A driver circuit for a piezoelectric speaker is described, wherein charge is transferred from a charge reservoir to the speaker. The crossline generator comprises a support body pendulously supported and having ear portions and a paddle. In response to the determination, the controller determines a time period since a most recent search of neighbor cells was performed. Due to pin limitations that may be caused by large buses, e. Hence, even in a situation in which an operator necessarily tightly presses hisher face against a front surface of a chassis, the voice transmission path is ensured to a certain extent, and thus the sound collecting property is ensured to some degree or more.