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DE2507428A1 - Air duct sound attenuator - with inlet pick-up processed to feed back cancelling sound at outlet of duct - Google Patents

Air duct sound attenuator - with inlet pick-up processed to feed back cancelling sound at outlet of duct

Info

Publication number
DE2507428A1
DE2507428A1 DE19752507428 DE2507428A DE2507428A1 DE 2507428 A1 DE2507428 A1 DE 2507428A1 DE 19752507428 DE19752507428 DE 19752507428 DE 2507428 A DE2507428 A DE 2507428A DE 2507428 A1 DE2507428 A1 DE 2507428A1
Authority
DE
Germany
Prior art keywords
sound
path
signal
point
processed
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.)
Pending
Application number
DE19752507428
Other languages
German (de)
Inventor
Henry Lawson-Tancred
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.)
LAWSON TANCRED HENRY
Original Assignee
LAWSON TANCRED HENRY
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
Priority claimed from GB8142/74A external-priority patent/GB1492963A/en
Application filed by LAWSON TANCRED HENRY filed Critical LAWSON TANCRED HENRY
Publication of DE2507428A1 publication Critical patent/DE2507428A1/en
Pending legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
    • F16L55/00—Devices or appurtenances for use in, or in connection with, pipes or pipe systems
    • F16L55/02—Energy absorbers; Noise absorbers
    • F16L55/033—Noise absorbers
    • F16L55/0333—Noise absorbers by means of an active system
    • 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
    • G10K11/1781—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 characterised by the analysis of input or output signals, e.g. frequency range, modes, transfer functions
    • G10K11/17813—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 characterised by the analysis of input or output signals, e.g. frequency range, modes, transfer functions characterised by the analysis of the acoustic paths, e.g. estimating, calibrating or testing of transfer functions or cross-terms
    • G10K11/17815—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 characterised by the analysis of input or output signals, e.g. frequency range, modes, transfer functions characterised by the analysis of the acoustic paths, e.g. estimating, calibrating or testing of transfer functions or cross-terms between the reference signals and the error signals, i.e. primary path
    • 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
    • G10K11/1781—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 characterised by the analysis of input or output signals, e.g. frequency range, modes, transfer functions
    • G10K11/17813—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 characterised by the analysis of input or output signals, e.g. frequency range, modes, transfer functions characterised by the analysis of the acoustic paths, e.g. estimating, calibrating or testing of transfer functions or cross-terms
    • G10K11/17817—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 characterised by the analysis of input or output signals, e.g. frequency range, modes, transfer functions characterised by the analysis of the acoustic paths, e.g. estimating, calibrating or testing of transfer functions or cross-terms between the output signals and the error signals, i.e. secondary path
    • 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
    • G10K11/1781—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 characterised by the analysis of input or output signals, e.g. frequency range, modes, transfer functions
    • G10K11/17813—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 characterised by the analysis of input or output signals, e.g. frequency range, modes, transfer functions characterised by the analysis of the acoustic paths, e.g. estimating, calibrating or testing of transfer functions or cross-terms
    • G10K11/17819—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 characterised by the analysis of input or output signals, e.g. frequency range, modes, transfer functions characterised by the analysis of the acoustic paths, e.g. estimating, calibrating or testing of transfer functions or cross-terms between the output signals and the reference signals, e.g. to prevent howling
    • 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
    • G10K11/1785—Methods, e.g. algorithms; Devices
    • G10K11/17857—Geometric disposition, e.g. placement of microphones
    • 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
    • G10K11/17873—General system configurations using a reference signal without an error signal, e.g. pure feedforward
    • 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
    • G10K11/17875—General system configurations using an error signal without a reference signal, e.g. pure feedback
    • 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
    • G10K2210/112—Ducts
    • 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
    • G10K2210/301—Computational
    • G10K2210/3011—Single acoustic input
    • 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
    • G10K2210/301—Computational
    • G10K2210/3013—Analogue, i.e. using analogue computers or circuits

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Soundproofing, Sound Blocking, And Sound Damping (AREA)

Abstract

The method is for reducing sound propagation along a channel, for example, in the suppression of fan noise in air ducts, and is of low cost and high efficiency at the lower frequencies. The sound is picked up at a point of the sound path and fed to a parallel path as a signal which is processed. At a point nearer the quiet area to be protected, the processed sound is fed back in the form of a compensation signal which reduces the total sound to nearly zero. The processor may take the form of filters with a suitable phase shift for each component frequency, or delay elements with an equal delay for all frequencies.

