Apparatus and method for reducing noise in a space caused by high-noise systems through electronic noise cancellation

Abstract

The innovative device (100) is configured to reduce noise generated by a high-noise system (10) in a defined, confined space (20) at a distance from the high-noise system (10). The device (100) includes a microphone (110) configured to receive noise (19) from the high-noise system (10) and generate a noise electrical signal (115), a loudspeaker (120) configured to receive an acoustic electrical signal (125) and thereby emit acoustic waves (109) toward the space (20), and a noise processor (130) having an input coupled to the microphone (110) and an output coupled to the loudspeaker (120). The noise processor (130) is configured to generate an acoustic electric signal (125) by processing the noise electric signal (115) so that the noise waves (19) coming from the high-noise system (10) and the acoustic waves (109) coming from the loudspeaker (120) combine and cancel each other out in the space (20).

Description

[Technical Field]

[0001] The subject matter disclosed herein relates to an apparatus and method for reducing noise in a space through electronic noise cancellation. [Background technology]

[0002] It is common experience that all machinery generates noise while in operation. The noise propagates around the machine as noise waves through the surrounding air. People in the vicinity of the machine are annoyed by this noise. The level of noise at any location around the machine depends on several factors, including the power of the noise generated by the machine and the distance from the machine. Generally, the larger the machine, the greater the noise it generates.

[0003] In some technical fields, for example oil and gas, machines or machine arrangements may be enclosed inside a (sound-) insulating enclosure, sometimes called a "package", in order to reduce the spread of noise to the surroundings. Alternatively or additionally, a (sound-) insulating cabinet, e.g. a so-called "control room", is provided around the machine, where people can stay and work under reduced noise conditions.

[0004] In either case, even when an insulating enclosure and / or insulating cabinet is used, the noise outside the insulating enclosure or inside the insulating cabinet is often not negligible to people in the vicinity of the machine, who may be present when they need to monitor and / or affect the machine (or equipment connected or coupled to the machine), for example, for maintenance purposes.

[0005] Thus, HPDs (= "Hearing Protection Devices"), such as earmuffs and earplugs, are known and used by operators. However, HPDs have some limitations: they are not particularly comfortable, especially if they have to be carried for long periods of time, and they do not allow the wearer to communicate with other people.

[0006] Solutions for noise cancellation or reduction are known, for example, from US Patent Application Publication No. 2015 / 104026 (A1), US Patent Application Publication No. 2010 / 131269 (A1) and US Patent No. 5,834,647 (corresponding to German Patent No. 69504204 (T2)). None of these solutions is entirely accurate and is applicable to industrial applications, i.e. environments where a fixed-position high-noise system and a fixed-position (limited-size) space to be silenced are located apart from each other and where the silencer device is configured to be located apart from both the high-noise system and the space to be silenced.

[0007] It is desirable to provide a solution for precisely reducing noise in spaces for industrial applications. Summary of the Invention

[0008] According to a first aspect, the subject matter disclosed herein relates to an innovative system that enables reducing noise generated from a high-noise system and propagating through ambient air as noise waves. The high-noise system includes one or more noise sources, and an apparatus configured to reduce noise in a predetermined, limited space at a distance from the high-noise system. The system includes at least one microphone, at least one loudspeaker, and a noise processor. The microphone is configured to receive the noise from the high-noise system and generate a noise electrical signal. The loudspeaker is configured to receive the acoustic electrical signal and thereby emit acoustic waves toward 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 loudspeaker. The noise processor is configured to generate the acoustic electrical signal by processing the noise electrical signal such that the noise waves from the high-noise system and the acoustic waves from the loudspeaker combine and cancel each other out in the space. The loudspeaker is located at a fourth distance from the microphone, the noise processor is configured so that the processing time of the noise electrical signal is equal to or less than the fourth distance divided by the speed of sound propagation in air, and a delay time is provided within the device, the sum of the processing time and the delay time being equal to the fourth distance divided by the speed of sound propagation in air.

