EP0429264A2 - Mikrofongerät - Google Patents

Mikrofongerät Download PDF

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Publication number
EP0429264A2
EP0429264A2 EP90312516A EP90312516A EP0429264A2 EP 0429264 A2 EP0429264 A2 EP 0429264A2 EP 90312516 A EP90312516 A EP 90312516A EP 90312516 A EP90312516 A EP 90312516A EP 0429264 A2 EP0429264 A2 EP 0429264A2
Authority
EP
European Patent Office
Prior art keywords
microphone
directional
directional microphone
vibration
noise
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP90312516A
Other languages
English (en)
French (fr)
Other versions
EP0429264A3 (en
Inventor
Kiminori Ono
Michio Matsumoto
Hiroyuki Naono
Hiroshi Kobayashi
Yuuji Yamashina
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Panasonic Holdings Corp
Original Assignee
Matsushita Electric Industrial Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Matsushita Electric Industrial Co Ltd filed Critical Matsushita Electric Industrial Co Ltd
Publication of EP0429264A2 publication Critical patent/EP0429264A2/de
Publication of EP0429264A3 publication Critical patent/EP0429264A3/en
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R5/00—Stereophonic arrangements
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R3/00—Circuits for transducers, loudspeakers or microphones
    • H04R3/005—Circuits for transducers, loudspeakers or microphones for combining the signals of two or more microphones
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R2410/00—Microphones
    • H04R2410/01—Noise reduction using microphones having different directional characteristics
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R2410/00—Microphones
    • H04R2410/07—Mechanical or electrical reduction of wind noise generated by wind passing a microphone

