No description available.

No description available.

Traditional methods for the investigation of sound fields generally rely on a microphone to convert sound pressure into an electrical signal which can be recorded, displayed, and so forth. The squared sound pressure is directly related to potential energy density. Consequently, the measurement of sound pressure alone does not inherently provide insight into the total energy density of the sound field. Specifically, no information about the kinetic energy density of the sound field is available from this measurement alone. However, it is possible to use two microphones to estimate particle velocity. The squared particle velocity magnitude is directly related to kinetic energy density. The two energy quantities combine to yield total acoustic energy density. The purpose of this work is to investigate and compare three probes designed to measure acoustic energy density. It is also to determine which probe may be most practically implemented in real-world applications. All three designs are based on a rigid spherical housing and are referred to as follows: the six microphone probe, the tetrahedron probe, and the orthogonal probe. The six microphone probe is so named because it is made up of six microphones, with one pair of microphones oriented along each Cartesian axis. The tetrahedron probe is so named because it has four microphones, one at each of the vertices of a regular tetrahedron. The orthogonal probe has four microphones positioned in such a way that the lines drawn from an origin microphone to the other microphones form an orthogonal set. The majority of the work presented in this thesis uses Matlab to numerically predict the behavior of the probes. Four numeric models are used to predict the behavior of the three different probes. The models match the geometric arrangement of the various probes. A simple experiment also shows how the probes respond to a source in an anechoic environment. The results of the numeric modeling indicate that the orthogonal probe has the greatest useable frequency range. Both the tetrahedron and the orthogonal probes have a greater frequency range than the six microphone probe. However, in the simple experiment, the orthogonal probe did not measure energy density as accurately as the tetrahedron probe when the orthogonal probe was rotated, such that no Cartesian axis was parallel to the radial axis of the source. The data indicate that more work must be done before a decision can be made between the tetrahedron probe and the orthogonal probe. It is clear that it is possible to measure acoustic energy density in 3-dimensions using only four microphones, instead of six.

Most research investigating vocal expressions of emotion has focused on one or more of three questions: whether there exist unique acoustic profiles of individual encoded emotions, whether the nature of emotion expression is universal across cultures, and how accurately decoders can identify expressed emotions. This dissertation begins to answer a fourth question, whether there exist unique patterns in the types of acoustic properties persons focus on to identify vocalized emotions. Three hypotheses were tested: first, whether acoustic patterns are interpreted idiographically or nomothetically as reflected in a comparison of individual vs. group lens model identification ratios; second, whether there exists a decoder by emotion interaction for scores of accuracy; and third, whether such an interaction is mediated by the acoustic properties of the vocalized emotions. Results from hypothesis one indicate there is no difference between individual and group identification ratios, demonstrating that vocalized emotions are decoded nomothetically. Results from hypothesis two indicate there is not a significant decoder by emotion interaction on scores of accuracy, demonstrating that decoders who are generally good (or bad) at identifying some vocalized emotions tend to be generally good (or bad) at identifying all vocalized emotions. There are, however, significant main effects for both emotion and decoder. Anger and happiness are more accurately decoded than fear and sadness. Perhaps most importantly, multivariate results from hypothesis three indicate strong and consistent differences across the four emotions in the way they are identified acoustically. Specifically, decoders identify anger by primarily focusing on spectral characteristics, fear by primarily focusing on frequency (F0), happiness by primarily focusing on rate, and sadness by focusing on both intensity and rate. These acoustic mediation differences across the emotions are also shown to be nomothetic, that is, they are surprisingly consistent across decoders.

Wireless surface acoustic wave (SAW) sensors offer unique advantages over other sensor technologies because of their inherent ability to operate in harsh environments and completely passive operation, providing a reliable, maintenance-free life cycle. For certain SAW sensor applications the challenge is building a wirelessly interrogatable device with the same lifetime as the SAW substrate. The design of these application intensive sensors is complicated by the degradation of device bond wires, die adhesive, and antenna substrate. In an effort to maximize the benefits of the platform, this dissertation demonstrates wafer-level integrated SAW sensors that directly connect the thin film SAW to a thick film on-wafer antenna. Fully integrated device embodiments are presented that operate over a wide range of temperatures using different fabrication techniques, substrates, and coding principles.

