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This book presents all aspects of situational awareness in a battlefield using acoustic signals. It starts by presenting the science behind understanding and interpretation of sound signals. The book then goes on to provide various signal processing techniques used in acoustics to find the direction of sound source, localize gunfire, track vehicles, and detect people. The necessary mathematical background and various classification and fusion techniques are presented. The book contains majority of the things one would need to process acoustic signals for all aspects of situational awareness in one location. The book also presents array theory, which is pivotal in finding the direction of arrival of acoustic signals. In addition, the book presents techniques to fuse the information from multiple homogeneous/heterogeneous sensors for better detection. MATLAB code is provided for majority of the real application, which is a valuable resource in not only understanding the theory but readers, can also use the code as a spring-board to develop their own application based software code. · Shows how acoustic signal processing can aid in situational awareness, intelligence, surveillance and reconnaissance (ISR) · Presents background on the type of microphone arrays one has to use and the techniques used to find the direction of sound source · Focuses on direction finding, transient event (such as gunfire) detection and localization, tracking targets and personnel detection · Provides multi-sensor data fusion techniques to achieve higher probability of detection with fewer false alarms and higher confidence.

This book presents all aspects of situational awareness using acoustic signals. It starts by presenting the science behind understanding and interpretation of sound signals. The book then goes on to provide various signal processing techniques used in acoustics to find the direction of sound source, localize gunfire, track vehicles and detect people. The necessary mathematical background and various classification and fusion techniques are presented. The book contains majority of the things one would need to process acoustic signals for all aspects of situational awareness in one location. The book also presents array theory, which is pivotal in finding the direction of arrival of acoustic signals. In addition, the book presents techniques to fuse the information from multiple homogeneous/heterogeneous sensors for better detection. MATLAB code is provided for majority of the real application, which is a valuable resource in not only understanding the theory but readers can also use the code as a spring-board to develop their own application based software code. Thyagaraju Damarla works at the U.S. Army Research Laboratory.

Trees can reduce noise by sound reflection and absorption and this is the first book bringing together the widely scattered literature on noise abatement by urban trees. The book will interest those concerned with environmental management, noise control, and urban forestry. It is an invaluable source of information for environmental managers, foresters, acousticians, engineers, architects, scientists, and students.

Previous themes of most scientific conferences, as well as publications addressing issues of noise have focused on SPL intervals: of danger (80-130 dB) and to a lesser extent of annoyance (45-80 dB). In the last two years, there have been a series of studies on to the range of acoustic comfort (20-45 dB). The paper discusses the importance of this range in several approaches (physical, metrological, legal). It also presents selected issues on very low sound pressure levels (below 20 dB).

Der Band faßt die Beiträge des 4. Symposiums der Psychologischen Akustik zusammen. Schwerpunkte der Diskussion sind die Lautwahrnehmung, die Lärmwirkungen, die geschlechtsspezifischen Aspekte der Lautwahrnehmung sowie die kulturellen Unterschiede bei der Lautbewertung. Die Oldenburger Symposien verstehen die psychologische Akustik in der Tradition von Hermann von Helmholtz und setzen folgenden Rahmen für die Forschung fest: a) die Verbindung von physischen, physiologischen und psychologischen Fakten ; b) die menschliche Stimme und ihre Lautstärke bei dem Sprachverständnis und den Testmethoden ; c) der Laut in Verbindung mit Umständen und Faktoren der Umwelt d) die transkulturelle Diskussion der Akustik e) die Lärmbekämpfung unter Berücksichtigung der Persönlichkeit derjenigen, die Lärm verursachen.

This paper investigates a way of determining and modeling uncertainty contributions in measurements of room acoustic parameters, which are commonly used to describe the acoustic situation of a room in an objective manner. If the range of uncertainty and the confidence interval are not given, the results remain incomparable to other measurement teams, since modern PC-based measurements still show appreciable sources of measurement errors. The Guide to the Expression of Uncertainty in Measurement (GUM) defines a unified guideline for determining uncertainties in all fields of measurement. Its application is increasingly required by modern measurement standards. However, the GUM procedures have not been applied to room acoustics yet. Hence, a scalable linear approach for calculating the combined uncertainty of room acoustic parameters with regard to the input quantities is proposed. In-situ measurement results of specially designed experiments show the significance of the main influence factors and are used to build the uncertainty budget.

