Accelerometer-based exterior sound monitoring during low-speed maneuvering

Abstract

Methods and apparatus for accelerometer-based exterior sound monitoring during low speed maneuvering are disclosed. An example vehicle includes accelerometers attached to windows of the vehicle, speakers located inside the vehicle, and an infotainment head unit. Each of the speakers is uniquely associated with one of the accelerometers. The infotainment head unit selects a zone corresponding to a direction of travel of the vehicle when a speed of the vehicle satisfies a threshold. Additionally, the infotainment head unit plays a signal captured by the accelerometer associated with the selected zone on the corresponding speaker.

Description

TECHNICAL FIELD

[0001] The present disclosure relates generally to vehicle sound systems, and more particularly, to accelerometer-based exterior sound monitoring during low speed maneuvers. BACKGROUND

[0002] In consideration of customer comfort, vehicles are increasingly manufactured with improved sealing and noise cancellation systems to isolate the outside noise from the cabin interior. This helps to keep the driving experience comfortable and noise-free. However, in some situations, blocking the outside noise can be disadvantageous. For example, when a vehicle is being pulled forward or backed out of a parking spot, the driver needs to be aware of obstacles that are not visible outside the vehicle. In such examples, because the cabin is noise-isolated, the driver has to rely on vision or distance detection sensors to detect those obstacles. However, the driver can perceive audible cues of a person or animal more quickly, thereby facilitating the driver to react more quickly. SUMMARY

[0003] The accompanying claims define the application. The disclosure summarizes aspects of the embodiments and is not to be used to limit the claims. Other implementations are contemplated as well, as will be apparent to those ordinarily skilled in the art from a review of the drawings and specific embodiments described below, and these implementations are intended to fall within the scope of the application.

[0004] Example embodiments for accelerometer-based exterior sound monitoring during low speed maneuvers are disclosed. An example vehicle includes accelerometers attached to windows of the vehicle, speakers located inside the vehicle, and an infotainment head unit. Each of the speakers is uniquely associated with one of the accelerometers. The infotainment head unit selects a region corresponding to a direction of travel of the vehicle when a speed of the vehicle satisfies a threshold. Additionally, the infotainment head unit plays a signal captured by the accelerometer associated with the selected region on the corresponding speaker.

[0005] An example method includes selecting a region corresponding to a direction of travel of a vehicle when a speed of the vehicle satisfies a threshold. The method also includes attenuating sound from other audio sources inside the vehicle. Additionally, the method includes driving a signal captured by an accelerometer associated with the selected region onto a corresponding speaker channel that is electrically coupled to a speaker inside the vehicle. BRIEF DESCRIPTION OF DRAWINGS

[0006] For a better understanding of the present application, reference can be made to the embodiments illustrated in the drawings. The components in the drawings are not necessarily to scale, and related elements can be omitted, or in some instances, can be shown exaggerated in scale, to facilitate explanation and understanding of the novel features described herein. Furthermore, system components can be arranged in different ways, as known in the art. Additionally, in the drawings, corresponding reference numerals indicate corresponding parts throughout the several views.

[0007] Figure 1 A vehicle operating in accordance with the teachings of the present disclosure is shown.

[0008] Figure 2 is a block diagram of electronic components of a vehicle. Figure 1

[0009] Figure 3 is a flowchart of a method of providing exterior noise into a cabin of a vehicle when the vehicle is performing low speed maneuvers, the method can be implemented by electronic components of Figure 1 Figure 2 DETAILED DESCRIPTION

[0010] While the application can be susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and will be described in detail herein. It should be understood that the application is not intended to be limited to the particular embodiments described herein, but rather, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the application as defined by the appended claims.

[0011] Generally, passenger comfort is increased by isolating the interior of the cabin from exterior noise. In some situations, isolating the interior of the cabin from exterior noise is undesirable. For example, when the vehicle is moving slowly (e.g., when stopped, when coming to a stop, when maneuvering in a residential area, etc.), the driver can desire to aurally be aware of the environment around the vehicle to detect obstacles (e.g., a child on a bicycle, a pet, etc.). Additionally, the driver can desire to hear messages from people outside the vehicle. For example, a person standing outside the vehicle can give directions to stop or notify the driver of an object left on the roof of the vehicle. A microphone on the exterior of the vehicle can broadcast the exterior sounds inside the vehicle, so the occupants are aware of their surroundings when the doors and windows are closed. However, conventional condenser microphones (ECM) are not configured for exterior use. Their delicate microphone diaphragm can be rendered unusable by dust, snow, rain, or mud.

