DK176409B1 - Hearing aid with telecoil and method of reducing magnetic noise fields in a hearing aid - Google Patents

Hearing aid with telecoil and method of reducing magnetic noise fields in a hearing aid Download PDF

Info

Publication number
DK176409B1
DK176409B1 DK41298A DK41298A DK176409B1 DK 176409 B1 DK176409 B1 DK 176409B1 DK 41298 A DK41298 A DK 41298A DK 41298 A DK41298 A DK 41298A DK 176409 B1 DK176409 B1 DK 176409B1
Authority
DK
Denmark
Prior art keywords
hearing aid
compensation
telecoil
compensation inductance
inductance
Prior art date
Application number
DK41298A
Other languages
Danish (da)
Other versions
DK41298A (en
Inventor
Benno Knapp
Kunibert Husung
Original Assignee
Siemens Audiologische Technik
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 Siemens Audiologische Technik filed Critical Siemens Audiologische Technik
Publication of DK41298A publication Critical patent/DK41298A/en
Application granted granted Critical
Publication of DK176409B1 publication Critical patent/DK176409B1/en

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
    • H04R25/00—Deaf-aid sets, i.e. electro-acoustic or electro-mechanical hearing aids; Electric tinnitus maskers providing an auditory perception
    • H04R25/55—Deaf-aid sets, i.e. electro-acoustic or electro-mechanical hearing aids; Electric tinnitus maskers providing an auditory perception using an external connection, either wireless or wired
    • H04R25/554—Deaf-aid sets, i.e. electro-acoustic or electro-mechanical hearing aids; Electric tinnitus maskers providing an auditory perception using an external connection, either wireless or wired using a wireless connection, e.g. between microphone and amplifier or using Tcoils
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R2225/00—Details of deaf aids covered by H04R25/00, not provided for in any of its subgroups
    • H04R2225/49—Reducing the effects of electromagnetic noise on the functioning of hearing aids, by, e.g. shielding, signal processing adaptation, selective (de)activation of electronic parts in hearing aid
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R2225/00—Details of deaf aids covered by H04R25/00, not provided for in any of its subgroups
    • H04R2225/51—Aspects of antennas or their circuitry in or for hearing aids

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Neurosurgery (AREA)
  • Otolaryngology (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Circuit For Audible Band Transducer (AREA)
  • Coils Or Transformers For Communication (AREA)
  • Amplifiers (AREA)

Description

DK 176409 B1DK 176409 B1

Titel: Høreapparat med telespole samt en fremgangsmåde til reduktion af magnetiske støifelter i et høreapparatTitle: Hearing aid with telecoil and a method for reducing magnetic noise fields in a hearing aid

Den foreliggende opfindelse angår et høreapparat med en telespole samt en 5 fremgangsmåde til reduktion af klir ved drift af høreapparater med telespoler ved kompensation for de i høreapparatet opstående støjfelter.The present invention relates to a hearing aid with a telecoil as well as to a method for reducing claws when operating hearing aids with telecoils by compensating for the noise fields encountered in the hearing aid.

Høreapparater med telespoler kendes fra DE 39 17 548 A1. Her modtager den tunghøre eksempelvis ved telefonering samtalepartnerens signaler ved indukti-10 on uden overføring via et lydfelt. Derudover kan omgivelsens lavfrekvente vekselfelter optages og i høreapparatet ændres til signalspændinger og forstærkes yderligere. Ved høreapparater sker det hyppigt, at der under telespolens drift. indtræder en klirandel, som er høj og derfor virker forstyrrende. Denne klirren ligger hovedsagelig i frekvensområdet under 1 kHz, da høreapparatets strøm-15 forbrug er særligt højt i dette område, og spændingsfaldene frembringer derfor magnetiske støjfelter ved forsyningsledningen. Disse støjfelter overlejrer det ønskede signal. Man har forsøgt at minimere støjfelterne ved en parallelføring af forsyningsledningerne, hvilket imidlertid ikke har kunnet overholdes på grund af de geometriske standardværdier (batterikontakternes og afbryderens positi-20 on) og på grund af udfletning.Hearing aids with telecoils are known from DE 39 17 548 A1. Here, for example, it hears the receiver hearing the caller's signals by inductance, for example, without transmission via a sound field. In addition, the low frequency alternating fields of the environment can be recorded and changed in the hearing aid to signal voltages and amplified further. With hearing aids, it often happens that during the operation of the telecoil. a high proportion of claws occurs which is therefore disturbing. This noise is mainly in the frequency range below 1 kHz, as the hearing aid's current consumption is particularly high in this area, and therefore the voltage drops produce magnetic noise fields at the supply line. These noise fields overlay the desired signal. Attempts have been made to minimize the noise fields by parallel supply of the supply lines, which, however, could not be observed because of the geometric standard values (the position of the battery contacts and switch) and due to the interlacing.

