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US3662124A - Directional microphone for hearing aid - Google Patents

Directional microphone for hearing aid Download PDF

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Publication number
US3662124A
US3662124A US75548A US3662124DA US3662124A US 3662124 A US3662124 A US 3662124A US 75548 A US75548 A US 75548A US 3662124D A US3662124D A US 3662124DA US 3662124 A US3662124 A US 3662124A
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US
United States
Prior art keywords
sound
diaphragm
housing
open
chamber
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 - Lifetime
Application number
US75548A
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English (en)
Inventor
Otto Hassler
Johannes Wittkowski
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.)
WILLCO HORGERATE MEDIZINISCHE
Original Assignee
WILLCO HORGERATE MEDIZINISCHE
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 WILLCO HORGERATE MEDIZINISCHE filed Critical WILLCO HORGERATE MEDIZINISCHE
Application granted granted Critical
Publication of US3662124A publication Critical patent/US3662124A/en
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Expired - Lifetime legal-status Critical Current

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    • 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

Definitions

  • the disclosure is directed to an improvement in a microphone used primarily in head-wom hearing aids in which the microphone achieves a directional characteristic.
  • the chamber and aperture in front of the diaphragm or other speech-responsive member is constructed in the normal manner while the chamber to the rear of the diaphragm or other speech-responsive member has a plurality of hollow elongated members secured within the walls of the microphone housing.
  • the elongated members may be formed from sintered porous material such as metal, glass, or plastic, and may be arranged side-by-side or in a honeycomb arrangement.
  • the elongated members attenuate the propagation of the sound waves, the attenuation being approximately 20 decibels lower than that reaching the other side of the diaphragm or other speech-responsive member without materially changing the inherent response characteristic of the microphone.
  • This invention relates to a microphone for hearing aids and, in particular, to a small and miniature microphone for use on head-worn hearing aids, such as the spectacle type or the type worn behind the ear.
  • the present invention makes use of a microphone in which a plurality of propagation-retarding acoustic resistances are formed in a chamber to the rear of the diaphragm of the microphone and in a general direction facing away from the direction of observation of the hearing aid wearer.
  • the propagation-retarding acoustic resistances are provided in elements forming a plurality of narrow passages within the chamber adjacent the diaphragm.
  • a preferred form of the embodiment for the propagation-retarding acoustic resistance elements is achieved by arranging a plurality of capillary tubes which are generally assembled into a block, the block being situated in the chamber at the rear of the diaphragm.
  • Another embodiment of the invention is achieved by providing a plurality of fine hairs, such as that of a camel within the confines of the chamber to the rear of the diaphragm, the fine hairs creating the plurality of substantially narrow and parallel passages.
  • the dimensions of the propagation wave-retarding resistances are chosen so that upon the pressure of the sound impinging upon the diaphragm from the referred direction reaching a maximum sound level, the sound pressure acting upon the rear of the diaphragm at the same time is at a minimum level, providing a ratio of the front pressure to the back pressure with a maximum value.
  • the certain corrugated foils of metal or synthetic plastic materials may be rolled or folded to form a pack or block of capillary tubes such as just described. It will also be found that the invention can be used with electro-magnetic type transducers or a piezo-electric transducer used as the element for changing the sound to an electrical signal within the microphone.
  • FIG. 1 is a diagrammatic longitudinal section of a typical microphone
  • FIG. 2 is a diagrammatic illustration of a frequencyresponse curve showing the operational effect of the microphone.
  • a microphone housing 11 has enclosed therein, a transducer or converter system 12, which as mentioned previously, may be of the electro-magnetic or piezoelectric type.
  • Transducer 12 is connected through a coupling pin 13 to a diaphragm 14, which is secured in the normal manner to the outer edges of housing 11.
  • Diaphragm 14 is secured at a spacially disposed position from the end wall of housing 11 so that a chamber 15 is formed therein and an aperture 16 is formed in the end of the housing to admit the sound waves to impinge upon diaphragm 13.
  • Another chamber 17 is formed to the rear of diaphragm 14 by the use of a block of propagation-retarding acoustic resistance material 18 which may be in one of the forms previously described.
  • the entire rearwardly facing end of housing 11 is open to create another aperture 19.
  • sound waves entering through aperture 19 pass through the block of propagation-retarding acoustic resistance material in order to reach chamber 17 and thus provide an actuating motion to diaphragm 14.
  • FIG. 2 shows a frequency-response curve for sound waves detected by the microphone emanating from a preferred direction for detection by the microphone.
  • Curve 20 is a frequency-response curve for a microphone of normal construction receiving the sound propagated waves from the preferred direction.
  • Curve 21 corresponds to the frequency response of the present invention for sound received from the preferred direction through aperture 16.
  • Curve 22 is the frequency-response curve for sound propagated waves arriving at the aperture 19 of the structure as seen in FlG. 1 when directed from a direction opposite to the preferred direction. It will be observed that the decibel difference between curves 21 and 22 exhibits the ratio of the gain of the microphone between the two directions of sound reception. lt will be seen that a mean value of approximately 20 decibels is achieved throughout the predominance of the audio range which insures that the user of such a microphone will be assured of directional hearing.
