| 摘要 |
A radiotelephone having a wave guide for channeling sound energy from a speaker to the ear of a person utilizing the radiotelephone. The wave guide is disposed adjacent the speaker and acts to direct sound energy from the speaker to the vicinity of a person's ear. The wave guide comprises an elongated wall structure having inlet and outlet end portions and a varying cross-sectional area that varies in a uniform and repeating manner between maximum and minimum values. This elongated wave guide with its varying cross-sectional areas forms an acoustical low-pass filter that efficiently transmits and propagates low frequencies, that is frequencies in the range of 300 Hz to 3,000 Hz. |
