Device and method for reducing noise induced by noise system in space by electronic noise cancellation

Abstract

An innovative device (100) is configured to reduce noise generated by a noise system (10) in a predetermined, limited space (20) at a distance from the noise system (10). The apparatus (100) comprises: a microphone (110) configured to receive noise (19) from a noise system (10) and to generate a noise electrical signal (115); a loudspeaker (120) configured to receive an acoustic electrical signal (125) and thereby emit an acoustic wave (109) towards the space (20); and a noise processor (130) having an input coupled to the microphone (110) and an output coupled to the speaker (120). The noise processor (130) is configured to generate an acoustic electrical signal (125) by processing the noise electrical signal (115) such that noise waves (19) from the noise system (10) and sound waves (109) from the loudspeaker (120) combine and cancel at the space (20).

Description

[0001] manual Technical Field

[0002] The subject matter disclosed herein relates to an apparatus and method for reducing noise in a space through electronic noise cancellation. Background Art

[0003] It's common knowledge that any machine generates noise when in operation. This noise propagates around the machine as waves through the ambient air. People near the machine are disturbed by the noise. The noise level at any location in the machine's surroundings depends on several factors, including the noise power generated by the machine and the distance from the machine. Generally speaking, larger machines generate more noise.

[0004] In some technical fields, such as, for example, oil and gas, machines or machine arrangements are sometimes enclosed in (sound) isolating housings (sometimes referred to as "enclosures") in order to reduce the noise transmitted into the surrounding environment. Alternatively or additionally, (sound) isolating cabinets are provided in the surroundings of the machines, for example so-called "control rooms", where people can stay and work under reduced noise conditions.

[0005] In any case, even when an isolation housing and / or isolation cabinet is used, the noise outside the isolation housing or inside the isolation cabinet is often not negligible to a person who is close to the machine. The person may be there because he needs to monitor the machine and / or operate the machine (or equipment connected or coupled to the machine), for example for maintenance purposes.

[0006] Therefore, operators know and use HPDs (= "Hearing Protection Devices"), such as earmuffs and earplugs. However, HPDs have several limitations; for example, HPDs are not particularly comfortable, especially when they need to be carried for long periods of time, and can hinder the person wearing them from communicating with others.

[0007] Solutions for noise cancellation or reduction are known from, for example, US 2015 / 104026 A1, US 2010 / 131269 A1, and US 5,834,647 (corresponding to DE 69504204 T2). None of these solutions is completely accurate and suitable for industrial applications, i.e., environments where a fixed-position noise system and a fixed-position (limited-size) room to be silenced are located far from each other and the silencer device is configured to be positioned far from both the noise system and the room to be silenced.

[0008] It is desirable to provide a solution for accurately reducing noise in industrial application spaces. Summary of the Invention

[0009] According to a first aspect, the subject matter disclosed herein relates to an innovative system that allows for reducing noise generated by a noise system and propagating as noise waves through ambient air. The noise system includes one or more noise sources, and a device configured to reduce the noise in a predetermined, limited space located a certain distance from the noise system. The system includes at least one microphone, at least one speaker, and a noise processor. The microphone is configured to receive noise from the noise system and generate an electrical noise signal. The speaker is configured to receive the acoustic electrical signal and thereby emit sound waves into the space. The noise processor has at least one input and at least one output; the input is electrically coupled to the microphone; the output is electrically coupled to the speaker. The noise processor is configured to generate an acoustic electrical signal by processing the noise electrical signal, such that the noise waves from the noise system and the sound waves from the speaker combine and cancel in the space. The speaker is positioned at a fourth distance from the microphone, and the noise processor is configured to process the noise electrical signal in such a way that a processing time is less than or equal to the fourth distance divided by the speed of sound wave propagation in air. A delay time is provided in the device; the sum of the processing time and the delay time is equal to the fourth distance divided by the speed of sound wave propagation in air.

