Abstract: A remotely installed transmitter capable of clearly picking up only the voice of a person who is talking despite being installed away from the speaker's mouth and without causing feedback despite increased sensitivity, and a hands-free two-way voice terminal device using such a transmitter.

Abstract: A two way voice communications earset which is situated in the ear of the user and which includes a filter in an audio signal loop coupling a microphone and a speaker of the earset.

Abstract: An ambient noise suppression electrical circuit to be used with a voice communication terminal comprising a gain control amplifier, whose input is a microphone, and a peak-hold circuit that includes a band-pass amplifier that amplifies a specified frequency range of the output signals of the microphone, a peak detection circuit that produces signals in proportion to the peak level of the output signals of the band-pass amplifier, and a holding circuit that controls reduction of output signals of the peak detection circuit for a specified period of time. The output signal from the peak-hold circuit controls the gain of the gain control amplifier. When a microphone is located far from a mouth and is used under high ambient noise, the present invention makes it possible for the microphone to perform as if it is a microphone which is located in a quality telephone handset that cuts off ambient noise.

Abstract: A one piece two way voice communications earset which is situated in or at the ear of the user and which includes either two unidirectional microphones having their outputs combined or a single bi-directional microphone. The earset also includes a combination circuit for adding or subtracting the first and second signals output from the first and second microphones respectively.

Abstract: A one piece two way voice communications earset which is situated in or at the ear of the user and which includes either two unidirectional microphones having their outputs combined or a single bi-directional microphone.

Abstract: A one-piece two-way voice communication earset is situated in or at the ear of the user and is operated hands-free. It includes either two separated microphones having their outputs combined or a single bidirectional microphone. In either case, the earset treats the user's voice as consisting of out-of-phase signals that are not canceled, but treats ambient noise, and any incidental feedback of sound from received voice signals, as consisting of signals more nearly in-phase that are canceled or greatly reduced in level. The microphones are preferably electret microphones. In addition, a logarithmic amplification circuit reduces residual ambient noise during non-speaking intervals. The earset includes a receiver coupled to a communication medium and a speaker coupled to the receiver for emitting sound from received voice signals primarily to the user's ear canal.

Abstract: A bone conduction microphone which fits into the ear of the user and which has means which abuts against the pinna of the ear causing a counteracting force to resiliently push the device against a wall of the ear canal nearest the back of the head, where bone conducted vibrations are detected most efficiently.

Abstract: An ear microphone for an external auditory canal insertion type two-way communication earpiece. Within the casing of the earpiece a fixed electrode and a vibrating electrode are positioned in capacitive relation with each other, the vibrating electrode for detecting acceleration vibration from outside the casing in the form of bone-conducted voice sound vibration within the external auditory canal. Electrical signals transduced from picked-up voice sounds pass through an impedance conversion circuit mounted in the ear microphone.