Formålet med opfindelsen er at tilvejebringe et høreapparat, som er udstyret med en telespole, og hvor den af støjfelterne forårsagede klirren kan undgås, og som kan fremstilles i serieproduktion. Det er desuden tilsigtet at anvise en 25 fremgangsmåde til at reducere magnetiske støjfelter og derigennem formindske klirren ved drift af høreapparater med spoler.The object of the invention is to provide a hearing aid which is equipped with a telecoil and where the noise caused by the noise fields can be avoided and which can be manufactured in series production. It is further intended to provide a method of reducing magnetic noise fields and thereby reducing the noise of operation of hearing aids with coils.

Dette formål er ifølge opfindelsen opnået ved hjælp af de i krav 1 og 9 angivne træk. Ifølge opfindelsen placeres en yderligere induktans i nærheden af telespo-30 len. Herved kan der kompenseres for uheldige spredningsfelter, dvs. støjfelter, og derved undgås en høj klirandel i det ønskede signal. Denne ekstra kompensationsinduktans kan desuden realiseres fremstillingsteknisk enkelt.This object according to the invention is achieved by the features of claims 1 and 9. According to the invention, a further inductance is placed in the vicinity of the telecoil. This can compensate for unfortunate spread fields, ie. noise fields, thereby avoiding a high pitch in the desired signal. Furthermore, this additional compensation inductance can be realized from a technical point of view.

DK 176409 B1 2DK 176409 B1 2

Kompensationsinduktansen skal på hensigtsmæssig måde være anbragt og/eller dimensioneret således, at der indtræder en tilstrækkelig magnetisk kobling mellem telespolens og kompensationsinduktansens magnetfelt.The compensation inductance must be suitably arranged and / or dimensioned so that a sufficient magnetic coupling occurs between the magnetic field of the telecoil and the compensation inductance.

5 Følgelig kan kompensationsinduktansen være anbragt parallelt eller antiparallelt med telespolen, således at kompensationsinduktansens feltlinjer er i det væsentlige identisk med telespolens feltlinjer, men anbragt forskudt til siden. Forekomsten af magnetiske støjfelter, dvs. telespoleklirren, undgås derved.Accordingly, the compensation inductance may be arranged parallel or antiparallel to the telecoil, so that the field lines of the compensation inductance are substantially identical to the telecoil field lines but positioned offset. The presence of magnetic noise fields, ie. thereby eliminating the telecoil.

10 Styrken af kompensationen for det af telespolen optagne magnetfelt kan indstilles ved en ændring af kompensationsinduktansens vindingstal og/eller ved en ændring af kompensationsinduktansens afstand, på hensigtsmæssig måde ved en ændring af begge standardværdier.The strength of the compensation for the magnetic field occupied by the coil can be adjusted by a change in the winding number of the compensation inductance and / or by a change in the distance of the compensation inductance, appropriately by a change of both standard values.

15 Der er på fordelagtig måde tilvejebragt en luftspole, især en SMD- (dvs. "surface mounted device") luftspole, som kompensationsinduktans. Sådanne SMD-luftspoler kan på enkel måde bestykkes automatisk.Advantageously, an air coil is provided, in particular an SMD (i.e., surface mounted device) air coil, as compensation inductance. Such SMD air coils can easily be fitted automatically.

