1980 年 36 巻 7 号 p. 366-373
The changes in the normal modes and the displacements due to forced vibration of the conical cone and the convex cone, resulting from the voice coil and the outer surround, are calculated by the finite element method. And the sound pressure response is calculated using the displacements. The displacement and the area between the innermost nodal circle and the next outer nodal circle of the cone mainly contribute to the formation of the sound pressure peaks. Attachment of the voice coil and the surround cause the shift to the nodal circles. An inward shift is resulted from the voice coil, and an outward shift is resulted from the surround. These shifts cause the change of area and displacement and the change of peak sound pressure level. In the conical cone, the attachment of the voice coil causes the change of the peak sound pressure level in the normal modes, a large increase in the 1st and 2nd order, a slight change in the 3rd order, and a large decrease in the 4th and higher order. The another attachment of the surround causes the change of the peak sound pressure level, a large decrease in the 1st order, a slight increase in the 2nd order, and a slight decrease in the 3rd and higher order.