[0012] ​​​As discussed below, accelerometers are placed on the edges of the vehicle glass surface. Sound causes oscillations as it travels through a medium such as a vehicle's glass surface. This oscillation is measured by the accelerometers as vibrations when a pressure wave strikes the vehicle's window. The resulting electrical output from the accelerometers is processed to reproduce the sound to be played in the cabin. The accelerometers are mounted on the vehicle's windows (e.g., windshield, rear glass, front left door glass, rear left door glass, front right door glass, rear right door glass, sunroof, etc.). The sound captured by the accelerometers is played only on the proximate speakers within the vehicle. For example, the signal from the front left door glass accelerometer can be played only on the speakers embedded in the front left door, the signal from the rear left door glass accelerometer can be played only on the speakers embedded in the rear left door, the signal from the front right door glass accelerometer can be played only on the speakers embedded in the front right door, the signal from the rear right door glass accelerometer can be played only on the speakers embedded in the rear right door, the signal from the windshield accelerometer can be played only on the speakers embedded in the dashboard, the signal from the rear glass accelerometer can be played only on the speakers embedded in the rear deck or rear door, and / or the signal from the sunroof accelerometer can be played only on the speakers embedded in the ceiling.

[0013] The sound system plays sound through the speakers only when the vehicle is traveling below a threshold speed (e.g., 5 miles per hour (mph), 10 mph, etc.). Additionally, the speakers are divided into zones corresponding to the direction of travel of the vehicle. For example, a front zone can be defined to include front speakers, while a rear zone can be defined to include rear speakers. When the vehicle is traveling in one direction at the threshold speed, the sound system plays sound only from the speakers in the corresponding zone. For example, when the vehicle is moving forward at a speed of 10 mph, the sound system can play sound only from the speakers in the front zone. In this way, the vehicle's sound system provides a directional sound experience that helps detect audible activity outside the vehicle in the direction of travel, while providing a robust system against environmental factors such as dust, snow, rain, or mud.

[0014] Figure 1A vehicle 100 is shown operating in accordance with the teachings of this disclosure. In some examples, the vehicle 100 is a police cruiser. The vehicle 100 can be a standard gasoline-powered vehicle, a hybrid vehicle, an electric vehicle, a fuel-cell vehicle, and / or any other mobility-implementation type of vehicle. The vehicle 100 includes mobility-related parts, such as a powertrain having an engine, a transmission, a suspension, drive axles, and / or wheels, etc. The vehicle 100 can be non-autonomous, semi-autonomous (e.g., some routine power functions are controlled by the vehicle 100), or autonomous (e.g., power functions are controlled by the vehicle 100 without direct driver input). In the illustrated example, the vehicle 100 includes windows 102a-102f, speakers 104a-104f, accelerometers 106a-106f, a powertrain control unit (PTCU) 108, and an infotainment head unit (IHU) 110.

[0015] The windows include a windshield 102a, a rear glass 102b, a left front door glass 102c, a left rear seat door glass 102d, a right front door glass 102e, a right rear seat door glass 102f, and / or a sunroof (not shown). Some of the windows 102a-102f are made of laminated glass (sometimes referred to as “safety glass”) (e.g., the windshield 102a, etc.), while some of the windows 102a-102f are made of non-laminated tempered glass (e.g., the left front door glass 102c, the left rear seat door glass 102d, the right front door glass 102e, the right rear seat door glass 102f, etc.). The glass of the windows 102a-102f vibrates when struck by a sound wave.