Description

Verfahren und Vorrichtung zur Unterdrückung oder Abschwächung der Schallfortpflanzung. Method and device for suppressing or attenuating the Sound propagation.

Die Erfindung betrifft ein Verfahren zur Unterdrückung oder Abschwächung der Schallfortpflanzung längs eines Schallweges von einer Schallquelle zu einem ruhigen Bereich sowie eine Vorrichtung zur Durchführung dieses Verfahrens.The invention relates to a method of suppression or attenuation the propagation of sound along a sound path from one sound source to one quiet area as well as a device for performing this procedure.

Man kennt bereits eine ganze Reihe von akustischen Einrichtungen, mit deren Hilfe die Schallfortpflanzung durch Leitungen oder Öffnungen aus einem umschlossenen Raum oder in einen umschlossenen Raum gedämmt werden soll, beispielsweise bei LUftungs-, Zentralheizungs- und Klimaanlagen. Derartige Einrichtungen sind jedoch zur Dämmung oder Abschwächung des Schalls bei niedrigen Frequenzen nicht sehr wirksam und können Energieverluste mit sich bringen, indem sie einen starken Druckabfall in Leitungen verursachen.We already know a number of acoustic facilities, with the help of which the sound propagation through lines or openings is to be insulated from an enclosed space or in an enclosed space, for example in ventilation, central heating and air conditioning systems. Such facilities However, they are not used to attenuate or attenuate the sound at low frequencies very effective and can entail energy losses by having a strong Cause pressure drop in pipes.

Die Erfindung hat sich daher die Aufgabe gestellt, ein Verfahren der eingangs genannten Art zu verwirklichen, welches bei geringen Kosten selbst bei niedrigen Frequenzen äußerst wirksam ist. Eine erfindungsgemäße Vorrichtung zur Durchführung dieses Verfahrens soll im Aufbau und im Betrieb äußerst preiswert sein.The invention has therefore set itself the task of providing a method of to realize initially mentioned type, which at low cost even with low frequencies is extremely effective. A device according to the invention for Implementation of this process should be extremely inexpensive to build and operate.

Zur Lösung dieser Aufgabe schlägt die Erfindung in verfahrensmäßiger Hinsicht vor, daß der Schall an einer ersten Stelle des Schallweges aufgefangen und in Form eines Signales einem Nebenweg zugeleitet und dort derart verarbeitet wird, daß an einer dem ruhigen Bereich näher gelegenen zweiten Stelle des Schallweges ein dem längs desselben sich fortpflanzenden Schall entsprechender, jedoch ihm gegenüber invertierter und dadurch auf ihn störend einwirkender Schall erzielbar ist.To solve this problem, the invention proposes in terms of method Consideration that the sound is captured at a first point in the sound path and fed to a bypass in the form of a signal and processed there in this way becomes that at a second point of the sound path closer to the quiet area a sound corresponding to the sound propagating along it, but opposite to it inverted and thereby disturbing sound can be achieved.

Wenn die Schallwellen reine Sinus form aufweisen, so hat der invertierte Schall die gleiche Tonhöhe bei gleicher Amplitude, ist jedoch um 1800 phasenverschoben.If the sound waves have a pure sinusoidal shape, the inverted one has Sound has the same pitch at the same amplitude, but is out of phase by 1800.