Definitions

  • This invention relates to a microphone apparatus to be built in an appliance having an acoustic noise and/or vibration source within it.
  • Sound pick up using a microphone is accompanied by the deterioration of the quality of audio signals due to acoustic noise (undesired sounds), vibration noise caused by the mechanical vibration given to the microphone, and wind noise by wind.
  • acoustic noise undesired sounds
  • vibration noise caused by the mechanical vibration given to the microphone
  • wind noise by wind.
  • built-in mechanical systems generate acoustic noise and vibration.
  • the S/N ratio(signal-to-noise ratio) at the time of sound pick up is reduced due to the following factors: - Location of the microphone close to the acoustic noise or vibration source increases the absolute level of acoustic noise or vibration applied to the microphone.
  • - Location of the microphone close to the acoustic noise source enhances the pressure sensitivity of the directional microphone in its front and rear due to the proximity effect, allowing the microphone to receive more influence of the acoustic noise generated by the mechanical system.
  • a directional microphone receives more influence of vibration than a non-directional microphone.
  • a directional microphone receives more influence of wind than a non-directional microphone.
  • a non-directional microphone cannot remove acoustic noise by directivity.
  • a microphone system which reduces vibration noise has already been disclosed in the Japanese Patent Publication No. 54-8295 (1 979).
  • This microphone system is so constructed that two microphone units made by attaching a diaphragm to an electroconductive frame under tense conditions are fitted to two windows located opposite in a case and these diaphragms are connected in series.
  • the two diaphragms of the microphone system constructed in this way vibrate in phase with sound pressure and out of phase with mechanical vibration.
  • This microphone system therefore, reduces vibration noise by offsetting mechanical vibration as well as has a pressure sensitivity twice as high as a single microphone unit.
  • the conventional microphone system mentioned above is, however, unable to reduce the influence of the acoustic noise generated by a mechanical system in an appliance with a built-in microphone.
  • An object of this invention is to provide a microphone apparatus which can reduce wind noise as well as acoustic noise and vibration noise generated by a mechanical system in an appliance with a built-in microphone, thereby preventing a reduction in the S/N ratio at the time of sound pick up.
  • a microphone apparatus of this invention comprises a non-directional microphone located near a noise source, a directional microphone located adjacent to the non-directional microphone with their main axes parallel with each other, a microphone holder for fixing thereto the non-directional microphone and the directional microphone to transmit an equal amount of vibration to the two microphones, an equalizer for filtering an output signal of the directional microphone to equalize a pressure response of the directional microphone in a certain direction of the noise source located close to the directional microphone to a pressure response of the non-directional microphone, and an operation unit for mixing an output signal of the non-­directional microphone and an output signal of the equalizer so that acoustic noise and vibration noise are canceled.
  • the microphone apparatus of this invention can reduce acoustic noise and vibration noise generated by a mechanical system in an appliance with a built-in microphone, thereby preventing reduction of the S/N ratio at the time of sound pick up.
  • the surface density of a diaphragm can be established so as to equalize the pressure response of the directional microphone, located near the sound source, in a certain direction of the noise source to the vibration response.
  • Fig. 1 shows a schematic block diagram of a microphone apparatus in an embodiment of this invention.
  • both the acoustic noise source and the vibration source mean the mechanical systems housed in an appliance with a built-in microphone.
  • the X direction shown in Fig. 1 is referred to as the front direction, the -X direction as the rear direction, and the Y direction as the side direction.
  • 1, 1 is a non-­directional microphone so arranged that it is located near the noise source and the noise source is positioned in the direction of the microphone's main axis
  • 2 is a directional microphone arranged to be located adjacent to and parallel with the non-directional microphone 1 (here, a bi-­directional microphone is used as the directional microphone 2)
  • 3 is a microphone holder to fix the non-directional microphone 1 and the directional microphone 2 so that an equal amount of vibration may be transmitted from the vibration source to the two microphone
  • 4 is an equalizer which, by filtering an output signal of the directional microphone 2, equalizes the pressure response of the directional microphone 2, if located near the sound source, in the rear direction to the pressure response of the non-­directional microphone 1 (specifically, the equalizer 4 may be an amplifier to adjust the gain when a bi-directional microphone is used as the directional microphone 2 or an equalizer having a frequency response as shown in Fig.
  • the operation circuit 5 is an operation circuit which mixes an output signal of the non-­directional microphone 1 and an output signal of the equalizer 4 so that acoustic noise and vibration noise are canceled
  • the operation circuit 5 may be a subtractor when the output signals of the non-directional microphone 1 and the equalizer 4 in response to the sound pressure in the rear direction are in phase with each other or an adder when they have opposite phases to each other).
  • the surface density of the diaphragm of the directional microphone is so established that the pressure response of the microphone, if located near the sound source, in the rear direction is equalized to the vibration response of the microphone as the vibration sensitivity of a microphone is proportional to the surface density of a diaphragm.
  • Fig. 2a and Fig. 2b show pressure responses of the non-­directional microphone 1 in the Fig. 1 microphone apparatus placed 1 meter and 2 centimeters apart from the sound source respectively.
  • the pressure sensitivity of the non-directional microphone 1 shows a flat response independent of the distance from the sound source.
  • Fig. 3a and Fig. 3b show pressure responses of the output signal of the equalizer 4 in the Fig. 1 microphone apparatus placed 1 meter and 2 centimeters apart from the sound source respectively.
  • phases of the output signals in response to the sound pressures in the front and rear directions are reverse to each other.
  • the pressure sensitivities in the front and rear directions of the directional microphone 2 decrease with decreasing frequencies when the sound source is distant from the microphone. apparatus but increase in the low-frequency region when the sound source is located near the apparatus (proximity effect).
  • the output signal of the directional microphone 2 is filtered by the equalizer 4 so that the pressure sensitivity in the rear direction of the directional microphone 2 in the microphone apparatus located near the sound source may be equalized to that of the non-­directional microphone 1.
  • the output signal of the equalizer 4 in response to the sound pressure in the rear direction of the directional microphone 2 shows an almost equal level to the output signal of the non-directional microphone 1.
  • the output signal of the equalizer 4 shows a lower level than that of the output signal of the non-­directional microphone 1.
  • the operation circuit 5 in Fig. 1 cancels the output signal of the equalizer 4 with that of the non-directional microphone 1 in the microphone apparatus located near the sound source in response to the sound pressure in the rear direction. More specifically, as the operation circuit 5, a subtractor is used when the phases of the output signals of the non-directional microphone 1 and the equalizer 4 in response to the sound pressure in the rear direction are in phase each other, and an adder is used when they are reverse to each other.
  • Fig. 6a and Fig. 6b show pressure responses of the Fig. 1 microphone apparatus placed 1 meter and 2 centimeters apart from the sound source respectively. The directivity of the Fig.
  • the 1 microphone apparatus takes a uni-­directional characteristic in the higher frequency region than about 1 KHz and a non-directional characteristic in the lower frequency region than about 1 KHz when the sound source is distant from the microphone apparatus.
  • the non-­directional characteristic taken in the low-frequency region leads to the reduction in wind noise.
  • the directional characteristic becomes uni-directional over a wide frequency range when the sound source is located near the microphone apparatus. Consequently, by arranging the microphone apparatus so that it is located near the acoustic noise source positioned in the rear direction, the acoustic noise generated from the acoustic noise source can be canceled to prevent the reduction of the S/N ratio at the time of sound pick up.
  • Fig. 4 shows a vibration response of the non-­directional microphone 1 in the Fig. 1 microphone apparatus.
  • Fig. 5 shows a vibration response of the output signal of the equalizer 4 in the Fig. 1 microphone apparatus
  • Fig. 7 illustrates a vibration response of the Fig. 1 microphone apparatus.
  • the output signal of the equalizer 4 in response to vibration takes the same frequency characteristic as that of the non-directional microphone 1. Therefore, as in the case of the sound pressure in the rear direction of the microphone apparatus located near the sound source, the vibration noise can be canceled, thereby preventing the reduction in the S/N ratio at the time of sound pick up.