[0016] Each of the loudspeakers 104a-104f is positioned to correspond to one of the vehicle windows 102a-102f. In some examples, the loudspeaker 104a corresponding to the windshield 102a is embedded in the dashboard, the loudspeaker 104b corresponding to the rear glass 102b is embedded in the rear shelf or rear door (e.g., liftgate, etc.), the loudspeaker 104c corresponding to the left front door glass 102c is embedded in the side panel of the left front door, the loudspeaker 104d corresponding to the left rear seat door glass 102d is embedded in the left rear seat door, the loudspeaker 104e corresponding to the right front door glass 102e is embedded in the side panel of the right front door, the loudspeaker 104f corresponding to the right rear seat door glass 102f is embedded in the side panel of the right rear seat door, and / or a loudspeaker (not shown) corresponding to the moonroof is embedded in the ceiling proximate the moonroof. Alternatively, in some examples, the loudspeakers 104a-104f are belt loudspeakers embedded in a ceiling lining proximate the perimeter of the ceiling of the cabin of the vehicle 100 around the corresponding vehicle windows 102a-102f. In some examples, the loudspeakers 104a-104f are integrated into an audio sound system (e.g., radio, digital media player, etc.) and / or a noise cancellation system of the vehicle 100. Alternatively, the loudspeakers 104a-104f are separate from loudspeakers associated with the audio sound system and / or noise cancellation system of the vehicle 100.

[0017] The accelerometers 106a-106f can be any type of accelerometer that (a) measures vibrations normal to the plane of the glass of the corresponding vehicle window 102a-102f and (b) measures a wide frequency range (e.g., the frequency range of audible sound, etc.), including single- or tri-axial accelerometers, micro-machined or piezoelectric accelerometers, etc. Each of the accelerometers 106a-106f is securely mounted on a respective one of the vehicle windows 102a-102f inside the cabin of the vehicle 100. In some examples, the accelerometers 106a-106f are mounted on the vehicle windows 102a-102f in a manner that does not obstruct the driver’s view. For example, the accelerometer 106a on the windshield 102a can be attached to the glass of the windshield 102a proximate where a rearview mirror is mounted. As another example, the accelerometer 106b on the rear glass 102b can be attached to the glass of the rear glass 102b proximate a rear defroster connector on the glass or where a rear brake light is mounted. The accelerometers are communicatively coupled, wired or wirelessly, to the infotainment head unit 110 to send vibration signals of the vehicle windows 102a-102f to the infotainment head unit 110.

[0018] The powertrain control module 108 includes hardware and firmware for controlling the ignition, fuel injection, emission systems, transmission, and / or braking systems of the vehicle 100. The powertrain control module 108 monitors sensors, such as fuel injection sensors, wheel speed sensors, exhaust sensors, etc., and uses control algorithms to control, for example, fuel mixture, ignition timing, variable cam timing, emission controls, fuel pumps, engine cooling fans, and / or charging systems. In the illustrated example, the powertrain control module 108 sends messages regarding the speed of the vehicle 100 via the vehicle data bus (e.g., via the vehicle data bus 202 of the Ford SYNC® Figure 2

[0019] The infotainment head unit 110 provides an interface between the vehicle 100 and a user. The infotainment head unit 110 includes digital and / or analog interfaces (e.g., input devices and output devices) to receive input from one or more users and to display information. The input devices can include, for example, control knobs, instrument panels, digital cameras for image capture and / or visual command recognition, touch screens, audio input devices (e.g., cabin microphones), buttons, or touch pads. The output devices can include instrument cluster outputs (e.g., dials, lighting devices), actuators, head-up displays, center stack displays (e.g., liquid crystal displays ("LCDs")), organic light-emitting diode ("OLED") displays, flat panel displays, solid state displays, and / or speakers. In some examples, the infotainment head unit 110 includes hardware (e.g., processors or controllers, memory, storage devices, etc.) and software (e.g., operating systems, etc.) for infotainment systems, such as the Ford SYNC®

[0020] ​​​​​​The sound monitor 112 divides the loudspeakers 104a-104f into a front region 114a and a rear region 114b. In the illustrated example, the front region 114a includes the loudspeaker 104a corresponding to the front windshield 102a, the loudspeaker 104c corresponding to the left front door glass 102c, and the loudspeaker 104e corresponding to the right front door glass 102e. The rear region 114b includes the loudspeaker 104b corresponding to the rear glass 102b, the loudspeaker 104d corresponding to the side panel of the left rear seat door glass 102d, and the loudspeaker 104f corresponding to the right rear seat door glass 102f. Based on the direction of travel of the vehicle 100 (e.g., forward or rearward), the sound monitor selects one of the front region 114a and the rear region 114b. In the illustrated example, the sound monitor 112 selects the front region 114a when the vehicle 100 is traveling forward (e.g., transmission is in forward gear). The sound monitor 112 selects the rear region 114b when the vehicle is traveling rearward (e.g., transmission is in reverse gear). The sound monitor 112 enables the accelerometers 106a-106f corresponding to the selected region 114a and 114b when the speed of the vehicle 100 satisfies (e.g., is less than or equal to) a threshold speed. In some examples, the threshold speed is 10 mph.