Der Schall kann durch ein herkömmliches Mikrofon aufgefangen werden und der Interferenzschall kann mittels eines Lautsprechers erzeugt werden. Das Mikrofonsignal kann elektronisch mit Hilfe von Filtern oder eines Analog-Schieberegisters (einer sogenannten "bucket brigadet'-Einrichtung) verarbeitet und auf den genauen Pegel verstärkt werden, bevor es dem Lautsprecher eingespeist wird. Ein Filter hat die Wirkung, die Phase des Eingangssignals zu verändern, indem dieses Signal tatsächlich um ein gegebenes Zeitintervall verzögert wird. Diese Phasenänderung wird derart vorgenommen, daß der Lautsprecherausgang um 1800 gegenüber dem Schall phasenverschoben ist, welcher längs des Schallweges zur zweiten Stelle, d.h. zum Lautsprecher gelangt, wobei zu diesem Zweck Phasenschieber-Steuerungen an jedem der Filter vorgesehen werden, die jeweils ein Bandpaß von beispielsweise 50 Hz haben, um den Frequenzbereich des zu unterdrückenden Schalls abzudecken. Amplitudenregler an den Filtern ermöglichen eine Anpassung des Lautsprecherausganges an den akustisch übertragenen Schall für jedes Frequenzband. Durch die Phasenschieber-Steueungen und die Amplitudenregler läßt sich die Vorrichtung ohne weiteres derart abstimmen, daß der Schallpegel in dem ruhigen Bereich in jedem Frequenzband herabgesetzt wird. Durch eine derartige Abstimmung läßt sich jegliche Nichtlinearität der Phasenverschiebung an die Frequenz anpassen, welche sich aus der Mikrofon-, Verstärker- und Lautsprecherschaltung ergibt.The sound can be picked up by a conventional microphone and the interference sound can be heard by means of a loudspeaker generated will. The microphone signal can be transmitted electronically with the help of filters or an analog shift register (a so-called "bucket brigadet" device) processed and on the exact Level before it is fed to the loudspeaker. Has a filter the effect of changing the phase of the input signal by actually changing this signal is delayed by a given time interval. This phase change becomes such made that the loudspeaker output was phase shifted by 1800 with respect to the sound is which along the sound path arrives at the second point, i.e. the loudspeaker, for this purpose phase shift controls are provided on each of the filters which each have a bandpass filter of, for example, 50 Hz to the frequency range of the noise to be suppressed. Enable amplitude controls on the filters an adaptation of the loudspeaker output to the acoustically transmitted sound for every frequency band. Through the phase shifter controls and the amplitude regulators the device can easily be tuned in such a way that the sound level in the quiet area in each frequency band. By such a Any non-linearity of the phase shift to the frequency can be tuned adapt which results from the microphone, amplifier and loudspeaker circuit.

Das Analog-Schieberegister verzögert alle Frequenzen gleichmäßig um das gleiche Zeitintervall und läßt sich preiswert als integrierte Schaltung aus einer Reihe von Dioden und Kondensatoren herstellen, durch welche das Signal hindurchgeleitet wird und welche mit einem einstellbaren Taktimpuls zeitmäßig abtasten. Diese Anordnung läßt sich durch Einstellung der Verzögerung, beispielsweise durch Einstellung der Taktimpuls-Frequenz, abstimmen, oder indem das Mikrofon oder der Lautsprecher bewegt werden. Wichtig ist, daß das Mikrofon, der Lautsprecher und der Verstärker derart ausgewählt werden, daß sie selbst keinerlei Phasenverschiebung einbringen, welche durch die zur Verfügung stehenden Abstimmeinrichtungen nicht anpaßbar wäre.The analog shift register evenly delays all frequencies the same time interval and can be inexpensive as an integrated circuit make a series of diodes and capacitors through which the signal is passed and which are timed to scan with an adjustable clock pulse. This arrangement can be adjusted by setting the delay, for example through Setting the clock pulse frequency, tuning, or by using the microphone or the Loudspeakers are moved. It is important that the microphone, the loudspeaker and the amplifier can be selected in such a way that it does not itself have any phase shift bring in which are not due to the voting facilities available would be customizable.

