Patent Publication Number: US-2020286460-A1

Title: System and method for noise cancellation in emergency response vehicles

Description:
TECHNICAL FIELD 
     This application relates to a system and method for noise cancellation in emergency response vehicles. 
     BACKGROUND 
     Sirens attached to emergency vehicles are used to inform neighboring vehicles an emergency situation. However, the long-term exposure of first responders to loud noise generated from the sirens may cause many severe medical issues such as deafness. 
     Thus, there is a need for a method and system to reduce the siren noise of emergency vehicles. 
     SUMMARY OF THE INVENTION 
     The objective of the present disclosure is to provide a system and method for effectively reducing or cancelling out a noise generated from the siren in an emergency vehicle. Aspects of the present disclosure are a system, method and storage medium for reducing or cancelling out a noise in an emergency vehicle. 
     In one aspect, there is provided a system for noise cancellation in a vehicle. The system includes a controller and a sound generator. 
     The controller is configured to determine a waveform of a first sound wave at a first location. The first sound wave is a noise sound generated from a noise source such as a siren attached to the vehicle. Based on the waveform of the first sound wave at the first location and a first distance between the first location and the second location, the controller is configured to calculate another waveform of the first sound wave which will arrive a second location where an operator is located. Further, the controller is configured to generate at least one control signal based on the determined another waveform of the first sound wave at the second location. 
     The at least one sound generator is positioned at a third location and is configured to generate a second sound wave based on the at least one control signal. The second sound wave, when being super-positioned with the first sound wave, acts to cancel out the first sound wave at the second location. To this end, at the second location, the amplitude and the frequency of the second sound wave are substantially the same as the amplitude and the frequency of the first sound wave, respectively, and the phase of the second sound wave is opposite to the first sound wave. For example, the sound generator is embodied with a speaker. 
     In one embodiment, the first location is where the noise source is located or in vicinity of the noise source. The waveform of the first sound wave at the first location (i.e., location of the noise source) are known to the system and are stored in memory. Thus, the controller is configured to read the information of the waveform of the first sound wave at the first location to determine the waveform of the first sound wave at the first location. 
     In one embodiment, the noise cancellation system further includes at least one sound receiver configured to detect the first sound wave at the first location as well as other measured locations throughout the vehicle and transmit the detected first sound wave to the controller. For example, the sound receiver is embodied with a microphone. 
     In order to cancel out the first sound wave at the second location, the waveform of the second sound wave generated from the sound generator is adapted in a manner to cancel out the first sound wave at the second location. 
     In one embodiment, the first sound wave can be a noise that should be reduced or cancelled out that is generated by the noise source. 
     In one embodiment, the noise source is positioned outside the vehicle (e.g., on top of the vehicle&#39;s roof), and the noise source is positioned at the first location which the controller determines the waveform of the first sound wave. For example, in this embodiment, no sound receiver (e.g., microphone) is needed to detect the first sound wave since the system has known the waveform of the first sound wave at the first location generated by the noise source. 
     In one embodiment, the system may include one or more optional sound receivers to detect the first sound wave at various locations to make it easier to determine the waveform of the first sound wave. In one example, a sound receiver can be positioned at the location which the noise source is positioned or in the vicinity of the noise source to detect the first sound wave output from the noise source. In another embodiment, the location at which the noise source is positioned at is not the same as the first location at which the controller determines the waveform of the first sound wave; for example, the noise source is positioned outside the vehicle, and the sound receiver is positioned at the first location inside the vehicle. Thus, the first sound wave generated from the noise source positioned outside the vehicle travels to the second location via the first location at which the waveform of the first sound wave are determined by the controller. 
     In one embodiment, the first location of the sound detector is positioned on a direct path of the first sound wave from the location of the noise source to the second location. 
     In one embodiment, the controller is configured to calculate the required waveform of the second sound wave at the third location of the sound generator. The second sound wave generated from the sound generator travels along a path from the third location to the second location, experiencing changes in at least amplitude, frequency, and/or phase over the path. The amount of the changes in amplitude, frequency, and/or phase of the second sound wave depends on a distance between the third location and the second location. Given that at the second location which the operator is positioned, the second sound wave is required to have the waveform to cancel out the first sound wave (as described above), the waveform of the second sound wave at the third location can be reversely calculated back from the target waveform of the second sound wave at the second location. 
     In one embodiment, the noise cancellation system further includes one or more sensors configured to scan a layout an interior of the vehicle and transmit information of the scanned layout to the controller. The controller is configured to determine the second location, the third location, and the fourth location based on the information of the scanned layout. 
     In one embodiment, the controller is configured to determine an angle at which the first sound wave generated from the noise source enters into a cabin of the vehicle through a surface (e.g., roof surface of the vehicle) and calculate the another waveform of the first sound wave at the second location based on the determined angle. For example, the angle is an angle at which a direction extending along a direct path between the location of the noise source and the second location of the operator crosses the surface of the vehicle which the first sound wave passes through. 
     In one embodiment, information regarding the angle may be stored in the memory, so that the controller reads the information of the angle from the memory. 
