THEORETICAL ANALYSIS OF PERFORMANCE OF AN AIR-MODULATED SPEAKER

A theory is developed that predicts the performance of the air modulated speaker by assuming that the pneumatic energy is converted to acoustic energy by a mixing process similar to that which takes place in the jet pump. To derive these relationships, it is necessary to assume, for certain portions of the flow that the effect of the nonsteady terms is negligible. Owing to the high intensity of the sound waves generated, it is not possible to use the usual small disturbance approximations normally employed in acoustic problems. The nature of the assumptions used requires that the results be limited to a frequency range that is above the rolloff frequency of the horn and below 100 500 Hz, depending on the slot geometry. The analytical results agree well with the available experimental data both for sound pressure level and efficiency; they should thus be useful for design purposes. © 1969, Acoustical Society of America. All rights reserved.