DE102007012611A1 - Method for active soundproofing in closed inner chamber, involves identifying secondary modulator or transmission path of interfering signal and arranging secondary modulator - Google Patents

Abstract

The method involves identifying a secondary modulator or a transmission path of an interfering signal and arranging secondary modulator such that a propagating direction of the secondary sound signal are located identically with the propagating direction of a primary sound signal in a closed inner chamber (1). An independent claim is also included for a device for active soundproofing in a closed inner chamber.

Description

The The invention relates to a method and a device for active Soundproofing in a closed interior after the The preamble of claim 1 and according to the preamble of claim 5th

In many technical applications are caused by machine noise, Propeller noise or other disturbances indoors standing wave fields induced, especially in low-frequency Range with frequencies below approx. 500 Hz. These interferences are i. a. difficult to compensate.

Due to noise regulations or to increase comfort, it may be necessary to take measures to prevent noise. Today, a variety of passive and active measures are available. Active systems provide substantial weight and space savings, especially in low frequency applications, but the efficient use of active indoor counter-noise systems requires a lot of effort in positioning the actuators and sensors. B. SJ Elliott, Signal Processing for Active Control, Academic Press, San Diego, CA, 2001 , The components of the Active Noise System (ANS) used in the system generally also have to be globally distributed for global indoor control performance.

in the Prior art is a variety of approaches for the active, "global" noise reduction indoors known.

Becomes the volume to be soothed from the outside can be stimulated with Using a self-mode analysis of the vibration state to several Natural oscillations are traced back. secondary sources are now placed so that they can couple into the eigenmodes and so erase them with destructive interference. With Although good results can be achieved with this process, however, this method assumes that the natural vibrations can be calculated, resulting in complicated interior geometries associated with high costs. Furthermore, there are large ones Volume or high frequencies the natural frequencies close to each other, that is, one needs for oppression the eigenmodes a correspondingly large number of secondary sources. In addition, this method needs a great deal Number of globally distributed sensors.

Another approach to solving the positioning problem of actuators and sensors is based on the use of appropriate optimization algorithms. Such a method was used by C. Gerner in "Optimal active noise reduction in aircrafts for high tonal noise levels", dissertation, Helmut Schmidt University / University of the Federal Armed Forces Hamburg, Hamburg, 2005 , described. Instead of analyzing the eigenmodes, speakers and microphones are placed in all available positions. Then the transmission behavior of each speaker is measured to each microphone. In addition, the primary noise to be extinguished is detected on the microphones. On the basis of these measured data, the best possible configuration of loudspeakers and microphones for the maximum reduction of the primary noise is then calculated in an optimization method from the available positions.

The in DE 10 2005 016 021 A1 from April 7, 2005, describes a sound compensation system whose actuators are arranged around the open interface of a semi-closed control volume. With this arrangement, a global noise reduction in the control volume is to be achieved. However, an application to closed spaces is not possible because in particular the global positioning problem of microphones remains unresolved.

In DE 198 32 517 describes a method for active sound attenuation in a channel through which a medium can flow. By means of a compensation loudspeaker, counter sound for the compensation of primary sound is generated as a function of signals of a reference microphone and an error microphone. Coherence measurement determines the frequencies or frequency ranges in which the signals measured by means of the reference microphone and the error microphone exceed a predeterminable degree of coherence, and these signals are taken into account in the further signal treatment.

Furthermore, in DE 21 39 941 a noise shield comprising a sound grid consisting of anti-sounder systems. The anti-sounder are controlled by microphones so that their radiated sound pressure signal both proportional to the negative pressure signal of the noise source at the location of the respective anti-sounder encoder as well as proportional to the cosine of the angle of the incident noise beam to the normal of the sound grid and also proportional to the mesh surface behaves.

All of the methods described above require a great deal of effort to optimally place the loudspeakers and microphones of a sound compensation system. However, if the frequency of the primary sound or the acoustic properties of the interior change, such a system may change I have very strong losses in their effectiveness or are no longer functional.

task The present invention is therefore to provide a method and to create a device, bringing in enclosed indoor spaces one over a wide frequency range as well as under different acoustic conditions effective active sound attenuation can achieve.

