Vehicle approach warning system and vehicle approach warning method

Abstract

To provide a vehicle proximity notification system capable of easily generating notification sound that satisfies regal restrictions.SOLUTION: A vehicle proximity notification system 1 includes a filter part 14, a notification sound control part 13 for generating a signal corresponding to notification sound for notifying vehicle proximity on the basis of a sound signal acquired from a sound source for notification sound, and a setting part 11 for acquiring vehicle information of a vehicle, and setting at least one of control parameters to be applied to the notification sound control part 13 in generating a sound source for notification sound to be used to generate notification sound, a filter characteristic to be applied to the filter part 14, and notification sound in accordance with the vehicle information. The notification sound control part 13 outputs the generated signal to a speaker 100 for outside of vehicle mounted on the vehicle through the filter part 14.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a vehicle approach warning system and a vehicle approach warning method for outputting a sound to notify the outside of an approaching vehicle. [Background technology]

[0002] Electric and hybrid vehicles are quiet, so there is a problem that it is difficult to notice the approach of the vehicle. For this reason, low-noise vehicles such as electric and hybrid vehicles are equipped with a device that warns pedestrians of the approach of the vehicle by outputting a sound (also called an alarm sound) that reminds pedestrians of the vehicle's running state while driving (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-161991 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the characteristics of the notification sound output from a vehicle are restricted by laws and regulations, and it is necessary to generate the notification sound that satisfies the restrictions.

[0005] Therefore, the present disclosure provides a vehicle approach warning system and the like that can easily generate a warning sound that satisfies regulatory constraints. [Means for solving the problem]

[0006] A vehicle approach warning system according to one embodiment of the present disclosure includes a filter unit; an alarm sound control unit that generates a signal corresponding to an alarm sound that warns of an approaching vehicle based on a sound signal acquired from an alarm sound source; and a setting unit that acquires vehicle information of the vehicle and sets, in accordance with the vehicle information, the alarm sound source used to generate the alarm sound, filter characteristics applied to the filter unit, and at least one of control parameters applied to the alarm sound control unit when generating the alarm sound, and the alarm sound control unit outputs the generated signal via the filter unit to an exterior speaker mounted in the vehicle.

[0007] A vehicle approach warning system according to one embodiment of the present disclosure includes an alarm sound control unit that generates a signal corresponding to an alarm sound that warns of the approach of a vehicle based on a sound signal obtained from an alarm sound source and outputs the generated signal to an exterior speaker mounted on the vehicle, and has acoustic characteristics that form at least two 1 / 3 octave band signals or sounds in the signal or sound transmission path from the alarm sound source to a listening position for the alarm sound.

[0008] A vehicle approach warning method according to one embodiment of the present disclosure includes a process of acquiring vehicle information from a vehicle, setting, in accordance with the vehicle information, at least one of a sound source for an alarm sound used to generate an alarm sound that warns of the approach of the vehicle, a filter characteristic applied to a filter unit, and a control parameter applied when generating a signal corresponding to the alarm sound, generating a signal corresponding to the alarm sound based on a sound signal acquired from the sound source for the alarm sound, and outputting the generated signal via the filter unit to an exterior speaker mounted on the vehicle.

[0009] These comprehensive or specific aspects may be realized by a system, a method, an integrated circuit, a computer program, or a computer-readable recording medium such as a CD-ROM, or may be realized by any combination of the system, the method, the integrated circuit, the computer program, and the recording medium. The recording medium may be a non-transitory recording medium. Effect of the Invention

[0010] According to an embodiment of the present disclosure, a vehicle approach warning device or the like can easily generate a warning sound that satisfies regulatory constraints. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a block diagram showing a configuration of a vehicle approach notification system according to the first embodiment. [Diagram 2] FIG. 2 is a block diagram showing another example of the configuration of the vehicle approach warning system according to the first embodiment. [Diagram 3] FIG. 3 is a block diagram showing a configuration of a vehicle approach notification system according to a variation of the first embodiment. [Figure 4] FIG. 4 is a block diagram showing a configuration of a vehicle approach notification system according to the second embodiment. [Diagram 5] FIG. 5 is a block diagram showing a specific example of the configuration of a vehicle approach warning system according to the second embodiment. [Figure 6] FIG. 6 is a graph showing the frequency characteristics of the informative sound, and the frequency characteristics and filter characteristics of the sound signal obtained from the informative sound source. [Figure 7] FIG. 7 is a block diagram showing a configuration of a vehicle approach notification system according to a first modification of the second embodiment. [Figure 8] FIG. 8 is a block diagram showing a configuration of a vehicle approach warning system according to the second modification of the second embodiment. [Figure 9] FIG. 9 is a flowchart showing a vehicle approach warning method according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] (Findings on which this disclosure is based) The characteristics of the alarm sound output from low-noise vehicles such as electric vehicles and hybrid vehicles are restricted by laws and regulations, and it is necessary to generate an alarm sound that satisfies the restrictions. For example, UN / ECE R138 requires that the sound pressure levels of at least two 1 / 3 octave bands included in the alarm sound must be equal to or greater than a specified overall (OA). For example, FMVSS 141 requires that the sound pressure levels of four non-adjacent 1 / 3 octave bands included in the alarm sound must be equal to or greater than a specified OA, or that the sum of the sound pressure levels of two non-adjacent 1 / 3 octave bands included in the alarm sound must be equal to or greater than a specified OA.

