DE19727657C1 - Anti-noise loudspeaker combating noise for direct use in MR tomography esp. control of sound in brain and heart studies - Google Patents

Anti-noise loudspeaker combating noise for direct use in MR tomography esp. control of sound in brain and heart studies

Info

Publication number
DE19727657C1
DE19727657C1 DE19727657A DE19727657A DE19727657C1 DE 19727657 C1 DE19727657 C1 DE 19727657C1 DE 19727657 A DE19727657 A DE 19727657A DE 19727657 A DE19727657 A DE 19727657A DE 19727657 C1 DE19727657 C1 DE 19727657C1
Authority
DE
Germany
Prior art keywords
noise
loudspeaker
sound
esp
direct use
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 - Fee Related
Application number
DE19727657A
Other languages
German (de)
Inventor
Frank Baumgart
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.)
INST NEUROBIOLOGIE DIREKTOR PR
Original Assignee
INST NEUROBIOLOGIE DIREKTOR PR
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 INST NEUROBIOLOGIE DIREKTOR PR filed Critical INST NEUROBIOLOGIE DIREKTOR PR
Priority to DE19727657A priority Critical patent/DE19727657C1/en
Application granted granted Critical
Publication of DE19727657C1 publication Critical patent/DE19727657C1/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
    • G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
    • G10K11/1785—Methods, e.g. algorithms; Devices
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
    • G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
    • G10K11/1787—General system configurations
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
    • G10K2210/10—Applications
    • G10K2210/116—Medical; Dental
    • G10K2210/1161—NMR or MRI
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
    • G10K2210/30—Means
    • G10K2210/321—Physical
    • G10K2210/3212—Actuator details, e.g. composition or microstructure
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R9/00—Transducers of moving-coil, moving-strip, or moving-wire type
    • H04R9/06—Loudspeakers

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Magnetic Resonance Imaging Apparatus (AREA)

Abstract

The anti-noise loudspeaker for actively combatting noise, esp. for direct use in magnetic resonance tomographs, without interfering with the image production. An electrodynamic low middle tone loudspeaker without its own magnets is provided. With the use of this loudspeaker for anti-noise production, the drive power of the moving coil of the antimagnetic loudspeaker, is producible by an inhomogeneous magnetic field spatially spread in the direction of the moving coil main axis.

Description

Ein Antischallautsprecher als elektrodynamischer Tiefmitteltonlautsprecher ohne eigenen Magneten zur Verwendung unmittelbar im Magnetresonanztomographen zur aktiven Lärmbekämpfung, ohne mit der Bildgebung zu interferieren.An anti-noise speaker as an electrodynamic low-mid speaker without its own Magnets for immediate use in magnetic resonance imaging for active noise abatement without interfering with imaging.