[0009] According to a second aspect, the subject matter disclosed herein relates to an innovative method for reducing noise generated by a high-noise system and propagating through ambient air as noise waves. The noise reduction is achieved by an apparatus in a predetermined, limited space at a distance from the high-noise system. The method includes the steps of generating acoustic waves, directing the generated acoustic waves into the space, and adjusting the generated acoustic waves so that the noise waves from the high-noise system and the generated acoustic waves combine and cancel each other in the space. The adjusting step provides for introducing a delay time related to the distance and having a value related to the location of the high-noise system, the space, and the components of the apparatus.

[0010] According to a third aspect, the subject matter disclosed herein relates to an arrangement comprising a high-noise system and an apparatus for reducing noise emanating from the high-noise system in a predetermined, confined space at a distance from the high-noise system, the apparatus being an innovative noise reduction apparatus and / or configured to implement an innovative noise reduction method. [Brief explanation of the drawings]

[0011] The disclosed embodiments of this invention and many of the attendant advantages thereof will be readily appreciated as the same become better understood by reference to the following detailed description when considered in connection with the accompanying drawings, in which: [Figure 1] 1 is a schematic block diagram of a first embodiment of an innovative device. [Figure 2] 2 shows the embodiment of FIG. 1 with several distances of interest. [Figure 3] FIG. 1 is a schematic block diagram of a possible high noise system. [Figure 4A] 1 is a schematic block diagram of two possible alternative spaces for noise reduction purposes. [Figure 4B] 1 is a schematic block diagram of two possible alternative spaces for noise reduction purposes. [Figure 5] FIG. 1 is a schematic block diagram of a second embodiment of the innovative device. [Figure 6] FIG. 6 is a detailed block diagram of an embodiment of a noise processor that may be used, for example, in the embodiment of FIG. 1 or FIG. 5. [Figure 7] 10 illustrates an embodiment of a loudspeaker configuration that may be used, for example, in the embodiment of FIG. 1 or FIG. 5. [Figure 8] 1 is a flowchart of an embodiment of an innovative method. [Figure 9] 9 is a flowchart of a possible implementation of certain steps of the innovative method of FIG. 8 . DETAILED DESCRIPTION OF THE INVENTION

[0012] According to the subject matter disclosed herein, noise reduction is achieved not throughout the entire surrounding area, but within a specific, limited space, such as the space where people are most likely to be present during the operation of a high-noise system. The space can 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. Given this assumption, noise reduction by electronic means can be achieved in an effective manner. The theoretical goal is to completely reduce noise. Innovative electronic devices emit acoustic waves that at least partially cancel out the noise waves from the high-noise system in the space. Outside of such a space, noise cancellation is significantly insufficient or even nonexistent.

[0013] An exemplary high noise system 10 is shown schematically in Figure 1. According to this example, system 10 includes three separate noise sources 11, 12, and 13. A better understanding of the high noise system can be derived from Figure 3, as will be explained later.

[0014] FIG. 1 illustrates a schematic representation of an exemplary high-noise system 10. According to this example, system 10 includes three distinct noise sources 11, 12, and 13. System 10, and in particular its noise sources 11, 12, and 13, generate noise that propagates through the surrounding air as noise waves 19. Note that the noise waves propagate in all directions around system 10, with arrow 19 oriented according to a specific direction of propagation that includes the exemplary innovative device 100 and the exemplary space 20 shown in FIG. 1. In FIG. 1, arrow 19 represents the propagating noise wave resulting from the combination of noises emanating from all noise sources in system 10. As distance from system 10 increases, it becomes less possible to distinguish between specific noise origins (i.e., noise sources 11, 12, and 13), and high-noise system 10 may come to be equated to a single noise-generating source. Furthermore, if a small area surface (e.g. perpendicular to the direction of propagation of the noise waves) is considered compared to the distance from a high-noise system, the noise waves arriving at this surface can be considered as plane waves.

