| 摘要 |
PROBLEM TO BE SOLVED: To provide a small-sized speech apparatus capable of improving the sound quality of a voice band and efficiency by suppressing a standing wave in the voice band generated in a rear air chamber. SOLUTION: The speech apparatus comprises a housing A1 of a speech module MJ, a speaker SP attached to the housing A1 for outputting voice information from one surface side to the outside of the housing A1, a rear air chamber Br formed on the other surface side of the speaker SP inside the housing A1, and a sound tube 40 formed in a hollow shape having an open end at its one end and a closed end at the other end and communicated with the inside of the rear air chamber through the opening. Respective surfaces surrounding the rear air chamber Br are formed such that a distance between the surfaces facing each other is equal to or shorter than 50 mm, and the sound tube 40 is set to a length based on the odd number multiple of 1/4 wavelength of a frequency between the first lowest resonance frequency of the speaker SP equivalent to the case of being attached to a baffle plate having the infinite size and the second lowest resonance frequency of the speaker SP attached to the housing A1 not provided with the sound tube 40. COPYRIGHT: (C)2009,JPO&INPIT
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