[0013] Based on this knowledge, the present inventors have investigated a vehicle approach warning system and the like that can easily generate a warning sound that satisfies regulatory constraints.

[0014] A vehicle approach warning system according to one embodiment of the present disclosure includes a filter unit; an alarm sound control unit that generates a signal corresponding to an alarm sound that warns of an approaching vehicle based on a sound signal acquired from an alarm sound source; and a setting unit that acquires vehicle information of the vehicle and sets, in accordance with the vehicle information, the alarm sound source used to generate the alarm sound, filter characteristics applied to the filter unit, and at least one of control parameters applied to the alarm sound control unit when generating the alarm sound, and the alarm sound control unit outputs the generated signal via the filter unit to an exterior speaker mounted in the vehicle.

[0015] With this, the sound source for the alarm sound used to generate the alarm sound, the filter characteristics of the filter section that filters the signal corresponding to the alarm sound, or the control parameters of the alarm sound control section that generates the alarm sound are automatically set according to vehicle information from the vehicle (e.g., information indicating the destination of the vehicle), making it possible to easily generate an alarm sound that satisfies the constraints of the laws and regulations applicable in the destination.

[0016] A vehicle approach warning system according to one embodiment of the present disclosure includes an alarm sound control unit that generates a signal corresponding to an alarm sound that warns of the approach of a vehicle based on a sound signal obtained from an alarm sound source and outputs the generated signal to an exterior speaker mounted on the vehicle, and has acoustic characteristics that form at least two 1 / 3 octave band signals or sounds in the signal or sound transmission path from the alarm sound source to a listening position for the alarm sound.

[0017] For example, regulations such as UN / ECE R138 or FMVSS 141 require that an alarm sound satisfy constraints regarding at least two 1 / 3 octave bands. For this reason, an alarm sound that satisfies the constraints imposed by such regulations can be easily generated by having acoustic characteristics that form signals or sounds of at least two 1 / 3 octave bands in the signal or sound transmission path from the alarm sound source to the alarm sound listening position.

[0018] For example, the vehicle approach warning system may include a speaker for use outside the vehicle cabin, and the speaker for use outside the vehicle cabin may have the acoustic characteristics.

[0019] In this manner, an acoustic characteristic in which at least two 1 / 3 octave band sounds are formed may be realized by the exterior speaker.

[0020] For example, the vehicle approach warning system may include a speaker for use outside the vehicle cabin, and a resonator mounted on the vehicle through which the warning sound output from the speaker for use outside the vehicle cabin passes, and the resonator may have the acoustic characteristics.

[0021] In this way, the resonator may provide an acoustic characteristic in which at least two 1 / 3 octave bands of sound are formed.

[0022] For example, the vehicle approach warning system may include a filter unit, the warning sound control unit may output the generated signal to an exterior speaker via the filter unit, and the filter unit may pass the at least two 1 / 3 octave band signals.

[0023] In this manner, the acoustic characteristics in which at least two 1 / 3 octave band signals are formed may be realized by the filter section.

[0024] For example, the filter section may be composed of a notch filter, a band elimination filter, or a band pass filter.

[0025] For example, at least two 1 / 3 octave band signals may be formed by attenuating some frequency bands using a notch filter or a band elimination filter, or at least two 1 / 3 octave band signals may be formed by passing some frequency bands using a band pass filter.

[0026] For example, the sound signal obtained from the notification sound source may have a frequency band including the at least two 1 / 3 octave bands.

[0027] In this way, at least two 1 / 3 octave bands are included in the frequency band of the sound signal acquired from the alarm sound source, so that at least two 1 / 3 octave band signals or sounds can be formed.

[0028] For example, the vehicle approach warning system may include a sound effect control unit that generates a signal corresponding to a sound effect to be output within the passenger compartment of the vehicle based on a sound signal obtained from the warning sound source.

[0029] According to this, sound effects such as a welcome sound can be outputted inside the vehicle cabin. Alternatively, sound effects such as the sound of vehicle acceleration can be outputted inside the vehicle cabin. For example, electric vehicles and hybrid vehicles are quiet, so the sound of acceleration during driving is small and it is difficult for passengers to feel one with the vehicle. However, by generating a signal corresponding to a sound effect (vehicle acceleration sound), the sound effect can be generated inside the vehicle cabin to enhance the presentation effect inside the vehicle cabin.

[0030] For example, the vehicle approach warning system may include a sound effect control unit that generates a signal corresponding to the sound effect based on a sound signal obtained from a sound effect source different from the warning sound source.

[0031] In this manner, a signal corresponding to a sound effect may be generated from a sound effect source.

[0032] For example, the notification sound control unit may generate a signal corresponding to the notification sound based on a sound signal acquired from the notification sound source and a sound signal acquired from the sound effect sound source. Specifically, the notification sound control unit may generate a signal corresponding to the notification sound based on a sum signal obtained by adding the sound signal acquired from the notification sound source and the sound signal acquired from the sound effect sound source.

[0033] For example, when an alarm sound is output to the outside of the vehicle cabin, the alarm sound may enter the vehicle cabin and mix with the sound effect output inside the vehicle cabin, causing discomfort to the passengers inside the vehicle cabin. Therefore, a signal corresponding to the alarm sound is formed from a sound signal acquired from an alarm sound source and a sound signal acquired from a sound effect sound source, specifically, generated from an added signal obtained by adding each sound signal, so that the alarm sound contains a sound effect component. In other words, since the alarm sound contains the same components as the sound effect output inside the vehicle cabin, it is possible to reduce discomfort to the passengers even if the alarm sound that has entered the vehicle cabin is mixed with the sound effect output inside the vehicle cabin.

