Loudspeakers and Microphones
Since the 1990s, distributed mode loudspeaker (DML) has been widely researched and developed. The DML can provide wideband-characteristics and wide directivity in spite of a single diaphragm by using bending waves based vibration on the plate for acoustic radiation. This property is significantly different from traditional loudspeakers. However, the DML has structural problems (e.g., maximum dimension becomes large), because it uses a two-dimensionally spread flat plate. In this paper, we examine the characteristics of shell-structured loudspeakers whose diaphragm is formed with an arbitrary curvature, and compare them with conventional DML. Our results strongly suggest that the problems of the DML using a flat plate can be improved by employing a shell structure for the diaphragm.