     In one embodiment, when the determined angle gets closer to 90 degrees with respect to the surface of the vehicle, the amplitude of the first sound wave after passing through the surface of the vehicle becomes increased and a frequency of the first sound wave perceived by the operator after passing through the surface becomes increased. 
     In one embodiment, when the determined angle gets farther away from the 90 degrees with respect to the surface of the vehicle, the amplitude of the first sound wave after passing through the surface of the vehicle becomes decreased and the frequency of the first sound wave perceived by the operator after passing through the surface becomes decreased. 
     In one embodiment, the frequency of the first sound wave perceived by the operator after passing through the surface of the vehicle is determined by a following equation: 
     f perceived =f actual  COS (θ), wherein f perceived  is the frequency of the first sound wave perceived by the operator after passing through the surface, f actual  is an actual frequency of the first sound wave before entering the surface, and θ is the determined angle. 
     In one embodiment, the first sound wave at the second location includes a directly transmitted portion and at least one reflected portion. The directly transmitted portion corresponds to the first sound wave transmitted directly from the first location without being reflected off a surface of the vehicle. The at least one reflected portion corresponds to the first sound wave reflected off at least one surface of the vehicle. Thus, the at least one control signal generated by the controller includes a first control signal and a second control signal. A portion of the second sound wave is generated based on the first control signal to cancel out the directly transmitted portion, and another portion of the second sound wave is generated based on the second control signal to cancel out the reflected portion. 
     In one embodiment, the first control signal is generated based on the first distance, and the second control signal is generated based on a distance of the travel path of the reflected portion of the second sound wave. 
     In another aspect of the present disclosure, there is provided a noise cancellation method for a vehicle. The method includes determining, by a controller, a waveform of a first sound wave at a first location; calculating, by the controller, another waveform of the first sound wave at a second location of an operator based on the waveform of the first sound wave at the first location and a first distance between the first location and the second location; generating, by the controller, at least one control signal based on the determined another waveform of the first sound wave at the second location; and generating, by a sound generator positioned at a third location, a second sound wave based on the at least one control signal. 
     In still yet another aspect of the present disclosure, there is provided a computer-readable storage medium having computer readable program instructions. The computer readable program instructions can be read and executed by at least one processor for performing a method for noise cancellation in a vehicle. The method includes determining a waveform of a first sound wave at a first location; calculating another waveform of the first sound wave at a second location of an operator based on the waveform of the first sound wave at the first location and a first distance between the first location and the second location; generating at least one control signal based on the determined another waveform of the first sound wave at the second location; and generating, using a sound generator positioned at a third location, a second sound wave based on the at least one control signal. 
     In one embodiment, the waveform of the second sound wave are formed to cancel out the first sound wave at the second location, and the first sound wave is generated by a noise source. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure will become more readily apparent from the specific description accompanied by the drawings. 
         FIG. 1  is a block diagram of an example emergency vehicle having a noise cancellation system according to an embodiment of the present disclosure; 
         FIG. 2  is a view illustrating an example travel path of a sound wave between a reference location and a target location according to an embodiment of the present disclosure; 
         FIG. 3A  is a view illustrating example travel paths of a noise sound wave and a compensation sound wave when a reference location is outside a vehicle according to an embodiment of the present disclosure; 
         FIG. 3B  is a view illustrating an example channel model of a noise sound wave in case of a reference location being outside a vehicle according to an embodiment of the present disclosure; 
         FIG. 4A  is a view illustrating example travel paths of a noise sound wave and a compensation sound wave in case of a reference location being inside a vehicle according to an embodiment of the present disclosure; 
         FIG. 4B  is a view illustrating an example channel model of a noise sound wave in case of a reference location being inside a vehicle according to an embodiment of the present disclosure; 
         FIG. 5  is a view illustrating an example travel path of a reflected noise sound wave according to an embodiment of the present disclosure; 
         FIG. 6A  is a view illustrating an example channel model of a noise sound wave in case of a reference location being outside a vehicle according to an embodiment of the present disclosure; 
         FIG. 6B  is a view illustrating an example channel model of a noise sound wave in case of a reference location being inside a vehicle according to an embodiment of the present disclosure; 
         FIG. 7  is a flow chart illustrating a noise cancellation method according to an embodiment of the present disclosure; 
         FIG. 8  is a block diagram of a computing system according to an embodiment of the present disclosure; and 
         FIG. 9  is a view illustrating an example neural network with hidden layers used for training an artificial intelligence according to an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure may be understood more readily by reference to the following detailed description of the disclosure taken in connection with the accompanying drawing figures, which form a part of this disclosure. It is to be understood that this disclosure is not limited to the specific devices, methods, conditions or parameters described and/or shown herein, and that the terminology used herein is for the purpose of describing particular embodiments by way of example only and is not intended to be limiting of the claimed disclosure. 
     Also, as used in the specification and including the appended claims, the singular forms “a,” “an,” and “the” include the plural, and reference to a particular numerical value includes at least that particular value, unless the context clearly dictates otherwise. Ranges may be expressed herein as from “about” or “approximately” one particular value and/or to “about” or “approximately” another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. 
