| 摘要 |
PROBLEM TO BE SOLVED: To provide an intercom device for preventing the content of conversation from being spread widely. SOLUTION: The intercom device has an outdoor microphone for enabling a visitor to input voice and an outdoor speaker for outputting voice from an indoor recipient at an outdoor side, and has an indoor microphone for enabling the recipient to input voice and an indoor speaker for outputting voice of the visitor at an indoor side. In this case, the outdoor speaker at the outdoor side is composed of an ultrasonic speaker having directivity. COPYRIGHT: (C)2007,JPO&INPIT |