[0015] FIG. 1 shows a schematic representation of an exemplary, bounded, predetermined "quieted" (i.e., noise-reduced) space 20. According to this example, a person 29 is present inside the space 20. A better understanding of the "quieted" (i.e., noise-reduced) space can be derived from FIGS. 4A and 4B, as will be explained later. In the example of FIG. 1, the space 20 is at a distance, specifically a first distance D1 (as shown in FIG. 2), from the high-noise system 10. It should be noted that, in general, the space 20 is not considered an area of ​​the ground, but rather a three-dimensional, limited volume (at any distance from the ground) that needs to be quieted.

[0016] The embodiment of the innovative device 100 of FIG. 1 can reduce noise emanating from a high-noise system 10 within a space 20. The device 100: a) at least one microphone 110 configured to receive noise, in particular noise waves 19, from the high-noise system 10 and generate a noise electrical signal 115, the at least one microphone 110 being configured to be located at a second distance D2 (see FIG. 2) from the high-noise system 10; b) at least one loudspeaker 120 configured to receive an acoustic electric signal 125 and consequently emit acoustic waves 109 towards the space 20, the at least one loudspeaker 120 configured to be positioned at a third distance D3 (see FIG. 2) from the space 20; 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 loudspeaker 120.

[0017] The noise processor 130 is an electronic processor configured to generate an acoustic electric signal 125 by processing the noise electric signal 115 so that the noise waves 19 coming from the high-noise system 10 and the acoustic waves 109 coming from the at least one loudspeaker 120 at least partially combine and cancel in the space 20. In practice, the cancellation may not be perfect and may vary slightly from point to point in the space and may depend on the size of the space. In either case, noise reduction throughout the space may be achieved.

[0018] Because the space 20 to be "silenced" is limited, the total power of the acoustic waves 109 emitted by the device 100 is much less than the total power of the noise waves emitted by the high-noise system 10.

[0019] It is advantageous to select the second distance D2 (see FIG. 2) to be greater than the third distance D3 (see FIG. 2). In other words, it is advantageous to place the innovative device 100 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 acoustic waves 109 emitted by the device 100 can be relatively small, since the amplitude of the propagating acoustic waves is a function of the inverse square of the distance. It should be noted that the third distance D3 is not negligible, for example, a few centimeters (or millimeters).

[0020] As already explained, it is advantageous to choose the first distance D1 (see FIG. 2) to be greater than a first predetermined value, for example 15 m or 30 m. In other words, it is advantageous to locate the space 20 to be "silenced" quite far from the high-noise system 10. One reason is that in this way the noise waves 19 reaching the space 20 can be considered as plane waves.

[0021] The second distance D2 (see FIG. 2) is advantageously chosen to be greater than a second predetermined value, for example 10 m or 20 m. In other words, it is advantageous to place the innovative device 100 quite far from the high-noise system 10. One reason is that in this way, the noise waves 19 reaching the device 100 can be considered as plane waves.

[0022] The third distance D3 (see FIG. 2) is advantageously chosen to be greater than a third predetermined value, for example 5 m or 10 m, but at least 1 m. In other words, it is advantageous to place the innovative device 100 quite far from the space 20. One reason is that in this way, the acoustic wave 109 reaching the space 20 can be considered as a plane wave. Typically, the third distance D3 is in the range of 1 / 2 to 1 / 10 of the first distance D1.

[0023] The innovative device may also comprise multiple microphones (not shown in any of the figures), which may be advantageous in order to capture noises of different frequencies (in which case the microphones are different) and / or to better capture all noises emitted by a high-noise system, for example by appropriately positioning the microphones (in which case the microphones may be the same).