     The phrases “at least one”, “one or more”, and “and/or” are open-ended expressions that are both conjunctive and disjunctive in operation. For example, each of the expressions “at least one of A, B and C”, “at least one of A, B, or C”, “one or more of A, B, and C”, “one or more of A, B, or C” and “A, B, and/or C” means A alone, B alone, C alone, A and B together, A and C together, B and C together, or A, B and C together. 
     For the sake of description, the present disclosure will be described with reference to a case where the noise cancellation system is used for an emergency vehicle as only an example. However, embodiments of the present disclosure are not limited thereto. It will be apparent that the noise cancellation system can be applied to any other vehicles or any space where the waveform of a noise sound wave is estimated. 
       FIG. 1  is a block diagram of an example emergency vehicle (EV)  10  having a noise cancellation system  150  according to an embodiment of the present disclosure. The noise cancellation system  150  can be installed to be attached on an emergency vehicle  10  or in the vicinity thereof. The noise cancelation system  150  is configured to cancel out or reduce a noise (or noise sound wave) generated from a noise source  100  attached to a surface  12  of the vehicle  10  or in the vicinity thereof. In one embodiment, the noise source  100  can be a siren and attached on a top surface  12  of the vehicle  10 , as exemplary depicted in  FIG. 1 . However, embodiments of the present disclosure are not limited thereto. For example, the noise source  100  can be an engine or any other elements generating noises. 
     Referring now to  FIG. 1 , the noise cancellation system  150  can include a control unit  200  and at least one speaker  300  in communication with the control unit  200 . As shown in  FIG. 1 , the control unit  200  includes at least one processor  210  (e.g., central processing unit (CPU)), a memory  220  coupled to the processor  210 , and a communication interface  230 . For example, the control unit  200  is implemented using an arm cortex m4 microcontroller for the floating-point calculations, which allows increase of the calculation speed and reduce latency of the compensation sound wave being outputted from the speaker  300  to match the phase better. In some aspects, a real time operating system will also be used to manage the different tasks involved in this calculation and manage the required deterministic timing of the calculations. 
     Referring further to  FIG. 2 , the control unit  200  estimates a waveform of the noise sound wave  110  arriving a target location L T . The noise sound wave  110  at the target location L T  is a wave which has been generated by the noise source  100  and transmitted over a certain path between the noise source  100  and the target location L T , experiencing changes in amplitude, phase and/or frequency over the path. The control unit  200  generates a control signal  201  based on the estimated waveform of the noise sound wave  110  at the target location L T  and transmit the control signal  201  to the speaker  300 . The speaker  300  is configured to generate a compensation sound wave  310  based on the control signal  201  and transmit the compensation sound wave  310  to the target location L T . 
     The target location L T  is a location at which the system  150  wants to have the noise cancelled out. As exemplary depicted in  FIG. 1 , the target location L T  can be at an operator (e.g., driver)&#39;s ears or in the vicinity thereof. By way of example only, the target location L T  can be set on a headrest of the operator&#39;s seat. 
     At the target location L T , the compensation sound wave  310  has to have a waveform which acts to reduce or cancel out the noise sound wave thereat. Referring to  FIG. 1 , the compensation sound wave  310  that has to be generated from the speaker  300  can be calculated back based on a target waveform at the target location L T  and a distance D S_T  of the speaker  300  positioned at a location L S  away from the target location L T . For example, at the target location L T , the target waveform of the compensation sound wave  310  can have substantially the same amplitude and frequency as the estimated waveform of the noise sound wave  110 , and the target waveform of the compensation sound wave  310  has an opposite phase to the estimated waveform of the noise sound wave  110  in order for the noise sound wave at the target location L T  to be cancelled out or reduced. 
     The noise sound wave  110  arriving the target location L T  may include a directly transmitted portion and one or more reflected portions. The directly transmitted wave corresponds to the noise sound wave transmitted directly from the noise source  100  to the target location L T  without being reflected off any internal surface of the vehicle  10 , and the reflected portion(s) correspond(s) to the noise sound wave reflected off at least one internal surface of the vehicle  10 . 
     Here below is described a mechanism for cancelling out the directly transmitted portion at the target location L T . 
     Cancellation of Directly Transmitted Portion of Noise Sound Wave 
     As described above, the waveform of the noise sound wave  110  arriving the target location L T  have to be determined in order to allow the speaker  300  to generate a compensation sound wave which acts to reduce or cancel out the noise sound wave  110  at the target location L T . 
     To that end, referring now to  FIG. 2 , the noise sound wave  110  at the target location L T  can be calculated back by using a reference waveform of the noise sound wave  110  and a distance D RF_T  between a location L RF  and the target location L T . The reference location L RF  is a location where the reference waveform is determined. Further, for the sake of description, the reference waveform of the noise sound wave can hereinafter be referred to as a “reference waveform”. 
     In one embodiment, referring to  FIG. 3A , the reference waveform may be a waveform of the noise sound wave at the location L NS  of the noise source  100 . In this case, as the location L NS  is positioned outside the vehicle  10 , the noise sound wave  110  may experience changes in amplitudes, frequencies and/or phases over a travel path from the location L NS  to the target location L T , a corresponding channel model of which is as conceptually depicted in  FIG. 3B . 
     Referring now to  FIG. 3B , a channel element  1310  is taken into account for a loss which the noise sound wave  110  undergoes when passing through a surface  12 . A channel element  1320  is taken into account for a frequency change due to an angle θ at which the noise sound wave  110  enters into the cabin of the vehicle  10  through the surface  12 . Channel elements  1330  and  1340  are taken into account for a loss and a phase change, respectively, during the noise sound wave traveling over a path with a distance (e.g., D 12_T ). The loss of energy in a sound wave through a surface is due primarily to the reflection of said sound wave when crossing between materials of varying acoustic impedances. 
     For example, a percentage R of energy reflected back can be calculated by the following Equation (1): 
     
