GB1407266A - Directional microphones - Google Patents

Directional microphones

Info

Publication number
GB1407266A
GB1407266A GB3370472A GB3370472A GB1407266A GB 1407266 A GB1407266 A GB 1407266A GB 3370472 A GB3370472 A GB 3370472A GB 3370472 A GB3370472 A GB 3370472A GB 1407266 A GB1407266 A GB 1407266A
Authority
GB
United Kingdom
Prior art keywords
tubes
chambers
cavity
microphone
acoustic
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.)
Expired
Application number
GB3370472A
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.)
AT&T Corp
Original Assignee
Western Electric Co Inc
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 Western Electric Co Inc filed Critical Western Electric Co Inc
Publication of GB1407266A publication Critical patent/GB1407266A/en
Expired legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R1/00—Details of transducers, loudspeakers or microphones
    • H04R1/20—Arrangements for obtaining desired frequency or directional characteristics
    • H04R1/32—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only
    • H04R1/34—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only by using a single transducer with sound reflecting, diffracting, directing or guiding means
    • H04R1/38—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only by using a single transducer with sound reflecting, diffracting, directing or guiding means in which sound waves act upon both sides of a diaphragm and incorporating acoustic phase-shifting means, e.g. pressure-gradient microphone

Landscapes

  • Health & Medical Sciences (AREA)
  • Otolaryngology (AREA)
  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Circuit For Audible Band Transducer (AREA)
  • Obtaining Desirable Characteristics In Audible-Bandwidth Transducers (AREA)

Abstract

1407266 Directional microphones WESTERN ELECTRIC CO Inc 19 July 1972 [21 July 1971] 33704/72 Heading H4J A directional microphone having a second order gradient pattern comprises two acoustic chambers 15, 16, a first pair of tubes 11, 13 of equal length, for delivering a sound sample into a respective chamber and a pair of tubes 10, 12 longer than tubes 11, 13, but of equal length, for delivering a sound sample into a respective one of the chambers 15, 16. The tubes sample a sound field at points on a substantially straight line, preferably passing through a diameter of a cylindrical casing 14. A transducer 17, 18 is common to both chambers 15, 16 for combining signals developed in the chambers. The structure may be regarded as comprising two first order gradient microphones of opposite polarities spaced apart from one another, a delay system, and an arrangement for adding the output of one gradient microphone to the delayed output of the other. The transducer is formed of a perforated backplate 17 and an adjacent electrode foil 18. The electrode foil 18 divides the casing 14 into the two chambers 15, 16. One of the chambers is adjustable, using a screw plunger (not shown). Backplate 17 is a brass disc, 4 cm. diameter, having four circular 25À4 Ám ridges on one side and 100 holes. Electret foil is a 25À4 Ám layer of fluoroethylenepropylene metallized on one side and charged using an electron beam. Tubes 10 and 12 are of the same length. Tubes 11 and 13 are of the same length different from that of tubes 10 and 12. All tubes are open at their ends and contain steel wool to damp acoustic resonances. The outer ends of tubes 10, 13 have the same spacing as the outer ends of tubes 11, 12. Each cavity 15, 16 and its associated tubes form a Helmholtz resonator or an acoustic low-pass filter. The resonance frequency is at the lower end of the frequency range of interest. If only two tubes are used, a short tube feeding a layerone cavity and a layer tube feeding the other cavity the microphone characteristic reduces to a cardioid pattern.
GB3370472A 1971-07-21 1972-07-19 Directional microphones Expired GB1407266A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US16450771A 1971-07-21 1971-07-21

Publications (1)

Publication Number Publication Date
GB1407266A true GB1407266A (en) 1975-09-24

Family

ID=22594801

Family Applications (1)

Application Number Title Priority Date Filing Date
GB3370472A Expired GB1407266A (en) 1971-07-21 1972-07-19 Directional microphones

Country Status (6)

Country Link
US (1) US3715500A (en)
JP (1) JPS5219966B1 (en)
AT (1) AT322650B (en)
CA (1) CA948305A (en)
DE (1) DE2235169C3 (en)
GB (1) GB1407266A (en)