[0021] When the accelerometer-based exterior sound monitoring system is enabled, the sound monitor 112 receives signals from the accelerometers 106a-106f and processes the signals. The sound monitor 112 plays sounds on the corresponding loudspeakers 104a-104f based on the signals. In some examples, the sound monitor 112 disables, mutes, or reduces the volume of other audio sources (e.g., radio, digital media player, etc.) when the exterior sound monitoring system is enabled. When the sound monitor 112 receives a signal from one of the accelerometers 106a-106f, the sound monitor processes the signal. In some examples, the sound monitor 112 processes the signal with a high-pass filter to filter out frequencies associated with low-frequency rumbles or rumbles (e.g., like sounds caused by wind, etc.). In some examples, the sound monitor 112 performs other sound signal processing, such as amplification and / or equalization.

[0022] The sound monitor 112 is coupled to separate channels, each of which is associated with one of the speakers 104a-104f. When a signal is received from one of the accelerometers 106a-106f, the sound monitor 112 drives the channel corresponding to the one of the speakers 104a-104f associated with the particular one of the accelerometers 106a-106f from which the signal was received. For example, when a signal is received from the accelerometer 106a attached to the windshield 102a, the sound monitor 112 drives the channel associated with the speaker 104a embedded in the dashboard. When multiple signals are received from multiple accelerometers 106a-106f, the sound monitor 112 drives multiple channels with corresponding signals. For example, when a first signal is received from the accelerometer 106a attached to the windshield 102a and simultaneously a second signal is received from the accelerometer 106b attached to the rear glass 102b, the sound monitor 112 drives the channel associated with the speaker 104a embedded in the dashboard with the first signal and drives the channel associated with the speaker 104b embedded in the rear deck or rear door with the second signal. In this way, the sound monitor 112 provides a surround sound experience based on the actual direction from which the noise originated so that one or more occupants of the vehicle 100 can determine the location of the noise. The sound monitor enables different channels based on the active zones 114a and 114b so that the channels associated with the accelerometers 106a-106f in different zones 114a and 114b are not simultaneously enabled. For example, if a dog is barking while sitting near the right rear corner of the vehicle 100 while the vehicle 100 is backing up at 5 mph, the accelerometer 106b attached to the rear glass 102b and the accelerometer 106f attached to the right rear door glass 102f can generate signals. In such an example, the sound monitor 112 can enable the channels associated with the accelerometers in the rear zone 114b and drive the signals from the accelerometers 106b and 106f onto the channels of the corresponding speakers 104b and 104f. In this way, even if one of the accelerometers 106a, 106d, and 106e associated with the forward zone 114a generates a signal in response to the dog barking, the sound monitor 112 does not drive the signal on those corresponding channels.

[0023] Figure 2 is Figure 1 a block diagram of electronic components 200 of the vehicle 100. In the illustrated example, the electronic components 200 include the speakers 104a-104f, the accelerometers 106a-106f, the powertrain control module 108, the infotainment head unit 110, and a vehicle data bus 202.

[0024] The infotainment head unit 110 includes channels 204a-204f, an amplifier / equalizer 206, a processor 208, and a memory 210. The channels 204a-204f are electrically coupled to the speakers 104a-104f. The channels 204a-204f are communicatively coupled to the amplifier / equalizer 206. When a signal is received from one of the accelerometers 106a-106f, the sound monitor 112 drives a signal on the corresponding channel 204a-204f via the amplifier / equalizer 206. The amplifier / equalizer 206 receives the signal from the accelerometer 106a-106f and processes the signal (e.g., amplifies the signal, etc.) to be suitable for reproduction on the speaker 104a-104f based on, for example, audio preferences and settings input by the occupant into the infotainment head unit 110.