[0010] According to a second aspect, the subject matter disclosed herein relates to an innovative method for reducing noise generated by a noise system and propagating as noise waves through ambient air. The noise reduction is achieved by a device in a predetermined, limited space located at a certain distance from the noise system. The method includes the following steps, performed by the device: generating a sound wave; directing the generated sound wave toward the space; and adjusting the generated sound wave so that the noise wave from the noise system and the generated sound wave combine and cancel at the space. The adjustment step provides for introducing a delay time, the value of which is related to the distance and the location of the noise system, the space, and components of the device.

[0011] According to a third aspect, the subject matter disclosed herein relates to an arrangement comprising a noise system and a device for reducing noise generated by the noise system in a predetermined, limited space at a certain distance from the noise system; the device is an innovative noise reaction device and / or is configured to implement an innovative noise reduction method. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] A more complete appreciation thereof will be readily obtained as the disclosed embodiments of the present invention and many of its attendant advantages become better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings, in which:

[0013] Figure 1 shows a schematic block diagram of a first embodiment of the innovative device,

[0014] Figure 2 Shown with some distances of interest Figure 1 implementation plan,

[0015] Figure 3 A schematic block diagram of a possible noise system is shown,

[0016] FIG4 shows a schematic block diagram of two possible alternative spaces for noise reduction,

[0017] Figure 5 shows a schematic block diagram of a second embodiment of the innovative device,

[0018] Figure 6 It is shown that, for example, Figure 1 or Figure 5 A detailed block diagram of an embodiment of a noise processor used in an embodiment of

[0019] Figure 7 It is shown that, for example, Figure 1 or Figure 5 Embodiments of the speaker arrangement used in the embodiments,

[0020] Figure 8 A flow chart illustrating an embodiment of the innovative method, and

[0021] Figure 9 Shown Figure 8 Flowchart of possible specific implementations of specific steps of the innovative method. DETAILED DESCRIPTION

[0022] According to the subject matter disclosed herein, noise reduction is achieved in a predetermined and limited space, such as the space where a person is most likely to be during operation of a noise system, rather than in the entire surrounding environment. The space may be a completely enclosed space, such as a room with a defined area and volume, or a partially enclosed space with one or more variations where the area and volume are not completely defined. With these assumptions in mind, noise reduction by electronic means can be performed effectively; the theoretical goal is complete noise reduction. The innovative electronic device emits sound waves that at least partially cancel out the noise waves from the noise system in such a space. Outside such a space, noise cancellation is quite poor or even non-existent.

[0023] exist Figure 1 In FIG. 1 , an exemplary noise system 10 is schematically shown. According to this example, the system 10 comprises three different noise sources 11, 12 and 13. As explained later, the noise can be obtained from Figure 3 A better understanding of noisy systems can be obtained from

[0024] exist Figure 1In FIG, an exemplary noise system 10 is schematically shown. According to this example, the system 10 includes three different noise sources 11, 12 and 13. The system 10, and in particular its sources 11, 12 and 13, generates noise that propagates through the ambient air as a noise wave 19; it is noted that the noise wave propagates everywhere around the system 10 in any direction and that the arrow 19 is oriented according to a particular direction because this propagation direction relates to Figure 1 The exemplary innovative device 100 shown and Figure 1 The exemplary space 20 is shown. Figure 1 In FIG, arrow 19 represents a propagating noise wave, which is generated by the combination of noise generated by all noise sources of system 10. As the distance from system 10 increases, the specific origins of the noise (i.e., sources 11, 12, and 13) cannot be distinguished, and the noisy system 10 can be equated with a single point noise source. In addition, if a surface with a small area compared to the distance from the noisy system is considered (e.g., perpendicular to the propagation direction of the noise wave), the noise wave reaching this surface can be considered a plane wave.