These Task is solved by the method and the device for active sound attenuation in closed interiors according to claim 1 or claim 5. Preferred embodiments of Invention are the subject of the respective subclaims.

According to the invention created an active acoustic barrier on the surface, at the coming from the outside noise in the considered interior is coupled. If you are on this surface Locally arranging secondary sounder, d. H. right in the critical transmission path, so can be with Help of destructive interference a global regulatory success achieve in the respective interior.

The inventive method for active sound damping in a closed interior with an outside wall, the at least one wall section with a primary sound source, which emits a primary sound signal induced by an interfering signal, comprising, with at least one secondary sounder in the Interior for generating a secondary sound signal, at least a sound receiving device in the interior for detecting a Sound signal in the interior and a control device, the with the at least one secondary sounder and with the at least one sound pickup device is connected and the the at least one secondary sounder in dependence from the output of the at least one sound pickup device controls so that the secondary sound signal substantially stored complementary to the primary sound signal is characterized by the steps: identifying the or the transmission paths of the interference signal and arranging from the at least one secondary sounder in or the transmission paths of the interfering signal, so that the spreading direction of the secondary sound signal substantially identical to the propagation direction of the primary sound signal will lie in the closed interior.

In particular, the method according to the invention has one or, if technically possible and sensible, several of the following characteristics, namely that:
the at least one secondary sounder is arranged next to and / or in the wall section with the primary sound source;
several secondary sounder can be arranged in a die or
several sound recording devices are arranged in a matrix form.

Analogous is a device for active sound attenuation in one closed interior with an exterior wall that at least a wall section having a primary sound source, one of emits an interference signal induced primary sound signal, comprises, provided with at least one secondary sounder in the interior for generating a secondary sound signal, at least one sound receiving device in the interior for detecting the sound signal in the interior and a control device, with the at least one secondary sounder and with the at least one sound pickup device is connected and the at least one secondary sounder in dependence from the output of the at least one sound pickup device controls so that the secondary sound signal substantially stored complementary to the primary sound signal is, which is characterized in that the at least one secondary sounder beside and / or in the wall section with the primary sound source is arranged, so that the propagation direction of the secondary sound signal essentially identical to the propagation direction of the primary sound signal into the closed interior is inside.

One Advantage of the inventive sound compensation arrangement is that by the direct arrangement of the "active acoustic Barrier "in the transmission path solved the positioning problem becomes. On the other hand, the performance of the system due to changes in the volume of air to be calmed affected. In addition, the inventive Sound compensation arrangement not only used indoors but it is also effective under free field conditions.

Further Advantages and features of the invention will become apparent from the following Description of preferred embodiments, wherein Reference is made to the accompanying drawings.

1 shows a schematic representation of the initial situation with background noise, which is coupled via a window in an interior.

2 shows a schematic representation of a noise cancellation according to the prior art.

3 shows a schematic representation of a Störschallkompensation invention.

In 1 is schematically a situation placed in the Störschall in an interior 1 is coupled. The interior 1 is through outer walls 2 limited. In the outer walls 2 there is wall section 3 and 4 , about which a stronger acoustic coupling of the interior 1 to the environment. These wall sections are especially windows and doors, as it is in the 1 is indicated. The efficiency of the acoustic coupling depends on the propagation direction of the sound and on its composition, ie on its frequency spectrum. Both aspects are not considered in the following, it is only assumed that the noise on the wall section 3 , ie the window, in the interior 1 coupled, but not over the wall section 4 , the door. Thus, the wall section 3 be regarded as a new primary sound source, and the propagation conditions of the sound outside the interior 1 can be disregarded.

As indicated, the wall section can be 3 in the illustration shown in several individual sources 6 divide. In the illustration, these are the individual elements of a subdivided window. In general, any sound radiating surface can be understood as a composition of point sources.