This dissertation proposes a system for weighing commercial vehicles in motion using acoustic emission sensors attached to a metal bar placed across the roadway. The signal from the sensors is analyzed by a computer and the vehicle weight is determined by a statistical model which correlates the acoustic emission parameters to the vehicle weight. Such a system would be portable and low-cost, allowing for the measurement of vehicle weights in much the same way commercial tube and radar counters routinely collect vehicle speed and count. The system could be used to collect vehicle speed and count data as well as weight information. Acoustic emissions are naturally occurring elastic waves produced by the rapid release of energy within a material. They are caused by deformation or fracturing of a solid due to thermal or mechanical stress. Acoustic emission sensors have been developed to detect these waves and computer software and hardware have been developed to analyze and provide information about the waveforms. Acoustic emission testing is a common form of nondestructive testing and is used for pressure vessel testing, leak detection, machinery monitoring, structural integrity monitoring, and weld monitoring, among other things (Miller, 1987). For this dissertation, acoustic emission parameters were correlated to the load placed on the metal test bar to determine the feasibility of using a metal test bar to measure the weight of a vehicle in motion. Several experiments were done. First, the concept was tested in a laboratory setting using an experimental apparatus. A concrete cylinder was mounted on a frame and rotated using a motor. The metal test bar was applied directly to the surface of the cylinder and iv acoustic emission sensors were attached to each end of the bar. As the cylinder rotated, a motorcycle tire was pushed up against the cylinder using a scissor jack to simulate different loads. The acoustic emission response in the metal test strip to the motorcycle tire rolling over it was detected by the acoustic emission sensors and analyzed by the computer. Initial examinations of the data showed a correlation between the force of the tire against the cylinder and the energy and count of the acoustic emissions. Subsequent field experiments were performed at a weigh station on I-95 in Flagler County, Florida. The proposed weigh-in-motion system (the metal test bar with attached acoustic emission sensors) was installed just downstream of the existing weigh-in-motion scale at the weigh station. Commercial vehicles were weighed on the weigh station weigh-in-motion scale and acoustic emission data was collected by the experimental system. Test data was collected over several hours on two different days, one in July 2008 and the other in April 2009. Initial examination of the data did not show direct correlation between any acoustic emission parameter and vehicle weight. As a result, a more sophisticated model was developed. Dimensional analysis was used to examine possible relationships between the acoustic emission parameters and the vehicle weight. In dimensional analysis, a dimensionally correct equation is formed using measurable parameters of a system. The dimensionally correct equation can then be tested using experimental data. Dimensional analysis revealed the following possible relationship between the acoustic emission parameters and the vehicle weight: ! = " # $% &2 , '(, )% *+( , ,% +( , ,-% +( , %3 +( . (/0% , 1% +( 2 v The definitions of these variables can be found in Appendix A. Statistical models for weight using the laboratory data and using the field data were developed. Dimensional analysis variables as well as other relevant measurable parameters were used in the development of the statistical models. The model created for the April 2009 dataset was validated, with only 27 lbs average error in the weight calculation as compared with the weight measurement made with the weigh station weigh-in-motion scale. The maximum percent error for the weight calculation was 204%, with about 65% of the data falling within 30% error. Additional research will be needed to develop an acoustic emission weigh-in-motion system with adequate accuracy for a commercial product. Nevertheless, this dissertation presents a valuable contribution to the effort of developing a low-cost acoustic emission weigh-in-motion scale. Future research needs that were identified as part of this dissertation include: ! Examination of the effects of pavement type (flexible or rigid), vehicle speeds greater than 50 mph, and temperature ! Determination of the best acoustic emission sensor for this system ! Exploration of the best method to separate the data from axles which pass over the equipment close together in time (such as tandem axles) ! Exploration of the effect of repeated measures on improving the accuracy of the system.