       
         
           
             
               
                 
                   R 
                   = 
                   
                     
                       
                         ( 
                         
                           
                             
                               Z 
                               2 
                             
                             - 
                             
                               Z 
                               1 
                             
                           
                           
                             
                               Z 
                               2 
                             
                             + 
                             
                               Z 
                               1 
                             
                           
                         
                         ) 
                       
                       2 
                     
                     × 
                     100 
                   
                 
               
               
                 
                   Equation 
                    
                   
                       
                   
                    
                   
                     ( 
                     1 
                     ) 
                   
                 
               
             
           
         
       
     
     Here, Z 1  and Z 2  are impedances of the mediums that the sound waves are traveling through. For example, Z 1  represents an impedance of air, and Z 2  represents an impedance of a surface (e.g., door) of the vehicle  10  that the sound wave will have to pass through in order to enter the cabin. The equation (1) is called Fresnel&#39;s equation. 
     In the case of air and steel, which a car door is primarily comprised of, this reflection accounts for greater than 99 percent of the sound energy being reflected back to the source instead of being transmitted into the cabin. This varies from material to material  12  which may be made of e.g., metal. The entering angle θ of the noise sound wave may be measured by using locations of the noise source  100 , an operator (e.g., target location L T ), the surface  12  of the vehicle  10 , etc. When the angle θ gets closer to 90 degrees with respect to the surface  12  of the vehicle, the amplitude of the noise sound wave after passing through the surface  12  will become increased. In addition, when the angle θ gets farther from 90 degrees with respect to the surface  12  of the vehicle, the amplitude of the noise sound wave after passing through the surface  12  will become decreased. 
     Stokes&#39;s law of sound attenuation is A(d)=A 0 e −αd  where d is a distance in meters A 0  is the initial amplitude of the sound and α is the attenuation of sound in that material. 
     In this example channel model of  FIG. 3B , frequency phase shift, and a difference of attenuation of the sound wave through the surface of the vehicle  12  are neglected for the sake of simplicity. 
     The phase that the sound wave is currently in can then be calculated using t=x/v where t is equal to the time it takes a waveform to travel a distance x moving at a velocity v of the speed of sound 343 m/s. 
     Once t is known, S NS =A(d)cos(w NS t−φ NS ) can be used to find the actual amplitude of the sound wave S NS  at a point with attenuation being accounted for. 
     Here A NS  is an amplitude, w NS  is an angular frequency, and φ NS  is the measured or known output phase. 
     Then, the waveform S T  of the noise sound wave arriving the target location L T  will be given as: 
     Referring again to  FIG. 3B , the amplitude A T  at the target location L T  will be given by αβA NS , here α and β are losses corresponding to the channel elements  1310  and  1330 , respectively. The frequency W T  at the target location L T  will be given by w NS  cosθ. The phase φ T  at the target location L T  will be given by φ NS +kD 12_T , here k is a wave number. The wave number is given by λ/s, here λ, is a wavelength and s is a speed of a sound wave (e.g., 340 meters/second). Thus, φ T =φ NS +λD 12_T /s, here λ=s/f. 
     Referring back to  FIG. 3A , in order to cancel out the directly transmitted portion of the noise sound wave  110 , the compensation sound wave  310  at the target location L T  has to be given by: 
       S c =A c  cos(w c t−φ c )   Equation (2)
 