Statt eines derartigen elektronischen Leitungsweges oder zusätzlich zu diesem kann ein akustischer Neben- oder Ausweichweg vorgesehen werden, indem beispielsweise längs des Hauptschallweges ein Rohr verlegt wird, welches auch in irgendeinem gewünschten Winkel zur Hauptschalleitung verlaufen kann. Dadurch läßt sich allerdings infolge der Tonverzerrung längs der beiden akustischen Leitungen keine einwandfreie Schalldämpfung erreichen, doch ist ein derartiges System sehr preiswert, da hier nur ein Mikrofon und ein mit der richtigen Polarität an den Lautsprecher angeschlossener Verstärker benötigt werden. Unter gewissen Umständen kann ein derartiges System jedenfalls durchaus brauchbar sein.Instead of such an electronic conduction path or in addition An acoustic secondary or alternative path can be provided for this by For example, a pipe is laid along the main sound path, which is also in may be at any desired angle to the main formwork line. This lets however, due to the sound distortion along the two acoustic lines do not achieve proper sound attenuation, but such a system is very inexpensive, as there is only one microphone and one with the correct polarity on the loudspeaker connected amplifier are required. Under certain circumstances such a thing can be The system can definitely be used.

Einige Ausführungsbeispiele der Erfindung werden nachstehend anhand der beiliegenden Zeichnungen im einzelnen erläutert, wobei die Figuren 1 - 4 unterschiedliche Ausführungsbeispiele zeigen.Some exemplary embodiments of the invention are based on the following of the accompanying drawings explained in detail, with Figures 1-4 different Show embodiments.

Die in den Figuren 1 und 2 dargestellten Ausführungsbeispiele arbeiten mit Filtern. Von der Schallquelle S ausgehender Schall läuft längs des Weges P zu einem ruhigen Bereich R. Bei dieser Schallquelle S kann es sich um einen Lüfter handeln, während der Weg P eine Leitung und der Bereich R ein Raum sein können. Ein Mikrofon 12 nimmt den Schall an einer ersten Stelle 11 auf und das Mikrofonsignal wird längs des Nebenweges P' durch die Filter 16, ein Analog-Addierwerk 17 und einen Verstärker 15 dem Lautsprecher 17 an einer zweiten Stelle 15 im Schallweg P zugeleitet.The exemplary embodiments shown in FIGS. 1 and 2 work with filters. Sound emanating from the sound source S travels along the path P. a quiet area R. This sound source S can be a fan act during the Path P is a line and area R is a room could be. A microphone 12 picks up the sound at a first point 11 and the microphone signal is passed along the bypass path P 'through the filter 16, an analog adder 17 and an amplifier 15 to the loudspeaker 17 at a second point 15 in the sound path P forwarded.

Bei der Ausführung gemäß Figur 1 liegen die Filter hinter dem Verstärker, während sie bei der Ausführung gemäß Figur 2 vor dem Verstärker angeordnet sind, wobei sich im letzteren Fall niedrigere Kosten für die Anlage ergeben können. Wenn auch in den Figuren übliche Lautsprecher dargestellt sind, so braucht es sich hier keineswegs um die zur Wiedergabe von Musik und Sprache üblichen Geräte zu handeln, sondern es kann vielfach vollkommen ausreichend sein, beispielsweise den Treiber eines Pilzlautsprechers zu verwenden, welcher mit dem Schallweg P durch ein einfaches Rohr verbunden ist.In the embodiment according to Figure 1, the filters are behind the amplifier, while in the embodiment according to FIG. 2 they are arranged in front of the amplifier, in the latter case, lower system costs may result. if The usual loudspeakers are also shown in the figures, so it is necessary here in no way to be dealing with the usual devices for the reproduction of music and speech, but it can often be completely sufficient, for example the driver of a mushroom loudspeaker, which is connected to the sound path P by a simple Pipe is connected.

Bei dem Ausführungsbeispiel gemäß Figur 5 ist anstelle der Filter 16 ein Analog-Schieberegister oder eine buckel brigade"-Einrichtung 19 in der elektronischen Leitung P' eingesetzt.In the embodiment according to FIG. 5, instead of the filter 16 an analog shift register or a humpback brigade "device 19 in the electronic Line P 'used.