Families Citing this family (27)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1515287A (en) * 1974-05-30 1978-06-21 Plessey Co Ltd Piezoelectric transducers
US4555598A (en) * 1983-09-21 1985-11-26 At&T Bell Laboratories Teleconferencing acoustic transducer
US4742548A (en) * 1984-12-20 1988-05-03 American Telephone And Telegraph Company Unidirectional second order gradient microphone
FI77347C (en) * 1987-04-23 1989-02-10 Uuden Teknologian Keskus Oy ANORDNING FOER ATT GOERA LAETTARE SAMTIDIGT TITTANDE OCH LYSSNANDE PAO ETT AVLAEGSET OBJEKT.
US5121426A (en) * 1989-12-22 1992-06-09 At&T Bell Laboratories Loudspeaking telephone station including directional microphone
US5226076A (en) * 1993-02-28 1993-07-06 At&T Bell Laboratories Directional microphone assembly
US5633935A (en) * 1993-04-13 1997-05-27 Matsushita Electric Industrial Co., Ltd. Stereo ultradirectional microphone apparatus
US5539834A (en) * 1994-11-03 1996-07-23 At&T Corp. Baffled microphone assembly
US5692060A (en) * 1995-05-01 1997-11-25 Knowles Electronics, Inc. Unidirectional microphone
US5745588A (en) * 1996-05-31 1998-04-28 Lucent Technologies Inc. Differential microphone assembly with passive suppression of resonances
US5848172A (en) * 1996-11-22 1998-12-08 Lucent Technologies Inc. Directional microphone
US6122389A (en) * 1998-01-20 2000-09-19 Shure Incorporated Flush mounted directional microphone
US7116792B1 (en) * 2000-07-05 2006-10-03 Gn Resound North America Corporation Directional microphone system
US7280014B2 (en) * 2001-03-13 2007-10-09 Rochester Institute Of Technology Micro-electro-mechanical switch and a method of using and making thereof
AU2002303933A1 (en) * 2001-05-31 2002-12-09 Rochester Institute Of Technology Fluidic valves, agitators, and pumps and methods thereof
US20030008676A1 (en) * 2001-07-03 2003-01-09 Baumhauer John Charles Communication device having a microphone system with optimal acoustic transmission line design for improved frequency and directional response
US6842009B2 (en) * 2001-09-13 2005-01-11 Nth Tech Corporation Biohazard sensing system and methods thereof
US6717488B2 (en) * 2001-09-13 2004-04-06 Nth Tech Corporation Resonator with a member having an embedded charge and a method of making thereof
US7378775B2 (en) * 2001-10-26 2008-05-27 Nth Tech Corporation Motion based, electrostatic power source and methods thereof
US7211923B2 (en) 2001-10-26 2007-05-01 Nth Tech Corporation Rotational motion based, electrostatic power source and methods thereof
US7217582B2 (en) * 2003-08-29 2007-05-15 Rochester Institute Of Technology Method for non-damaging charge injection and a system thereof
US7287328B2 (en) * 2003-08-29 2007-10-30 Rochester Institute Of Technology Methods for distributed electrode injection
US8581308B2 (en) * 2004-02-19 2013-11-12 Rochester Institute Of Technology High temperature embedded charge devices and methods thereof
US20070074731A1 (en) * 2005-10-05 2007-04-05 Nth Tech Corporation Bio-implantable energy harvester systems and methods thereof
US7656749B2 (en) * 2007-09-04 2010-02-02 The United States Of America As Represented By The Secretary Of The Army Systems and methods for analyzing acoustic waves
NO326892B1 (en) * 2007-12-21 2009-03-16 Tandberg Telecom As microphone device
EP2551846B1 (en) * 2011-07-26 2022-01-19 AKG Acoustics GmbH Noise reducing sound reproduction

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2228886A (en) * 1938-10-31 1941-01-14 Rca Corp Electroacoustical apparatus
US2301744A (en) * 1941-05-31 1942-11-10 Rca Corp Electroacoustical signal translating apparatus
US2793255A (en) * 1950-11-13 1957-05-21 Rca Corp Third order, pressure gradient responsive microphone
US2699473A (en) * 1950-11-13 1955-01-11 Rca Corp Pressure gradient responsive microphone
US3573400A (en) * 1968-08-14 1971-04-06 Bell Telephone Labor Inc Directional microphone

Also Published As

Publication number Publication date
US3715500A (en) 1973-02-06
JPS5219966B1 (en) 1977-05-31
DE2235169C3 (en) 1974-02-21
AT322650B (en) 1975-05-26
DE2235169A1 (en) 1973-02-01
DE2235169B2 (en) 1973-07-26
CA948305A (en) 1974-05-28

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Legal Events

Date Code Title Description
PS Patent sealed [section 19, patents act 1949]
PCNP Patent ceased through non-payment of renewal fee