     Here, at the location L T , the amplitude A c  and the frequency w c  of the compensation sound wave 310 are substantially the same as those (A T  and w T ) of the noise sound wave  110 , and the phase φ c  of the compensation sound wave  310  is opposite to the phase φ T  of the noise sound wave  110  (e.g., φ c =−φ T ). As described above, the control unit  200  calculates the compensation sound wave  310  that has to be generated from the speaker  300  based on the target waveform and a distance D S1_T  of the speaker  300  away from the target location L T , generates the control signal  201  based on the calculation, and transmits the control signal  201  to the speaker  300 . 
     In one embodiment, the reference waveform of the noise sound wave at the location L NS  (e.g., reference location) may be known to the system  150 . For example, information of the noise sound waveform regarding amplitude, frequency and phase at the location L NS  are stored in the memory  220  of the control unit  200 . The control unit  200  may read such information of the reference waveform at the location L NS  from the memory  220  and calculate the waveform change of the noise sound wave  110  over the path from the noise source  100  to the target location L T , e.g., based on the channel model shown in  FIG. 3B . 
     In one embodiment, the reference waveform of the noise sound wave at the location L NS  can be measured by using at least one microphone. In one example, one or more microphones can be attached to the noise source  100 , or positioned around the location L NS  of the noise source  100 . The measured reference waveform of the noise sound wave may be transmitted to the control unit  200  via the communication interfaces  230 . The control unit  200  may have a sound analyzing module  240  for determining the characteristics (e.g., amplitude, frequency, and phase) of the noise sound wave transmitted from the microphone(s). 
     In one embodiment, referring to  FIG. 4A , the reference waveform can be a waveform at a location positioned inside the vehicle  10 . For example, the reference waveform is measured by using at least one microphone positioned at a location L M1  inside the vehicle  10 . The microphone can be positioned in a direct path  122  from the noise source  100  to the target location L T . 
     Depicted in  FIG. 4B  is an example channel model from the location L M1  to the target location L T . Referring to  FIG. 4B , channel elements  1410  and  1420  are taken into account for a loss and a phase change, respectively, during the noise sound wave traveling over a path from the location L M1  to the target location L T  having a distance D M1_T . As the microphone is positioned inside the vehicle  10 , no consideration is made with regard to loss and frequency shift through the surface  12  which correspond to the channel elements  1310  and  1320 , respectively. 
     Referring back to  FIG. 1 , the noise cancellation system  150  may further include at least one space scanner such as a time of flight sensor, sonar module, or camera&#39;s tracking for facial features located at specific positions to measure a layout of the interior of the vehicle and the position of the drivers ears  10  which allows the system  150  to be aware of positions of the microphone(s) (e.g.,  400 ), the speaker  300 , the target location L T , the surfaces (e.g.,  12  and  14 ), etc. The measured layout information of the interior of the vehicle  10  may be transmitted to the control unit  200  and/or stored in the memory  220 . 
     Cancellation of Reflected Portion of Noise Sound Wave (Optional) 
     The noise sound wave  110  may travel over different paths than the direct path  122  toward the target location L T , being reflected off one or more internal surfaces of the vehicle. Since the cabin of a vehicle is typically less than tens of meters (e.g., less than 17 meters) long, the reflections of the noise sound wave off cabin&#39;s internal surface(s) may create a perceived lengthening of tones to the operator instead of an echo. The waveform of the reflected noise sound wave at the target location L T  can be estimated by taking into account the paths over which the noise sound wave has to travel to reach the target location L T . 
     The speaker  300  or at least one another speaker (not shown) may be used to generate a compensation sound wave to cancel out the estimated waveform of the reflected noise sound wave, as described above. Duplicate description will be omitted for the sake of simplicity. 
     For the sake of explanation only, let us consider an example reflection path  123  which the noise sound wave will travel over, as shown in  FIG. 5 . The noise sound wave generated by the noise source  100  will pass through the surface  12 , travels over an air path from the surface  12  to the surface  14 , reflect off the surface  14 , and travels over another air path from the surface  14  to the target location L T . 