Figur 4 zeigt einen Neben-Schallweg P', längs welchem das ak stische Signal von der ersten Stelle 11 beim Eintreffen am Mikrofon 12 um das gleiche Zeitintervall verzögert wird, wie der längs des Hauptschallweges P zur zweiten Stelle 13 sich fortpflanzende Schall. Alles was nötig ist, vorausgesetzt, daß das Mikrofon 12, der Verstärker 15 und der Lautsprecher 14 keine Phasenverschiebung mit sich bringen, ist die Invertierung oder Umkehrung des Ausganges des Lautsprechers 14 gegenüber dem Schall an der Stelle 15 durch entsprechende Verbindung des Verstärkers mit dem Lautsprecher.Figure 4 shows a secondary sound path P ', along which the ac tical Signal from the first point 11 when it arrives at the microphone 12 at the same time interval is delayed, as is the case along the main sound path P to the second point 13 propagating sound. All that is necessary, provided that the microphone 12, the amplifier 15 and the loudspeaker 14 do not bring about a phase shift, is the inversion or inversion of the output of the loudspeaker 14 opposite the sound at the point 15 by appropriate connection of the amplifier with the Speaker.

Die Figuren 2 und 4 zeigen herkömmliche Schallbrecher 18, durch welche die Hochfrequenztöne von etwa über 500 Hz abgeschwächt werden und außerdem ein Rückfluß des Schalls vom Lautsprecher zum Mikrofon verhindert wird.Figures 2 and 4 show conventional sound breakers 18 through which the high frequency tones of about 500 Hz are attenuated and also a reflux the sound from the loudspeaker to the microphone is prevented.

Die erfindungsgemäße Vorrichtung läßt sich in bereits bestehende Leitungssysteme einbauen oder kann zum Einbau in Klimaanlagen oder andere Anlagen in standardmäßigen Leitungslängen vorgefertigt werden. Das Anwendungsgebiet der Erfindung beschränkt sich keineswegs auf die Unterdrückung von Luftschall> sondern es läßt sich beispielsweise mit geeigneten Wandlern, wie beispielsweise piezoekektrischen oder magnetostriktiven Einrichtungen die Schallfortpflanzung auch in irgendwelchen Anordnungen dämpfen, welche Flüssigkeit enthalten.The device according to the invention can be incorporated into existing line systems build in or can be built into air conditioners or other systems in standard Cable lengths are prefabricated. The scope of the invention is limited in no way on the suppression of airborne sound> but it can be, for example with suitable transducers, such as piezoelectric or magnetostrictive Devices that dampen sound propagation in any arrangement, which contain liquid.

Claims (10)