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Otolaryngology (AREA)
  • Circuit For Audible Band Transducer (AREA)
  • Details Of Audible-Bandwidth Transducers (AREA)
  • Telephone Set Structure (AREA)
  • Obtaining Desirable Characteristics In Audible-Bandwidth Transducers (AREA)
EP19900312516 1989-11-20 1990-11-16 Microphone apparatus Withdrawn EP0429264A3 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP1301699A JPH03162100A (ja) 1989-11-20 1989-11-20 マイクロホン装置およびマイクロホン装置を搭載したビデオ一体型カメラ
JP301699/89 1989-11-20

Publications (2)

Publication Number Publication Date
EP0429264A2 true EP0429264A2 (de) 1991-05-29
EP0429264A3 EP0429264A3 (en) 1992-03-04

Family

ID=17900089

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19900312516 Withdrawn EP0429264A3 (en) 1989-11-20 1990-11-16 Microphone apparatus

Country Status (3)

Country Link
EP (1) EP0429264A3 (de)
JP (1) JPH03162100A (de)
KR (1) KR910011082A (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1028601A2 (de) * 1999-02-10 2000-08-16 Andreas Peiker Vorrichtung zur Erfassung von Schallwellen in einem Fahrzeug
EP1339055A2 (de) * 2002-02-25 2003-08-27 Canon Kabushiki Kaisha Aufzeichnungsgerät

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3102530A1 (de) * 1980-01-28 1981-11-26 Victor Company Of Japan, Ltd., Yokohama, Kanagawa Variable richtmikrofonanlage
EP0084982A2 (de) * 1982-01-27 1983-08-03 Racal Acoustics Limited Kommunikationssysteme
US4442323A (en) * 1980-07-19 1984-04-10 Pioneer Electronic Corporation Microphone with vibration cancellation

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3102530A1 (de) * 1980-01-28 1981-11-26 Victor Company Of Japan, Ltd., Yokohama, Kanagawa Variable richtmikrofonanlage
US4442323A (en) * 1980-07-19 1984-04-10 Pioneer Electronic Corporation Microphone with vibration cancellation
EP0084982A2 (de) * 1982-01-27 1983-08-03 Racal Acoustics Limited Kommunikationssysteme

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
IEEE TRANSACTIONS ON CONSUMER ELECTRONICS. vol. 36, no. 3, August 1990, NEW YORK US K. ONO ET AL.: 'NOISE-CANCELLING MICROPHONE FOR VIDEO CAMERAS' *

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1028601A2 (de) * 1999-02-10 2000-08-16 Andreas Peiker Vorrichtung zur Erfassung von Schallwellen in einem Fahrzeug
EP1028601A3 (de) * 1999-02-10 2002-06-12 Andreas Peiker Vorrichtung zur Erfassung von Schallwellen in einem Fahrzeug
EP1339055A2 (de) * 2002-02-25 2003-08-27 Canon Kabushiki Kaisha Aufzeichnungsgerät
EP1339055A3 (de) * 2002-02-25 2004-06-16 Canon Kabushiki Kaisha Aufzeichnungsgerät
US7054248B2 (en) 2002-02-25 2006-05-30 Canon Kabushiki Kaisha Recording apparatus

Also Published As

Publication number Publication date
EP0429264A3 (en) 1992-03-04
JPH03162100A (ja) 1991-07-12
KR910011082A (ko) 1991-06-29

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