Matsushita Electric Industrial Co., Ltd.

Kiminori Ono

Satoru Ibaraki

Yuji Yamashina

Hiroshi Kobayashi

Michio Matsumoto

Hiroyuki Naono

Takeo Kanamori

Hiroki Furukawa

Junichi Tagawa

Yuuji Yamashina

A stereo ultradirectional microphone apparatus for detecting a sound to produce stereo sound signals, comprises: first and second ultradirectional microphones arranged side by side with a given distance in parallel for converting a sound into first and second sound signals respectively, first and second delays for delaying an output of the first and second microphones by a delay time .tau. respectively, and first and second subtractors for subtracting for subtraction between the first sound signal and an output of the second delay and subtracting for subtraction between the second sound signal and an output of the first delay. The delay time .tau. corresponds to a difference between the timings of a sound from a sound source in a direction making a clockwise angel .theta. from the front where a dead angel should be made. The subtraction provides the dead angle. Similarly, a dead angle on the side is also made to obtain a stereo characteristic. The directivity in the frequency characteristic of microphone is equalized to cancel the sensitivity in the dead angle. A stereo apparatus for forming the dead angles with two set of two filters having respective transfer characteristics determined by measurement and an adder is also disclosed.

Stereo ultradirectional microphone apparatus

A reference microphone is disposed close to a primary microphone through an enclosure wall of an appliance incorporating microphones, and a noise generated by mechanical systems and included in an output of the primary microphone is canceled by an adaptive filter. In a smaller hardware scale than a case of mounting a sensor for noise reference directly to a noise source, a noise component can be canceled more effectively depending on changes of noise environments.

Microphone apparatus

In a small-sized pressure gradient type microphone apparatus, a plurality of omni-directional microphone units are encased within a microphone holder. A plurality of acoustic passages having first and second ends are provided within the microphone holder for coupling the sound inlets of the plurality of omni-directional microphone units respectively to an outer space of the microphone holder. The second ends of the acoustic passages opened to the outer space of the microphone holder are arranged to be apart from each other at distances larger than distances between the sound inlets of the corresponding microphone units coupled at the first ends of the acoustic passages.

Pressure gradient type microphone apparatus with acoustic terminals

A microphone apparatus comprises two non-directional microphones in case of monaural sound pickup or three non-directional microphones in case of stereo sound pickup, and a signal processing means for processing output signals of the non-directional microphones so that a directivity becomes non-directional in a low frequency region and a first order pressure gradient type in a high frequency region. Accordingly, the microphone apparatus can attenuate the level of unwanted acoustic and vibration noises caused by its onboard moving mechanism as well as wind noise, thus ensuring no declination in the S/N ratio during sound pickup action.

A microphone apparatus using two microphones has a circuit for processing output signals of the two microphones so as to obtain non-directional characteristics in a low frequency region and uni-directional characteristics in a high frequency region. When this microphone apparatus is incorporated in an appliance containing an acoustic noise source and vibration source therein, acoustic noise, vibration noise and wind noise are reduced to prevent a reduction of the S/N ratio when picking up the sound, so that the recording of an excellent quality sound can be realized.

Growing community of inventors

Katano, Japan

Kiminori Ono