| 摘要 |
PROBLEM TO BE SOLVED: To provide high voice sensitivity and to eliminate noise by providing four ports on a gradient plane, arranging the adjacent different two pairs of the ports on an outer side in the direction of the lips of a speaker and bringing the ports on an inner side closer to the lips of the speaker at all times. SOLUTION: For the two each of outer side ports 102 and 103 and inner side ports 104 and 105 to which the sound advances at the bottom surface 101 of a handset 100, the respective outer side port pairs of 102 and 103 and outer port pairs of 104 and 105 form dipoles. Since the axis of each dipole is passed through the center of the port and the respective ports are arranged by a colinear form, a polarity directional pattern is turned to a pattern in the shape of the figure 8. The voice reaching the respective dipoles from a speaker lip position T is made incident at the angle 6 of about 28 degrees and the peak of the polarity directional pattern in the shape of the figure 8 is attained nearδ=0 relatively. Thus, the output sensitivity of a broad side SOG microphone becomes close to optimum output sensitivity, the high voice sensitivity is obtained and the noise is eliminated.
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