Acoustic Waves Generated By Parametric Array Loudspeakers
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Acoustic Waves Generated By Parametric Array Loudspeakers
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Author : Jiaxin Zhong
language : en
Publisher: CRC Press
Release Date : 2024-08-13
Acoustic Waves Generated By Parametric Array Loudspeakers written by Jiaxin Zhong and has been published by CRC Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2024-08-13 with Technology & Engineering categories.
Parametric array loudspeakers (PALs) are capable of generating highly directional audio beams from nonlinear interactions of intense airborne ultrasound waves. This unique capability holds great potential in audio engineering. This book systematically introduces the physical principles of acoustics waves generated by PALs, along with the commonly used and the state-of-the-art numerical models, such as the Westervelt model, the convolution directivity model, the Gaussian beam expansion method, and the spherical wave expansion method. The properties of sound fields generated by PALs are analyzed. Also analyzed are various phenomena including the reflection of acoustics waves generated by PALs from a surface, transmission through a thin partition, scattering by a rigid sphere, and propagation in rooms. Furthermore, the steering and focusing of acoustics waves generated by PALs and potential applications of PALs in active sound control are investigated. Finally, the implementation issues of hardware, signal processing techniques, measurement, and safety are discussed. The book is tailored to meet the needs of researchers in this field, as well as audio practitioners and acoustics engineers.
Acoustic Waves Generated By Parametric Array Loudspeakers
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Author : Jiaxin Zhong (Acoustical engineer)
language : en
Publisher:
Release Date : 2024
Acoustic Waves Generated By Parametric Array Loudspeakers written by Jiaxin Zhong (Acoustical engineer) and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2024 with Acoustical engineering categories.
"Parametric array loudspeakers (PALs) are capable of generating highly directional audio beams from nonlinear interactions of intense airborne ultrasound waves. This unique capability holds great potential in audio engineering. This book systematically introduces the physical principles of acoustics waves generated by PALs, along with the commonly used and the state-of-the-art numerical models, such as the Westervelt model, the convolution directivity model, the Gaussian beam expansion method, and the spherical wave expansion method. The book is tailored to meet the needs of researchers in this field, as well as audio practitioners and acoustics engineers"--
Sound From Ultrasound
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Author : Frank Joseph Pompei
language : en
Publisher:
Release Date : 2002
Sound From Ultrasound written by Frank Joseph Pompei and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2002 with categories.
A parametric array exploits the nonlinearity of the propagation medium to emit or detect acoustic waves in a spatially versatile manner, permitting concise, narrow directivity patterns otherwise possible only with physically very large transducer geometries. This thesis explores the use of the parametric array as an audible sound source, permitting audible sound to be generated with very high directivity compared to traditional loudspeakers of comparable size. The thesis begins with a review of basic underlying mathematics and relevant approximate solutions of nonlinear acoustic systems. Then, these solutions are used to construct suitable methods of ultrasonic synthesis for low-distortion audio reproduction. Geometrical modelling methods for predicting the acoustic distribution are presented and evaluated, and practical applications are explored experimentally. Issues of risk associated with ultrasonic exposure are presented, and the feasibility of a phased-array system for beam control is explored.
Sound Propagation Via Narrow Beam Audio Projection
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Author : Felipe Andres Farias Alvarez
language : en
Publisher:
Release Date : 2018
Sound Propagation Via Narrow Beam Audio Projection written by Felipe Andres Farias Alvarez and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018 with Electro-acoustics categories.
