| From 1881 until the present day, many excellent scholars have studied acoustic horns. This dissertation begins by discussing over eighty results of such study. Next, the methods of modeling horn behavior are examined with an emphasis on the prediction of throat impedance. Because of the time constraints in a product-design environment, in which the results of this study may be used, boundary-element and cascaded-section types of analysis were not considered due to their time intensiveness. Of the methods studied, an analytical process based upon Olson's adaptation of Webster's analysis is selected as the most accurate of the rapid methods, although other good methods exist. Reasons and extent of inaccuracy are discussed. The concept of interleaved horn loading is introduced: it involves using two horns of different parameters, fed by a single driver, with a view toward interleaving and thus smoothing the impedance peaks of the separate horns to produce a smoother response. The validity of the technique is demonstrated both theoretically and practically. Then the reactance annulling technique is explained and tested experimentally. It is found to work well, but the exact parameter values involved are not found to be critical. Finally, the considerations involved in building a practical working system are discussed, and a preliminary working model reviewed. Future work could be directed toward finding the optimum parameter values for the two "parallel horns" whose impedances are to be interleaved, as well as the system parameters that determine these optimum values. Also, further experimental investigation or ported loading of the back air chamber would be useful. |
