Matching Items (19)

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Acoustic Gunshot Detection Device Design and Power Management

Description

The following report provides details on the development of a protective enclosure and power system for an anti-poaching gunshot detection system to be implemented in Costa Rica. The development of

The following report provides details on the development of a protective enclosure and power system for an anti-poaching gunshot detection system to be implemented in Costa Rica. The development of a gunshot detection system is part of an ongoing project started by the Acoustic Ecology Lab at Arizona State University in partnership with the Phoenix Zoo. As a whole, the project entails the development of a gunshot detection algorithm, wireless mesh alert system, device enclosure, and self-sustaining power system. For testing purposes, four devices, with different power system setups, were developed. Future developments are discussed and include further testing, more specialized mounting techniques, and the eventual expansion of the initial device network. This report presents the initial development of the protective enclosure and power system of the anti-poaching system that can be implemented in wildlife sanctuaries around the world.

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Date Created
  • 2020-05

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Identification of the Origins of Blade-Vortex Interaction (BVI) Noise in Helicopters

Description

One of the leading concerns regarding the commercial and military applications of rotary wing powered vehicles is the issue of blade-vortex interaction (BVI) noise occurring during forward descent. This impulsive

One of the leading concerns regarding the commercial and military applications of rotary wing powered vehicles is the issue of blade-vortex interaction (BVI) noise occurring during forward descent. This impulsive noise-generating phenomenon occurs due to the close proximity and interference between the main rotor blades and the wake vortices generated by the rotor blades from previous revolutions. Throughout the descent phase of a helicopter in forward flight, the rotating blades pass through these induced vortices, thus generating an impulsive "slap" noise that is characteristic of the common sound associated with helicopter flight among the general population. Therefore, parameterization of the variables of interest that affect BVI noise generation will allow for thorough analysis of the origins of the noise and open pathways for innovation that may offer significant improvements in acoustic performance. Gaining an understanding of the factors that govern the intensity of the BVI acoustic signature provides a strong analytical and experimental basis for enhanced rotor blade design.

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Date Created
  • 2016-05

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Techniques for soundscape retrieval and synthesis

Description

The study of acoustic ecology is concerned with the manner in which life interacts with its environment as mediated through sound. As such, a central focus is that of the

The study of acoustic ecology is concerned with the manner in which life interacts with its environment as mediated through sound. As such, a central focus is that of the soundscape: the acoustic environment as perceived by a listener. This dissertation examines the application of several computational tools in the realms of digital signal processing, multimedia information retrieval, and computer music synthesis to the analysis of the soundscape. Namely, these tools include a) an open source software library, Sirens, which can be used for the segmentation of long environmental field recordings into individual sonic events and compare these events in terms of acoustic content, b) a graph-based retrieval system that can use these measures of acoustic similarity and measures of semantic similarity using the lexical database WordNet to perform both text-based retrieval and automatic annotation of environmental sounds, and c) new techniques for the dynamic, realtime parametric morphing of multiple field recordings, informed by the geographic paths along which they were recorded.

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Created

Date Created
  • 2013

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Concert Hall Acoustics and Piano Lid Height: A Study of Five Arizona Concert Halls

Description

Traditional consensus in duos with grand piano has been that issues of balance between piano and the other instrument can be corrected through lowering the lid on the piano, particularly

Traditional consensus in duos with grand piano has been that issues of balance between piano and the other instrument can be corrected through lowering the lid on the piano, particularly when the other instrument has been thought of as less forceful. The perceived result of lowering the lid on the piano is to quiet the piano enough so as not to overwhelm the other instrument, though the physics of the piano and acoustics suggest that it is incorrect to expect this result. Due to the physics of the piano and natural laws such as the conservation of energy, as well as the intricacies of sound propagation, the author hypothesizes that lowering the lid on the piano does not have a significant effect on its sound output for the audience of a musical performance. Experimentation to determine empirically whether the lid has any significant effect on the piano's volume and tone for the audience seating area was undertaken, with equipment to objectively measure volume and tone quality produced by a mechanical set of arms that reproduces an F-major chord with consistent power. The chord was produced with a wooden frame that input consistent energy into the piano, with measurements taken from the audience seating area using a sound pressure level meter and recorded with a Zoom H4N digital recorder for analysis. The results suggested that lowering the lid has a small effect on sound pressure level, but not significant enough to overcome issues of overtone balance or individual pianists’ touch.

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Created

Date Created
  • 2017

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Development of hardware and software for a game-like wireless spatial sound distribution system

Description

Several music players have evolved in multi-dimensional and surround sound systems. The audio players are implemented as software applications for different audio hardware systems. Digital formats and wireless networks allow

Several music players have evolved in multi-dimensional and surround sound systems. The audio players are implemented as software applications for different audio hardware systems. Digital formats and wireless networks allow for audio content to be readily accessible on smart networked devices. Therefore, different audio output platforms ranging from multispeaker high-end surround systems to single unit Bluetooth speakers have been developed. A large body of research has been carried out in audio processing, beamforming, sound fields etc. and new formats are developed to create realistic audio experiences.