The connection with the outdoor acoustic environment created by open windows has so far been one of the main impediments to the adoption of natural ventilation (NV), due to indoor noise levels easily exceeding design requirements. Starting from the apparent conflict between ventilation and acoustic comfort needs, and the potential offered by NV for low-energy cooling and ventilation, the study explores the opportunities for shaping healthy and supportive acoustic environments through sound transmitted via ventilation openings. The research question challenges the traditional approach to acoustic design, which assumes noise annoyance reduction by merely reducing decibel noise levels, drawing inspiration from the soundscape concept. Soundscape science characterises the human response to the acoustic environment in context and can help understand if and how NV may contribute to defining spaces that sound good to their occupants. The aim is to go beyond an exclusive focus on the ‘noise’ – ‘noise annoyance’ binomial, and to employ ‘wanted’ sounds as a design resource for creating acoustically pleasant environments. However, the soundscape framework, as described by ISO 12913 standard series, has been primarily developed for use in the context of urban planning. This has led to question (i) how the soundscape approach can be applied to the indoor built environment, (ii) what factors positively influence it and (iii) how it can be measured in residential buildings. A systematic literature review categorized the factors that positively influence acoustic perception in domestic environments, highlighting its strongly multi-factorial nature. Beyond noise level, a combination of acoustic and non-acoustic factors was found to affect acoustic perception, such as the urban context, house and person-related factors, socio-economic, situational, and environmental factors. The study benefited from a round of interview with experts in the field of urban soundscape, indoor soundscape, acoustic design, and public health and well-being. The collective discussion encompassed the characterization, management, and design of indoor (and indoor versus outdoor) soundscapes to identify current research gaps in the objective and subjective evaluation of the indoor acoustic environments. In response, based on a laboratory listening test, a model of perceived affective quality of indoor acoustic environments has been derived to guide the measurement and improvement of indoor residential soundscapes. During the test, 35 participants were asked to rate 20 different sound scenarios each. Scenarios were defined by combining four indoor sound sources and five urban environments, filtered through a window ajar, on 97 attribute scales. Comfort, content, and familiarity were extracted as the main perceptual dimensions explaining respectively 58%, 25% and 7% of the total variance in subjective ratings. A measurement system was proposed, based on a 2-D space defined by two orthogonal axes, comfort, and content, and two derivative axes, engagement and privacy – control, rotated 45° on the same plane. The model was tested in a large-scale online survey to assess the influences of different acoustic and non-acoustic factors on indoor soundscape dimensions, window-opening behavior, and occupant well-being. Evaluating the affective response to the indoor acoustic environment through the comfort – content model helped identifying the impacts that acoustical factors (e.g., sound typology), building (e.g., house size), urban (e.g., availability of a quiet side), situational (e.g., number of people at home), and person-related factors (e.g., noise sensitivity) determine on building occupants depending on the specific activity people are engaged with at home, reaching a more in-depth knowledge compared to appraisals based on annoyance evaluation alone. By disentangling the positive and negative contributions of sound stimuli according to people’s perception, it was possible to highlight the opportunity provided by NV to create a sense of place and enhance indoor soundscapes, providing useful masking opportunities in the presence of disturbing indoor noise sources. Results pointed to the existence of benefits from NV able to compensate for a reduced acoustic comfort in case of outdoor acoustic pollution. However, the availability of ‘positive’ urban soundscapes is essential for occupants’ well-being, and is linked primarily to access to natural sounds, but also to other commonly available urban sounds. The ‘quieter’ is therefore not always the better, but it really depends on the composition of indoor and outdoor sound types according to people’s preference and on the interaction with different domains (e.g., visual). Such evidence reinforces the role of acoustics in building and urban design, integrated with the other disciplines involved and based on multi-domain research. Overall, the doctoral study contributes to framing the ‘indoor soundscape’ concept, addressing scientific, industrial, social, and environmental implications, and suggesting future lines of research.