Increasing awareness of the issues of climate change and sustainable energy use has led to growing levels of interest in small-scale, decentralised power generation. Small-scale wind power has seen significant growth in the last ten years, partly due to the political support for renewable energy and the introduction of Feed In Tariffs, which pay home owners for generating their own electricity. Due to their ability to respond quickly to changing wind conditions, small-scale vertical axis wind turbines (VAWTs) have been proposed as an efficient solution for deployment in built up areas, where the wind is more gusty in nature. If VAWTs are erected in built up areas they will be inherently close to people; consequently, public acceptance of the turbines is essential. One common obstacle to the installation of wind turbines is noise annoyance, so it is important to make the VAWT rotors as quiet as possible. To date, very little work has been undertaken to investigate the sources of noise on VAWTs. The primary aim of this study was therefore to gather experimental data of the noise from various VAWT rotor configurations, for a range of operating conditions. Experimental measurements were carried out using the phased acoustic array in the closed section Markham wind tunnel at Cambridge University Engineering Department. Beamforming was used in conjunction with analysis of the measured sound spectra in order to locate and identify the noise sources on the VAWT rotors. Initial comparisons of the spectra from the model rotor and a full-scale rotor showed good qualitative agreement, suggesting that the conclusions from the experiments would be transferable to real VAWT rotors. One clear feature observed in both sets of spectra was a broadband peak around 1-2kHz, which spectral scaling methods demonstrated was due to laminar boundary layer tonal noise. Application of boundary layer trips to the inner surfaces of the blades on the model rotor was found to eliminate this noise source, and reduced the amplitude of the spectra by up to 10dB in the region of the broadband peak. This method could easily be applied to a full-scale rotor and should result in measurable noise reductions. At low tip speed ratios (TSR) the blades on a VAWT experience dynamic stall and it was found that this led to significant noise radiation from the upstream half of the rotor. As the TSR was increased the dominant source was seen to move to the downstream half of the rotor; this noise was thought to be due to the interaction of the blades in the downstream half of the rotor with the wake from the blades in the upstream half. It was suggested that blade wake interaction is the dominant noise source in the typical range of peak performance for the full-scale QR5 rotor. Different solidity rotors were investigated by using 2-, 3- and 4-bladed rotors and it was found that increasing the solidity had a similar effect to increasing the TSR. This is due to the fact that the induction factor, which governs the deflection of the flow through the rotor, is a function of both the rotor solidity and the TSR. With a large body of experimental data for validation, it was possible to investigate computational noise prediction methods. A harmonic model was developed that aimed to predict the sound radiated by periodic fluctuations in the blade loads. This model was shown to agree with similar models derived by other authors, but to make accurate predictions very high resolution input data was required. Since such high resolution blade loading data is unlikely to be available, and due to the dominance of stochastic sources, the harmonic model was not an especially useful predictive tool. However, it was used to investigate the importance of the near-field components of the sound radiated by the wind tunnel model to the acoustic array. It was shown that the near-field terms were significant over a wide range of frequencies, and the total spectrum was always greater than that of the far-field component. This implied that the noise levels measured by the acoustic array represented an upper bound on the sound radiated to the far-field, and hence that the latter would also be dominated by stochastic components. An alternative application of the harmonic model, which attempted to determine the blade loading harmonics from the harmonics in the sound field was proposed. This inversion method utilised a novel convex optimisation technique that was found to generate good solutions in the simulated test cases, even in the presence of significant random noise. The method was found to be insensitive at low frequencies, which made it ineffective for inverting the real microphone data, although this was shown to be at least partly due to the limitations imposed by the array size. In addition to the harmonic models, an empirical noise prediction method using the spectral scaling laws derived by \citet*{Brooks_1989} was trialled, and was found to be capable of making predictions that were in agreement with the measured data. The model was shown to be sensitive to the exact choice of turbulence parameters used and was also found to require good quality aerodynamic data to make accurate noise predictions. If such data were available however, it is expected that this empirical model would be able to make useful predictions of the noise radiated by a VAWT rotor. ; This work was supported by the Engineering and Physical Sciences Research Council and Quiet Revolution Ltd.

Tuneable phononic crystals and topological acoustics
Sourav Banerjee, Professor from the University of South Carolina, navigates the field of tuneable phononic crystals and topological acoustics. Acoustics, an age-old field of study, has recently revealed new physics with new degrees of freedom of wave propagation. These new findings are invaluable for information processing using acoustic modality. Information processing using acoustics is called acoustic computing. Computing Boolean algebra, which has already been demonstrated, could pave the pathways even for quantum computing using acoustics. Not in the very distant future, the recently discovered quantum and topological behavior of acoustics could be an integral part of computing modalities.

This paper presents the Portuguese policy to assess the overall acoustic quality of residential buildings, in order to issue the corresponding permission for use and trade them within the urban market. The Portuguese policy rely on the legal frame set forth by the national Building Acoustics code, which imposes the existence of an acoustic project for each new building, covering the sound insulation in terms of airborne and impact noise, and requirements for service equipment noise and reverberation times. The assessment is done by testing after the construction has been completed and when all the service equipment is installed and operating accordingly. The tests have to be done by accredited laboratories. In order to avoid testing all possibilities in terms of partitions, service equipment, volumes and surfaces, a simplified sampling is adopted. ; 1 ; 1 ; 5p ; DED/NAICI ; 2012 ; 20 a 22 de agosto