Superschnelle Methoden der Kernspintomographie zur bildlichen Darstellung von z. B. Hirnleistungs- und Herzfunktionsstörungen sind durch ihre hohen Schallemissionen, denen im niederfrequen­ ten Bereich durch passive Maßnahmen nur unzureichend begegnet werden kann, in Anwendung und klinischer Verbreitung einge­ schränkt (Zeitschrift "British Journal of Radiology", Jahrgang 1994, Heft 67, Seiten 413 bis 415; Zeitschrift "Radiology", Jahrgang 1994, Heft 191, Seiten 91 bis 93 in Verbindung mit der "Empfehlung der Strahlenschutzkommission, verabschiedet in der 131. Sitzung am 22. Juni 1995", Seite 17). Auch unterhalb der gesetzlichen Grenzwerte stellen die Schallemissionen eine Redu­ zierung von Patientenkomfort und Kommunikationsmöglichkeiten und damit der Patientensicherheit dar. Aktive Lärmbekämpfung ("Antischall") stellt ein aussichtsreiches Verfahren zur Redu­ zierung der Schallemissionen von MRT-Anlagen dar (Zeitschrift "Radiology" Jahrgang 1989, Heft 173, Seiten 549 bis 550 und Zeitschrift "Proceedings of the Society of Magnetic Resonance" Jahrgang 1995, Heft 2, Seite 1223). Eine wirksame Störgeräusch­ auslöschung ist für Frequenzen bis etwa 1 kHz aber nur möglich, wenn I.) der Antischallautsprecher einen sehr geringen räumli­ chen Abstand zur Störgeräuschquelle (dem Gradientenrohr inner­ halb des MRT-Magneten) hat und II.) der Antischallautsprecher das akustische Feld der Störquelle spiegeln kann (Buch "Active Control of Sound", Academic Press: London, Jahr 1992). Es ist bisher kein mit Magnetresonanztomographen kompatibler Schaller­ zeuger beschrieben worden, der diese Forderungen erfüllt.Superfast methods of magnetic resonance imaging for imaging Representation of z. B. Brain performance and cardiac dysfunction are due to their high sound emissions, those in the low frequency Passive measures are insufficient to address this area can be used in application and clinical spread limits (British Journal of Radiology, vintage 1994, No. 67, pages 413 to 415; Journal "Radiology", 1994, issue 191, pages 91 to 93 in connection with the "Recommendation of the Radiation Protection Commission, adopted in the 131st meeting on June 22, 1995 ", page 17). Also below the statutory limit values reduce noise emissions decoration of patient comfort and communication possibilities and thus represents patient safety. Active noise abatement ("Antischall") represents a promising method for reducing of noise emissions from MRI systems (magazine "Radiology" volume 1989, number 173, pages 549 to 550 and Proceedings of the Society of Magnetic Resonance magazine 1995, Issue 2, page 1223). An effective noise cancellation is only possible for frequencies up to 1 kHz, if I.) the anti-noise speaker a very small spatial Chen distance to the noise source (inside the gradient tube half of the MRI magnet) and II.) the anti-sound speaker can reflect the acoustic field of the source of interference (book "Active  Control of Sound ", Academic Press: London, 1992). It is So far no sound generator compatible with magnetic resonance tomographs has been described who meets these requirements.

Der im Patentanspruch angegebenen Erfindung liegt das Problem zugrunde, daß die hohen Störschallpegel von MRT-Anlagen durch aktive Lärmbekämpfung wirkungsvoll gesenkt werden können, wenn ein leistungsstarker Antischallerzeuger im Gradientenrohr der MRT-Anlage installiert werden kann. Insbesondere muß hierbei dem Umstand Rechnung getragen werden, daß die Handhabung magneti­ scher Materialien in heutzutage zur Anwendung gelangenden Ma­ gnetfeldflußdichten (1 T bis 3 T im klinischen Betrieb) ein äu­ ßerst großes Gefahrenpotential darstellt.The invention specified in the patent claim is the problem based on the fact that the high noise levels of MRI systems active noise abatement can be effectively reduced if a powerful anti-noise generator in the gradient tube of the MRI system can be installed. In particular, the The fact that the handling magneti materials used today gnetfield flow densities (1 T to 3 T in clinical operation) represents an extremely high risk potential.

Anordnungen zur Auslöschung von Schallwellen, basierend auf dem Prinzip der Erzeugung eines um 180° phasenverschobenen Signals, sind vielfach auch außerhalb der Magnetresonanztomographie be­ schrieben worden (DE 195 28 888 A1), können jedoch im Bereich der Magnetresonanztomographie aufgrund der dort vorliegenden Ge­ gebenheiten nicht verwandt werden.Arrangements for canceling sound waves based on the Principle of generating a 180 ° phase-shifted signal, are often also outside of magnetic resonance imaging have been written (DE 195 28 888 A1), but can in the area magnetic resonance imaging based on the Ge present there circumstances are not used.

Frühere Entwicklungen von Störgeräuschunterdrückungssystemen in der Magnetresonanztomographie beschränken sich auf die Stör­ geräuschverminderung zur Verbesserung der Patientenüberwachung außerhalb des Magnetresonanztomographen, in einem vom Magnetre­ sonanztomographen akustisch isolierten Kontrollraum. Hierbei wird zudem kein Antischall erzeugt, sondern ein durch Verwendung geeigneter adaptiver Filter um das Störsignal vermindertes Si­ gnal mit einem herkömmlichen Lautsprecher innerhalb des magnet­ feldfreien Kontrollraumes ausgegeben (EP 0 655 730 A1). Previous developments in noise suppression systems in Magnetic resonance imaging is limited to the sturgeon noise reduction to improve patient monitoring outside of the magnetic resonance scanner, in one of the magnetre sonography tomograph acoustically isolated control room. Here no sound is generated, but one through use suitable adaptive filter Si reduced by the interference signal gnal with a conventional speaker inside the magnet field-free control room issued (EP 0 655 730 A1).  

