PURPOSE: To simultaneously measure sound pressure intensities at a plural points on a measuring surface, by displaying sound pressure intensity distribution wherein a receiving signal is equal to or more than the predetermined sound pressure by arranging microphones at a plurality of points on the measuring surface of a frame.
CONSTITUTION: The exposed surfaces of the ultrasonic microphones 11 of a frame 3 is directed to the front of the transmission antenna 6 of a vehicle to which an ultrasonic pulse SONAR is mounted and the output of a comparison voltage generating circuit 2 is supplied to receivers 1 while matched with a predetermined value by a variable resistor 23. The ultrasonic pulse emitted from the antenna 6 is received by the microphones 11 and inputted to the positive phase input of a comparator through an amplifier, a band filter and an amplifier. When the sound pressure of the received ultrasonic waves is larger than comparison voltage, a pulse is emitted fromthe comparator and inputted to a display device 17 through a pulse amplitude extending circuit.
AKITA SHIGEO
KODERA MASAO
