149,000 ft{dollar}\sp3{dollar} were examined. Two sets of sound tests, reverberation times and sound pressure levels, were conducted in …
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Prediction of low-frequency sound-pressure fields in fitted rooms for active noise control
… which relies on destructive interference of sound waves to reduce noise levels. However, this depends on phase, and how it is affected when sound waves encounter diffracting obstacles. In addition, the geometrical configuration of the active-control system must be optimized, which can be done …
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Prediction of sound pressure and intensity fields in rooms and near surfaces by ray tracing
… a room’s occupants is greatly influenced by the sound field within it. An acoustical engineer is often consulted during the design of a room to prevent or alleviate unwanted acoustical problems. Prediction models are often used to find the most cost-effective solution to a given acoustical …
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Support vs. Steady Airflow: The Effect of Two Different Instructions on Subglottal Pressure, Sound Pressure Level, and Airflow Rate during Singing and Speaking
… that the word promotes the use of increased air pressure. The purpose of the present investigation was to test that hypothesis by examining differences in a variety of physiological parameters, comparing a conventional singing instruction that uses the word “support” with an alternative …
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Determination of acoustic ray paths in enclosed spaces
… of all the reflecting surfaces to determine the sound pressure levels at specified receiver locations. A computer program was developed to perform the necessary calculations for reflection points and sound pressure levels. The output was in the form of ray tracing plots which showed the unique …
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The development of a computer program using a modified room acoustics approach to determine sound levels in regular rooms
A program was developed which calculated sound pressure levels at an array of points in a room. Necessary inputs are the room dimensions, sound power or sound pressure levels for the sources, absorption coefficients for the room surfaces, the temperature, relative humidity, and if sound pressure …
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A turbulent combustion noise model
… in this thesis. The model predicts (1) the pressure time series, (2) Sound Pressure Level (SPL) spectrum, (3) Over-All Sound Pressure Level (OASPL), (4) the thermoacoustic efficiency, (5) the peak frequency, and (6) the sound power of combustion generated noise. In addition, a correlation …
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Changes of voice production in artificial acoustic environments
… setting on voice production in terms of sound pressure level and the relationship with the perceived voice comfort and voice control. Three independent room acoustic parameters were considered: gain (alteration of the sidetone or playback of one's own voice), reverberation time and …
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A computer model for sound propagation around conical seamounts
… a technique for computing the long-range sound pressure field around a penetrable conical seamount. The pressure field is generated by a harmonic point source. The seamount is positioned in a vertically stratified ocean. It is modeled as an outgrowth of the sediment layer covering the …
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Psychoacoustic Entropy Theory and Its Implications for Performance Practice
… system perceives instantaneous disorder within a sound pressure wave. Chapter one explains the importance of harmonic analysis as a tool for performance practice. It also outlines the critical limitations for many of the most influential historical approaches to modeling harmonic stability, …
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Characterisation and modelling of loudspeaker cone resonance
… cause of ripple in the electrical impedance and sound pressure responses of electrodynamic loudspeakers. In this thesis, the dependence of the characteristics of loudspeaker cone resonances on the material properties and thickness profile of the cone is extensively determined by creating 2D and …
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Experimental measurement of combustion noise and comparison to a predictive model
… The data are presented in the form of acoustic pressure spectra and over-all sound pressure levels. The experiment consisted of a geometrically simple pre-mixed burner with five interchangeable nozzles whose diameters varied from 0.117 cm to 0.541 cm. The fuels examined in the experiment were …
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Evidence of inner-ear mechanisms in bone conduction in chinchillas
… much is known about the process of how airborne sound is conducted to the inner-ear via the outer ear and middle ear, so-called air conduction (AC), the mechanisms by which vibrations of the head and body, so-called bone conduction (BC), produce an auditory response are not well understood. It is …
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Anomaly detection for environmental noise monitoring
Octave-band sound pressure level is the preferred measure for continuous environmental noise monitoring over raw audio because accepted standards and devices exist, these data do not compromise voice privacy, and thus an octave-band sound meter can legally collect data in public. By setting up an …
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Aerodynamic and Acoustic Modeling for eVTOL Rotor Noise Prediction
… these spectral variations, integrated overall sound pressure level predictions show limited sensitivity to turbulence model choice. At 2000 RPM, broadband noise mechanisms dominate the total sound pressure level, with transitional turbulence models predicting thinner boundary layers and reduced …
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Comfort studies on aircraft interior sound and vibration
… (BE97-4056) addressed the effects of combined sound and vibration (vibro-acoustics) on comfort sensation in aircraft. In the first study, seven cruising situations were presented in an aircraft mock-up and rated by 117 subjects using 15 polarities of a semantic differential. Principal component …
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Flow -Induced Noise in Heat Exchangers
… of the duct in which travelling hydrodynamic pressure fluctuations produced by vortex shedding do not contaminate the results was investigated by measuring sound pressure levels. Many of the results are believed to be unique. The measurements were then used to infer noise source strength and …
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A Unified Measure of Audio System Fidelity
… of distortion as a function of the perceived Sound Pressure Level (SPL).
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Helmholtz Equation Least Squares Based Near-Field Acoustic Holography With Laser
… The conventional HELS based NAH uses acoustic pressure as input to reconstruct sound field quantities, while this modified HELS based NAH with laser utilizes the normal surface velocities measured by LDV to reconstruct the acoustic quantities at interested positions. Theoretical principles of …
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