Histotripsy is a noninvasive mechanical ablation method that uses focused ultrasound to disintegrate target tissues into acellular homogenate through the generation of acoustic cavitation and is currently being developed for numerous clinical applications. Histotripsy uses high-pressure (>10 MPa), short-duration (<15 cycles) pulses to cause the rapid expansion and collapse of nuclei at the focus resulting in large applied stress and strain in the adjacent tissue. At a sufficiently high pressure above the target medium's intrinsic cavitation threshold and an adequate number of applied pulses, cavitation "bubble clouds" create precise lesions with high fidelity to the region of the focus. Despite advances in histotripsy, additional research is still needed to better understand the acoustic cavitation nucleation process and its effects on therapies using focused ultrasound. This understanding is critical to better predict and control pulse dose for more rapid and efficient ablation procedures, to reduce off-target cavitation events for safer focused ultrasound therapies, and to localize ablation for high-precision procedures near critical structures or treatments without active imaging guidance. In this dissertation, I investigate the nucleation and dynamics of ultrasonically generated acoustic cavitation for novel applications of focused ultrasound. My Ph.D. thesis focuses on (1) investigating the effect of histotripsy pulsing parameters on bubble cloud cavitation nucleation, bubble dynamics, and ablation efficiency, (2) investigating the effect of nuclei characteristics on the threshold for cavitation nucleation and resulting bubble dynamics for therapeutic applications, and (3) developing methods alter select characteristics and dynamics of acoustic cavitation by adjusting pulsing parameters to optimize ablation efficiency in conventional and nanoparticle-mediated histotripsy. The culmination of this thesis will advance our understanding of the nucleation and behavior of acoustic cavitation from pulsed focused ultrasound and develop innovative systems to improve the efficacy, efficiency, and safety of clinical focused ultrasound therapies. / Doctor of Philosophy / Histotripsy is a noninvasive focused ultrasound method that precisely destroys target tissues such as tumors through the acoustic generation of cavitation and is currently being developed for numerous clinical applications. Histotripsy uses high-pressure, short-duration pulsed soundwaves to cause the bubbles to rapidly expand and collapse within a precise region called the focus. This rapid cavitation results in large mechanical strain in the targeted tissue. With increasingly higher pressure, numerous bubbles form in the shape of cavitation "bubble clouds" that create lesions, closely matching their shape, in the target tissue after a sufficient number of pulses have been applied. Despite advances in histotripsy, additional research is still needed to better understand the initiation of the acoustic cavitation process in histotripsy and its effects on focused ultrasound therapies. This understanding is critical to better predict and control ablation procedures, improve procedure efficiency, reduce off-target cavitation events for safer focused ultrasound therapies, and further increase ablation precision for procedures near critical structures or treatments without active image guidance. In this dissertation, I investigate the initiation, growth, and collapse of ultrasonically generated acoustic cavitation for novel applications of focused ultrasound. My Ph.D. thesis focuses on (1) investigating the effect of histotripsy pulsing parameters on bubble cloud cavitation initiation, bubble growth and collapse, and treatment efficiency, (2) investigating the effect of particle characteristics on the threshold for cavitation initiation and resulting bubble behavior for therapeutic applications, and (3) adjusting pulsing parameters to optimize ablation efficiency in conventional and particle mediated histotripsy. The culmination of this thesis will advance our understanding of the initiation and behavior of acoustic cavitation from pulsed focused ultrasound and develop innovative systems to improve the efficacy, efficiency, and safety of clinically focused ultrasound therapies.

In architectural design, few materials compare to the degree of use of concrete. Due its high compressive strength and economic efficiency, concrete excels in architectural applications. While impressive, concrete has shortcomings in its acoustic absorption properties and ability to be used sustainably. To address both concerns, the proposed solution is to introduce waste wood fibers into concrete's composition. Due to wood's fibrous nature, acoustic absorption can be bolstered while improving sustainability by recycling waste wood products. While manufacturing wood infused concretes and measuring acoustic absorption is not difficult, it is time consuming and resource intensive. Therefore, a model to estimate acoustic absorption coefficients of fiber-infused concretes is developed to aid in bypassing the need for experimental trial-and-error. The model utilizes the Delany-Bazley (DBz) and Johnson-Champoux-Allard-Lafarge (JCAL) models to predict acoustic absorption coefficients of given fiber-infused concretes. The DBz model provides an estimate of the characteristic impedance and wave number of a sample based on a power-law relationship that considers sound medium and airflow resistivity. The DBz model estimates are then refined by the JCAL model using estimated viscous and thermal properties of the sample. Finally, using these refined acoustic property estimates, the acoustic absorption coefficients are estimated. Using varying wood-infused concrete samples, results are experimentally verified using an impedance tube and absorption coefficients are calculated using the transfer-function method. After comparing estimated and measured absorption values, the current model was found to have the potential of providing a relative comparison of acoustic performance between compositions. However, estimated values were not accurate, nor considered representative of samples. Further, multiple aspects of the model could be improved to better represent different concrete compositions in model estimations.

No description available.