A positional relation sensing section (23) of a control section (22) senses the relative position relation between first and second cabinets (30 and 31) based on output of magnetic sensing elements (20a and 20b) and outputs a position determination signal (S3). If the state is “transition state” in which one cabinet slides and moves based on the position determination signal (S3), a voice control section (24) outputs a mute control signal (S4) to a voice processing section (11) as a muting instruction. Accordingly, all outputs of voice signals collected by a microphone (10) to a receiver (12), a loudspeaker (13), a wireless communication section (16), a short-range wireless communication section (17), and a voice output terminal (14) are stopped.