In 2 is an approach to compensate for background noise in the interior 1 shown in the prior art. For the sake of clarity, the individual sources 6 not shown. A prior art sound compensation system consists essentially of a spatial arrangement of loudspeakers (actuators) and error microphones (sensors) connected to a digital controller. The noise to be minimized, also referred to as primary sound, is superimposed with the generated sound field (secondary sound) of the loudspeakers. The error microphones measure the resulting sound pressure level. This information is processed by the digital controller and controls the speakers so that the sound pressure level at the sensors is minimal. As a result, noise reduction is achieved locally at the microphone positions.

The background noise, which is in 2 from the wall section 3 propagates in the interior leads to a primary sound field in the interior 1 , This sound field is compensated by that of secondary sounders 7 a secondary sound field is built, which extinguished the latter when superimposed on the primary sound field, so that the room is "calmed down". In order to generate the secondary sound field, the primary sound field with sound pickups 10 captured, which are distributed in the interior. The signal of the sound field sensors 10 is via connection cable 11 to a control device 8th directed. This control device 8th analyzes the detected primary sound field signal according to intensity, frequency and local distribution. These parameters are used by the control device 8th Secondary sound field signals generated via connecting lines 9 to several secondary sounders 7 in the interior 1 be issued. These secondary sounders 7 are in the interior 1 distributed so that they can produce a secondary sound field that is as complete as possible for the compensation of the primary sound field.

The problem that can not be solved with this approach according to the prior art is that the generation of the secondary sound field of the concrete geometric conditions of the interior 1 depends. This also applies to the same extent for the detection of the primary sound field. In other words, as soon as the geometric conditions of the interior change, the arrangement of secondary sounders is sufficient 7 for a complete compensation of the primary sound is no longer sufficient.

This problem is solved by the special arrangement of the secondary sounders according to the present invention, which will be described below 3 is explained. 3 shows essentially the same elements as 2 except for the secondary sounder 7 with the connecting lines 9 as known in the art.

For the procedure in the arrangement of the secondary sounder according to the invention first or the transmission paths of the interference signal in the interior 1 identified. This can preferably be done with the sound recording devices 10 take place, which are needed for the generation of the secondary sound signal. But just as well specially provided for this Schallaufnehmer can be used, which are not shown in the drawing and will not be discussed further here. In the case shown, this means that the window 3 is detected as the primary sound source. Next, according to the invention, at least one secondary sounder is then positioned in the transmission path of the interference signal itself. This positioning of the secondary sounder takes place in such a way that the propagation direction of the secondary sound signal is substantially identical to the propagation direction of the primary sound signal into the closed interior.

For this purpose, it is necessary that the secondary sounders are adapted to the spatial conditions, ie that an arrangement in the transmission path of the noise itself is even possible. Instead of the usual speakers 7 As a secondary sounder are therefore according to the invention special sounder 12 used, for example, can be attached to window surfaces, without affecting the function of the component. In In the special case of a window, it is possible in particular to use piezo-surface crystals which do not obstruct the optical transmission. Analogous to the prior art, these special sounders 12 via connecting lines 9 from the control device 8th driven.

The arrangement of special sounders 12 is not limited to that they are positioned in the transmission path of the noise itself. In addition, the secondary sounders 12 Of course, right next to the wall section 3 with the primary sound source 6 are arranged, as long as it is ensured that the propagation direction of the secondary sound signal is substantially identical to the propagation direction of the primary sound signal in the closed interior inside.

It is particularly advantageous if when using multiple secondary sounders 12 these are arranged in a matrix form.

As already indicated above, this applies to the same extent to the sound recording devices 10 , In other words, if several sound recording devices 10 are used, they are preferably arranged in a die form.

For the expert it is understood that the basis of 3 explained method for active sound attenuation in a closed interior 1 leads to a device composed of said components. The device accordingly comprises a plurality of secondary sounders 12 in the interior 1 for generating a secondary sound signal. The control device 8th that with the secondary sounder 12 and with the sound recording devices 10 connected, controls the secondary sounder 12 in response to the output of the sound pickup devices 10 such that the secondary sound signal is substantially complementary to the primary sound signal. Here are the secondary sounder 12 next to or in the wall section 3 or optionally 4 in which is the primary sound source 6 is arranged, so that the propagation direction of the secondary sound signal is substantially identical to the propagation direction of the primary sound signal in the closed interior 1 into it.