[0025] In the illustrated example, the infotainment head unit 110 is structured to include the sound monitor 112. The processor or controller 208 can be any suitable processing device or group of processing devices, such as but not limited to: a microprocessor, a microcontroller-based platform, a digital signal processor, a suitable integrated circuit, one or more field programmable gate arrays (FPGA), and / or one or more application specific integrated circuits (ASIC). The memory 210 can be a volatile memory (e.g., RAM, which can include non-volatile RAM, magnetic RAM, ferroelectric RAM, and any other suitable form); a non-volatile memory (e.g., disk memory, FLASH memory, EPROM, EEPROM, non-volatile solid state memory, etc.), an unalterable memory (e.g., EPROM), read only memory, and / or a high capacity storage device (e.g., a hard drive, a solid state drive, etc.). In some examples, the memory 210 includes multiple types of memory, particularly volatile memory and non-volatile memory.

[0026] The memory 210 is a computer readable medium or media, such as one or more sets of instructions for operating the methods of the present disclosure, can be embedded thereon. The instructions can embody one or more of the methods or logic as described herein. In particular embodiments, the instructions can reside completely, or at least partially, within the memory 210, the computer readable medium, and / or within the processor 208 during execution thereof.

[0027] The terms "non-transitory computer-readable medium" and "tangible computer-readable medium" should be understood to include a single medium or multiple media, such as a centralized database or distributed database, and / or associated caches and servers that store one or more sets of instructions. The terms "non-transitory computer-readable medium" and "tangible computer-readable medium" also include any tangible medium that can store, encode, or carry a set of instructions for execution by a processor or to cause a system to perform any one or more of the methods or operations disclosed herein. As used herein, the term "tangible computer-readable medium" is expressly defined to include any type of computer-readable storage device and / or storage disk and to exclude propagating signals.

[0028] The vehicle data bus 202 communicatively couples the powertrain control module 108 with the infotainment system head unit 110. In some examples, the vehicle data bus 202 includes one or more data buses. The vehicle data bus 202 may be configured in accordance with standards defined by the International Organization for Standardization (ISO) 11898-1, the Media Oriented Systems Transport (MOST) bus protocol, the Controller Area Network (CAN) Flexible Data (CAN-FD) bus protocol (ISO 11898-7), and / or the K-line bus protocol (ISO 9141 and ISO 14230-1), and / or Ethernet. TM It is implemented using the CAN bus protocol defined by bus protocols such as IEEE 802.3 (since 2002).

[0029] Figure 3 is to provide external noise to the vehicle 100 when the vehicle 100 is performing a low-speed maneuver. Figure 1 Flowchart of a method in the cabin of a vehicle 100, which may be performed by Figure 2 The method is implemented by the electronic component 200 of FIG. Initially, at block 302, the acoustic monitor 112 waits until the speed of the vehicle 100 (e.g., as determined by the powertrain control module 108 or the like) is less than a threshold speed. At block 304, the acoustic monitor determines, for example, via the powertrain control module 108 or the like, whether the transmission of the vehicle 100 is in a forward (e.g., drive) gear or a reverse gear. When the transmission of the vehicle 100 is in a forward gear, the method continues at block 306. Otherwise, when the transmission is in a reverse gear, the method continues at block 314.

[0030] At block 306, the sound monitor 112 activates the accelerometers 106a, 106c, and 106e in the front region 114a. At block 308, the sound monitor attenuates or mutes sound from other audio sources. At block 310, the sound monitor 112 processes one or more signals from the activated accelerometers 106a, 106c, and 106e into one or more audio signals. At block 312, the sound monitor 112 drives the audio signals onto one or more corresponding ones of the loudspeakers 104a, 104c, and 104e.

[0031] At block 314, the sound monitor 112 activates the accelerometers 106b, 106d, and 106f in the back region 114b. At block 316, the sound monitor attenuates or mutes sound from other audio sources. At block 318, the sound monitor 112 processes one or more signals from the activated accelerometers 106b, 106d, and 106f into one or more audio signals. At block 320, the sound monitor 112 drives the audio signals onto one or more corresponding ones of the loudspeakers 104b, 104d, and 104f.