An emerging trend is seen towards high definition AV systems, virtual reality gears as well as gaming applications with multidimensional audio. Next generation media technology is concentrating around Virtual reality experience and devices. It has applications not only in gaming but all other fields including medical, entertainment, engineering, and education. All such systems also require realistic audio corresponding with the visuals.

In the project presented in this thesis, a new portable audio hardware system is designed and developed along with a dedicated mobile android application to render immersive surround sound experiences with real-time audio effects. The tablet and mobile phone allow the user to control or “play” with sound directionality and implement various audio effects including sound rotation, spatialization, and other immersive experiences. The thesis describes the hardware and software design, provides the theory of the sound effects, and presents demonstrations of the sound application that was created.

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Created

Date Created
  • 2016

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Investigations of environmental effects on freeway acoustics

Description

The role of environmental factors that influence atmospheric propagation of sound originating from freeway noise sources is studied with a combination of field experiments and numerical simulations. Acoustic propagation models

The role of environmental factors that influence atmospheric propagation of sound originating from freeway noise sources is studied with a combination of field experiments and numerical simulations. Acoustic propagation models are developed and adapted for refractive index depending upon meteorological conditions. A high-resolution multi-nested environmental forecasting model forced by coarse global analysis is applied to predict real meteorological profiles at fine scales. These profiles are then used as input for the acoustic models. Numerical methods for producing higher resolution acoustic refractive index fields are proposed. These include spatial and temporal nested meteorological simulations with vertical grid refinement. It is shown that vertical nesting can improve the prediction of finer structures in near-ground temperature and velocity profiles, such as morning temperature inversions and low level jet-like features. Accurate representation of these features is shown to be important for modeling sound refraction phenomena and for enabling accurate noise assessment. Comparisons are made using the acoustic model for predictions with profiles derived from meteorological simulations and from field experiment observations in Phoenix, Arizona. The challenges faced in simulating accurate meteorological profiles at high resolution for sound propagation applications are highlighted and areas for possible improvement are discussed.

A detailed evaluation of the environmental forecast is conducted by investigating the Surface Energy Balance (SEB) obtained from observations made with an eddy-covariance flux tower compared with SEB from simulations using several physical parameterizations of urban effects and planetary boundary layer schemes. Diurnal variation in SEB constituent fluxes are examined in relation to surface layer stability and modeled diagnostic variables. Improvement is found when adapting parameterizations for Phoenix with reduced errors in the SEB components. Finer model resolution (to 333 m) is seen to have insignificant ($<1\sigma$) influence on mean absolute percent difference of 30-minute diurnal mean SEB terms. A new method of representing inhomogeneous urban development density derived from observations of impervious surfaces with sub-grid scale resolution is then proposed for mesoscale applications. This method was implemented and evaluated within the environmental modeling framework. Finally, a new semi-implicit scheme based on Leapfrog and a fourth-order implicit time-filter is developed.

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Created

Date Created
  • 2014

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Psychophysical and neural correlates of auditory attraction and aversion

Description

This study explores the psychophysical and neural processes associated with the perception of sounds as either pleasant or aversive. The underlying psychophysical theory is based on auditory scene analysis, the

This study explores the psychophysical and neural processes associated with the perception of sounds as either pleasant or aversive. The underlying psychophysical theory is based on auditory scene analysis, the process through which listeners parse auditory signals into individual acoustic sources. The first experiment tests and confirms that a self-rated pleasantness continuum reliably exists for 20 various stimuli (r = .48). In addition, the pleasantness continuum correlated with the physical acoustic characteristics of consonance/dissonance (r = .78), which can facilitate auditory parsing processes. The second experiment uses an fMRI block design to test blood oxygen level dependent (BOLD) changes elicited by a subset of 5 exemplar stimuli chosen from Experiment 1 that are evenly distributed over the pleasantness continuum. Specifically, it tests and confirms that the pleasantness continuum produces systematic changes in brain activity for unpleasant acoustic stimuli beyond what occurs with pleasant auditory stimuli. Results revealed that the combination of two positively and two negatively valenced experimental sounds compared to one neutral baseline control elicited BOLD increases in the primary auditory cortex, specifically the bilateral superior temporal gyrus, and left dorsomedial prefrontal cortex; the latter being consistent with a frontal decision-making process common in identification tasks. The negatively-valenced stimuli yielded additional BOLD increases in the left insula, which typically indicates processing of visceral emotions. The positively-valenced stimuli did not yield any significant BOLD activation, consistent with consonant, harmonic stimuli being the prototypical acoustic pattern of auditory objects that is optimal for auditory scene analysis. Both the psychophysical findings of Experiment 1 and the neural processing findings of Experiment 2 support that consonance is an important dimension of sound that is processed in a manner that aids auditory parsing and functional representation of acoustic objects and was found to be a principal feature of pleasing auditory stimuli.