With The invention thus makes it possible to use a primary source in an interior with an equal secondary source, which has the same emission characteristics, the penetrating into the interior Extinguish noise globally.

Especially in airplanes, but also in other vehicles is the global distribution of system components in the interior due to structural and design requirements problematic. In many applications, however, the most stationary harmonic noise over a limited number transmitted by transmission paths in the interior. The means that the disturbing primary sound in most technical applications just over one low number of transmission paths (transmission paths) gets into the calming interior. These transmission paths For example, openings or vibrating structures include. Thus, these systems are particularly suitable for the application of the method according to the invention and the device according to the invention, independently of it, whether the interior about airborne sound or structure-borne noise is stimulated.

1

inner space

2

outer wall

3

first Wall section with primary sound source

4

second Wall section with primary sound source

5

excitation sound

6

Primary sound source (s)

7

Secondary sounder

8th

control device

9

connection Secondary sounder controller

10

Sound recording device

11

connection Sound acquisition apparatus controller

12

Local sound sources

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• DE 102005016021 A1 [0007]
• - DE 19832517 [0008]
• - DE 2139941 [0009]

Cited non-patent literature

• SJ Elliott, "Signal Processing for Active Control", Academic Press, San Diego, CA, 2001 [0003]
• - C. Gerner in "Optimal Active Noise Reduction in Airplanes for High Tonal Noise Levels", dissertation, Helmut Schmidt University / University of the Federal Armed Forces Hamburg, Hamburg, 2005 [0006]

Claims (5)

Method for active sound damping in a closed interior ( 1 ) with an outer wall ( 2 ), which has at least one wall section ( 3 . 4 ) with a primary sound source ( 6 ), one of a jamming signal ( 5 ) induced primary sound signal, comprising, with at least one secondary sounder ( 7 ; 12 ) in the interior ( 1 ) for generating a secondary sound signal, at least one sound recording device ( 10 ) in the interior space for detecting a sound signal in the interior space ( 1 ) and a control device ( 8th ), which with the at least one secondary sounder ( 7 ; 12 ) and with the at least one sound recording device ( 10 ) and the at least one secondary sounder ( 7 ; 12 ) in dependence on the output signal of the at least one sound recording device ( 10 ) is controlled so that the secondary sound signal is stored substantially complementary to the primary sound signal, characterized by the steps of: identifying the or the transmission paths of the interference signal ( 5 ) and arranging the at least one secondary sounder ( 7 ; 12 ) in the transmission path or paths of the interfering signal ( 5 ), so that the propagation direction of the secondary sound signal will be substantially identical to the direction of propagation of the primary sound signal into the closed interior. Method according to Claim 1, in which the at least one secondary sounder ( 7 ; 12 ) next to and / or in the wall section ( 3 . 4 ) with the primary sound source ( 6 ) is arranged. Method according to Claim 1, in which a plurality of secondary sounders ( 7 ; 12 ) are arranged in a matrix form. Method according to one of Claims 1 to 3, in which a plurality of sound recording devices ( 10 ) are arranged in a matrix form. Device for active sound damping in a closed interior ( 1 ) with an outer wall, the at least one wall section ( 3 . 4 ) with a primary sound source ( 6 ), one of a jamming signal ( 5 ) induced primary sound signal, comprising, with at least one secondary sounder ( 7 ; 12 ) in the interior space for generating a secondary sound signal, at least one sound recording device ( 10 ) in the inner space for detecting the sound signal in the inner space and a control device ( 8th ), which with the at least one secondary sounder ( 7 ; 12 ) and with the at least one sound recording device ( 10 ) and the at least one secondary sounder ( 7 ; 12 ) in dependence on the output signal of the at least one sound recording device ( 10 ) so that the secondary sound signal is stored substantially complementary to the primary sound signal, characterized in that the at least one secondary sounder ( 7 ; 12 ) next to and / or in the wall section ( 3 . 4 ) with the primary sound source ( 6 ) is arranged, so that the propagation direction of the secondary sound signal is substantially identical to the propagation direction of the primary sound signal in the closed interior ( 1 ) is inside.