[0032] Figure 3 The flowchart of FIG. 1 represents machine-readable instructions stored in a memory (such as the memory 210 of FIG. 2) that, when executed by a processor (such as the processor 208 of FIG. 2), cause the vehicle 100 to implement the example sound monitor 112, and more generally, Figure 2 the infotainment head unit 110 of FIG. 2. Moreover, while one or more example procedures are described with reference to the flowchart illustrated in FIG. 1, many other methods of implementing the example sound monitor 112 can alternatively be used. For example, the order of execution of the blocks can be changed, and / or some of the blocks described can be changed, eliminated, or combined. Figure 2 Figure 1 and Figure 2 the infotainment head unit 110 of FIG. 2. Moreover, while one or more example procedures are described with reference to the flowchart illustrated in FIG. 1, many other methods of implementing the example sound monitor 112 can alternatively be used. For example, the order of execution of the blocks can be changed, and / or some of the blocks described can be changed, eliminated, or combined. Figure 3

[0033] ​​In this application, the use of transitional conjunctions is intended to include conjunctions. The use of definite or indefinite articles is not intended to indicate cardinality. Specifically, reference to "the" object or "an" object is also intended to indicate one of a possible plurality of such objects. In addition, the conjunction "or" can be used to convey the characteristics of alternative forms that exist simultaneously rather than mutually exclusive. In other words, the conjunction "or" should be understood to include "and / or". As used herein, the terms "module" and "unit" refer to hardware having a circuit that is typically combined with a sensor to provide communication, control and / or monitoring capabilities. "Module" and "unit" may also include firmware executed on the circuit. The terms "includes", "including" and "include" are inclusive and have the same scope as "comprises", "comprising" and "comprise", respectively.

[0034] The above-described embodiments, particularly any "preferred" embodiments, are possible embodiments of implementations and are set forth merely for a clear understanding of the principles of the present invention. Numerous variations and modifications may be made to one or more of the above-described embodiments without departing substantially from the spirit and principles of the technology described herein. All modifications are intended to be included herein within the scope of this disclosure and protected by the following claims.

Claims

1. A vehicle comprising: accelerometers attached to windows of the vehicle; speakers located inside the vehicle, each of the speakers being uniquely associated with one of the accelerometers; and an infotainment head unit to: select an accelerometer in an area corresponding to a direction of travel of the vehicle when a speed of the vehicle satisfies a threshold; and play a signal captured by the accelerometer associated with the selected area on a speaker corresponding to the accelerometer.

2. The vehicle of claim 1, comprising at least six of the accelerometers, each of the accelerometers being attached to a different one of the windows.

3. The vehicle of claim 1, wherein the infotainment head unit is to select a forward area when the direction of travel is forward.

4. The vehicle of claim 3, wherein the forward area comprises at least two of the accelerometers attached to different ones of the windows in a front portion of the vehicle.

5. The vehicle of claim 3, wherein the forward area comprises a first one of the accelerometers attached to a windshield, a second one of the accelerometers attached to a driver side front window, and a third one of the accelerometers attached to a passenger side front window.

6. The vehicle of claim 1, wherein the infotainment head unit is to select a rear area when the direction of travel is rearward.

7. The vehicle of claim 6, wherein the rear area comprises at least two of the accelerometers attached to different ones of the windows in a rear portion of the vehicle.

8. The vehicle of claim 6, wherein the rear area comprises a first one of the accelerometers attached to a rear glass, a second one of the accelerometers attached to a driver side rear window, and a third one of the accelerometers attached to a passenger side rear window.

9. The vehicle of claim 1, wherein the accelerometers are to measure vibrations normal to a glass surface of the windows and mounted inside a vehicle cabin.

10. The vehicle of claim 1, wherein the infotainment head unit is to attenuate other audio sources when the speed of the vehicle satisfies the threshold.

11. A method of external sound monitoring comprising: selecting, with a processor, an accelerometer of an area corresponding to a direction of travel of a vehicle when a speed of the vehicle satisfies a threshold; attenuating sound from other audio sources inside the vehicle; and driving a signal captured by an accelerometer associated with the selected area and attached to a window of the vehicle onto a speaker channel of a speaker electrically coupled to the vehicle interior corresponding to the accelerometer.

12. The method of claim 11, wherein selecting the area comprises: selecting a forward area when the direction of travel is forward; and selecting a rear area when the direction of travel is rearward. ​ ​ ​ ​ 13. The method of claim 12, wherein the front region includes at least two of the accelerometers attached to different ones of the vehicle windows in a front portion of the vehicle, and the rear region includes at least two of the accelerometers attached to different ones of the vehicle windows in a rear portion of the vehicle.

14. The method of claim 11, including measuring, with the accelerometers, vibrations perpendicular to glass surfaces of the vehicle windows.

15. The method of claim 11, wherein the loudspeakers are band loudspeakers positioned in a headliner of the vehicle.

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