Ein zur Verwendung innerhalb des homogenen Teils des Magnetfel­ des eines Magnetresonanztomographen geeigneter elektrodynami­ scher Lautsprecher ohne eigenen Magneten unter Verwendung ferro­ magnetischer Feldinhomogenisierer sowie von Schlauchleiter­ systemen zur Weiterleitung des erzeugten Schalls ist bereits be­ schrieben worden (US 005 450 499 A). Dieser liefert jedoch auf­ grund des verwendeten Schlauchleitersystems weder die zur Erzeu­ gung von Antischall erforderlichen Schalldrücke über das benö­ tigte Frequenzband in definierter Phasenlage, noch erlaubt die Verwendung von wesentlichen ferromagnetischen Bauteilen die un­ bedingt zu fordernde gefahrlose Handhabung in von Magnetfeldern durchdrungenen Räumen. Desweiteren entstehen bei Verwendung fer­ romagnetischer Bauteile innerhalb des ursprünglich homogenen Teils des Magnetfeldes durch die lokale Erzeugung nichtdefinier­ ter Magnetfeldinhomogenitäten Interferenzen mit der Bildgebung.One for use within the homogeneous part of the magnetic field that of a magnetic resonance tomograph suitable electrodynami shear speaker without its own magnet using ferro magnetic field inhomogenizer and hose conductor systems for forwarding the sound generated is already be have been written (US 005 450 499 A). However, this delivers due to the hose line system used, neither the required sound pressure over the required frequency band in a defined phase position, still allows Use of essential ferromagnetic components the un Safe handling in magnetic fields is required permeated spaces. Furthermore, arise when using fer romagnetic components within the originally homogeneous Part of the magnetic field due to the local generation undefined Magnetic field inhomogeneities interference with imaging.

Diese Probleme werden durch den im Patentanspruch aufgeführten Antischallautsprecher gelöst.These problems are exacerbated by that in the claim Anti-sound speaker solved.

Die mit der Erfindung erzielten Vorteile bestehen darin, daß ei­ ne aktive Lärmbekämpfung über einen, mit Schlauchleitersystemen nicht erzielbaren, ausreichend großen Frequenzbereich bei MRT- Anlagen, insbesondere im Bereich unterhalb 1 kHz bis 50 Hz, er­ möglicht wird, da das akustische Problem der Erzeugung phasende­ finierten Antischalls auf den einfachen eindimensionalen Fall von Schallwellen im Inneren einer Röhre reduziert wird und der Abstand zwischen Störquelle und Antischallautsprecher so verrin­ gert wird, daß Störschallauslöschung bis zu einer Frequenz von ca. 1 kHz möglich wird. Oberhalb dieser Frequenz ist passiver Schallschutz ausreichend wirksam.The advantages achieved by the invention are that egg ne active noise abatement via one, with hose line systems not attainable, sufficiently large frequency range with MRI Systems, especially in the range below 1 kHz to 50 Hz, he is possible because the acoustic problem of generation is phased refined anti-noise on the simple one-dimensional case is reduced by sound waves inside a tube and the Reduce the distance between the source of interference and the anti-noise speaker is that noise cancellation up to a frequency of  approx. 1 kHz becomes possible. Above this frequency is more passive Sound insulation sufficiently effective.

Weitere Vorteile bietet die offene Bauform der Schwingspule des Tiefmitteltonlautsprechers, sie ermöglicht I.) eine vollkommen symmetrische und damit (Lorentz-) kraftfreie Stromzuführung, II.) eine Gebläsekühlung zur Erhöhung der Dauerlastfestigkeit sowie III.) eine axiale Verlängerung des Schwingspulenträgers zur räumlichen Trennung der Membran, nahe dem untersuchten Volu­ men im homogenen Teil des Magnetfeldes, von der Schwingspule im inhomogenen Teil des Magnetfeldes am Rand des Magneten.The open design of the voice coil of the Low-mid speaker, it enables I.) a perfect symmetrical and thus (Lorentz) force-free power supply, II.) Fan cooling to increase the permanent load resistance and III.) an axial extension of the voice coil former for spatial separation of the membrane, close to the examined volu in the homogeneous part of the magnetic field, from the voice coil in the inhomogeneous part of the magnetic field at the edge of the magnet.