[0034] For example, at least one of the notification sound source and the sound effect sound source may be rewritten.

[0035] According to this, the sound source for the notification sound or the sound source for the sound effect can be rewritten, and the notification sound or the sound effect can be output according to the user's preference. Also, if laws and regulations change, the system can be easily adapted.

[0036] For example, the sound source for the sound effects may be stored in an external memory.

[0037] This makes it possible to output sound effects from a sound source for sound effects stored in an external memory, and also makes it possible to easily comply with changes in regulations.

[0038] For example, the sound effect control unit may output the generated signal to a speaker for use in the vehicle cabin that is mounted in the vehicle.

[0039] This allows sound effects to be output from the vehicle interior speaker.

[0040] For example, the vehicle approach warning system may include an in-vehicle sound system having an amplifier unit that drives an audio speaker mounted in the vehicle and an external input unit to which a signal from the outside is input, and the sound effect control unit may output the generated signal to the audio speaker via the external input unit of the in-vehicle sound system.

[0041] According to this, it is possible to output sound effects from existing audio speakers that output music and the like, without having to prepare a dedicated speaker for inside the vehicle for outputting sound effects.

[0042] A vehicle approach warning method according to one embodiment of the present disclosure acquires vehicle information from a vehicle, and sets, in accordance with the vehicle information, at least one of a sound source for the warning sound used to generate a warning sound that warns of the approach of the vehicle, filter characteristics applied to a filter unit, and control parameters applied when generating a signal corresponding to the warning sound, generates a signal corresponding to the warning sound based on a sound signal acquired from the sound source for the warning sound, and outputs the generated signal to an exterior speaker mounted on the vehicle via the filter unit.

[0043] With this, the sound source for the alarm sound used to generate the alarm sound, the filter characteristics of the filter section that filters the signal corresponding to the alarm sound, or the control parameters applied when generating the alarm sound are automatically set according to vehicle information from the vehicle (e.g., information indicating the destination of the vehicle), so that an alarm sound that satisfies regulatory constraints can be easily generated.

[0044] Hereinafter, the embodiment will be specifically described with reference to the drawings.

[0045] The embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, the arrangement and connection of the components, steps, and the order of steps shown in the following embodiments are merely examples and are not intended to limit the present disclosure.

[0046] (Embodiment 1) A vehicle approach warning system according to the first embodiment will be described with reference to FIG.

[0047] FIG. 1 is a block diagram showing a configuration of a vehicle approach notification system 1 according to the first embodiment.

[0048] The vehicle approaching warning system 1 is a system for outputting a warning sound to notify the outside of the approach of a low-noise vehicle such as an electric vehicle or a hybrid vehicle, and as shown in FIG. 1, includes a vehicle approaching warning device 10 and a speaker 100.

[0049] The speaker 100 is an exterior speaker mounted on a vehicle.

[0050] The vehicle approaching notification device 10 is a device for notifying the approach of a vehicle by using a speaker 100 mounted on the vehicle. The vehicle approaching notification device 10 notifies the approach of a vehicle by causing the speaker 100 to output an alarm sound (e.g., a warning sound) to a pedestrian or the like outside the vehicle. The vehicle approaching notification device 10 is, for example, an ECU (Electronic Control Unit) mounted on the vehicle. The vehicle approaching notification device 10 includes a setting unit 11, a memory unit 12, an alarm sound control unit 13, a filter unit 14, and an amplifier unit 15.

[0051] The vehicle approach warning device 10 is a computer including a processor (CPU: Central Processing Unit) and a memory. The memory is a ROM (Read Only Memory) and a RAM (Random Access Memory), etc., and can store a program executed by the processor. The setting unit 11 and the warning sound control unit 13 are realized by a processor that executes a program stored in the memory. The storage unit 12 is realized by a memory, etc. Note that the storage unit 12 may be a memory separate from the memory in which the program is stored.

[0052] The setting unit 11 acquires vehicle information of the vehicle, and sets at least one of the sound source for the alert sound used to generate the alert sound, the filter characteristic applied to the filter unit 14, and the control parameter applied to the alert sound control unit 13 when generating the alert sound, according to the vehicle information. For example, the vehicle information is information acquired via a CAN (Controller Area Network), and the vehicle information includes information indicating the intended destination of the vehicle. The storage unit 12 stores a plurality of sound sources for the alert sound, a plurality of filter characteristics, or a plurality of control parameters. The setting unit 11 selects the sound source for the alert sound, the filter characteristic, or the control parameter corresponding to the vehicle information (information indicating the intended destination of the vehicle) from the plurality of sound sources for the alert sound, the plurality of filter characteristics, or the plurality of control parameters stored in the storage unit 12. The alert sound is generated using the selected sound source for the alert sound, the filter characteristic, or the control parameter.

