. Elements of acoustical engineering. Electro-acoustics; Sound. NONLINEAR DISTORTION 159 A = projected area of the air chamber upon the diaphragm, in square centimeters, d! = distance between the diaphragm and front boundary of the air chamber in the absence of motion, in centimeters, and X = displacement of the diaphragm, in centimeters. The equivalent circuit of the mechanical system shows the effect of the nonlinear element upon the sound power output. In the case of a single frequency the distortion which this element introduces is small, because for constant sound power output the amplitu
. Elements of acoustical engineering. Electro-acoustics; Sound. NONLINEAR DISTORTION 159 A = projected area of the air chamber upon the diaphragm, in square centimeters, d! = distance between the diaphragm and front boundary of the air chamber in the absence of motion, in centimeters, and X = displacement of the diaphragm, in centimeters. The equivalent circuit of the mechanical system shows the effect of the nonlinear element upon the sound power output. In the case of a single frequency the distortion which this element introduces is small, because for constant sound power output the amplitude of the diaphragm is inversely proportional to the frequency. At low frequencies where the amplitude Iâ1SW- ll EQUIVALENT CIRCUIT DIAPHRAGM. ELECTRIC INPUT ACOUSTIC OUTPUT LOW FREQUENCY BVVVWVWVWWVVV B'WVWVAAAAAAAAAA; HIGH FREQUENCY â ai OUTPUT VOICE COIL LEADS' COMBINATION HIGH AND LOW FREQUENCY FIELD COIL ^VOICE COIL CROSS-SECTIONAL VIEW Fig. A mechanism with an air chamber coupling the diaphragm to the horn. The variation in volume of the air chamber introduces a nonhnear element in the form of the acoustic capacitance Cai- The equivalent electrical circuit indicates the effect of the non- hnear element upon the system. The wave shapes of the electrical input and the acoustical output for a low, high, and a combination of a high and a low frequency illustrates the effect of the nonlinear element upon the acoustical output. of the diaphragm may be so large that the volume of the air chamber becomes alternately zero and two times the normal volume, the acoustic reactance of the acoustic capacitance is very small compared to the acoustic resistance of the horn. See Fig. At the high frequencies where the acoustic reactance of the acoustic capacitance is comparable to the acoustic resistance, the amplitude of the diaphragm for the same output is so small that the variation in acoustic capacitance may be neglected. See Fig. However, the conditions are different
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