Abstract: A microphone apparatus includes an array of equally spaced microphones divided into a center subarray and a pair of side subarrays located one on each side of the center subarray. A first weighting network having a plurality of weighting factors impresses a first weighting function on signals from the center subarray. Second and third weighting networks each having a plurality of weighting factors impress second and third weighting functions respectively on signals from the side subarrays. The first, second and third weighting functions correspond respectively to center and side portions of a total function. Signals from the first weighting network are summed in a first adder, signals from the second and third weighting networks being summed in a second adder and cmbined with the output of the first adder in a third adder to produce an output signal.

Abstract: A phased-array sound pickup apparatus has an array of directional microphones having individual directivity patterns equally oriented in a given direction. The directivity patterns of the microphones combine into the main lobe of the array. A plurality of variable delay circuits are connected to be responsive respectively to individual signals from the microphones for providing incremental delays to the individual signals and combining the delayed signals for delivery as an output of the apparatus. A delay control circuit is coupled to the variable delay circuits for generating a delay control signal for controlling the amount of the incremental delays to cause the main lobe to be steered at an angle to the given direction as a function of the delay control signal.

Abstract: In a phased-array sound pickup apparatus microphones are divided into a first and second subarrays, the microphones of the first subarray having individual unidirectional response patterns oriented on one side of the normal to the array and the microphones of the second subarray having their response patterns oriented on the other side of the normal so that the array's main lobe assumes different orientation from the orientation of the microphone's individual response patterns so that the array's unwanted back lobe falls outside of the microphone's response patterns. The microphones may be grouped into a plurality of pairs and the signals from the paired microphones are mixed so that different individual response patterns are generated in correlation with the array's main front lobe to cause the unwanted back lobe to occur outside of the individual response patterns.

Abstract: A variable directivity microphone device comprises a microphone unit assembly provided and arranged with at least three microphone units, wherein the three microphone units are mutually separated by predetermined distances, and front faces of a first and second microphone units of the three microphone units are provided and arranged facing the front surface of the microphone unit assembly while the front face of a third microphone unit is provided and arranged in a direction opposite to those of the first and second microphone units, a first and second variable resistors respectively having a terminal at one end, an intermediate terminal, and a terminal at the other end, wherein respective sliders are mutually linked or ganged and movable between a first, second, and third positions corresponding to the terminals, where the first variable resistor has the terminals at both ends thereof respectively connected to the output sides of the second and third microphone units and the intermediate terminal thereof con

Abstract: Three microphone units of first order sound pressure gradient unidirectional type are disposed in a casing having front and rear portions at both sides in such a manner that the center axes of the microphone units are aligned on the same axis. Two among the three microphone units are arranged to face the front portion of the casing, and remaining one microphone unit is arranged to face the rear portion of the casing. The output signals of the three microphone units are combined at a variable ratio so that the directivity of the microphone system can widely vary from nondirectivity via first order sound pressure gradient unidirectivity to second order sound pressure gradient unidirectivity. The output signals of two microphone units used for obtaining second order sound pressure gradient unidirectivity may be respectively applied to high pass filters before being combined, and the combined signal is fed to an equalizer.

Abstract: A variable-directivity microphone device comprises a microphone unit having a plurality of microphones, a circuit which resultingly adds the low-frequency range components of the output signal of one of the microphones of the microphone unit and mixes with the output signal of the other microphone so that only the high-frequency range components cancel each other, and an equalizer which corrects the characteristic of the mixed signal. The above effective mixing is performed under varying mixing states.

Abstract: A variable-directivity microphone device comprises at least three microphones. First and second microphones spaced apart by specific distances and facing in the same direction and a third microphone facing in the opposite direction. A directivity varying control capable of undergoing displacement between at least three positions, a first mixer operating, while the control is between a first and a second position, to mix, in accordance with the position thereof, the third microphone signal with the first microphone signal and, while the control is between the second and third positions, to cause the third microphone output signal to be zero, and a second mixer operating, while the control is between the second and third positions, to mix the first and second microphone output signals with varied mixing quantity and, while the control is between the first and second positions, to cause the output signal of the second microphone to be zero.

Abstract: An open-back type headphone comprises a driver unit for operating as a sound generating source, a case accommodating therewithin said driver unit and having a front face on the side to confront and be pressed against an ear of a listener and a back face on the side opposite that of the front face, said back face being acoustically open, an ear pad provided on said front face of the case and forming at the center thereof a front air chamber, and an attachment detachably attached to said back face of the case. The attachment has an open end communicable with the back face of the case and an internal space of a specific volume and is adapted to cover and seal the back face of the case. The attachment and said case have an attaching mechanism by which the attachment can be detachably attached to the case.