     Depending on a location of the reference waveform of the noise sound wave  110 , a channel model that has to be considered may vary. For example, if the reference location of the reference waveform is where the noise source  100  is positioned or near the noise source  100 , the channel model may have to consider at least a loss through the surface  12  (see e.g.,  1610  of  FIG. 6A ), a frequency shift through the surface  12  (see e.g.,  1620  of  FIG. 6A ), a loss through the air path D 12_14  between the surface  12  and the surface  14  (see e.g.,  1630  of  FIG. 6A ), a phase shift through the air path D 12_14  (see e.g.,  1640  of  FIG. 6A ), an effect of reflection off the surface  14  (see e.g.,  1650  of  FIG. 6A ), a loss through the air path D 14_T  between the surface  14  and the target location L T  (see e.g.,  1660  of  FIG. 6A ) , and a phase shift through the air path D 14_T  (see e.g.,  1670  of  FIG. 6A ). In order to consider the effect of the reflection off the surface  14 , an angle at which the sound wave is reflected off the surface  14  and a material which the surface  14  is made of can be considered to determine the waveform change in e.g., amplitude, frequency and phase. 
     In addition, if the reference location of the reference waveform is where a microphone is positioned, as depicted in an example embodiment of  FIG. 5  (for example, the microphone is positioned at a location L M2  on a travel path between the last reflection surface  14  and the target location L T ), the channel model may only consider the loss through the air path D 14_T  between the surface  14  and the target location L T  (see e.g.,  1680  of  FIG. 6B ) and the phase shift through the air path D 14_T  (see e.g.,  1690  of  FIG. 6B ), as depicted in  FIG. 6B . 
     Practically, due to large numbers of surfaces in the vehicle cabin between a noise source  100  and the target location L T , there may be a lot of different reflection paths of the noise sound wave other than the example path  123  of  FIG. 5 , which may cause the calculation for the resultant waveform of the noise sound wave at the target location L T  to be harder. For example, this can be addressed by testing different kinds of vehicles with different placements of microphones and/or different frequencies of the noise sound wave so as to find out dominant reflection paths of the noise sound wave and optimal locations of microphones to calculate the waveform of the noise sound wave at the target location L T . 
     As described above, the noise cancellation system  150  can use at least one space scanner  500  such as a time of flight sensor or sonar module to map out a layout of the interior of the vehicle  10  which allows the system  150  to be aware of positions of the microphones (e.g.,  400 ), the speaker  300 , the target location L T , the surface (e.g.,  12  and  14 ), etc. The measured information of the interior of the vehicle  10  can be used to estimate distances among the locations at interest or amount of time which it will take for the reflected sound to reach the target location L T . 
     In one embodiment, in order to reduce these reflections of the noise sound wave off the surfaces as well as the leakage of noise sound wave into the vehicle cabin, one or more internal surfaces (e.g.,  12  and  14 ) of the vehicle  10  can be made of a sound absorbing or dampening material such as porous material which is outfitted in the vehicle. The use of the sound absorbing or dampening material for the internal surfaces of the vehicle may make the estimation of the waveform of noise sound at the target location more predictable. 
     In one embodiment, the at least one speaker  300  can be provided as a stand-alone, or a part of the OEM sound system built in the vehicle. The speaker(s) can have the ability to outfit the vehicle interior with a noise absorbing material to reduce the reflections of the wave off itself. 
     In some aspects, the waveform of the noise sound wave  110  arriving the target location L T  can be determined by leveraging an artificial intelligence (AI) platform based on machine learning algorithms. For example, instead of calculating the waveform of the noise sound wave at the target location, an AI-powered platform for testing different vehicle types with different placements of speakers and a range of frequencies outputted by the noise source can be used, so that various parameters of the AI platform such as weights of the equations between the nodes in a neural network can be trained so as to reduce the measured volume at a known distance from the noise source by a greatest amount throughout a range of frequencies. 
     An example of a neural network with hidden layers used for training the AI platform is depicted in  FIG. 9 . For example, electronics (e.g., Omron Electronics B5T-007001-020) of a camera can be used to detect a person&#39;s face as well as its pitch. In combination with a second camera at a known distance and angle from the first this can be used to triangulate the position of the driver and each of their ears. This is one variable that can be plugged into the input layer  910  of the neural network of  FIG. 9  along with the frequency amplitude phase and distance from the noise source as well as the vehicle the air is being trained on itself. The output layer  930  would then consist of only one output which is the decibel level within a narrow frequency around the outputted frequency of the siren at that time at the drivers ears which can be measured using a microphone. The hidden layer  920  of the AI then will vary the weights of the equations contained within it to minimize the decibel level within this narrow frequency band. 
