Thesis (M.S.)--University of Alabama at Birmingham, 2006. / Description based on contents viewed Jan. 29, 2007; title from title screen. Includes bibliographical references.

The purpose of this thesis is the construction of a test bench for the assessment of the NVH behaviour of a newly manufactured VW Polo 5. This will be done in collaboration with Volkswagen South Africa. Firstly, in order to gain a better understanding of the requirements such a test bench has to fulfill, the VW Polo, the guidelines prescribed by VW as well as the actual testing procedure implemented by VW Uitenhage will be analysed. Thereafter, the main section of the thesis will deal with the construction of the test bench. As agreed upon with Volkswagen Uitenhage, a test bench will be built during the course of the studies. This test bench will allow stimulation in low frequency as well as high frequency ranges and in addition to that, a second version of the test bench with optimised costing will be derived from the first one. The second model will only allow stimulation in high frequency ranges. During the thesis, a version of the test bench, the RTB-HC, has been developed which enables the stimulation of the high and low frequencies. In addition, a cost optimized version was developed. This version will be referred as RTB-LC. This version allows only a high frequency excitation.

Noise exposure is a common hazard to workforce in general although at varying degrees depending on the occupation, as many workers are exposed for long periods of time to potentially hazardous noise. Every year, twenty-two million workers are exposed to potentially damaging noise at work. In 2015 U.S. businesses paid over $1.5 million in penalties for not protecting workers from noise. (OSHA, 2016). There may be a direct or indirect consequence of the possibilities of overexposure to noise notwithstanding the compulsory hearing protection requests for the occupations with potential hazards, and these exposures usually arise from the various types of heavy repair equipment and tools related to the job functions. In the United States ten million people have noise related hearing loss (CDC, 2016) and damage done to the ear is not noticed until earing diminishes significantly. One of the noisiest occupations there are include the flight ground crews and flight maintenance personnel otherwise categorized as Ground Operation Workers. These categories of workers have varying functions in the noisiest area at the ramp, and this exposes them to noise that could lead to hearing impairment or permanent ear damage. This study was focused on workers on the ramps at the international airport of a large US city. These workers also are known as ground handling staff, and these employees perform different tasks on the airline ramp, which include unloading luggage from the airline, picking up and moving luggage from the belt room, and to loading baggage onto the airline. This study was conducted using personal dosimeters which were calibrated before and after each sampling event out on four different employees over a period of four days and the collected data were downloaded to a personal computer for further analysis. From the results of this study, the highest noise exposures occurred on a ground operation worker 3 (GOW3) with an 8-hr TWA exposure of 85.6 dBA using OSHA PEL measurement specifications and this occurred on the fourth day of sampling which was a Saturday. The second highest exposure occurred on ground operation worker 1 (GOW1) on the fourth day with an 8-hr TWA exposure of 85.0 dBA. For ground operations worker 2 (GOW2) and ground operation worker 4 (GOW4), the highest exposure occurred on the second day with 79.8 dBA and 73.4 dBA as their time weighted averages, respectively. None of the workers exposures exceeded the OSHA permissible exposure limit of 90 dBA. The United States Navy uses the OSHA noise standard to evaluate noise exposure on ships and all Navy installations. According to University of South Florida institutional review Board, this study is categorized as a program evaluation that has no intervention with human subjects. The workers that participated in this study did so voluntarily.

The diploma thesis deals with the noise level of the harvester when pressing round balers. The sound pressure levels were measured at a selected distance from the harvesting set when pressing fodder. The measurement of operator noise in the machine cab (tractor) was also measured. These measured noise values are displayed in charts. The harvesting set is evaluated for environmental noise pollution according to the characteristics of the harvested land and the working conditions of the operator.

[Summary] Chapter I . The general characteristics of solar radiation at metre wavelengths are described, with reference to data published in the literature. A brief description of some aspects of solar physics relevant to the study of solar noise is given, and the literature relating to the correlation of radio effects with solar disturbances is reviewed. Chapter II. A concise description of the apparatus constructed for the continuous recording of the flux density of solar radio noise at a frequency of 300 Mc/s is given, with some mention of difficulties experienced, and how these were overcome. Full circuit diagrams of electronic apparatus, and illustrative photographs, are supplied. Chapter III. The development of theories of the origin and propagation of solar noise radiation is historically reviewed and the success of each theory in explaining or predicting observed phenomena, is assessed. A working model is chosen from among these theories, and reasons for its adoption are given. Chapter IV. Observations made by the author of solar radiation at a frequency of 300 Mc/s are described, together with a description of the objects and methods, of analysis of the records. Chapter V. Phenomena observed by the author are compared with those observed by other workers. It is concluded that storm bursts are caused by transients similar to those producing Type II and Type ITI bursts, and a model for the production of storm bursts is tentatively suggested. Chapter VI. Suggestions for further research, including suggestions for methods of testing the author's conclusions, are made.