[0024] The innovative device may comprise multiple loudspeakers. Figure 7 shows a loudspeaker configuration consisting of a first loudspeaker 121, a second loudspeaker 122, and a third loudspeaker 123, all of which are electrically coupled to a noise processor 130. Multiple loudspeakers may be used, for example, to cover a larger space to be "silenced." The use of multiple loudspeakers, preferably arranged as a horizontal or vertical array (as shown in Figure 7), may make it possible to control (typically fine-tune, for example during pre-tuning) the wave group propagation direction of the emitted acoustic waves by adjusting the relative phase of the different acoustic electrical signals fed to the separate loudspeakers.

[0025] Considering the embodiment of FIG. 1, loudspeaker 120 is positioned a fourth distance D4 (see FIG. 4) from microphone 110. The entire device 100 may include a casing, e.g., having the shape of a tube, that houses all of its components, with the loudspeaker at a first end of the casing and the microphone at a second (opposite) end of the casing. Such a feature may also be present in the embodiment of FIG. 5. Indeed, device 100 of FIG. 1 and devices 100' and 100'' of FIG. 5 are very similar.

[0026] Considering specifically the particularly advantageous embodiment of FIG. 1 , the high-noise system 10, the space 20, and the device 100 can be considered to be aligned or "in a straight line." In this case, the first distance D1 is equal to the sum of the second distance D2 and the third distance D3. Advantageously, the fourth distance D4 divided by the speed of sound propagation in air is greater than (or equal to) the processing time of the noise electrical signal 115 by the noise processor 130. In other words, the electronic processing time by the device is less than (or equal to) the propagation time of the wave along the device. More precisely and advantageously, the noise processor 130 may be configured so 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 propagation in air, and a delay time is provided in the device 100 so that the sum of the processing time and the delay time is equal to the fourth distance D4 divided by the speed of sound propagation in air. In this way, the acoustic waves from device 100 and system 10 arrive at space 20 simultaneously. Generally, the delay times are adjusted for optimal combination and cancellation of noises in the space of interest, taking into account various parameters of the configuration, including the frequency and phase of the noise from the high-noise system.

[0027] Alternatively, considering specifically the embodiment of FIG. 5, the high-noise system 10, the space 20, and the apparatus 100′ are not aligned. In this case, it is also desirable for the apparatus 100′ to be quick in processing signals, but all distances—specifically, referring to FIG. 5 , D6, D7, D8, and D9—must be considered (D6 may, for example, be equal to D1, but less than the sum of D7, D8, and D9, and D9 may be equal to D4). For example, the propagation time of a wave along distance D6 must be greater than the sum of the propagation time of a wave along distance D7, the propagation time of a wave along distance D8, and the processing time of the apparatus 100. Because D6 must be less than D7+D8 (and also less than D7+D8+D9), it is expected that the microphone 110 should be positioned closer to the high-noise system 10 and / or the loudspeaker 120 should be positioned closer to the space 20. In general, optimal combination and cancellation of noises in a space of interest is achieved by considering various parameters of the configuration, including the frequency and phase of the noise from high-noise systems.

[0028] Considering the embodiment of FIG. 5 specifically, it is advantageous to have two identical (or very similar) pieces of equipment 100′ and 100″, which can be considered two sections of the same innovative device. Each of these two sections 100′ and 100″ may be similar or identical to the device 100 of FIG. 1. These two sections are preferably positioned symmetrically with respect to the high-noise system 10 and symmetrically with respect to the space 20 (see FIG. 5). In this way, noise cancellation can be much better (or even nearly complete).

[0029] In light of the above discussion, FIGS. 1 and 5 depict the components of systems 100, 100′, and 100″ in close proximity to one another. However, this should not be construed as limiting the subject matter disclosed herein. In particular, the location of microphones and / or loudspeakers may be suitably distant from noise processor 130 and / or suitably close to system 10 and / or space 20.