  • diaphragm 14 is approximated by the cross-sectional area of housing 11 and aperture 19, the compartment being enclosed with the block of extremely fine capillary tubes or other appropriate material as set forth herein. It will also be observed that the microphone has achieved a directional characteristic which is somewhat kidney shaped when worn upon the head as opposed to the general microphone pickup characteristics which are generally spherical in nature.
  • An improved miniature microphone constructed and arranged to be used in a hearing aid housing to be worn on the head of the wearer wherein the improvement comprises:
  • a miniature elongated microphone housing having a substantially enclosed end and an open end, said enclosed end having a sound admitting aperture formed therein which is considerably smaller than said open end,
  • transducer for producing electrical signals representative of sound waves operably connected to said sound pressure-responsive member and secured within said second chamber in said housing;
  • a propagation-retarding acoustic resistance mechanism disposed within and obstructing said open end of the housing, said mechanism forming a plurality of narrow elongated passages, each having substantially the same length to admit the sound waves to said sound pressureresponsive member, said mechanism containing a plurality of elongated elements in juxtaposition arrangement forming said plurality of narrow elongated passages and extending between the open end of said housing and said transducer in said second chamber, said transducer producing electrical signals from sound waves received through said acoustic resistance mechanism which has a frequency response having a profile substantially the same as that produced by said transducer from sound waves received from said aperture.
  • a microphone for a hearing aid to be worn on a persons head for detecting a sound and discriminating the direction of the source of the sound comprising a sound pressure-responsive diaphragm having opposite sides,
  • an electric signal-generating transducer connected to the diaphragm and producing such signals in response to diaphragm movement
  • a housing confining and mounting the diaphragm and defining open and substantially enclosed chambers respectively disposed at the opposite sides of the diaphragm, the housing having a sound admitting aperture communicating with the substantially enclosed chamber, the open chamber being disposed to the rear of the diaphragm and having an open end to face away from the source of sound, the housing defining unobstructed space adjacent the transducer to freely transmit sound past the transducer and to the diaphragm,
  • a sound wave propagation-retarding acoustic resistance mechanism obstructing the open rear end of the open chamber, said mechanism including a plurality of elongate and substantially parallel capillaries, the individual capillaries having a size of opening of the order of the size of passages existing between confined camel hairs, and said capillaries being assembled into a block and confined in the elongate open chamber of the housing the open ends of the capillaries confronting the open end of the open chamber to face the direction opposite the source of sound, the sound waves creating minimum and maximum pressures impinging the diaphragm and producing movement thereof, the sound wave propagation being retarded by the resistance mechanism to the extend that at the time the sound waves impinge the front side of the diaphragm with a maximum pressure, the sound waves impinge the back side of the diaphragm with less than maximum pressure, whereby to achieve directional effect with the microphone.
  • a microphone for a hearing aid to be worn on a person's head for detecting a sound and discriminating the direction of the sound comprising,
  • an electric signal-generating transducer connected to the diaphragm and producing such signals in response to diaphragm movement
  • a housing confining and mounting the diaphragm and defining open and substantially enclosed chambers respectively disposed at the back and front sides of the diaphragm, the housing having a sound-admitting aperture communicating with the substantially enclosed chamber, the open chamber being elongate and disposed at the rear of the housing and having an open rear end to face away from the source of the sound and for admitting sound for propagation to the back side of the diaphragm,
  • a sound wave propagation-retarding acoustic resistance mechanism obstructing the open rear end of the open chamber, said mechanism including a plurality of elongate and substantially parallel capillaries, the individual capillaries having a size of opening of the order of the size of the discrete passages existing between confined camel hairs, said capillaries being assembled into a block and confined in the elongate open chamber of the housing, the capillaries in the block extending generally longitudinally of the chamber and toward the open end thereof, the open ends of the capillaries confronting the open end of the chamber to face the direction opposite the source of sound, the sound waves creating maximum and minimum pressures impinging the diaphragm and producing movement thereof, the sound wave propagation being retarded by the resistance mechanism to the extent that at the time the sound waves impinge the front side of the diaphragm with a maximum pressure, the sound waves impinge the back side of the diaphragm with substantially minimum pressure, to thereby substantially maximize the ratio of sound wave pressure applied
  • a directional microphone for use in a hearing aid to be worn on a persons head, comprising;
  • a diaphragm-operated transducer generating electric signals related to the sound pressures sensed by the diaphragm
  • a microphone housing enclosing the diaphragm and defining front and rear chambers at opposite sides of the diaphragm, the housing having a sound opening communicating with the front chamber and freely admitting sound pressures to impinge upon the diaphragm;

