| 摘要 |
An electrodynamic transducer (1) comprises a diaphragm with a central part (2) and a peripheral part (3) and a voice-coil device (9, 10) coupled to the central part (2). The diaphragm (2, 3) cooperates with an enclosed volume (6), the enclosed volume being such that <IMAGE> where fo and fo' are the anti-resonance frequencies of a transducer respectively with or without the enclosed volume behind the diaphragm. These frequencies each correspond to a local minimum situated between two maxima (f1 and f1' respectively, and f2 and f2' respectively) in the input impedance curves Z1 in the case of a transducer with the enclosed volume and in the case of a transducer without the enclosed volume. The maxima correspond to the two resonance frequencies for which the central part of the peripheral part move in phase and in phase opposition relative to one another, and S1 and S2 are the surface areas of the central part and the peripheral part, respectively, where S2/S1>/=2.
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