[0030] As already mentioned, the innovative device is an electronic device since it processes electrical signals. Figure 6 shows a possible digital implementation of the device 100 of Figures 1 and 5. In particular, the noise processor 130 comprises 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 loudspeaker 120, and an electronic processor 136, e.g., a microprocessor with associated program and data memory, electrically coupled between the analog-to-digital converter 132 and the digital-to-analog converter 134. It should be noted that there is a component called a DSP (= "Digital Signal Processor") that incorporates at least the processor, memory, digital-to-analog converter, and analog-to-digital converter.

[0031] Considering FIG. 3 , a system 300 is shown corresponding to an exemplary high-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 combustor 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 coupling 360 corresponding to the sixth possible noise source 16, and a second coupling 370 corresponding to the seventh possible noise source 17. As is clear from this diagram, the various noise sources can be considered to be concentrated at different specific locations. The noise from the various noise sources may differ from one another in terms of spectral composition. According to the subject matter disclosed herein, the noise may be in the range of 20 Hz to 20 KHz, which corresponds to all audible frequencies, or in a narrower range, for example, 20 Hz to 5 KHz. For purposes of determining the operating range, note that a turbomachine rotating at, for example, 12,000 RPM will generate noise at a first fundamental frequency of 200 Hz and its harmonics, as well as a second fundamental frequency of, for example, 200 Hz multiplied by the number of blades in any stage and its harmonics.

[0032] Considering FIG. 4, FIG. 4A shows a first exemplary space 20′ to be sound-silenced, which is an open space, i.e., not delimited by any elements, and FIG. 4B shows a second exemplary space 20″ to be sound-silenced, which is delimited, for example, by cabinet walls. In both cases, the space to be sound-silenced may be, for example, 2-4 m (height) by 2-4 m (width) by 2-4 m (depth). In FIG. 4A, a person is shown inside the space 20′, for example, at three locations, for example, 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 pre-conditioning and / or pre-training, the noise reduction device is set so that the noise is particularly low (or even zero) at these locations. In FIG. 4B, a person is shown inside the space 20″, in particular inside a closed cabinet. According to this example, only a limited number of positions, for example, one position 27, are of particular interest. As will be better explained below, during preconditioning and / or pretraining, the noise reduction devices are set so that during operation of a high-noise system, the noise is particularly low (or even zero) at these locations.

[0033] Generally, the innovative noise reduction method comprises the following steps (performed by a silencer device) from steps "b", "c", and "d": step "a" which is typical, but not strictly necessary, and will be described later; b) generating acoustic waves (see, for example, arrow 109 in Figures 1 and 5); c) directing the generated acoustic waves into the space to be "silenced" (see, for example, circle 20 in Figures 1 and 5); d) adjusting the generated acoustic waves (see, for example, arrow 109 in Figures 1 and 5) so that noise waves (see, for example, arrow 19 in Figures 1 and 5) coming from a high-noise system (see, for example, circle 10 in Figures 1 and 5) and the generated acoustic waves (see, for example, arrow 109 in Figures 1 and 5) combine and cancel in the space to be "quieted" (see, for example, circle 20 in Figures 1 and 5); As already explained, the space to be "quieted" is a defined, limited space, located at a certain distance from the noisy system.

[0034] In this case, both noise and acoustic waves are sound pressure waves propagating through the ambient air. When both waves reach the same confined space, they interfere in this space. The innovative method aims for destructive interference in this space, causing low (ideally zero) local sound pressure everywhere inside the space to be silenced (see, for example, Figure 4).

[0035] When considering a pressure wave propagating through a propagation means (in this case the ambient air), the following parameters should be taken into account: distance from the emission point (or more generally, the location of the silencer device and its components), amplitude (or power) at the emission point, phase at the emission point, frequency, and propagation speed in the propagation means, resulting in a 3D field that, under certain assumptions, can be considered a 2D field or even a 1D field (i.e., a plane wave). According to the subject matter disclosed herein, by simplification, one can consider the superposition of two 3D fields, one due to the high-noise system and one due to the innovative device.