[0025] exist Figure 1 In FIG. 1 , a limited and predetermined exemplary “anechoic” (ie, where noise is reduced) space 20 is schematically shown. According to this example, a person 29 is present inside the space 20. Figure 4A and Figure 4B A better understanding of the "anechoic" (i.e., where noise is reduced) space is obtained in Figure 1 In the example of FIG. 1 , the space 20 is at a certain distance from the noise system 10, specifically a first distance D1 (e.g. Figure 2 Note that, in general, the space 20 should not be considered as an area of the ground surface, but rather as a three-dimensional finite volume (at any distance from the ground) that requires sound attenuation.

[0026] Figure 1 An embodiment of the innovative device 100 in the invention is capable of reducing noise generated by a noise system 10 in a space 20. The device (100) comprises:

[0027] a) at least one microphone 110, the at least one microphone being configured to receive noise, in particular noise waves 19, from the noise system 10 and to generate a noise electrical signal 115, the at least one microphone 110 being configured to be positioned at a second distance D2 from the noise system 10 (see Figure 2 )

[0028] b) at least one loudspeaker 120 configured to receive the acoustic electrical signal 125 and thereby emit sound waves 109 towards the space 20, the at least one loudspeaker 120 being configured to be positioned at a third distance D3 from the space 20 (see Figure 2 ) and

[0029] c) a noise processor 130 having at least one input and at least one output, wherein the at least one input is electrically coupled to the at least one microphone 110 and the at least one output is electrically coupled to the at least one speaker 120;

[0030] The noise processor 130 is an electronic processor and is configured to generate an acoustic electrical signal 125 by processing the noise electrical signal 115 so that the noise waves 19 from the noise system 10 and the sound waves 109 from the at least one speaker 120 are at least partially combined and canceled at the space 20. In practice, the cancellation may not be perfect; it may vary slightly from point to point within the space; it may depend on the size of the space; in any case, noise reduction may be achieved throughout the space.

[0031] Since the space 20 to be “silenced” is limited, the total power of the sound waves 109 emitted by the device 100 is much smaller than the total power of the noise waves emitted by the noise system 10 .

[0032] Advantageously, the distance D3 is selected to be greater than the third distance D3 (see Figure 2 ) of the second distance D2 (see Figure 2 ); In other words, the innovative device 100 is placed relatively close to the space 20 to be "silenced," more specifically, closer to the space 20 than the system 10. In this way, the total power of the sound waves 109 emitted by the device 100 can be relatively small; because the amplitude of the propagating sound waves is a function of the inverse square of the distance. It should be noted that the third distance D3 is not negligible, such as, for example, several centimeters (or millimeters).

[0033] As already explained, it is advantageous to select the first distance D1 (see Figure 2 ) is greater than a first predetermined value, such as 15m or 30m; in other words, the space 20 to be "silenced" is placed quite far away from the noise system 10. One reason is that in this way, the noise waves 19 reaching the space 20 can be considered as plane waves.

[0034] Advantageously, the second distance D2 is selected (see Figure 2 ) is greater than a second predetermined value, such as 10m or 20m; in other words, the innovative device 100 is placed quite far away from the noise system 10. One reason is that in this way the noise waves 19 reaching the device 100 can be considered as plane waves.

[0035] Advantageously, the third distance D3 is selected (see Figure 2) is greater than a third predetermined value, such as 5m or 10m, but at least 1m; in other words, the innovative device 100 is placed quite far from the space 20. One reason for this is that in this way, the sound waves 109 reaching the space 20 can be considered plane waves. Typically, the third distance D3 is in the range between 1 / 2 and 1 / 10 of the first distance D1.

[0036] The inventive device may include multiple microphones (not shown in any of the figures). This may be advantageous in order to capture noise of different frequencies (in which case the microphones are different) and / or in order to better capture all noise emitted by the noise system, for example by appropriately positioning the microphones (in which case the microphones may be identical).

[0037] The innovative device may include multiple speakers. Figure 7 A speaker arrangement is shown consisting of a first speaker 121, a second speaker 122 and a third speaker 123, all of which are electrically connected to a noise processor 130. Multiple speakers can be used, for example, to cover a larger space to be "silenced". The preferred arrangement is a horizontal array or a vertical array (e.g. Figure 7 Multiple speakers (as shown) can allow the direction of propagation of the wave group of the emitted sound waves to be controlled (usually fine-tuned, for example during preliminary adjustment) by adjusting the relative phases of different acoustic electrical signals supplied to different speakers.