[0053] For example, the storage unit 12 stores sound sources for the notification sound, filter characteristics, or control parameters corresponding to different laws and regulations depending on the destination. For example, when three different laws and regulations exist, three sound sources for the notification sound, three filter characteristics, or three control parameters are stored. The multiple sound sources for the notification sound are sound sources of notification sounds that satisfy the constraints of different laws and regulations, respectively. The multiple control parameters are parameters that are applied to the notification sound control unit 13 when the notification sound control unit 13 generates a signal corresponding to the notification sound based on a sound signal acquired from the notification sound source, and are parameters for generating a signal corresponding to the notification sound that satisfies the constraints of different laws and regulations, respectively. The multiple filter characteristics are characteristics that are applied to the filter unit 14 that filters the signal generated by the notification sound control unit 13, and are characteristics for filtering into a signal corresponding to the notification sound that satisfies the constraints of different laws and regulations, respectively.

[0054] The setting unit 11 may set any one of the sound source for the notification sound, the filter characteristic, and the control parameter according to the vehicle information. In this case, the storage unit 12 may store any one of the sound sources for the notification sound, the filter characteristic, and the control parameter, and may not store the other two. The setting unit 11 may set two of the sound source for the notification sound, the filter characteristic, and the control parameter according to the vehicle information. In this case, the storage unit 12 may store two of the sound sources for the notification sound, the filter characteristic, and the control parameter, and may not store the other one. The setting unit 11 may set all of the sound source for the notification sound, the filter characteristic, and the control parameter according to the vehicle information. In this case, the storage unit 12 stores all of the sound sources for the notification sound, the filter characteristic, and the control parameter.

[0055] The notification sound control unit 13 generates a signal corresponding to a notification sound that notifies the approach of a vehicle based on a sound signal acquired from a sound source for the notification sound. For example, the notification sound control unit 13 processes the sound signal so that the frequency characteristics of the notification sound become desired characteristics based on the applied control parameters. In other words, the notification sound control unit 13 processes the sound signal so that the frequency characteristics of the notification sound become characteristics that satisfy the constraints imposed by the laws and regulations in the destination based on the control parameters according to the information indicating the destination. For example, the control parameters include parameters such as the pitch increase rate or volume with respect to the vehicle speed, and the notification sound control unit 13 can adjust the pitch or volume of the notification sound according to the vehicle speed. Then, the notification sound control unit 13 outputs the generated signal to the speaker 100 via the filter unit 14 (specifically, via the filter unit 14 and the amplifier unit 15).

[0056] The filter unit 14 is provided between the alarm sound control unit 13 and the speaker 100 (specifically, the amplifier unit 15), and is a filter that passes or attenuates a predetermined frequency band. For example, the filter unit 14 is a filter that can change its pass characteristic or attenuation characteristic according to the applied filter characteristic, such as a digital filter. For example, the filter unit 14 filters the signal generated by the alarm sound control unit 13 so that the frequency characteristic of the alarm sound becomes a desired characteristic based on the applied filter characteristic. In other words, the filter unit 14 filters the signal generated by the alarm sound control unit 13 based on the filter characteristic according to the information indicating the destination so that the frequency characteristic of the alarm sound becomes a characteristic that satisfies the constraints imposed by the laws and regulations of the destination.

[0057] The amplifier unit 15 is connected between the filter unit 14 and the speaker 100. The amplifier unit 15 amplifies, with a predetermined amplification degree, a signal that is output from the alert sound source, processed by the alert sound control unit 13, and filtered by the filter unit 14, and outputs the amplified signal to the speaker 100. As a result, the alert sound is output from the speaker 100.

[0058] In addition, when the sound source for the alarm sound is set according to the information indicating the destination, the sound signal acquired from the sound source for the alarm sound may be a signal corresponding to the alarm sound that satisfies the constraints imposed by the laws and regulations in the destination. Therefore, in this case, the setting unit 11 does not need to set the control parameters and the filter characteristics. In other words, in this case, the control parameters and the filter characteristics may be fixed values.

[0059] Furthermore, when control parameters are set according to information indicating the destination, the signal generated by the notification sound control unit 13 may be a signal corresponding to a notification sound that satisfies the constraints imposed by the laws and regulations of the destination. Therefore, in this case, the setting unit 11 does not need to set the sound source for the notification sound and the filter characteristics. In other words, in this case, the sound source for the notification sound may be a fixed sound source, and the filter characteristics may be fixed values.

[0060] Furthermore, when filter characteristics are set according to the information indicating the destination, the signal filtered by the filter unit 14 and output from the filter unit 14 may be a signal corresponding to an alarm sound that satisfies the constraints imposed by the laws and regulations of the destination. Therefore, in this case, the setting unit 11 does not need to set the sound source and control parameters for the alarm sound.

[0061] As described above, the sound source for the alarm sound used to generate the alarm sound, the filter characteristics of the filter unit 14 that filters the signal corresponding to the alarm sound, or the control parameters of the alarm sound control unit 13 that generates the alarm sound are automatically set according to vehicle information from the vehicle (e.g., information indicating the destination of the vehicle), so that an alarm sound that satisfies the constraints of the laws and regulations applicable in the destination can be easily generated.

[0062] The setting unit 11, the storage unit 12, the alarm sound control unit 13, the filter unit 14, and the amplifier unit 15 may be distributed and arranged in a plurality of housings. This will be described with reference to FIG.

[0063] FIG. 2 is a block diagram showing another example of the configuration of the vehicle approach warning system 1 according to the first embodiment.

[0064] The vehicle approach warning system 1 may include a vehicle approach warning device 10a and a speaker system 101, instead of the vehicle approach warning device 10 and the speaker 100. The vehicle approach warning device 10a differs from the vehicle approach warning device 10 in that it does not include the filter unit 14 and the amplifier unit 15.