Der vollständige Verzicht auf ferromagnetische Materialien er­ möglicht die unter allen Umständen sichere Handhabung des Anti­ schallautsprechers. Anderenfalls können ferromagnetische Teile geschoßartig in Richtung des Zentrums des permanenten Magnetfel­ des beschleunigt werden. Es sind keinerlei Sicherungsmaßnahmen zur Beherrschung von ferromagnetischen Kräften in der Nähe von MRT-Magneten erforderlich.The complete absence of ferromagnetic materials enables safe handling of the Anti under all circumstances sound speaker. Otherwise, ferromagnetic parts projectile towards the center of the permanent magnetic field be accelerated. There are no security measures for the control of ferromagnetic forces in the vicinity of MRI magnets required.

Ein Ausführungsbeispiel ist in der Zeichnung dargestellt und wird im folgenden näher beschrieben.An embodiment is shown in the drawing and is described in more detail below.

Der elektrodynamische Tiefmitteltonlautsprecher ist aus einem kommerziell erhältlichen Tieftonlautsprecher mit Aluminiumdruck­ gußkorb (Hersteller: Baltlains, Lettland, Typ 75 GDN) herge­ stellt worden. Der Lautsprechermagnet mit Polplatte sowie die Spulenzuleitungen wurden entfernt. Die nun offenliegende Schwingspule wurde direkt an ein geschirmtes Kabel (RG 58 CU) angeschlossen und mit einer Gebläsekühlung versehen. Durch die Inhomogenität des starken Magnetfeldes am Rande des MRT-Magneten erfährt die Schwingspule nun je nach eigener Polarität eine Kraft in Richtung abnehmender bzw. zunehmender Feldstärke. Auf einer Holzplatte am Ende des Gradientenrohres innerhalb des MRT- Magneten (Bruker, 3 T/60 cm Magnet mit Gradientenrohr SK330) in­ stalliert, liefert dieser Lautsprecher Schalldrücke bis zu 130 dB bei 100 Hz und bis zu 115 dB bei 6 kHz - gemessen mit einem Brüel & Kjaer Typ 2233 Schallpegelmesser im Zentrum des Magne­ ten - bei einer Verstärkerleistung von etwa 100 Watt. Diese Lei­ stungen reichen aus, um wirksam Antischall erzeugen zu können.The electrodynamic low-mid speaker is made of one commercially available woofer with aluminum printing cast basket (manufacturer: Baltlains, Latvia, type 75 GDN) herge has been put. The loudspeaker magnet with pole plate as well as the Coil leads have been removed. The now exposed Voice coil was connected directly to a shielded cable (RG 58 CU) connected and provided with fan cooling. Through the Inhomogeneity of the strong magnetic field at the edge of the MRI magnet  the voice coil now experiences one depending on its polarity Force in the direction of decreasing or increasing field strength. On a wooden plate at the end of the gradient tube inside the MRI Magnets (Bruker, 3 T / 60 cm magnet with gradient tube SK330) in installed, this speaker delivers sound pressures up to 130 dB at 100 Hz and up to 115 dB at 6 kHz - measured with a Brüel & Kjaer Type 2233 sound level meter in the center of the Magne ten - with an amplifier output of around 100 watts. This lei Stations are sufficient to be able to effectively generate anti-noise.

Claims (1)

Ein Antischallautsprecher zur aktiven Lärmbekämpfung, insbeson­ dere zur Verwendung unmittelbar im Magnetresonanztomographen, ohne mit der Bildgebung zu interferieren, dadurch gekennzeichnet, daß ein elektrodynamischer Tiefmitteltonlautsprecher ohne eigenen Magneten vorgesehen ist, bei dem zur Antischallerzeugung die An­ triebskraft der Schwingspule des antimagnetischen Lautsprechers durch ein externes, räumlich ausgedehntes, in Richtung der Schwingspulenhauptachse inhomogenes Magnetfeld erzeugbar ist.An anti-noise loudspeaker for active noise abatement, in particular for use directly in the magnetic resonance tomograph without interfering with the imaging, characterized in that an electrodynamic low-mid-range loudspeaker is provided without its own magnet, in which the driving force of the voice coil of the antimagnetic loudspeaker by an external, spatially extended, inhomogeneous magnetic field in the direction of the main voice coil axis can be generated.
DE19727657A 1997-06-30 1997-06-30 Anti-noise loudspeaker combating noise for direct use in MR tomography esp. control of sound in brain and heart studies Expired - Fee Related DE19727657C1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
DE19727657A DE19727657C1 (en) 1997-06-30 1997-06-30 Anti-noise loudspeaker combating noise for direct use in MR tomography esp. control of sound in brain and heart studies

