| 摘要 |
PROBLEM TO BE SOLVED: To obtain a loudspeaker for a bus stop which prevents sound from spreading to the surrounding area and can simultaneously broadcast a plurality of types of sound. SOLUTION: This loudspeaker for a bus stop is provided with modulators 22 for modulating a carrier, belonging to an ultrasonic wave band by an audible sound signal, parametric speakers 10 for emitting modulated signals from the modulators 22 as a super-directivity sound wave to transfer an audible sound via the super-directivity sound wave, human detection sensors 11 for sensing that a person enters an audible area 30 where the audible sound from the parametric speakers 10 is audible, and a sound control part 21 for storing a plurality of pieces of sound guide data, and selecting the sound guide data, corresponding to a signal indicating that a person has entered the audible area, to convert the sound guide data into an audible sound signal, supplying the audible sound signal to the modulators 22, when the signal is received from the human detection sensors. COPYRIGHT: (C)2006,JPO&NCIPI |