[0065] The speaker system 101 is a system including a filter section 14, an amplifier section 15, and a speaker 100. As in the speaker system 101, the filter section 14 and the amplifier section 15 may be formed integrally with the speaker 100.

[0066] For example, the vehicle approach warning device 10a and the speaker system 101 can be connected by a cable that transmits digital audio signals or the like, and the signal generated by the warning sound control unit 13 and the filter characteristics set by the setting unit 11 may be transmitted to the speaker system 101 via such a cable or the like.

[0067] In this way, the setting unit 11, the storage unit 12, the alarm sound control unit 13, the filter unit 14 and the amplifier unit 15 do not have to be arranged in one housing (device), and may be distributed across multiple housings.

[0068] (Modification of the first embodiment) In the first embodiment, the vehicle approach warning system 1 has been described as having a function of outputting a warning sound, but may further have a function of outputting sound effects into the vehicle cabin. This will be described as a modified example of the first embodiment with reference to FIG.

[0069] FIG. 3 is a block diagram showing a configuration of a vehicle approach warning system 1a according to a modification of the first embodiment.

[0070] Vehicle approach warning system 1a differs from vehicle approach warning system 1 in the first embodiment in that vehicle approach warning system 1a includes vehicle approach warning device 10b instead of vehicle approach warning device 10, and further includes speaker 200. Vehicle approach warning device 10b differs from vehicle approach warning device 10 in the first embodiment in that vehicle approach warning device 10b further includes sound effect control unit 16 and amplifier unit 17. The functions of setting unit 11, alarm sound control unit 13, filter unit 14, amplifier unit 15 and speaker 100 are the same as those in the first embodiment, and therefore description thereof will be omitted.

[0071] The speaker 200 is a speaker for use inside a vehicle.

[0072] The storage unit 12 further stores control parameters for the sound effect control unit 16 .

[0073] The sound effect control unit 16 generates a signal corresponding to a sound effect to be outputted in the vehicle cabin based on a sound signal acquired from a sound source for an alarm sound. That is, the sound effect control unit 16 generates a signal corresponding to a sound effect by using a sound signal acquired from a sound source for an alarm sound. The sound effect may be, for example, a welcome sound or an acceleration sound of the vehicle. For example, the sound effect control unit 16 may process a sound signal acquired from a sound source for an alarm sound so that the pitch of the sound effect (acceleration sound) changes according to a control parameter. For example, the control parameter of the sound effect control unit 16 may change the pitch of the sound effect according to the speed of the vehicle or the number of revolutions of the engine. The sound effect control unit 16 outputs the generated signal to the speaker 200 via the amplifier unit 17.

[0074] The amplifier unit 17 is connected between the sound effect control unit 16 and the speaker 200. The amplifier unit 17 amplifies the signal processed by the sound effect control unit 16 at a predetermined amplification degree and outputs the signal to the speaker 200. As a result, the sound effect is output from the speaker 200. The vehicle approach warning device 10b may not include the amplifier unit 17, and the amplifier unit 15 may amplify the signal filtered by the filter unit 14 at a predetermined amplification degree and output the signal to the speaker 100, and also amplify the signal processed by the sound effect control unit 16 at a predetermined amplification degree and output the signal to the speaker 200. Alternatively, the vehicle approach warning device 10b may not include the amplifier unit 15, and the amplifier unit 17 may amplify the signal filtered by the filter unit 14 at a predetermined amplification degree and output the signal to the speaker 100, and also amplify the signal processed by the sound effect control unit 16 at a predetermined amplification degree and output the signal to the speaker 200.

[0075] Vehicles such as electric vehicles and hybrid vehicles are quiet, so the sound of acceleration while driving is small, making it difficult for passengers to feel a sense of unity with the vehicle. However, by generating a signal corresponding to a sound effect (the sound of the vehicle accelerating), the sound effect can be generated inside the vehicle cabin, enhancing the dramatic effect inside the vehicle.

[0076] The storage unit 12 may further store a sound effect source different from the notification sound source. In this case, the sound effect control unit 16 may generate a signal corresponding to a sound effect to be outputted into the vehicle cabin based on a sound signal acquired from the sound effect source. In other words, the sound effect control unit 16 may use a sound signal acquired from a sound signal acquired from the sound effect source, without using the sound signal acquired from the notification sound source.

[0077] The informative sound control unit 13 may generate a signal corresponding to the informative sound based on a sound signal acquired from the informative sound source and a sound signal acquired from the sound effect source. Specifically, the informative sound control unit 13 may generate a signal corresponding to the informative sound based on a sum signal obtained by adding the sound signal acquired from the informative sound source and the sound signal acquired from the sound effect source.

[0078] For example, when an alarm sound is output to the outside of the vehicle cabin, the alarm sound may also enter the vehicle cabin and mix with the sound effect output inside the vehicle cabin, causing discomfort to the passengers inside the vehicle cabin. Therefore, a signal corresponding to the alarm sound is formed from a sound signal acquired from an alarm sound source and a sound signal acquired from a sound effect sound source, specifically, generated from an added signal obtained by adding each sound signal, so that the alarm sound contains a sound effect component. In other words, since the alarm sound contains the same components as the sound effect output inside the vehicle cabin, it is possible to reduce discomfort to the passengers even if the alarm sound that has entered the vehicle cabin mixes with the sound effect output inside the vehicle cabin.