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19727657A DE19727657C1 (en) 1997-06-30 1997-06-30 Anti-noise loudspeaker combating noise for direct use in MR tomography esp. control of sound in brain and heart studies

Publications (1)

Publication Number Publication Date
DE19727657C1 true DE19727657C1 (en) 1999-01-14

Family

ID=7834023

Family Applications (1)

Application Number Title Priority Date Filing Date
DE19727657A Expired - Fee Related DE19727657C1 (en) 1997-06-30 1997-06-30 Anti-noise loudspeaker combating noise for direct use in MR tomography esp. control of sound in brain and heart studies

Country Status (1)

Country Link
DE (1) DE19727657C1 (en)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19910018C1 (en) * 1999-03-08 2000-10-19 Siemens Ag Magnetic resonance tomography apparatus operating method
DE10018032C1 (en) * 2000-04-04 2001-08-16 Leibniz Inst Fuer Neurobiologi Acoustic transducer for headphones
WO2001076320A2 (en) * 2000-04-04 2001-10-11 Leibnitz-Institut Für Neurobiologie Acoustic transducer for broad-band loudspeakers or headphones
DE10018033C1 (en) * 2000-04-04 2001-11-29 Leibniz Inst Fuer Neurobiologi Acoustic transducer has membrane(s) of elastic, non-magnetic or weakly magnetic material connected to conducting tracks on which Lorenz force acts
DE10343006A1 (en) * 2003-09-17 2005-04-14 Siemens Ag Electroacoustic system for reproduction of acoustic signals within MR diagnosis equipment, has a loudspeaker with an electrodynamic vibration system that is designed taking into account the tomograph static base magnetic field
DE102005000848B3 (en) * 2005-01-05 2006-06-22 Siemens Ag Device for protecting ear from noises of magnetic resonance tomography system has protective sound generating mechanism electronically connected to it for generating protective sound of steadily rising amplitude
US9702947B2 (en) 2012-10-24 2017-07-11 Samsung Electronics Co., Ltd. MRI acoustic system, acoustic output device, and electro-acoustic transducer
US9791524B2 (en) 2012-10-24 2017-10-17 Samsung Electronics Co., Ltd. MRI acoustic system, acoustic output device, and electro-acoustic transducer
US11601742B2 (en) 2016-11-28 2023-03-07 Innovere Medical Inc. Systems, methods and devices for communication in noisy environments

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0665730A1 (en) * 1992-10-20 1995-08-09 Premier Laser Systems, Inc. Methods and apparatus for applying thermal energy to luminal tissue
US5450499A (en) * 1992-11-25 1995-09-12 Magnetic Resonance Equipment Corporation Audio speaker for use in an external magnetic field
DE19528888A1 (en) * 1995-07-20 1997-01-23 Nokia Deutschland Gmbh Arrangement for canceling sound waves

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0665730A1 (en) * 1992-10-20 1995-08-09 Premier Laser Systems, Inc. Methods and apparatus for applying thermal energy to luminal tissue
US5450499A (en) * 1992-11-25 1995-09-12 Magnetic Resonance Equipment Corporation Audio speaker for use in an external magnetic field
DE19528888A1 (en) * 1995-07-20 1997-01-23 Nokia Deutschland Gmbh Arrangement for canceling sound waves