     In some aspects, at least one microphone (not shown) can be placed around the vehicle  10  for measuring ambient noise. The ambient noise can be amplified and provided to the control unit  200 . The information of the ambient noise can be used by the control unit  200  to allow the operator (e.g., police officer) monitor the surroundings of the vehicle or patrol for someone on foot. 
       FIG. 7  is a flow chart illustrating a noise cancellation method according to an embodiment of the present disclosure. 
     Referring now to  FIG. 7 , the method commences with step S 710  of the control unit  200  determines the reference waveform of the noise sound wave  100  at a reference location L RF . 
     In step S 720 , the control unit calculates a waveform of the noise sound wave at the target location based on the determined reference waveform and a distance between the reference location and the target location. 
     In step S 730 , the control unit generates the control signal  201  based on the waveform of the noise sound wave at the target location to transmit the control signal to at least one speaker  300 . 
     In step S 740 , the speaker  300  generates the compensation sound wave based on the control signal to transmit the compensation sound wave to the target location. 
       FIG. 8  is a block diagram of a computing system  4000  according to an exemplary embodiment of the present disclosure. 
     Referring to  FIG. 8 , the computing system  4000  may be used as a platform for performing: the functions or operations described hereinabove with respect to at least one of the noise cancellation system  150  of  FIG. 1  and/or the method described with reference to  FIG. 7 . 
     Referring to  FIG. 8 , the computing system  4000  may include a processor  4010 , I/O devices  4020 , a memory system  4030 , a display device  4040 , and/or a network adaptor  4050 . 
     The processor  4010  may drive the I/O devices  4020 , the memory system  4030 , the display device  4040 , and/or the network adaptor  4050  through a bus  4060 . 
     The computing system  4000  may include a program module for performing: the functions or operations described hereinabove with respect to at least one of the noise cancellation system  150  of  FIG. 1  and/or the method described with reference to  FIG. 7 . For example, the program module may include routines, programs, objects, components, logic, data structures, or the like, for performing particular tasks or implement particular abstract data types. The processor (e.g.,  4010 ) of the computing system  4000  may execute instructions written in the program module to perform: the functions or operations described hereinabove with respect to at least one of the noise cancellation system  150  of  FIG. 1  and/or the method described with reference to  FIG. 7 . The program module may be programmed into the integrated circuits of the processor (e.g.,  4010 ). In an exemplary embodiment, the program module may be stored in the memory system (e.g.,  4030 ) or in a remote computer system storage media. 
     The computing system  4000  may include a variety of computing system readable media. Such media may be any available media that is accessible by the computer system (e.g.,  4000 ), and it may include both volatile and non-volatile media, removable and non-removable media. 
     The memory system (e.g.,  4030 ) can include computer system readable media in the form of volatile memory, such as RAM and/or cache memory or others. The computer system (e.g.,  4000 ) may further include other removable/non-removable, volatile/non-volatile computer system storage media. 
     The computer system (e.g.,  4000 ) may communicate with one or more devices using the network adapter (e.g.,  4050 ). The network adapter may support wired communications based on Internet, local area network (LAN), wide area network (WAN), or the like, or wireless communications based on code division multiple access (CDMA), global system for mobile communication (GSM), wideband CDMA, CDMA-2000, time division multiple access (TDMA), long term evolution (LTE), wireless LAN, Bluetooth, Zig Bee, or the like. 
     Exemplary embodiments of the present disclosure may include a system, a method, and/or a non-transitory computer readable storage medium. The non-transitory computer readable storage medium (e.g., the memory system  4030 ) has computer readable program instructions thereon for causing a processor to carry out aspects of the present disclosure. 
     The computer readable storage medium can be a tangible device that can retain and store instructions for use by an instruction execution device. The computer readable storage medium may be, for example, but not limited to, an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. A non-exhaustive list of more specific examples of the computer readable storage medium includes the following: a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EEPROM or Flash memory), a static random access memory (SRAM), a portable compact disc read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, or the like, a mechanically encoded device such as punch-cards or raised structures in a groove having instructions recorded thereon, and any suitable combination of the foregoing. A computer readable storage medium, as used herein, is not to be construed as being transitory signals per se, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through a waveguide or other transmission media (e.g., light pulses passing through a fiber-optic cable), or electrical signals transmitted through a wire. 