[0038] consider Figure 1 In an embodiment of the present invention, the speaker 120 is positioned at a fourth distance D4 (see FIG4 ) from the microphone 110. The entire device 100 may comprise a housing having, for example, a tubular shape, which contains all its components, with the speaker being located at a first end of the housing and the microphone being located at a second (opposite) end of the housing. Such features may also be present in Figure 5 In the implementation scheme; in fact, Figure 1 The device 100 and Figure 5 The devices 100' and 100" are very similar.

[0039] Specific considerations Figure 1In a particularly advantageous embodiment, the noise system 10, the space 20, and the device 100 can be considered to be aligned or "in line." In this case, the first distance D1 is equal to the sum of the second distance D2, the third distance D3, and the fourth distance D4. The fourth distance D4 divided by the speed of sound wave propagation in air is advantageously greater than (or equal to) the processing time of the noise processor 130 for the noise electrical signal 115. In other words, the electronic processing time of the device is less than (or equal to) the wave propagation time along the device. More precisely and advantageously, the noise processor 130 can be configured such that the processing time of the noise electrical signal 115 is less than or equal to the fourth distance D4 divided by the speed of sound wave propagation in air, and the delay time is set in the device 100 such that the sum of the processing time and the delay time is equal to the fourth distance D4 divided by the speed of sound wave propagation in air; in this way, the sound waves from the device 100 and the sound waves from the system 10 arrive at the space 20 simultaneously. In general, the delay time is adjusted to achieve optimal combination and optimal cancellation of the noise at the space of interest, taking into account various parameters of the arrangement, including one or more frequencies and one or more phases of the noise from the noise system.

[0040] Alternatively, specific consideration Figure 5 In this embodiment, the noise system 10, the space 20 and the device 100' are not aligned. In this case, it is also expected that the device 100' processes the signal quickly, but all distances need to be taken into account (see Figure 5 ) D6, D7, D8, and D9 (D6 can be equal to, for example, D1, but less than the sum of D7, D8, and D9, and D9 can be equal to distance D4); for example, the wave propagation time along distance D6 should be greater than the sum of the wave propagation time along distance D7, the wave propagation time along distance D8, and the processing time of device 100. Since D6 should be less than D7+D8 (and also less than D7+D8+D9), it is expected that microphone 110 should be positioned close to noise system 10 and / or speaker 120 should be positioned close to space 20. In general, optimal combination and optimal cancellation of noise at the space of interest are achieved by considering various parameters of the arrangement, including one or more frequencies and one or more phases of the noise from the noise system.

[0041] Specific considerations Figure 5 An embodiment advantageously has two identical (or very similar) pieces of equipment 100'e100", which can be considered as two parts of the same innovative device; each of these two parts 100' and 100" can be connected to Figure 1 The two parts are preferably positioned symmetrically relative to the noise system 10 and symmetrically relative to the space 20 (see Figure 5 ). In this way, noise cancellation can be much better (or even almost perfect).

[0042] In view of the above considerations, Figure 1 and Figure 5 The components of systems 100 , 100 ′, and 100 ″ are shown in proximity to one another; however, this should not be construed as a limitation of the subject matter disclosed herein. In particular, the microphones and / or speakers may be positioned appropriately remote from noise processor 130 and / or appropriately close to system 10 and / or space 20 .

[0043] As already mentioned, the innovative device is an electronic device that processes electrical signals. Figure 6 Shown Figure 1 and Figure 5 100 . Specifically, its noise processor 130 includes an analog-to-digital converter 132 electrically coupled to at least one microphone 110, a digital-to-analog converter 134 electrically coupled to at least one speaker 120, and an electronic processor 136 electrically coupled between the analog-to-digital converter 132 and the digital-to-analog converter 134, such as a microprocessor with associated program and data storage. It should be noted that there is a component known as a DSP (digital signal processor) that combines at least a processor, a memory, a digital-to-analog converter, and an analog-to-digital converter.