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19910018C1 (en) * 1999-03-08 2000-10-19 Siemens Ag Magnetic resonance tomography apparatus operating method
DE10018032C1 (en) * 2000-04-04 2001-08-16 Leibniz Inst Fuer Neurobiologi Acoustic transducer for headphones
WO2001076320A2 (en) * 2000-04-04 2001-10-11 Leibnitz-Institut Für Neurobiologie Acoustic transducer for broad-band loudspeakers or headphones
DE10018033C1 (en) * 2000-04-04 2001-11-29 Leibniz Inst Fuer Neurobiologi Acoustic transducer has membrane(s) of elastic, non-magnetic or weakly magnetic material connected to conducting tracks on which Lorenz force acts
WO2001076320A3 (en) * 2000-04-04 2002-04-18 Leibnitz Inst Fuer Neurobiolog Acoustic transducer for broad-band loudspeakers or headphones
DE10343006A1 (en) * 2003-09-17 2005-04-14 Siemens Ag Electroacoustic system for reproduction of acoustic signals within MR diagnosis equipment, has a loudspeaker with an electrodynamic vibration system that is designed taking into account the tomograph static base magnetic field
DE102005000848B3 (en) * 2005-01-05 2006-06-22 Siemens Ag Device for protecting ear from noises of magnetic resonance tomography system has protective sound generating mechanism electronically connected to it for generating protective sound of steadily rising amplitude
US7804964B2 (en) 2005-01-05 2010-09-28 Siemens Aktiengesellschaft Device for protecting the hearing from loud MRT sounds
CN1801320B (en) * 2005-01-05 2011-08-31 西门子公司 Device to protect hearing against mrt noise
US9702947B2 (en) 2012-10-24 2017-07-11 Samsung Electronics Co., Ltd. MRI acoustic system, acoustic output device, and electro-acoustic transducer
US9791524B2 (en) 2012-10-24 2017-10-17 Samsung Electronics Co., Ltd. MRI acoustic system, acoustic output device, and electro-acoustic transducer
US11601742B2 (en) 2016-11-28 2023-03-07 Innovere Medical Inc. Systems, methods and devices for communication in noisy environments

Similar Documents

Publication Publication Date Title
DE19727657C1 (en) Anti-noise loudspeaker combating noise for direct use in MR tomography esp. control of sound in brain and heart studies
DE2536439A1 (en) SPEAKER SYSTEM
DE1167896B (en) Electroacoustic converter
CH694607A5 (en) Hearing aid with inductor and method for reducing interference fields.
EP1027818A1 (en) Method and system for controlling the propagation of magnetic fields by electrodynamic/-magnetic transducers, especially in telecommunications devices
DE2446982A1 (en) PROCEDURE FOR SPEAKER SYSTEM OPERATION
DE10156816B4 (en) Multi-function signal generator
DE2821617C2 (en) Microphone with an arrangement for suppressing structure-borne noise
US4933981A (en) Sound system
DE102016202658A1 (en) Speaker module for a hearing aid and hearing aid
DE69908930T2 (en) TELEPHONE WITH LOW-FREQUENCY ENHANCEMENT MEANS
EP0242856B1 (en) Coaxial loud speaker
DE2854912A1 (en) ELECTROACOUSTIC CONVERTER
EP1273204B1 (en) Acoustic transducer for broad-band loudspeakers or headphones
DE3025391C2 (en)
USRE34219E (en) Sound system
DE10018033C1 (en) Acoustic transducer has membrane(s) of elastic, non-magnetic or weakly magnetic material connected to conducting tracks on which Lorenz force acts
DE1163386B (en) Dynamic headphones based on the two-way system.
DE19819452C1 (en) Method and device for the electroacoustic transmission of sound energy
DE10343006A1 (en) Electroacoustic system for reproduction of acoustic signals within MR diagnosis equipment, has a loudspeaker with an electrodynamic vibration system that is designed taking into account the tomograph static base magnetic field
DE10018032C1 (en) Acoustic transducer for headphones
DE3312318A1 (en) Explosion-proof electro-acoustic transducer
DE3233990C2 (en) Methods and devices for improved reproduction of phantom sound sources
EP0208907B1 (en) Magnetic system for a dynamic loudspeaker
EP0081780B1 (en) Electrodynamic transducer

Legal Events

Date Code Title Description
8100 Publication of the examined application without publication of unexamined application
D1 Grant (no unexamined application published) patent law 81
8364 No opposition during term of opposition
R119 Application deemed withdrawn, or ip right lapsed, due to non-payment of renewal fee

Effective date: 20120103