Patentansprüche. Claims. Verfahren zur Unterdrückung oder Abschwächung der Schallfortpflanzung längs eines Schallweges von einer Schallquelle zu einem ruhigen Bereich, d a d u r c h g e k e n n z e i c h -n e t , daß der Schall an einer ersten Stelle (11) des Schallweges (P) aufgefangen und in Form eines Signales einem Nebenweg (P') zugeleitet und dort derart verarbeitet wird, daß an einer dem ruhigen Bereich (R) näher gelegenen zweiten Stelle (13) des Schallweges (P) ein dem längs desselben sich fortpflanzenden Schall entsprechender, jedoch ihm gegenüber invertierter und dadurch auf ihn störend einwirkender Schall erzielbar ist.Method for suppressing or attenuating the propagation of sound along a sound path from a sound source to a quiet area, d a d u r c h g e k e n n z e i c h -n e t that the sound at a first point (11) of the sound path (P) and fed to a secondary path (P ') in the form of a signal and is processed there in such a way that one is closer to the quiet area (R) second point (13) of the sound path (P) one that propagates along the same Sound more appropriate, but more inverted in relation to it and thereby disturbing it acting sound can be achieved. 2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß das Signal durch Filter (16) hindurchgeleitet wird, deren jedes unterschiedliche Frequenzkomponenten mit einer geeigneten Phasenverschiebung beaufs chlagt. 2. The method according to claim 1, characterized in that the signal is passed through filters (16) each having a different frequency component beaufs with a suitable phase shift. 3. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß das Signal durch eine Verzögerungsanordnung (19) hindurchgeleitet wird, welche allen Frequenzen gleichmäßig eine Verzögerung erteilt. 3. The method according to claim 1, characterized in that the signal is passed through a delay arrangement (19), which all frequencies uniformly granted a delay. 4. Vorrichtung zur Durchführung des Verfahrens nach den Ansprechen 1 - 3, dadurch gekennzeichnet, daß einen ein Signal erzeugenden Schallempfänger (12) an einer ersten Stelle (11) des Schallweges (P) angeordnet ist, ferner Verarbeitungsanordnungen (15, 16, 17, 19) zur Fortleitung und Verarbeitung dieses Signals längs eines Nebenweges (P') und an einer dem ruhigen Bereich (R) näher gelegenen zweiten Stelle (1)) in dem Schallweg (P) einen Schallerzeuger (14), mittels welchem aus dem verarbeiteten Signal ein dem sich längs des Schallweges (P) fortpflanzenden Schall entsprechender, Jedoch ihm gegenüber invertierter und dadurch auf ihn störend einwirkender Schall erzeugbar ist. 4. Device for carrying out the method after the response 1-3, characterized in that a sound receiver generating a signal (12) is arranged at a first point (11) of the sound path (P), furthermore processing arrangements (15, 16, 17, 19) for forwarding and processing this Signal along a byway (P ') and on a nearer to the quiet area (R) second point (1)) in the sound path (P) a sound generator (14), by means of which from the processed signal to that propagating along the sound path (P) Sound more appropriate, but more inverted in relation to it and thereby disturbing it acting sound can be generated. 5. Vorrichtung nach Anspruch 4, dadurch gekennzeichnet, daß der Schallempfänger aus einem Mikrofon (12) und der Schallerzeuger aus einem Lautsprecher (14) besteht.5. Apparatus according to claim 4, characterized in that the sound receiver consists of a microphone (12) and the sound generator consists of a loudspeaker (14). 6. Vorrichtung nach Anspruch 4 und 5, dadurch gekennzeichnet, daß Kanäle mit Filtern (16) für unterschiedliche Frequenzbänder sowie in jedem Kanal Phasenschieber-Steuerungen und Verstärkungsregler vorgesehen sind, so daß eine Abstimmung der Vorrichtung erzielbar ist.6. Apparatus according to claim 4 and 5, characterized in that Channels with filters (16) for different frequency bands and in each channel Phase shifter controls and gain regulators are provided so that tuning the device can be achieved. 7. Vorrichtung nach Anspruch 4 und 5, dadurch gekennzeichnet, daß zwischen dem Schallempfänger (12) und dem Schallerzeuger (14) eine gleichmäßig auf alle Frequenzen einwirkende Verzögerungseinrichtung (19) angeordnet ist.7. Apparatus according to claim 4 and 5, characterized in that between the sound receiver (12) and the sound generator (14) a uniform Delay device (19) acting on all frequencies is arranged. 8. Vorrichtung nach Anspruch 7, dadurch gekennzeichnet, daß die Verzögerungseinrichtung (19) aus einem Analog-Schieberegister oder einer sogenannten buckel brigade-Einrichtung besteht.8. Apparatus according to claim 7, characterized in that the delay device (19) from an analog shift register or a so-called hump brigade device consists. 9. Vorrichtung nach Anspruch 7, dadurch gekennzeichnet, daß die Verzögerungseinrichtung aus einem Schallnebenweg (P') besteht.9. Apparatus according to claim 7, characterized in that the delay device consists of a secondary sound path (P '). 10. Vorrichtung nach einem der Ansprüche 4 - 9, dadurch gekennzeichnet, daß im Hauptschallweg (P) außerdem eine herkömmliche Schallimpedanz (18) vorgesehen ist.10. Device according to one of claims 4 - 9, characterized in that that a conventional sound impedance (18) is also provided in the main sound path (P) is. L e e r s e i t eL e r s e i t e
DE19752507428 1974-02-22 1975-02-21 Air duct sound attenuator - with inlet pick-up processed to feed back cancelling sound at outlet of duct Pending DE2507428A1 (en)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
GB8142/74A GB1492963A (en) 1974-02-22 1974-02-22 Preventing or reducing transmission of sound
GB2303674 1974-05-23
GB3482574 1974-08-07
GB3726074 1974-08-23
GB3730374 1974-08-27