[0036] It should be noted that although steps "b," "c," and "d" are presented above as separate and sequential, when such a method is implemented by an apparatus, such steps actually occur simultaneously and by the same device. Particularly and advantageously, the adjustment in step "d" is open-loop, at least during noise reduction operation. In contrast, during tuning (particularly pre-tuning) and / or training (particularly pre-training), the adjustment of the acoustic waves is typically closed-loop, for example, based on a feedback signal or signals from the space to be "quieted."

[0037] Typically, in step "b", the timing of the generated acoustic waves is adjusted. Typically, in step "b", the amplitude of the generated acoustic waves is adjusted. Typically, in step "b", the phase of the generated acoustic waves is adjusted. Advantageously, the timing of step "b" adjusts the amplitude and phase of the generated acoustic waves.

[0038] The adjustments in step "b" are made to achieve very good (or "optimal") cancellation of noise in the space.

[0039] The above-mentioned step "a" (performed by the silencer device) includes receiving a noise wave (see, for example, arrow 19 in Figures 1 and 5) and is performed before step "b". In this case, in step "b", an acoustic wave is generated based on the received noise wave, i.e., by processing the noise wave. More specifically, the timing, amplitude, and / or phase of the generated acoustic wave depends on the timing, amplitude, and / or phase of the received acoustic wave. In this case, the adjustment in step "d" provides for introducing a delay time having a value related to the distance and related to the high-noise system (e.g., 10), the space (e.g., 20), and the positions of the noise wave receiving and acoustic wave generating components (e.g., 110, 120) of the silencer device (e.g., 100). Considering FIG. 5, the positions of the high-noise system 10 and the space 20 identify a first line segment (having a length equal to D6), the positions of the high-noise system 10 and the noise wave receiving component 110 identify a second line segment (having a length equal to D7), the positions of the acoustic wave generating component 120 and the space 20 identify a third line segment (having a length equal to D8), and the positions of the noise wave receiving component 110 and the noise sound wave generating component 120 identify a fourth line segment (having a length equal to D9). The delay time may be related to the length of the projection of the second and third line segments onto the first line segment, and the length of the projection of the fourth line segment onto the first line segment. The delay time value may be calculated based on the propagation time of the waves along these three projections so that the noise waves from the high-noise system and the acoustic waves from the innovative device arrive at the space to be silenced simultaneously and / or with the same phase shift and cancellation.

[0040] According to some embodiments, the received noise waves are filtered into multiple bandwidths, and a different acoustic wave is generated for each bandwidth, which may allow for taking into account, for example, that the propagation speed of a wave may depend on the frequency of the wave and / or that the sensitivity of the human ear may depend on the frequency of the sound.

[0041] As expected, to achieve good noise reduction in a space, it is advantageous to perform pre-adjustment and / or pre-training and generate acoustic waves in step "b" based on such pre-adjustment and / or pre-training. For example, pre-adjustment of the noise reduction device is performed after installation of the noise reduction device but before the noise adjustment operation, and to some extent, may be performed when the high-noise system is not in operation, and generally lasts for a short period of time (e.g., several seconds to several minutes). For example, pre-training of the noise reduction device is performed after installation but before the noise adjustment operation, and is performed when the high-noise system is not in operation, and generally lasts for a long period of time (e.g., tens of minutes or even several hours). The purpose of both pre-adjustment and pre-training is to set processing parameters so that, during operation of the high-noise system, noise is particularly low (or even zero) anywhere in the space to be "quieted" (see, for example, FIG. 4). To this end, one or more specific locations within the space may be considered, for example, to run an optimization algorithm.

[0042] Figure 4B is very unusual in terms of noise. In fact, both noise waves and acoustic waves do not reach the person in the space, i.e., the cabinet, directly. They at least partially interfere in the walls of the cabinet (typically the walls facing the high-noise system and noise reduction device, especially its loudspeaker), and the acoustic pressure inside the cabinet may depend in part on the vibration of such walls. In either case, the innovative method still applies.