Landscapes

  • Health & Medical Sciences (AREA)
  • Otolaryngology (AREA)
  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Obtaining Desirable Characteristics In Audible-Bandwidth Transducers (AREA)
  • Piezo-Electric Transducers For Audible Bands (AREA)
  • Details Of Audible-Bandwidth Transducers (AREA)
  • Audible-Bandwidth Dynamoelectric Transducers Other Than Pickups (AREA)
US75548A 1967-06-05 1970-09-25 Directional microphone for hearing aid Expired - Lifetime US3662124A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DEW44116A DE1277347B (de) 1967-06-05 1967-06-05 Mikrophon fuer Hoergeraete

Publications (1)

Publication Number Publication Date
US3662124A true US3662124A (en) 1972-05-09

Family

ID=7603933

Family Applications (1)

Application Number Title Priority Date Filing Date
US75548A Expired - Lifetime US3662124A (en) 1967-06-05 1970-09-25 Directional microphone for hearing aid

Country Status (9)

Country Link
US (1) US3662124A (es)
AT (1) AT309551B (es)
BE (1) BE716073A (es)
CH (1) CH491575A (es)
DE (1) DE1277347B (es)
ES (1) ES353937A1 (es)
FR (1) FR1568515A (es)
GB (1) GB1180865A (es)
NL (1) NL6807102A (es)

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3749853A (en) * 1972-05-18 1973-07-31 Zenith Radio Corp Hearing aid with directional microphone system
US3856995A (en) * 1970-10-22 1974-12-24 Int Standard Electric Corp Pressure gradient piezoelectric microphone
US3963881A (en) * 1973-05-29 1976-06-15 Thermo Electron Corporation Unidirectional condenser microphone
US4041251A (en) * 1973-05-01 1977-08-09 U.S. Philips Corporation Hearing aid to be worn behind the ear of the user and provided with a pressure-gradient microphone
US4903249A (en) * 1988-03-24 1990-02-20 Nelson Industries Rigid foraminous microphone probe for acoustic measurement in turbulent flow
US5878147A (en) * 1996-12-31 1999-03-02 Etymotic Research, Inc. Directional microphone assembly
US6031922A (en) * 1995-12-27 2000-02-29 Tibbetts Industries, Inc. Microphone systems of reduced in situ acceleration sensitivity
WO2000049836A1 (en) 1999-02-18 2000-08-24 Etymotic Research, Inc. Directional microphone assembly
WO2002030156A1 (en) 2000-10-05 2002-04-11 Etymotic Research, Inc. Directional microphone assembly
US20080025545A1 (en) * 2006-07-28 2008-01-31 Symphony Acoustics, Inc. Apparatus Comprising a Directionality-Enhanced Acoustic Sensor
US20090094817A1 (en) * 2007-10-11 2009-04-16 Killion Mead C Directional Microphone Assembly
US20100034411A1 (en) * 2008-08-08 2010-02-11 Nokia Corporation Apparatus incorporating an adsorbent material, and methods of making same
US7881486B1 (en) * 1996-12-31 2011-02-01 Etymotic Research, Inc. Directional microphone assembly
US9636259B2 (en) 2014-07-31 2017-05-02 3M Innovative Properties Company Water resistant acoustic port in ear-mouthed hearing device