Kompensationsinduktansen gennemstrømmes af forsyningsstrømmen eller i det 20 mindste en del af denne. Kompensationens styrke fastlægges ved hjælp af antallet af trådvindinger.The compensation inductance is flowed through the supply current or at least a portion thereof. The strength of the compensation is determined by the number of thread turns.

Kompensationsinduktansens værdi ligger i området 2 - 200 nH, især i området 10 - 120 nH. Den ohmske andel ligger i et område på mindre end eller lig 1 Ω.The value of the compensation inductance is in the range 2 - 200 nH, especially in the range 10 - 120 nH. The ohmic proportion is in an area of less than or equal to 1 Ω.

25 Kompensationsinduktansen gør det muligt at undgå klirren. Samtidig udelukkes, at andre elektriske komponenter i høreapparatkredsløbet påvirkes negativt. Redesign på grund af for høje telespole-klirfaktorer bortfalder, da kompensationen nu kun afhænger af kompensationsinduktansens værdi. Kompensationsinduktansens position er ukritisk, da deraf følgende virkninger kan udlignes ved hjælp 30 af kompensationsinduktansens vindingstal.25 The compensation inductance makes it possible to avoid the rattle. At the same time, it is excluded that other electrical components of the hearing aid circuit are adversely affected. Redesign due to excessive telecoil clutch factors lapses, as compensation now depends only on the value of the compensation inductance. The position of the compensation inductance is uncritical, as the resulting effects can be offset by the winding number of the compensation inductance.

En udformning af opfindelsen forklares nærmere i det følgende under henvisning til tegningen, hvor DK 176409 B1 3 fig. 1 viser en stærkt forenklet, skematisk gengivelse af de væsentlige moduler i høreapparatet ifølge opfindelsen som er udstyret med en telespole og en kompensationsspole og 5 fig. 2 placeringen af kompensationsspolens magnetfelt i forhold til telespolen.An embodiment of the invention is explained in more detail below with reference to the drawing, in which FIG. 1 shows a greatly simplified, schematic representation of the essential modules of the hearing aid according to the invention equipped with a telecoil and a compensation coil; and FIG. 2 shows the position of the magnetic coil of the compensation coil relative to the telecoil.

Det i fig. 1 viste høreapparat har henvisningstallet 1. Det omfatter en mikrofon 2 til omformning af et lydsignal til et elektrisk signal. Endvidere er der indrettet en 10 telespole 3, ved hjælp af hvilken en tunghør får mulighed for ved telefonering at modtage samtalepartnerens signaler ved induktion uden overføring via et lydfelt. Endvidere kan den tunghøre herved eksempelvis høre uden baggrundsstøj og efterklang i kirker eller teatre med induktionssløjfer, til hvilke der er tilsluttet nærtalemikrofoner.The FIG. 1 has the reference numeral 1. It comprises a microphone 2 for converting an audio signal into an electrical signal. Furthermore, a telecoil 3 is arranged, by means of which a heavy-hearing instrument is given the opportunity to receive, by telephone, the interlocutor's signals by induction without transmission via a sound field. In addition, it can hear heavy listening, for example, without background noise and reverberation in churches or theaters with induction loops, to which microphone microphones are connected.

1515

Signalerne fra henholdsvis mikrofonen 2 og telespolen 3 forstærkes i en indgangsforstærker 4, filtreres i et lavpasfilter 6 og et højpasfilter 7 og føres til en lydgiver 9 via en forstærkningsindstilling (GC-regulator) 8. Høreapparatet drives ved hjælp af et batteri 5.The signals from the microphone 2 and the telecoil 3, respectively, are amplified in an input amplifier 4, filtered into a low-pass filter 6 and a high-pass filter 7, and fed to a sound transducer 9 via an amplifier setting (GC controller) 8. The hearing aid is powered by a battery 5.

2020

Ifølge opfindelsen er der - som det fremgår af fig. 2 - i umiddelbar nærhed anbragt en SMD-kompensationsspole 10 parallelt med telespolen 3, men forskudt til siden i forhold dertil.According to the invention, as shown in FIG. 2 - in the immediate vicinity, an SMD compensation coil 10 is arranged parallel to the telecoil 3, but displaced laterally relative thereto.

