| 摘要 |
A radiotelephone having an acoustical wave guide for channeling and directing sound energy into a microphone forming a part of the radiotelephone. The wave guide includes an elongated tube structure that varies in cross-sectional area from an inlet end to an outlet end thereof. More particularly, the wave guide is formed by a wall structure that includes portions that assume a wave configuration. This wave configuration gives rise to the varying cross-sectional area that is repeatedly found between the inlet and outlet end portions of the wave guide. This wave type configuration for the wave guide forms an acoustical low-pass filter that propagates and transmits non-resonant low frequencies in the range of 300 Hz to 3,000 Hz. |