[0079] At least one of the sound source for the notification sound and the sound source for the sound effect stored in the storage unit 12 may be rewritten. For example, the sound source for the notification sound may be rewritten, the sound source for the sound effect may be rewritten, or both the sound source for the notification sound and the sound source for the sound effect may be rewritten. For example, the sound source for the notification sound or the sound source for the sound effect may be rewritten by a rewriting unit (rewriting function) included in the vehicle approach warning system 1a, or may be rewritten by a rewriting unit included in an external device of the vehicle approach warning system 1a. Specifically, the rewriting unit may be operated by a vehicle occupant or a mechanic, so that the rewriting unit rewrites the sound source for the notification sound or the sound source for the sound effect stored in the storage unit 12 to a sound source stored in an external memory. The rewriting unit may also automatically perform the rewriting. The rewriting unit may download a sound source from a network and rewrite the sound source for the alert sound or the sound source for the sound effect stored in the storage unit 12 to the downloaded sound source. An external device having a rewriting unit may be connected to the vehicle approach alert system 1a to perform rewriting. This allows the sound source for the alert sound or the sound source for the sound effect to be rewritten, and the alert sound according to the preferences of the passengers or the like can be output outside the vehicle cabin, and sound effects according to the preferences of the passengers or the like can be output inside the vehicle cabin. Furthermore, when laws and regulations change, it is easy to respond to such changes.

[0080] The sound effect source may be stored in an external memory such as an SD memory card or a USB (Universal Serial Bus) memory. This allows sound effects according to the preferences of passengers to be output into the vehicle cabin from the sound effect source stored in the external memory. Furthermore, changes in regulations can be easily accommodated.

[0081] (Embodiment 2) A vehicle approach warning system according to the second embodiment will be described with reference to FIG.

[0082] FIG. 4 is a block diagram showing a configuration of a vehicle approach warning system 2 according to the second embodiment.

[0083] The vehicle approach warning system 2 is a system for outputting a warning sound to warn the outside of the approach of a low-noise vehicle such as an electric vehicle or a hybrid vehicle, and as shown in FIG. 4, includes a vehicle approach warning device 20 and a speaker 100.

[0084] The speaker 100 is an exterior speaker mounted on a vehicle.

[0085] The vehicle approaching notification device 20 is a device for notifying the approach of a vehicle by using a speaker 100 mounted on the vehicle. The vehicle approaching notification device 20 notifies the approach of a vehicle by causing the speaker 100 to output an alarm sound (e.g., a warning sound) to pedestrians outside the vehicle. The vehicle approaching notification device 20 is, for example, an ECU mounted on the vehicle. The vehicle approaching notification device 20 includes a memory unit 22, an alarm sound control unit 23, and an amplifier unit 25.

[0086] The vehicle approach warning device 20 is a computer including a processor (CPU) and a memory. The memory is a ROM, a RAM, etc., and can store a program executed by the processor. The warning sound control unit 23 is realized by the processor or the like that executes a program stored in the memory. The storage unit 22 is realized by a memory or the like. Note that the storage unit 22 may be a memory separate from the memory in which the program is stored.

[0087] The storage unit 22 stores a sound source for the notification sound.

[0088] The alert sound control unit 23 generates a signal corresponding to an alert sound that notifies of the approach of a vehicle based on a sound signal acquired from the alert sound source, and outputs the generated signal to the speaker 100. Specifically, the alert sound control unit 23 outputs the generated signal to the speaker 100 via the amplifier unit 25.

[0089] The amplifier unit 25 is connected between the informative sound control unit 23 and the speaker 100. The amplifier unit 25 amplifies the signal output from the informative sound source and processed by the informative sound control unit 23 at a predetermined amplification level and outputs the amplified signal to the speaker 100. As a result, the informative sound is output from the speaker 100.

[0090] The vehicle approach warning system 2 has acoustic characteristics that at least two ⅓ octave band signals or sounds are formed in a signal or sound transmission path from a sound source for the warning sound (eg, the memory unit 22) to a listening position of the warning sound.

[0091] For example, regulations such as UN / ECE R138 or FMVSS 141 require that the alert sound satisfy a constraint regarding at least two 1 / 3 octave bands. Specifically, UN / ECE R138 requires that the sound pressure levels of at least two 1 / 3 octave bands included in the alert sound must satisfy a constraint of a predetermined OA or higher. For example, FMVSS 141 requires that the sound pressure levels of four non-adjacent 1 / 3 octave bands included in the alert sound must satisfy a constraint of a predetermined OA or higher, or that the sum of the sound pressure levels of two non-adjacent 1 / 3 octave bands included in the alert sound must satisfy a constraint of a predetermined OA or higher. Therefore, the vehicle approach alert system 2 has acoustic characteristics that form at least two 1 / 3 octave band signals or sounds in a transmission path of the signal or sound from the alert sound source to the alert sound listening position.

[0092] For example, the vehicle approach warning system 2 has acoustic characteristics such that the sound pressure levels of at least two 1 / 3 octave bands included in the alert sound are equal to or greater than a predetermined OA in the signal or sound transmission path from the alert sound source to the alert sound listening position. Also, for example, the vehicle approach warning system 2 has acoustic characteristics such that the sound pressure levels of four non-adjacent 1 / 3 octave bands included in the alert sound are equal to or greater than a predetermined OA in the signal or sound transmission path from the alert sound source to the alert sound listening position. Also, for example, the vehicle approach warning system 2 has acoustic characteristics such that the sum of the sound pressure levels of two non-adjacent 1 / 3 octave bands included in the alert sound are equal to or greater than a predetermined OA in the signal or sound transmission path from the alert sound source to the alert sound listening position.

