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the branch of applied acoustics that comprises the theory, design methods, and construction of electroacoustic transducers. It often includes the theory and design methods of electromechanical transducers (such as acoustic pickups, recorders, vibration meters, electromechanical filters and transformers, and the like), which are of interest in applied acoustics to the extent that they share common physical mechanisms, design methods, and construction. Electroacoustics is also closely associated with many other branches of applied acoustics inasmuch as electroacoustic transducers may be used in acoustic equipment (in sound broadcasting, sound recording and reproduction, ultrasonic flaw detection and technology, hydroacous-tics, acoustical holography, and other fields) as well as experimental studies (for example, in architectural and building acoustics, medicine, geology, oceanography, seismic exploration, and noise measurement).
The principal task of electroacoustics is to establish relationships between signals at the input and output of a transducer and to find conditions under which conversion can be achieved most efficiently or with minimum distortion.
Electroacoustics became established as an independent branch of applied acoustics during the first half of the 20th century, with the large-scale use of electroacoustic transducers and their gradual application in newer fields of science and technology. The first works on design methods of electroacoustic transducers date from the late 19th and early 20th centuries and were associated with the development of telephony and studies on the vibration of piezoelectric and magnetostriction resonators. An important technological advance in the field was the creation of the methods of electroacoustical analogies and equivalent circuits. Another important step in design theory was the subsequent use of the methods of electromechanical multiterminal networks and equivalent circuits for systems with distributed constants, where the vibration amplitudes are intrinsically a function of their coordinates, as in wave guides and lines of great electrical length.
Important contributions to the development of electroacoustics have been made by the American scientists P. M. Morse and L. L. Foldy (general theory of electromechanical transducers with distributed couplings), H. F. Olson (theory of electromechanical analogies and equivalent circuits), and W. P. Mason (design of piezoelectric transducers and filters) and the Soviet scientists N. N. Andreev and L. Ia. Gutin (who laid the foundations of modern design methods of piezoelectric and magnetostriction transducers), V. V. Furduev (who established various types of relationships based on the reciprocity theorem in electromechanical systems), and A. A. Kharkevich (who developed and systematized the general theory of electroacoustic transducers).
REFERENCESGutin, L. la. “Magnitostriktsionnye izluchateli i priemniki.” Zhurnal tekhnicheskoi fiziki, 1945, vol. 15, issue 12.
Gutin, L. Ia. “P’ezoelektricheskie izluchateli i priemniki.” Ibid., 1946, vol. 16, issue 1.
Furduev, V. V. Elektroakustika. Moscow-Leningrad, 1948.
Kharkevich, A. A. Teoriia preobrazovatelei. Moscow-Leningrad, 1948.
Fizicheskaia akustika. Edited by W. P. Mason. Moscow, 1966. (Translated from English.)
Skudrzyk, E. Osnovy akustiki, vols. 1–2. Moscow, 1976. (Translated from English.)
|Electrical quantities||Mechanical quantities||Acoustical quantities|
|First system||Second system|
|Note: S is area, p is the density of the medium, c is the speed of sound In the medium, and V is volume|
|Voltage (emf) U||Force F||Velocity v||Sound pressure p|
|Current i||Velocity v||Force F||Volume velocity Sv|
|Inductance L||Mass m||Compliance CM||Acoustic mass m = ρl/S|
|Capacitance C||Compliance CM||Mass m||Acoustic compliance CA = V/ρc2|
|Resistance R||Mechanical resistance rM||Effective mechanical conductance l/rM||Acoustic resistance rA|