25 Støjfeltet omkring en støjkilde 13, som påvirker telespolen 3, har henvisningstallet 11. Kompensationsfeltet bestående af kompensationsspolens 10 feltlinjer har henvisningstallet 12. Kompensationsstrømmen gennem kompensationsspolen 10 har henvisningstallet 14. Det skal bemærkes, at der er en god magnetisk kobling mellem de to spoler 3 og 10. En i og for sig kendt kompensationssløjfe i 30 telespolen 3 erstattes af kompensationsspolens 10 induktans. Derved gennemstrømmes kompensationsspolen 10 af en del af forsyningsstrømmen.The noise field around a noise source 13 which affects the telecoil 3 has the reference number 11. The compensation field consisting of the field lines of the compensation coil 10 has the reference number 12. The compensation current through the compensation coil 10 has the reference number 14. It should be noted that there is a good magnetic coupling between the two coils 3 and 10. A compensation loop known per se in the telecoil 3 is replaced by the inductance of the compensation coil 10. Thereby, the compensation coil 10 is flowed by a portion of the supply current.

DK 176409 B1 4DK 176409 B1 4

Kompensationsfeltets 12 styrke kan fastlægges ved hjælp af kompensationsspolens 10 vindingstal.The strength of the compensation field 12 can be determined by the winding numbers of the compensation coil 10.

Hvis man anvender en SMD-kompensationsspole 10 på aluminiumoxid-5 bærerbasis af konstruktionsstørrelsen 0603, andrager vindingstallet ca. 1-20 vindinger. Induktansen vil da være ca. 2 - 200 nH med en ohmsk andel på maksimalt 1Ω. Følgelig ville denne komponent ikke have nogen negativ indflydelse på andre elektriske komponenter eller parametre i høreapparatkredsløbet.If an SMD compensation coil 10 is used on alumina support base of construction size 0603, the winding number is approx. 1-20 turns. The inductance will then be approx. 2 - 200 nH with an ohmic proportion of maximum 1Ω. Accordingly, this component would not adversely affect other electrical components or parameters of the hearing aid circuit.

10 Kompensationsspolens 10 position er ukritisk, da virkningerne heraf kan udlignes ved hjælp af antallet af vindinger. Ifølge opfindelsen kan dyre redesign på grund af for høje telespole-klirfaktorer derved bortfalde.10 The position of the compensation coil 10 is uncritical, as its effects can be offset by the number of turns. According to the invention, expensive redesign due to excessive telecoil clutch factors may thereby lapse.

1515

Claims (12)