[0093] This makes it easy to generate warning sounds that meet the constraints of regulations such as UN / ECE R138 or FMVSS 141.

[0094] There are various methods for realizing the above acoustic characteristics. For example, the speaker 100 may have the above acoustic characteristics. Also, for example, the vehicle approach warning system 2 may include a resonator (not shown) that is mounted on the vehicle and through which the warning sound output from the speaker 100 passes, and the resonator may have the above acoustic characteristics. Also, for example, the above acoustic characteristics may be realized by a filter unit. Also, the above acoustic characteristics may be realized by a combination of these. Note that, hereinafter, an example in which the above acoustic characteristics are realized by a filter unit will be described with reference to FIG. 5.

[0095] FIG. 5 is a block diagram showing a specific example of the configuration of a vehicle approach warning system 2 according to the second embodiment.

[0096] The vehicle approach warning device 20 includes a filter unit 24. The filter unit 24 is provided between the warning sound control unit 23 and the speaker 100 (specifically, the amplifier unit 25), which is on a signal or sound transmission path from a sound source for the warning sound to a listening position of the warning sound, and the warning sound control unit 23 outputs the generated signal to the speaker 100 via the filter unit 24 (specifically, via the filter unit 24 and the amplifier unit 25).

[0097] The filter unit 24 is a filter that passes at least two 1 / 3 octave band signals. Therefore, by filtering the signal output from the alert sound control unit 23 by the filter unit 24, an acoustic characteristic is realized in which at least two 1 / 3 octave band signals or sounds are formed in the signal or sound transmission path from the alert sound source to the alert sound listening position.

[0098] The filter unit 24 may be configured with a notch filter, a band elimination filter, or a band pass filter. For example, at least two 1 / 3 octave band signals can be formed by passing at least two 1 / 3 octave band signals by a band pass filter. Also, for example, at least two 1 / 3 octave bands can be passed by a notch filter or a band elimination filter, and a frequency band between the at least two 1 / 3 octave bands can be attenuated, thereby forming at least two 1 / 3 octave band signals. The frequency characteristics of the alert sound, the frequency characteristics of the sound signal acquired from the alert sound source, and the filter characteristics when a notch filter is used will be described with reference to FIG. 6.

[0099] Fig. 6 is a graph showing the frequency characteristics of the alarm sound, the frequency characteristics of the sound signal obtained from the alarm sound source, and the filter characteristics. Fig. 6(a) shows the frequency characteristics of the alarm sound, Fig. 6(b) shows the frequency characteristics of the sound signal obtained from the alarm sound source, and Fig. 6(c) shows the filter characteristics of the filter unit 24.

[0100] For example, assume that a sound signal having a frequency characteristic as shown in (b) of Fig. 6 is acquired from an alarm sound source. In order to form at least two 1 / 3 octave band signals from such a sound signal, the filter unit 24 has a filter characteristic as shown in (c) of Fig. 6. By filtering the sound signal shown in (b) of Fig. 6 by the filter unit 24 shown in (c) of Fig. 6, an alarm sound including, for example, two 1 / 3 octave band components is generated as shown in (a) of Fig. 6.

[0101] As shown in (a) and (b) of Figures 6, the sound signal obtained from the alarm sound source has a frequency band including at least two 1 / 3 octave bands (the range indicated by the double arrows in (b) of Figure 6), and therefore it is possible to form signals or sounds of at least two 1 / 3 octave bands.

[0102] In addition, the higher the center frequency of the 1 / 3 octave band, the wider the bandwidth. Therefore, by making the Q value of the filter section 24 smaller as the center frequency of the 1 / 3 octave band to be formed becomes higher, the bandwidth of the 1 / 3 octave band with a high center frequency can be made wider.

[0103] In this manner, the acoustic characteristics that form at least two 1 / 3 octave band sounds may be realized by the speaker 100 for the exterior of the vehicle, may be realized by a resonator, or may be realized by the filter section 24.

[0104] (First modification of the second embodiment) In the second embodiment, the vehicle approach warning system 2 has been described as having a function of outputting a warning sound, but may further have a function of outputting sound effects into the vehicle cabin. This will be described as a first modification of the second embodiment with reference to FIG.

[0105] FIG. 7 is a block diagram showing a configuration of a vehicle approach warning system 2a according to a first modification of the second embodiment.

[0106] The vehicle approaching warning system 2a differs from the vehicle approaching warning system 2 in the second embodiment in that it includes a vehicle approaching warning device 20a instead of the vehicle approaching warning device 20, and further includes a speaker 200. The vehicle approaching warning device 20a differs from the vehicle approaching warning device 20 in the second embodiment in that it further includes a sound effect control unit 26 and an amplifier unit 27. The functions of the warning sound control unit 23, the filter unit 24, the amplifier unit 25 and the speaker 100 are the same as those in the second embodiment, so a description thereof will be omitted.

[0107] The speaker 200 is a speaker for use inside a vehicle.

[0108] The sound effect control unit 26 generates a signal corresponding to a sound effect to be outputted into the vehicle cabin based on a sound signal acquired from the sound source for the notification sound. That is, the sound effect control unit 26 generates a signal corresponding to a sound effect by using the sound signal acquired from the sound source for the notification sound. For example, the sound effect control unit 26 outputs the generated signal to the speaker 200 via the amplifier unit 27.