[0044] consider Figure 3 , shows a system 300 corresponding to an exemplary noise system 10 including several noise sources 11, 12, 13, 14, 15, 16, and 17. The system includes a compressor 310 corresponding to the first possible noise source 11, a burner 320 corresponding to the second possible noise source 12, an expander 330 corresponding to the third possible noise source 13, an air filter 340 corresponding to the fourth possible noise source 14, a generator 350 corresponding to the fifth possible noise source 15, a first coupler 360 corresponding to the sixth possible noise source 16, and a second coupler 370 corresponding to the seventh possible noise source 17. As is apparent from this figure, the various noise sources can be considered to be concentrated in specific, distinct locations. The spectral composition of the noise from the various noise sources can vary from source to source. According to the subject matter disclosed herein, the noise can be within the range of 20 Hz to 20 kHz, corresponding to all audible frequencies, or within a narrower range, such as 20 Hz to 5 kHz. To determine the operating range, note that a turbine rotating at, for example, 12,000 RPM generates noise at a first fundamental frequency of 200 Hz and its harmonics and at a second fundamental frequency of, for example, 200 Hz times the number of blades in any stage and its harmonics.

[0045] Consider Figure 4, Figure 4A The first exemplary space 20' to be silenced is shown to be an open space (ie, not bounded by any elements), and Figure 4BA second exemplary space 20" to be silenced is shown as being bounded by walls of, for example, a cabinet; in both cases, the space to be silenced may be, for example, 2m to 4m (height) by 2m to 4m (width) by 2m to 4m (depth). Figure 4A In FIG, a person is shown inside a space 20 ′, for example at three places along a path; according to this example, a limited number of positions (for example six positions 21 , 22, 23, 24, 25 and 26) are of particular interest; as will be better explained below, during preliminary adjustments and / or during preliminary training, the noise reduction device will be set so that the noise is particularly low (or even zero) at these positions. Figure 4B In the example, a person is shown inside a space 20", in particular inside a closed cabinet; according to this example, a limited number of positions (for example only one position 27) are of particular interest; as will be better explained below, during preliminary adjustments and / or during preliminary training, the noise reduction device will be set so that during operation of the noise system, the noise is particularly low (or even zero) at these positions.

[0046] Generally speaking, the innovative noise reduction method comprises the following steps (performed by the silencer device): "b", "c" and "d", while step "a" is typical but not strictly necessary and will be described later:

[0047] b) generating sound waves (see e.g. Figure 1 and Figure 5 Arrow 109 in the figure,

[0048] c) towards the space to be “silenced” (see e.g. Figure 1 and Figure 5 20) to guide the generated sound waves, and

[0049] d) Modulating the generated sound waves (see e.g. Figure 1 and Figure 5 109 in the figure), so that the noise system (see e.g. Figure 1 and Figure 5 The noise wave of the circle 10 in FIG. Figure 1 and Figure 5 19 in the figure) and the generated sound waves (see e.g. Figure 1 and Figure 5 Arrow 109 in the figure) in the space to be “silenced” (see e.g. Figure 1 and Figure 5 Combine and eliminate the circle 20) in the middle;

[0050] As already explained, the space to be "silenced" is predetermined, limited and at a certain distance from the noisy system.

[0051] In the present case, both noise and sound waves are acoustic pressure waves propagating through the ambient air. When the two waves reach the same confined space, they interfere there. The innovative method aims to achieve destructive interference in this space, thereby "silencing" low (ideally zero) local sound pressures anywhere within the space (see, for example, Figure 4).