1. Høreapparat med forskellige moduler til optagelse, viderebehandling og tilpasning af et lydsignal til en tunghørs høreevne, hvilket høreapparat er udstyret 5 med en telespole (3) til induktiv optagelse af signaler, kendetegnet ved en kompensationsinduktans til frembringelse af et kompensationsfelt (12), som gennemstrømmes af i det mindste en del af forsyningsstrømmen, hvilken kompensationsinduktans er anbragt og/eller dimensioneret således, at der indtræder en magnetisk kobling mellem telespolen (3) og kompensationsinduktansen. 10Hearing aids with various modules for recording, processing and adapting a sound signal to a hearing ability, which hearing aid is provided with a telecoil (3) for inductively recording signals, characterized by a compensation inductance to produce a compensation field (12), which is flowed by at least a portion of the supply current, which compensation inductance is arranged and / or dimensioned such that a magnetic coupling occurs between the telecoil (3) and the compensation inductance. 10 2. Høreapparat ifølge krav 1, kendetegnet ved, at kompensationsinduktansen er anbragt parallelt med telespolen (3).Hearing aid according to claim 1, characterized in that the compensation inductance is arranged parallel to the telecoil (3). 3. Høreapparat ifølge krav 1, kendetegnet ved, at kompensationsinduktan-15 sen er anbragt antiparallelt med telespolen (3).Hearing aid according to claim 1, characterized in that the compensation inductance is arranged antiparallel with the telecoil (3). 4. Høreapparat ifølge krav 1, kendetegnet ved, at kompensationens styrke kan indstilles ved ændring af kompensationssinduktansens vindingstal. 20Hearing aid according to claim 1, characterized in that the strength of the compensation can be adjusted by changing the winding number of the compensation inductance. 20 5. Høreapparat ifølge krav 1, kendetegnet ved, at kompensationens styrke kan indstilles ved en ændring af kompensationssinduktansen afstand til telespolen (3).Hearing aid according to claim 1, characterized in that the strength of the compensation can be adjusted by changing the compensation inductance distance from the telecoil (3). 6. Høreapparat ifølge kravene 1 - 5, kendetegnet ved, at der som kompen-25 sationsinduktans er tilvejebragt en luftspole, især en SMD-luftspole (10).Hearing aid according to claims 1 to 5, characterized in that an air coil, in particular an SMD air coil (10), is provided as a compensation inductance. 7. Høreapparat ifølge kravene 1 - 6, kendetegnet ved, at kompensationssinduktansen har en værdi, der ligger i området 2- 200 nH, fortrinsvis 10 - 120 nH. 30Hearing aid according to claims 1 - 6, characterized in that the compensation inductance has a value in the range of 2- 200 nH, preferably 10 - 120 nH. 30 8. Høreapparat ifølge kravene 1 - 7, kendetegnet ved, at kompensationen kan ændres på det færdige høreapparat. DK 176409 B1 6Hearing aid according to claims 1 - 7, characterized in that the compensation can be changed on the finished hearing aid. DK 176409 B1 6 9. Fremgangsmåde til reduktion af magnetiske støjfelter ved drift af høreapparater med telespoler ifølge et af kravene 1 - 8, kendetegnet ved, at en kom-pensationssinduktans positioneres således i området ved det støjfelt (11), som optages af telespolen (3), at en magnetisk kobling mellem telespole og kom- 5 pensationsinduktans er fremherskende, og at i det mindste en del af høreapparatets forsyningsstrøm gennemstrømmer kompensationsinduktansen.Method for reducing magnetic noise fields by operating hearing aids with telecoils according to one of claims 1 to 8, characterized in that a compensation inductance is positioned in the area of the noise field (11) occupied by the telecoil (3), that a magnetic coupling between the telecoil and the compensation inductance is prevalent and that at least part of the supply current of the hearing aid flows through the compensation inductance. 10. Fremgangsmåde ifølge krav 9, kendetegnet ved, at kompensationsinduktansens feltstyrke bestemmes ved en tilpasning af vindingstallet. 10Method according to claim 9, characterized in that the field strength of the compensation inductance is determined by an adjustment of the winding number. 10 11. Fremgangsmåde ifølge krav 9, kendetegnet ved, at den ohmske andel af kompensationsinduktansen er mindre end eller lig 1Ω.Method according to claim 9, characterized in that the ohmic proportion of the compensation inductance is less than or equal to 1Ω. 12. Fremgangsmåde ifølge krav 9, kendetegnet ved, at kompensationsinduk-15 tansen har en værdi, der ligger i området 2- 200 nH, fortrinsvis 10-120 nH.Method according to claim 9, characterized in that the compensation inductance has a value in the range of 2- 200 nH, preferably 10-120 nH.
DK41298A 1997-03-24 1998-03-24 Hearing aid with telecoil and method of reducing magnetic noise fields in a hearing aid DK176409B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE1997112236 DE19712236C1 (en) 1997-03-24 1997-03-24 Hearing aid with inductive hearing coil
DE19712236 1997-03-24

Publications (2)

Publication Number Publication Date
DK41298A DK41298A (en) 1998-09-25
DK176409B1 true DK176409B1 (en) 2007-12-27

Family

ID=7824400

Family Applications (1)

Application Number Title Priority Date Filing Date
DK41298A DK176409B1 (en) 1997-03-24 1998-03-24 Hearing aid with telecoil and method of reducing magnetic noise fields in a hearing aid

Country Status (3)

Country Link
CH (1) CH692885A5 (en)
DE (1) DE19712236C1 (en)
DK (1) DK176409B1 (en)