This study investigated the effect of hearing six background noise conditions (silent baseline, pink noise, monologue, lively conversation, one-sided phone call, and cocktail noise) on acoustic measures of speech production during story retells in people with aphasia. Eleven individuals with aphasia and 11 age- and gender-matched control participants took part in the study. Participants heard the background noise conditions through open-back headphones while they retold six short stories. The examiner calculated mean and standard deviation of intensity, mean and standard deviation of fundamental frequency (F0), and speech rate in words per minute. A Matlab application that identified pauses (i.e., periods of silence greater than 200 ms) computed a speaking time ratio measure (i.e., time speaking versus time pausing). With the exception of the monologue and one-sided phone call condition, both people with aphasia and control participants significantly increase their intensity and F0 in the presence of background noise. Additionally, participants with aphasia have significantly lower speaking time ratios and speaking rates when compared to control participants. Participants make acoustic changes while hearing background noise; speech intensity rises in an effort to increase the signal-to-noise ratio, while mean F0 increases due to a presumed rise in subglottal pressure. Further research is suggested to investigate other acoustic differences, possibly at the segmental level, between speech produced in informational and energetic background noise.

The aim of this thesis is to create a noise map in a geographic information system. First of all, physical features of sound and the basics concerning the spatial, physiological and atmospheric acoustics domain will be introduced. Furthermore, we will analyse noise and its possible influence on the health of people. Substantial part of this thesis will be devoted to the methodology of noise measurement in urban agglomerations and to the issue of creating noise maps. The methodology of noise measurement in a particular area will be determined on the basis of the theoretical background. Geographic information system ArcView 9.2 from the ARCDATA firm (Ltd.) will be used for creating the noise map. The final noise map will be compared to the current hygienic limits. For comparison reasons an analysis of noise map using software CadnaA, which is used in professional analysis of noise studies, will be included in this thesis too.

The purpose of this Master Thesis has been to investigate the possibilities for a new type of noise reduction solution that could decrease the negative effects resulting from larger traffic roads. The idea has been to construct a noise barrier with a roof – like a tunnel placed on a road. The choice of material has been focused on transparent materials in order to lower visual intrusion and barrier effects. This project idea is called the Noise tunnel. After having investigated the current offer of noise solutions, it has been concluded that these solutions rarely provide a sufficient level of noise reduction – at least not when government regulations of acceptable noise levels are applied. To reach these acceptable noise levels at large traffic roads, noise barriers must be constructed at a larger scale or else the roads must be built below ground level. The Noise tunnel has therefore been investigated as an alternative noise solution. With the reduced noise levels resulting from the Noise tunnel, it will be possible to exploit new land for construction –something which would contribute to the funding of the Noise tunnel. In order to investigate the Noise tunnel in a more concrete way, a part of Nynäsvägen has been studied. Nynäsvägen is a large road situated south of Stockholm, and some parts of the road, as well as its surroundings, suffer from severe noise problems. Moreover, there is unexploited land available near Nynäsvägen, and this could be used for constructions. The result of the investigations shows that the Noise tunnel is approximately 10 times more expensive than a noise barrier, but 10 times cheaper than decking over the road. Furthermore, it has been found that it is possible to construct the Noise tunnel with today’s production methods. This conclusion is supported by both primary research and observations from similar projects conducted abroad. It has been found that the Noise Tunnel represent an alternative solution at large traffic roads in urban environments where noise problems are of concern. This thesis concludes that although there are no technical problems preventing the Noise tunnel from becoming reality, the incentives to implement it are likely to represent a greater barrier.

Switched reluctance motors (SRMs) possess many desirable qualities for the long-term sustainability of electrified transportation such as cheap production costs and simple, robust configurations. However, high acoustic noise and torque ripple are two performance imperfections that have prevented the widespread implementation of SRMs. This thesis investigates design techniques to reduce the acoustic noise produced by an 8/6 SRM while also analyzing the impact each design has on the motor’s performance. The fundamentals of SRMs are discussed including the operating principles, modelling and control strategies. The multiphysics finite element analysis (FEA) toolchain used to accurately model acoustic noise and vibrations of SRMs is described. Using the network of FEA tools, nodal forces and natural frequencies of a four phase 8/6 SRM are analyzed to study the acoustic noise and vibration behaviours. The FEA process is validated experimentally by matching measured vibration modes and acoustic noise sound pressure level (SPL) with FEA numerical results. Through inspiration from an extensive literature review, various design techniques are applied to a baseline four phase 8/6 SRM and compared for both acoustic noise reduction and EM performance criteria. The investigated designs were split into two categories, stator-housing modifications that aim to increase the stiffness of the assembly and rotor modifications that aim to reduce the magnitude of radial forces while preserving performance. The best design strategies as determined by the comparative analysis were then further optimized to combine the best techniques together for the 8/6 SRM. The proposed structural improvements included the modifications of the stator yoke shape along with increasing the number of fastening components involved in the assembly. Additionally, an iterative procedure for the parametric modelling of windows introduced to the rotor poles is outlined. The best design considerations are combined to create the design of a novel 8/6 SRM which significantly reduces the acoustic noise produced by the motor with little impact to performance. / Thesis / Master of Applied Science (MASc)

Previous work has shown that active noise control is a feasible solution to attenuate tonal noise radiated by small axial cooling fans, such as those found in desktop computers. One such control system reduced noise levels of a baffled 80-mm fan in the free field with four small loudspeakers surrounding the fan. Due to industry specified spatial constraints, a smaller fan and speaker configuration was desirable. The smaller configuration maintains similar control performance, further facilitating practical implementation of the control system. The smaller control system employs a smaller fan running at a higher speed. Different loudspeaker configurations for control exist and have been tested. A configuration consisting of four control sources spaced symmetrically around and coplanar to the fan exhibits global control of the tonal component of the fan noise. A configuration with three symmetrically spaced sources is shown to perform similarly, agreeing with theoretical prediction. An analysis of the control system in a non-ideal reflective environment is also discussed.