[0043] The innovative method can be embodied in many different ways. For example, the silencer device may be positioned in-line with the high-noise system and the space to be silenced, as shown, for example, in Figure 1. Alternatively, for example, the silencer device may not be positioned in-line with the high-noise system and the space to be silenced, as shown, for example, in Figure 5. Specifically, for example, as also shown in Figure 5, the silencer device may be divided into first and second identical sections positioned symmetrically with respect to the high-noise system and symmetrically with respect to the space to be silenced.

[0044] When the innovative method is incorporated into a device, for example, process 800 of the flowchart in FIG. 8 may be performed. The process begins at block 810 and ends at block 880. In block 820, the components of the innovative device (e.g., device 100 of FIG. 1 or FIG. 5) are arranged with respect to the space to be "quieted" with a high-noise system, particularly at least one microphone, at least one loudspeaker, and a sound processor. In block 830, the device is calibrated as previously described, for example, before starting the high-noise system. In block 840, the device is trained as previously described, for example, after starting the high-noise system, but preferably with no people in the space to be "quieted." Now, the device is ready to be used to quiet the space, and in block 850, the device is first switched on and then activated (when the device is active, it is ready to emit acoustic waves). In block 860, acoustic waves are actually generated through the device and directed to the space to be "quieted," so that such space is actually "quieted," i.e., noise reduced. In block 870, the device is first deactivated and then turned off.

[0045] 9 illustrates in more detail possible activities corresponding to block 860. First, block 862 corresponds to receiving a noise wave and generating a noise electrical signal. Then, block 864 corresponds to processing the noise signal. Then, block 866 corresponds to generating an acoustic electrical signal. Finally, block 868 corresponds to emitting an acoustic wave based on the acoustic signal.

[0046] It should be noted that according to some embodiments, the innovative device may be activated only when needed (i.e., not at random times, but when a high-noise system is operating), e.g., only when a person is present or expected in the space, e.g., it may be activated before the person's arrival and deactivated after the person's exit.

[0047] It should be noted that according to some embodiments, for example, if the high-noise system may have two or more operating modes, the innovative device may be activated taking into account the specific operating mode of the high-noise system. In other words, the innovative device may have two or more operating modes. The decision regarding the operating mode of the innovative device may be made, for example, at each activation time. The decision regarding the operating mode of the innovative device may result, for example, from a control signal received from the innovative device and / or a user command received from the innovative device.

[0048] It should be noted that the innovative device for reducing noise may be integrated into a configuration at least together with a high-noise system, the device being intended to reduce the noise generated by the high-noise system in a predetermined, limited space at a certain distance from the high-noise system. In particular, the device may be configured to implement an innovative noise reduction method.

Claims

1. An apparatus (100) for reducing noise emanating from a high-noise system (10) and propagating through ambient air as noise waves, said high-noise system (10) including one or more noise sources (11, 12, 13), said apparatus (100) comprising: a) at least one microphone (110) configured to receive noise (19) from the high-noise system (10) and generate a noise electrical signal (115); b) at least one loudspeaker (120) configured to receive an acoustic electric signal (125) and consequently emit acoustic waves (109) towards said space (20); c) a noise processor (130) having at least one input and at least one output, the at least one input being electrically coupled to the at least one microphone (110) and the at least one output being electrically coupled to the at least one loudspeaker (120); The device (100) is configured to reduce noise in a space (20), the space (20) being a predetermined, limited space and being a first distance (D1) from the high-noise system (10); the at least one microphone (110) is configured to be located at a second distance (D2) from the high-noise system (10), and the at least one loudspeaker (120) is configured to be located at a third distance (D3) from the space (20); the noise processor (130) is configured to generate the acoustic electric signal (125) by processing the noise electric signal (115) so that noise waves (19) coming from the high-noise system (10) and the acoustic waves (109) coming from the at least one loudspeaker (120) combine and cancel each other in the space (20); the at least one loudspeaker (120) is positioned at a fourth distance (D4) from the at least one microphone (110); The noise processor (130) is configured so that the processing time of the noise electrical signal (115) is equal to or less than the fourth distance (D4) divided by the speed of sound propagation in air, and a delay time is provided within the device (100), and the sum of the processing time and the delay time is equal to the fourth distance (D4) divided by the speed of sound propagation in air.