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Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2721754A1 (en) * 1976-05-13 1977-11-24 Sound Attenuators Ltd METHOD AND DEVICE FOR REDUCING THE LEVEL OF INTERFERENCE NOISE
DE2712534A1 (en) * 1977-03-22 1978-09-28 Sound Attenuators Ltd Active sound attenuation using secondary wave - has stored programme used to obtain signal representing secondary wave
DE3144052A1 (en) * 1980-12-05 1982-07-08 Lord Corp., 16512 Erie, Pa. "ACTIVE ACOUSTIC DAMPING DEVICE"
WO1983000580A1 (en) * 1981-08-11 1983-02-17 Chaplin, George, Brian, Barrie Method and apparatus for low frequency active attenuation
WO1986006533A1 (en) * 1985-04-29 1986-11-06 Boenke Knut Method and apparatus for attenuating sound and acoustic noise
DE3541201A1 (en) * 1985-11-21 1987-05-27 Voith Gmbh J M Device for oscillation damping
DE4011658A1 (en) * 1990-04-11 1991-10-17 Messerschmitt Boelkow Blohm Anti-sound wave generator - incorporates at least fluidic amplifier with input and output connections
DE4130559A1 (en) * 1991-09-10 1993-03-25 Calsonic Corp Silencing system with expansion chamber formed in main pipe - incorporates combination of active and passive reflecting surfaces in pipes of different dia.
US5662136A (en) * 1995-09-11 1997-09-02 Defense Research Technologies, Inc. Acousto-fluidic driver for active control of turbofan engine noise
DE10021031A1 (en) * 2000-05-02 2001-11-08 Mann & Hummel Filter Line system with electromechanical transducer for generating a correction noise

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2721754A1 (en) * 1976-05-13 1977-11-24 Sound Attenuators Ltd METHOD AND DEVICE FOR REDUCING THE LEVEL OF INTERFERENCE NOISE
DE2712534A1 (en) * 1977-03-22 1978-09-28 Sound Attenuators Ltd Active sound attenuation using secondary wave - has stored programme used to obtain signal representing secondary wave
DE3144052A1 (en) * 1980-12-05 1982-07-08 Lord Corp., 16512 Erie, Pa. "ACTIVE ACOUSTIC DAMPING DEVICE"
US4473906A (en) * 1980-12-05 1984-09-25 Lord Corporation Active acoustic attenuator
WO1983000580A1 (en) * 1981-08-11 1983-02-17 Chaplin, George, Brian, Barrie Method and apparatus for low frequency active attenuation
WO1986006533A1 (en) * 1985-04-29 1986-11-06 Boenke Knut Method and apparatus for attenuating sound and acoustic noise
DE3541201A1 (en) * 1985-11-21 1987-05-27 Voith Gmbh J M Device for oscillation damping
DE4011658A1 (en) * 1990-04-11 1991-10-17 Messerschmitt Boelkow Blohm Anti-sound wave generator - incorporates at least fluidic amplifier with input and output connections
DE4130559A1 (en) * 1991-09-10 1993-03-25 Calsonic Corp Silencing system with expansion chamber formed in main pipe - incorporates combination of active and passive reflecting surfaces in pipes of different dia.
US5347585A (en) * 1991-09-10 1994-09-13 Calsonic Corporation Sound attenuating system
US5662136A (en) * 1995-09-11 1997-09-02 Defense Research Technologies, Inc. Acousto-fluidic driver for active control of turbofan engine noise
DE10021031A1 (en) * 2000-05-02 2001-11-08 Mann & Hummel Filter Line system with electromechanical transducer for generating a correction noise

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