[0052] When considering a pressure wave propagating through a propagation means (in the present case, the ambient air), the following parameters should be taken into account: the distance from the emission point (or more generally, the location of the silencer device and its components), the amplitude (or power) at the emission point, the phase at the emission point, the frequency of the propagation means, and the propagation speed; this results in a 3D field, which, under certain assumptions, can be considered as a 2D field or even a 1D field (i.e., the field of a plane wave). According to the subject matter disclosed herein, we can consider it by simplifying the superposition of two 3D fields, one 3D field due to the noise system and one 3D field due to the innovative device.

[0053] It should be noted that although steps "b," "c," and "d" are described above as separate and sequential, when such a method is implemented by a device, these steps actually occur simultaneously and by the same means. In particular and advantageously, the adjustment in step "d" is of an open-loop type, at least during the noise reduction operation. In contrast, during adjustment (particularly preliminary adjustment) and / or during training (particularly preliminary training), the adjustment of the sound waves is typically of a closed-loop type, for example based on one or more feedback signals from the space to be "silenced."

[0054] Generally speaking, at step "b", the timing of the generated sound wave is adjusted. Generally speaking, at step "b", the amplitude of the generated sound wave is adjusted. Generally speaking, at step "b", the phase of the generated sound wave is adjusted. Advantageously, at step "b", the timing, amplitude and phase of the generated sound wave are adjusted.

[0055] The adjustment at step "b" is performed so as to achieve a very good (one could say "optimal") cancellation of the noise at the room.

[0056] Step "a" above (performed by the silencer device) comprises receiving a noise wave (see e.g. Figure 1 and Figure 5) and is performed before step "b". In this case, at step "b", a sound wave is generated based on the received noise wave, i.e. by processing the noise wave. More specifically, the timing and / or amplitude and / or phase of the generated sound wave depends on the timing and / or amplitude and / or phase of the received noise wave. In this case, the adjustment at step "d" provides for the introduction of a delay time, the value of which is distance-dependent and is related to the position of the noise wave receiving and sound wave generating components (e.g. 110, 120) of the noise system (e.g. 10), the space (e.g. 20) and the silencer device (e.g. 100). Consider Figure 5 , the position of the noise system 10 and the space 20 is identified by a first line segment (having a length equal to D6), the position of the noise system 10 and the noise wave receiving component 110 is identified by a second line segment (having a length equal to D7), the position of the sound wave generating component 120 and the space 20 is identified by a third line segment (having a length equal to D8), and the position of the noise wave receiving component 110 and the sound wave generating component 120 is identified by a fourth line segment (having a length equal to D9); the delay time is related to the projection lengths of the second line segment, the third line segment on the first line segment, and the projection length of the fourth line segment on the first line segment; the value of the delay time can be calculated based on the wave propagation time along these three projections, so that the noise wave from the noise system and the sound wave from the innovative device arrive at the space to be silenced simultaneously and / or with the same phase shift and elimination.

[0057] According to some embodiments, the received noise wave is filtered into multiple bandwidths and a different sound wave is generated for each bandwidth. This can allow, for example, to take into account that the propagation speed of a wave can depend on the wave frequency and / or the sensitivity of the human ear can depend on the sound frequency.

[0058] As already anticipated, in order to achieve good noise reduction in the space, it is advantageous to perform preliminary adjustments and / or preliminary training and to generate sound waves at step "b" based on such preliminary adjustments and / or preliminary training. For example, preliminary adjustments of the noise reduction device are performed after its installation but before the noise adjustment operation; to a certain extent, they can be performed when the noise system is not in operation; generally speaking, they last for a short time (for example, from a few seconds to a few minutes). For example, preliminary training of the noise reduction device is performed after its installation but before the noise adjustment operation, and it is performed when the noise system is not in operation; generally speaking, it lasts for a long time (for example, tens of minutes or even hours). The purpose of both preliminary adjustments and preliminary training consists in setting the processing parameters so that during the operation of the noise system, the noise is particularly low (or even zero) anywhere in the space to be "silenced" (for example, see Figure 4); for this purpose, one or more specific locations in the space can be taken into account in order to perform, for example, an optimization algorithm.