     Computer readable program instructions described herein can be downloaded to the computing system  4000  from the computer readable storage medium or to an external computer or external storage device via a network. The network may include copper transmission cables, optical transmission fibers, wireless transmission, routers, firewalls, switches, gateway computers and/or edge servers. A network adapter card (e.g.,  4050 ) or network interface in each computing/processing device receives computer readable program instructions from the network and forwards the computer readable program instructions for storage in a computer readable storage medium within the computing system. 
     Computer readable program instructions for carrying out operations of the present disclosure may be assembler instructions, instruction-set-architecture (ISA) instructions, machine instructions, machine dependent instructions, microcode, firmware instructions, state-setting data, or either source code or object code written in any combination of one or more programming languages, including an object oriented programming language such as Smalltalk, C++ or the like, and conventional procedural programming languages, such as the “C” programming language or similar programming languages. The computer readable program instructions may execute entirely on the user&#39;s computer, partly on the user&#39;s computer, as a stand-alone software package, partly on the user&#39;s computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the computing system (e.g.,  4000 ) through any type of network, including a LAN or a WAN, or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider). In an exemplary embodiment, electronic circuitry including, for example, programmable logic circuitry, field-programmable gate arrays (FPGA), or programmable logic arrays (PLA) may execute the computer readable program instructions by utilizing state information of the computer readable program instructions to personalize the electronic circuitry, in order to perform aspects of the present disclosure. 
     Aspects of the present disclosure are described herein with reference to flowchart illustrations and/or block diagrams of methods, system (or device), and computer program products (or computer readable medium). It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer readable program instructions. 
     These computer readable program instructions may be provided to a processor of a general-purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks. These computer readable program instructions may also be stored in a computer readable storage medium that can direct a computer, a programmable data processing apparatus, and/or other devices to function in a particular manner, such that the computer readable storage medium having instructions stored therein comprises an article of manufacture including instructions which implement aspects of the function/act specified in the flowchart and/or block diagram block or blocks. 
     The computer readable program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other device to cause a series of operational steps to be performed on the computer, other programmable apparatus or other device to produce a computer implemented process, such that the instructions which execute on the computer, other programmable apparatus, or other device implement the functions/acts specified in the flowchart and/or block diagram block or blocks. 
     The flowchart and block diagrams in the Figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present disclosure. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of instructions, which comprises one or more executable instructions for implementing the specified logical function(s). In some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems that perform the specified functions or acts or carry out combinations of special purpose hardware and computer instructions. 
     The corresponding structures, materials, acts, and equivalents of all means or step plus function elements, if any, in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the present disclosure has been presented for purposes of illustration and description but is not intended to be exhaustive or limited to the present disclosure in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the present disclosure. The embodiment was chosen and described in order to best explain the principles of the present disclosure and the practical application, and to enable others of ordinary skill in the art to understand the present disclosure for various embodiments with various modifications as are suited to the particular use contemplated. 
     While the present invention has been particularly shown and described with respect to preferred embodiments thereof, it will be understood by those skilled in the art that the foregoing and other changes in forms and details may be made without departing from the spirit and scope of the present invention. It is therefore intended that the present invention not be limited to the exact forms and details described and illustrated but fall within the scope of the appended claims.