Abstract: In a land mobile radio telephone apparatus, a microphone unit for inputting speeches to be transmitted in incorporated in a plug that can be connected to a cigar lighter socket provided near a driver's seat in a vehicle, and the plug with the microphone unit built therein is connected to a radio telephone apparatus body via cables for supplying power from a power source and a cable for inputting the speech voices. A speaker unit is built in the radio telephone apparatus body. An end portion of a casing of the plug is formed into a tubular shape, and the microphone having a directivity is incorporated in the tubular end portion in such a manner that it can be semi-fixed. Directivity of the microphone is thus directed toward the driver. The microphone unit has a directivity adjusting mechanism, and is supported by supporting member having a vibration-proof effect.

Abstract: A voice transducer used for telecommunication by a telephone installed in a motor vehicle or the like, including: a main body having a side surface to be contacted with an operator's head so as to detect vibrations of produced voice waves when they are transmitted through the skull of the head, and convert them into electric signals; a holder member of the main body; and a connecting member which connects the main body to the holder member in such a manner that the position of the side surface of the main body with respect to the operator's head can be adjusted. The main body includes a piezoelectric transducer to detect the vibrations, a damper material which surrounds the piezoelectric transducer, and a casing which surrounds the damper material and includes the side surface to be contacted with the operator's head, and the side surface of the casing is pre-treated to have a small coefficient of friction.