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19809567C2 (en) * 1998-03-05 2003-02-20 Siemens Audiologische Technik Hearing aid and method for suppressing magnetic interference fields
DE19854201C2 (en) * 1998-11-24 2001-05-23 Siemens Audiologische Technik Hearing aid with induction coil to reduce magnetic interference fields
US6829364B2 (en) 2001-06-22 2004-12-07 Topholm & Westermann Aps, Ny Hearing aid with a capacitor having a large capacitance
DE10223544C1 (en) * 2002-05-27 2003-07-24 Siemens Audiologische Technik Amplifier device for hearing aid with microphone and pick-up coil inputs, has amplifier provided with separate filters for acoustic and inductive feedback compensation
DE102004051226B3 (en) * 2004-10-20 2006-01-19 Siemens Audiologische Technik Gmbh Hearing aid with a loop to compensate for inductive interference
DE102006005286B3 (en) 2006-02-06 2007-06-21 Siemens Audiologische Technik Gmbh Battery contacting device for hearing aid, has spiral contact, which is provided for contacting negative terminal of battery and is formed in partial section as induction coil through which current supplied by battery is derived
DE102007007800B3 (en) * 2007-02-16 2008-08-28 Siemens Audiologische Technik Gmbh Hearing device with receiver compensation coil
DE102009007233B4 (en) * 2009-02-03 2012-07-26 Siemens Medical Instruments Pte. Ltd. Hearing device with noise compensation and design method

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3231029A1 (en) * 1982-08-20 1984-02-23 Robert Bosch Gmbh, 7000 Stuttgart Hearing aid amplifier circuit
DE8708892U1 (en) * 1987-06-26 1988-10-27 Siemens AG, 1000 Berlin und 8000 München Hearing aid coil with one coil winding
JPH01300748A (en) * 1988-05-30 1989-12-05 Rion Co Ltd Receiving device

Also Published As

Publication number Publication date
DK41298A (en) 1998-09-25
CH692885A5 (en) 2002-11-29
DE19712236C1 (en) 1998-10-22

Similar Documents

Publication Publication Date Title
DK176339B1 (en) Hearing aid with induction coil and method for reducing magnetic noise fields
DE102007046437B4 (en) Fully automatic switching on / off for hearing aids
US8265312B2 (en) Hearing aid having improved RF immunity to RF electromagnetic interference produced from a wireless communications device
US9071214B2 (en) Audio signal controller
KR101465378B1 (en) Hearing aid and a method of driving an output stage
US7657046B2 (en) IC chip type hearing aid module for mobile communication terminal
US20130108093A1 (en) Integrated automatic telephone switch
US20090208025A1 (en) Active noise reduction system
US20030002699A1 (en) Method for the operation of a digital, programmable hearing aid as well as a digitally programmable hearing aid
EP1651006A2 (en) Hearing aid with line loop to compensate the inductive disturbance fields
DK176409B1 (en) Hearing aid with telecoil and method of reducing magnetic noise fields in a hearing aid
EP1926343A1 (en) Hearing aid with automatic deactivation and a corresponding method
EP2028881A2 (en) Hearing aid device system with magnetic field sensors
JPS5857199U (en) hearing aid
EP1692778A1 (en) Resonance frequency shift canceling in wireless hearing aids
JP2008205598A (en) Speaker apparatus, speaker driving device and control method thereof
EP1773098A1 (en) A system and method for matching microphones
EP2501158B1 (en) Hearing aid magnetic sensor with counter windings
AU2004214555B2 (en) Hearing aid with magnetic-field-controlled switch and corresponding method for operating a hearing aid
WO2003092327A1 (en) Method and device for reducing high frequency error components of a multi-channel modulator
EP0843427A1 (en) An arrangement for suppressing harmonic interference in signal transmission
US20080292066A1 (en) Telephone handset coupling system
EP0028241A1 (en) Feedback arrangement
US7813100B2 (en) Demagnetization circuit of a mobile phone
EP0777403B1 (en) A system of sound diffusion, particularly for large spaces

Legal Events

Date Code Title Description
PUP Patent expired

Expiry date: 20180324