[0059] Figure 4BNoise is very specific. In reality, noise and sound waves don't directly reach people in the space (i.e., inside the cabinet). They at least partially intersect at the cabinet walls (typically the walls facing the noise system and noise reduction equipment (particularly its speakers)), and the sound pressure inside the cabinet may depend in part on the vibrations of these walls. In any case, the innovative approach remains applicable.

[0060] The innovative method can be embodied in many different ways. For example, the silencer device can be positioned in line with the noise system and the space to be silenced, such as Figure 1 Alternatively, for example, the silencer device may be positioned out of alignment with the noise system and the space to be silenced, such as Figure 5 As shown; in particular, Figure 5 As shown, the silencer device can be divided into identical first and second parts which are positioned symmetrically with respect to the noise system and symmetrically with respect to the space to be silenced.

[0061] When an innovative approach is embodied in a device, it can occur, for example Figure 8 The process 800 of the flowchart of FIG. The process starts at box 810 and ends at box 880. At box 820, the innovative device (e.g., Figure 1 or Figure 5 100); in particular, at least one microphone, at least one loudspeaker and a sound processor are placed. At box 830, for example before starting the noise system, the device is adjusted as already explained. At box 840, for example after starting the noise system, but preferably when there is no one in the space to be "silenced", the device is trained as already explained. Now, the device is ready for silencing the space, and at box 850, the device is first turned on and then activated (when the device is active, it is ready to emit sound waves). At box 860, sound waves are actually formed by the device and directed to the space to be "silenced", so that such space is actually "silenced", that is, the noise is reduced. At box 870, the device is first deactivated and then turned off.

[0062] Figure 9 The flowchart of FIG. 1 illustrates the possible activities corresponding to block 860 in more detail. Initially, block 862 corresponds to receiving a noise wave and generating a noise electrical signal. Next, block 864 corresponds to processing the noise signal. Next, block 866 corresponds to generating an acoustic electrical signal. Finally, block 868 corresponds to emitting an acoustic wave based on the acoustic signal.

[0063] Note that according to some embodiments, the innovation device may be activated only when necessary (i.e., not at any time when the noise system is operating), for example only when people are present or expected to be in the space; for example, it may be activated before a person arrives and deactivated after the person leaves.

[0064] It should be noted that, according to some embodiments, the innovative device may also be activated based on a specific operating mode of the noise system, for example, if the noise system can have more than one operating mode. In other words, the innovative device may also have more than one operating mode. For example, a decision regarding the operating mode of the innovative device may be made each time the device is activated. The decision regarding the operating mode of the innovative device may, for example, be based on a control signal received from the innovative device and / or a user command received from the innovative device.

[0065] It is noted that the innovative device for reducing noise can be integrated into an arrangement together with at least one noise system. The device is intended to reduce the noise generated by the noise system in a predetermined, limited space at a certain distance from the noise system. In particular, the device can be configured to implement an innovative noise reduction method.

Claims

1. A device (100) for reducing noise, the noise being generated by a noise system (10) and propagating as noise waves through ambient air, wherein the noise system (10) comprises one or more noise sources (11, 12, 13), wherein the device (100) comprises: a) at least one microphone (110) configured to receive noise (19) from the noise system (10) and generate a noise electrical signal (115), b) at least one loudspeaker (120) configured to receive the acoustic electric signal (125) and thereby emit sound waves (109) towards the space (20), and c) a noise processor (130) having at least one input and at least one output, wherein the at least one input is electrically coupled to the at least one microphone (110) and the at least one output is electrically coupled to the at least one speaker (120); wherein the device (100) is configured to reduce noise in a space (20), the space (20) being predetermined, finite, and located a first distance (D1) from the noise system (10); wherein the at least one microphone (110) is configured to be positioned at a second distance (D2) from the noise system (10), and the at least one speaker (120) is configured to be positioned at a third distance (D3) from the space (20); and wherein the noise processor (130) is configured to generate the acoustic electric signal (125) by processing the noise electric signal (115) so that the noise wave (19) from the noise system (10) and the sound wave (109) from the at least one speaker (120) are combined and canceled in the space (20); wherein the at least one speaker (120) is positioned at a fourth distance (D4) from the at least one microphone (110), The noise processor (130) is configured such that a processing time of the noise electrical signal (115) is less than or equal to the fourth distance (D4) divided by the speed of sound wave propagation in air, and a delay time is set in the device (100), wherein the sum of the processing time and the delay time is equal to the fourth distance (D4) divided by the speed of sound wave propagation in air.