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2549963A (en) * 1945-12-03 1951-04-24 Hartford Nat Bank & Trust Co Electroacoustic transducer

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2549963A (en) * 1945-12-03 1951-04-24 Hartford Nat Bank & Trust Co Electroacoustic transducer

Cited By (22)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3856995A (en) * 1970-10-22 1974-12-24 Int Standard Electric Corp Pressure gradient piezoelectric microphone
US3749853A (en) * 1972-05-18 1973-07-31 Zenith Radio Corp Hearing aid with directional microphone system
US4041251A (en) * 1973-05-01 1977-08-09 U.S. Philips Corporation Hearing aid to be worn behind the ear of the user and provided with a pressure-gradient microphone
US3963881A (en) * 1973-05-29 1976-06-15 Thermo Electron Corporation Unidirectional condenser microphone
US4903249A (en) * 1988-03-24 1990-02-20 Nelson Industries Rigid foraminous microphone probe for acoustic measurement in turbulent flow
US6031922A (en) * 1995-12-27 2000-02-29 Tibbetts Industries, Inc. Microphone systems of reduced in situ acceleration sensitivity
US6567526B1 (en) 1996-12-31 2003-05-20 Etymotic Research, Inc. Directional microphone assembly
US7286677B2 (en) 1996-12-31 2007-10-23 Etymotic Research, Inc. Directional microphone assembly
US6285771B1 (en) 1996-12-31 2001-09-04 Etymotic Research Inc. Directional microphone assembly
US7881486B1 (en) * 1996-12-31 2011-02-01 Etymotic Research, Inc. Directional microphone assembly
US5878147A (en) * 1996-12-31 1999-03-02 Etymotic Research, Inc. Directional microphone assembly
US20040247146A1 (en) * 1996-12-31 2004-12-09 Killion Mead C. Directional microphone assembly
WO2000049836A1 (en) 1999-02-18 2000-08-24 Etymotic Research, Inc. Directional microphone assembly
US6798890B2 (en) 2000-10-05 2004-09-28 Etymotic Research, Inc. Directional microphone assembly
WO2002030156A1 (en) 2000-10-05 2002-04-11 Etymotic Research, Inc. Directional microphone assembly
US20080025545A1 (en) * 2006-07-28 2008-01-31 Symphony Acoustics, Inc. Apparatus Comprising a Directionality-Enhanced Acoustic Sensor
US7894618B2 (en) * 2006-07-28 2011-02-22 Symphony Acoustics, Inc. Apparatus comprising a directionality-enhanced acoustic sensor
US20090094817A1 (en) * 2007-10-11 2009-04-16 Killion Mead C Directional Microphone Assembly
US7832080B2 (en) 2007-10-11 2010-11-16 Etymotic Research, Inc. Directional microphone assembly
US20100034411A1 (en) * 2008-08-08 2010-02-11 Nokia Corporation Apparatus incorporating an adsorbent material, and methods of making same
US8630435B2 (en) * 2008-08-08 2014-01-14 Nokia Corporation Apparatus incorporating an adsorbent material, and methods of making same
US9636259B2 (en) 2014-07-31 2017-05-02 3M Innovative Properties Company Water resistant acoustic port in ear-mouthed hearing device

Also Published As

Publication number Publication date
CH491575A (de) 1970-05-31
ES353937A1 (es) 1969-10-16
FR1568515A (es) 1969-05-23
GB1180865A (en) 1970-02-11
AT309551B (de) 1973-08-27
BE716073A (es) 1968-11-04
NL6807102A (es) 1968-12-06
DE1277347B (de) 1968-09-12

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