The parametric acoustic array is a nonlinear phenomenon of physics theoretically described over fifty years ago. It consists in the generation of secondary sound waves by the propagation of two collimated primary ultrasonic waves at a close frequency. The sound wave generated corresponds to the difference of the frequencies propagated and its existence is independent from the ultrasonic waves, but it maintains the high directivity of the primary waves. According to Berktay's far-field solution, one of the main equations describing this phenomenon, the sound wave produced is proportional to the second derivative of the envelope of the original ultrasonic wave. Hence, the implementation of the parametric acoustic array is based on the modulation of signals to be transmitted as ultrasound, but demodulated in the propagation medium. Due to the nonlinear nature of the phenomenon and the use of modulation techniques in the implementation of the parametric acoustic array, harmonic distortion is generated. Moreover, the models describing the parametric acoustic array are based on many approximations so the results from the equations are inaccurate in many cases. Despite Westervelt introduced the theory over five decades ago, the research on parametric acoustic arrays presents many challenges in the present day. The majority of the efforts for increasing the quality of the demodulated signal have been focused on improving the modulation stage of the parametric acoustic array based on Berktay's solution. Furthermore, recent advances in the field of parametric acoustic arrays have demonstrated the frequency response of transducers has a big impact on the generation of secondary sound waves. This thesis aims to provide a model capable of improving the representation of the parametric acoustic array. For this reason, simulations using the KZK Texas code, a time-domain algorithm which calculates the Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation, were carried out to replicate the parametric acoustic array in air. These results establish how the diffraction term of the KZK equation impacts on the generation of the secondary sound waves. As a result, a Burgers like equation was used instead of the KZK equation, decreasing the computation time significantly. In addition, parametric loudspeakers were simulated using k-Wave, a toolbox capable of computing linear and nonlinear propagation of acoustic waves. The results show the effects of Rayleigh distance and absorption length on the demodulated waves. Increasing the Rayleigh distance beyond the absorption length was proposed to obtain a demodulated wave 10 dB higher in the far-field, if compared to the cases where this condition is not met. Finally, an electroacoustic model describing the frequency response of the transducer generating the parametric acoustic array was developed in order to include it into the far-field solution. This model is based on a Van Dyke equivalent circuit capable of representing the frequency response of the array of piezoelectric transducers. The transfer function of the circuit was applied as a filter for the original signal and as per the definition of the far-field solution, the elements of the circuit become part of the demodulated wave. The model and the method used are based on mathematical development, simulations and experimental validation.
A Theoretical And Experimental Investigation Of The Parametric Acoustic Receiving Array
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Author : James Joseph Truchard
language : en
Publisher:
Release Date : 1974
A Theoretical And Experimental Investigation Of The Parametric Acoustic Receiving Array written by James Joseph Truchard and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1974 with Electro-acoustics categories.
The parametric reception of a low frequency plane wave by the use of nonlinear interactions between acoustic waves is examined both theoretically and experimentally. The parametric reception of a low frequency wave is accomplished by the use of a high frequency acoustic pump wave which interacts with the low frequency signal wave to produce sound waves at the sum and difference frequencies. These sound waves are received by a second transducer placed on the axis of the pump transducer. This type of parametric array allows for the possibility of narrowbeam detection of a low frequency acoustic signal wave. The interaction of two plane waves is examined theoretically in a manner similar to that considered by Westervelt. Of particular interest is the case in which the pump wave is assumed to be a plane wave originating at and propagating perpendicular to some planar boundary. The low frequency signal wave is assumed to be present over all space. The interaction of two plane waves is of interest for two reasons: (l) This interaction produces a truncated end-fire array (i.e., the parametric receiving array) with a length equal to the spacing between the planar boundary and the observer, and (2) this interaction relates directly to the problem of sound scattered by sound as formulated by Westervelt. Next, the solution for the interaction of a high frequency spherical wave from a point source and a low frequency plane wave is obtained theoretically using a two-dimensional stationary phase solution of Westervelt's scattering integral. The point source solution is in turn used to generate the solution for parametric receiving arrays with various pump transducers including a truncated line source transducer, a rectangular piston transducer, and a circular piston transducer. In each case, the observer is assumed to be in the farfield of the pump transducer. However, the result includes the effects of interaction in the nearfield of the pump transducer. The solution of the parametric receiving array with a point source pump and a truncated line receiver is also found. The theoretical solutions also include the effects of misalignment of either the pump or receiving transducer. With either the pump transducer or the receiver misaligned, the difference frequency beam pattern is an asymetrical beam pattern and is the mirror image of the sum frequency beam pattern. This property is examined in detail in terms of the problem of two sound waves interacting at nonzero angles. A series of experiments were conducted with a 48 ft parametric receiving array with a pump frequency of 90 kHz. In the experiments, an omnidirectional transducer was used with either a rectangular piston transducer or a square piston transducer. Each transducer could be used as either the pump transducer or the receiver so that a variety of parametric receiving array configurations could be realized. A small rotator was used to allow independent rotation of the piston transducer for measurement of the effects of misalignment of the piston transducer. Theoretical and experimental results are compared for the parametric receiving array with several transducer arrangements. The agreement between the theory and the experiment was excellent.
Intelligent Robotics And Applications
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Author : Xin-Jun Liu
language : en
Publisher: Springer Nature
Release Date : 2021-10-19
Intelligent Robotics And Applications written by Xin-Jun Liu and has been published by Springer Nature this book supported file pdf, txt, epub, kindle and other format this book has been release on 2021-10-19 with Computers categories.