2. The apparatus (100) of claim 1, wherein the second distance (D2) is greater than the third distance (D3).

3. The apparatus (100) of claim 1, wherein the third distance (D3) is greater than a third predetermined value.

4. 2. The device (100) according to claim 1, comprising a plurality of loudspeakers (121, 122, 123), in particular arranged in a horizontal or vertical array.

5. The apparatus (100) of claim 1, wherein the apparatus (100) is configured to be aligned with the high-noise system (10) and the space (20).

6. A method for reducing noise emanating from a high-noise system (10) and propagating through ambient air as noise waves (19), wherein the noise reduction is achieved by an apparatus (100) in a defined, confined space (20) at a distance from the high-noise system (10), and the method is performed by the apparatus (100). b) generating an acoustic wave (109); c) directing the generated acoustic waves (109) into the space (20); d) adjusting the generated acoustic waves (109) so that noise waves (19) coming from the high-noise system (10) and the generated acoustic waves (109) combine and cancel each other in the space (20), The method provides for adjusting in step "d" introducing a delay time having a value related to the distance and related to the positions of the high-noise system (10), the space (20), and the components (110, 120) of the apparatus (100).

7. 7. The method of claim 6, wherein said adjusting in step "d" is open-loop during noise reduction operation.

8. 7. The method of claim 6, wherein in step "b" the timing of the generated acoustic waves (109) is adjusted.

9. The method of claim 6, wherein in step "b" the amplitude of the generated acoustic waves (109) is adjusted.

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

11. a step "a" performed by said device (100) of receiving said noise waves (19), Step "a" is performed before step "b", In step "b", the acoustic wave (109) is generated based on the received noise wave (19), 7. The method of claim 6, wherein the adjusting in step "d" provides for introducing a delay time having a value related to the distance and related to the positions of the high-noise system (10), the space (20), and the noise wave receiving and acoustic wave generating components (110, 120) of the device (100).

12. The positions of the high-noise system (10) and the space (20) identify a first line segment (D6); the positions of the high-noise system (10) and the noise wave receiving component (110) identify a second line segment (D7); the positions of said acoustic wave generating component (120) and said space (20) identify a third line segment (D8); 12. The method of claim 11, wherein the delay time is related to the length of the projection of the second line segment (D7) and the third line segment (D8) onto the first line segment (D6).

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

14. The method of claim 6, wherein in step "b", the acoustic waves (109) are generated based on a preconditioning.

15. 15. The method of claim 14, wherein in step "b", the acoustic waves (109) are generated based on a pre-training following the pre-conditioning.

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

17. 7. The method of claim 6, wherein the steps performed by the device (100) are divided into first and second identical sections (100′, 100″) positioned symmetrically with respect to the high-noise system (10) and symmetrically with respect to the space (20).

18. A configuration comprising a high-noise system (10) and a device (100) for reducing noise generated by the high-noise system (10) in a predetermined, limited space (20) at a certain distance from the high-noise system (10), The arrangement (100) comprises the features of any one of claims 1 to 5.

19. A configuration comprising a high-noise system (10) and a device (100) for reducing noise generated by the high-noise system (10) in a predetermined, limited space (20) at a certain distance from the high-noise system (10), The arrangement (100) is configured to implement the method according to any one of claims 6 to 17.

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