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Created

Date Created
  • 2014

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Thin film transistor control circuitry for MEMS acoustic transducers

Description

ABSTRACT This work seeks to develop a practical solution for short range ultrasonic communications and produce an integrated array of acoustic transmitters on a flexible substrate. This is done using

ABSTRACT This work seeks to develop a practical solution for short range ultrasonic communications and produce an integrated array of acoustic transmitters on a flexible substrate. This is done using flexible thin film transistor (TFT) and micro electromechanical systems (MEMS). The goal is to develop a flexible system capable of communicating in the ultrasonic frequency range at a distance of 10 - 100 meters. This requires a great deal of innovation on the part of the FDC team developing the TFT driving circuitry and the MEMS team adapting the technology for fabrication on a flexible substrate. The technologies required for this research are independently developed. The TFT development is driven primarily by research into flexible displays. The MEMS development is driving by research in biosensors and micro actuators. This project involves the integration of TFT flexible circuit capabilities with MEMS micro actuators in the novel area of flexible acoustic transmitter arrays. This thesis focuses on the design, testing and analysis of the circuit components required for this project.

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Created

Date Created
  • 2012

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Non-invasive methods to detect underground leaks

Description

Water is one of, if not the most valuable natural resource but extremely challenging to manage. According to old research in the field, many Water Distribution Systems (WDSs) around the

Water is one of, if not the most valuable natural resource but extremely challenging to manage. According to old research in the field, many Water Distribution Systems (WDSs) around the world lose above 40 percent of clean water pumped into the distribution system because of unfortune leaks before the water gets anywhere from the fresh water resources. By reducing the amount of water leaked, distribution system managers can reduce the amount of money, resources, and energy wasted on finding and repairing the leaks, and then producing and pumping water, increase system reliability and more easily satisfy present and future needs of all consumers. But having access to this information pre-amatively and sufficiently can be complex and time taking. For large companies like SRP who are moving tonnes of water from various water bodies around phoenix area, it is even more crucial to efficiently locate and characterize the leaks. And phoenix being a busy city, it is not easy to go start digging everywhere, whenever a loss in pressure is reported at the destination.

Keeping this in mind, non-invasive methods to geo-physically work on it needs attention. There is a lot of potential in this field of work to even help with environmental crisis as this helps in places where water theft is big and is conducted through leaks in the distribution system. Methods like Acoustic sensing and ground penetrating radars have shown good results, and the work done in this thesis helps us realise the limitations and extents to which they can be used in the phoenix are.

The concrete pipes used by SRP are would not be able to generate enough acoustic signals to be affectively picked up by a hydrophone at the opening, so the GPR would be helpful in finding the initial location of the leak, as the water around the leak would make the sand wet and hence show a clear difference on the GPR. After that the frequency spectrum can be checked around that point which would show difference from another where we know a leak is not present.

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Created

Date Created
  • 2019

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Language in Trauma: A Pilot Study of Pause Frequency as a Predictor of Cognitive Change Due to Post Traumatic Stress Disorder

Description

With the rise of Posttraumatic Stress Disorder (PTSD) among adults in the United States, understanding the processes of trauma, trauma related disorders, and the long-term impact of living with them

With the rise of Posttraumatic Stress Disorder (PTSD) among adults in the United States, understanding the processes of trauma, trauma related disorders, and the long-term impact of living with them is an area of continued focus for researchers. This is especially a concern in the case of current and former military service members (veterans), whose work activities and deployment cycles place them at an increased risk of exposure to trauma-inducing experiences but who have a low rate of self-referral to healthcare professionals. There is thus an urgent need for developing procedures for early diagnosis and treatment. The present study examines how the tools and findings of the field of linguistics may contribute to the field of trauma research. Previous research has shown that cognition and language production are closely linked. This study focuses on the role of prosody in PTSD and pilots a procedure for the data collection and analysis. Data consist of monologic talk from a sample of student-veterans and analyzed with speech software (Praat) for pauses greater than 250 milliseconds per 100 words. The pause frequency was compared to a PCL-5 score, an assessment used to check for PTSD symptoms and evaluate need for further assessment and possible diagnosis of PTSD. This pilot study found the methods successfully elicited data that could be used to measure and test the research questions. Although the findings of the study were inconclusive due to limitations of the participant pool, it found that the research model proved effect as a model for future linguistic research on trauma.

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Created

Date Created
  • 2020