The 4-volume set LNAI 13013 – 13016 constitutes the proceedings of the 14th International Conference on Intelligent Robotics and Applications, ICIRA 2021, which took place in Yantai, China, during October 22-25, 2021. The 299 papers included in these proceedings were carefully reviewed and selected from 386 submissions. They were organized in topical sections as follows: Robotics dexterous manipulation; sensors, actuators, and controllers for soft and hybrid robots; cable-driven parallel robot; human-centered wearable robotics; hybrid system modeling and human-machine interface; robot manipulation skills learning; micro_nano materials, devices, and systems for biomedical applications; actuating, sensing, control, and instrumentation for ultra-precision engineering; human-robot collaboration; robotic machining; medical robot; machine intelligence for human motion analytics; human-robot interaction for service robots; novel mechanisms, robots and applications; space robot and on-orbit service; neural learning enhanced motion planning and control for human robot interaction; medical engineering.
Characteristics And Use Of A Parametric End Fired Array For Acoustics In Air
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Author :
language : en
Publisher:
Release Date : 2007
Characteristics And Use Of A Parametric End Fired Array For Acoustics In Air written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007 with categories.
The parametric array exploits two highly collimated ultrasound beams interacting in a given volume producing a single beam with very high directivity and almost no side lobes. The high directivity of the difference frequency signal of the parametric array is due to the interaction of the waves in the volume effectively producing a virtual end fired array boosting pressure levels along the interaction region which is limited by the absorption coefficient. This thesis focuses on experiments conducted in an anechoic room using AS-18-B Audio Spotlight system from Holosonic(TradeMark). Furthermore, nonlinear theory was modeled by a linear discrete array. The beam pattern of the parametric loudspeaker, range dependence of primary and secondary signals and total harmonic distortion (THD) were measured and then compared to theory. Experimental data for the beam pattern of the parametric loudspeaker agreed with the theory. It was all shown that the parametric array had a very narrow beam width and almost no side lobes as opposed to conventional loudspeakers. Both primary waves and difference wave frequency signals were examined for their range dependence. Due to the complicated interference of the primary waves, it was impossible to compare experimental results with theoretical predictions. For the difference wave signals, experimental data was verified by theory, which was modified in order to accommodate both wave generation and spreading region. Finally, THD of the parametric loudspeaker was measured for different amplitude modulation depths. Experimental results showed that preprocessing should be applied in order to decrease THD and achieve clean audio signal reproduction.
Scientific And Technical Aerospace Reports
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Author :
language : en
Publisher:
Release Date : 1992
Scientific And Technical Aerospace Reports written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1992 with Aeronautics categories.
An Analysis Of The Parametric Acoustic Array For Spherical Wave Fields
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Author : Thomas Gustave Muir
language : en
Publisher:
Release Date : 1971
An Analysis Of The Parametric Acoustic Array For Spherical Wave Fields written by Thomas Gustave Muir and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1971 with Acoustical engineering categories.
The nonlinear interaction of two collinear acoustic waves to produce a modulation product in the lower sideband is examined both theoretically and experimentally. The modulation takes place in a portion of the medium specified by the beamwidth and the absorption of the primary radiations. The difference-frequency sound so created has significance in engineering applications because of the high directivity it derives from the great length of the zone of interaction. In this sense, the phenomenon may be thought of as a parametric, end-fired acoustic array. The theoretical approach of Westervelt is adapted to obtain solutions for the interacting fields composed to beams of monochromatic spherical waves emitted by circular piston projectors. The analysis is accomplished by an asymptotic method that is valid at long ranges from the interaction volume and by a more exact method involving a numerical integration that is valid in the farfield of the electroacoustic source. Beam pattern and sound propagation data resulting from several experiments conducted in a fresh water lake are presented to demonstrate the validity of the numerical solution. (Author).
Active Control Of Noise And Vibration
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Author : Colin Hansen
language : en
Publisher: CRC Press
Release Date : 2012-11-02
Active Control Of Noise And Vibration written by Colin Hansen and has been published by CRC Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012-11-02 with Technology & Engineering categories.
Integrating active control of both sound and vibration, this comprehensive two-volume set combines coverage of fundamental principles with the most recent theoretical and practical developments. The authors explain how to design and implement successful active control systems in practice and detail the pitfalls one must avoid to ensure a reliable and stable system. Extensively revised, updated, and expanded throughout, the second edition reflects the advances that have been made in algorithms, DSP hardware, and applications since the publication of the first edition.