2. The device (100) according to claim 1, The second distance (D2) is greater than the third distance (D3).

3. The device (100) according to claim 1, Wherein the third distance (D3) is greater than a third predetermined value.

4. The device (100) according to claim 1, The device comprises a plurality of loudspeakers (121, 122, 123), which are particularly arranged in a horizontal array or a vertical array.

5. The device (100) according to claim 1, The device (100) is configured to be positioned in line with the noise system (10) and the space (20).

6. A method for reducing noise generated by a noise system (10) and propagating as noise waves (19) through the ambient air, wherein the noise reduction is achieved by means of a device (100) in a predetermined, limited space (20) at a distance from the noise system (10), wherein the method comprises the following steps performed by the device (100): b) generating sound waves (109), c) directing the generated sound waves (109) towards the space (20), and d) adjusting the generated sound wave (109) so that the noise wave (19) from the noise system (10) and the generated sound wave (109) combine and cancel at the space (20); The adjustment at step "d" provides an introduction delay time, the value of which is related to the distance and to the positions of the noise system (10), the space (20) and the components (110, 120) of the device (100).

7. The method according to claim 6, wherein the regulation at step "d" is of open loop type during the noise reduction operation.

8. The method of claim 6, wherein at step "b", the timing of the generated sound wave (109) is adjusted.

9. The method of claim 6, wherein at step "b", the amplitude of the generated sound wave (109) is adjusted.

10. The method of claim 6, wherein at step "b", the phase of the generated sound wave (109) is adjusted.

11. The method according to claim 6, The method comprises the step "a" performed by the device (100): receiving the noise wave (19), Where step "a" is performed before step "b", wherein at step "b", said sound wave (109) is generated based on the received noise wave (19), The adjustment at step "d" provides an introduction delay time, the value of which is related to the distance and to the positions of the noise system (10), the space (20) and the noise wave receiving component and the sound wave generating component (110, 120) of the device (100).

12. The method according to claim 11, wherein the positions of the noise system (10) and the space (20) are identified by a first line segment (D6), wherein the positions of the noise system (10) and the noise wave receiving component (110) are marked by a second line segment (D7), wherein the positions of the sound wave generating component (120) and the space (20) determine a third line segment (D8), The delay time is related to the projection lengths of the second line segment (D7) and the third line segment (D8) on the first line segment (D6).

13. The method of claim 11, wherein the received noise wave (19) is filtered into a plurality of bandwidths and a different sound wave (109) is generated for each bandwidth.

14. The method of claim 6, wherein at step "b", the sound wave (109) is generated based on a preliminary adjustment.

15. The method according to claim 14, wherein at step "b", the sound wave (109) is generated based on preliminary training after the preliminary adjustment.

16. The method of claim 6, wherein the steps performed by the device (100) are positioned in line with the noise system (10) and the space (20).

17. The method according to claim 6, wherein the steps are performed by the device (100) being divided into identical first and second parts (100', 100") located symmetrically relative to the noise system (10) and symmetrically relative to the space (20).

18. An arrangement comprising a noise system (10) and a device (100) for reducing noise generated by the noise system (10) in a predetermined, limited space (20) at a distance from the noise system (10), Wherein said device (100) comprises the features set out in one or more of the preceding claims 1 to 5.

19. An arrangement comprising a noise system (10) and a device (100) for reducing noise generated by the noise system (10) in a predetermined, limited space (20) at a distance from the noise system (10), Wherein the device (100) is configured to implement the method according to one or more of the preceding claims 6 to 17.

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