[0109] The amplifier unit 27 is connected between the sound effect control unit 26 and the speaker 200. The amplifier unit 27 amplifies the signal processed by the sound effect control unit 26 at a predetermined amplification degree and outputs the signal to the speaker 200. As a result, the sound effect is output from the speaker 200. The vehicle approach warning device 20a may not include the amplifier unit 27, and the amplifier unit 25 may amplify the signal filtered by the filter unit 24 at a predetermined amplification degree and output the signal to the speaker 100, and also amplify the signal processed by the sound effect control unit 26 at a predetermined amplification degree and output the signal to the speaker 200. Alternatively, the vehicle approach warning device 20a may not include the amplifier unit 25, and the amplifier unit 27 may amplify the signal filtered by the filter unit 24 at a predetermined amplification degree and output the signal to the speaker 100, and also amplify the signal processed by the sound effect control unit 26 at a predetermined amplification degree and output the signal to the speaker 200.

[0110] The storage unit 22 may further store a sound effect source different from the notification sound source. In this case, the sound effect control unit 26 may generate a signal corresponding to a sound effect to be outputted into the vehicle cabin based on a sound signal acquired from the sound effect source. In other words, the sound effect control unit 26 may use a sound signal acquired from a sound signal acquired from the sound effect source, without using the sound signal acquired from the notification sound source.

[0111] The functions related to the sound effects of the vehicle approach warning device 20a are the same as those of the vehicle approach warning device 10b in the modified example of the first embodiment, and therefore a description thereof will be omitted.

[0112] In this manner, a signal corresponding to a sound effect is generated, so that the sound effect can be generated within the vehicle cabin, thereby enhancing the dramatic effect within the vehicle cabin.

[0113] (Modification 2 of the second embodiment) In the first modification of the second embodiment, the vehicle approach warning system 2a is described as having the dedicated in-vehicle speaker 200 for outputting sound effects, but the system may not have the speaker 200. This will be described as the second modification of the second embodiment with reference to FIG.

[0114] FIG. 8 is a block diagram showing a configuration of a vehicle approach warning system 2b according to the second modification of the second embodiment.

[0115] Vehicle approaching warning system 2b differs from vehicle approaching warning system 2a in variant example 1 of embodiment 2 in that vehicle approaching warning system 2b has vehicle approaching warning device 20b instead of vehicle approaching warning device 20a, does not have speaker 200, and further has in-vehicle sound system 30 and speaker 300.

[0116] The vehicle approaching warning device 20b differs from the vehicle approaching warning device 20a in the first modification of the second embodiment in that it does not include the amplifier unit 27 and outputs a signal generated by the sound effect control unit 26 to the in-vehicle sound system 30. Other points are the same as those in the first modification of the second embodiment, and therefore description thereof will be omitted.

[0117] The speaker 300 is an audio speaker mounted in a vehicle, and typically outputs music or the like into the vehicle cabin.

[0118] The in-vehicle sound system 30 includes a storage unit 31 in which an audio sound source is stored, a control unit 32 that generates a signal corresponding to music based on an audio signal acquired from the audio sound source, an adder unit 33 that adds the signal generated by the control unit 32 and a signal generated by the sound effect control unit 26, an amplifier unit 34 that drives the speaker 300, and an external input unit to which a signal from the outside is input. The signal generated by the sound effect control unit 26 is input to the external input unit. For example, the external input unit is an AUX terminal.

[0119] The sound effect control unit 26 outputs the generated signal to the speaker 300 via an external input unit of the in-vehicle sound system 30. When music is being output into the vehicle cabin, the signal corresponding to the sound effect may be added by the adder 33 to the signal generated by the control unit 32, and the sound effect may be output from the speaker 300 together with the music. Also, when music is not being output into the vehicle cabin, only the sound effect may be output from the speaker 300.

[0120] This makes it possible to output sound effects from the existing audio speaker 300 that outputs music and the like, without having to prepare a dedicated in-vehicle speaker 200 for outputting sound effects.

[0121] In addition, even in the modified example of embodiment 1, the vehicle approach warning system 1a does not need to include the amplifier unit 17 and the speaker 200, and the signal generated by the sound effect control unit 16 may be output to the audio speaker 300 via the external input unit of the in-vehicle sound system 30.

[0122] (Other embodiments) Although the vehicle approach warning system according to the embodiment of the present disclosure has been described above, the present disclosure is not limited to the above embodiment.

[0123] For example, the vehicle approach warning system does not have to include a speaker.For example, the vehicle approach warning system may be a device (for example, a vehicle approach warning device) configured in a single housing.

[0124] For example, the vehicle approach warning system does not need to include an amplifier unit.

[0125] The present disclosure can be realized not only as a vehicle approach warning system, but also as a vehicle approach warning method including steps (processing) performed by each component of the vehicle approach warning system.

[0126] FIG. 9 is a flowchart showing a vehicle approach warning method according to another embodiment.

[0127] As shown in FIG. 9, the vehicle approach warning method includes processes of acquiring vehicle information from a vehicle (step S11), setting, according to the vehicle information, at least one of a sound source for the warning sound used to generate a warning sound that warns of the approach of a vehicle, a filter characteristic applied to the filter unit, and a control parameter applied when generating a signal corresponding to the warning sound (step S12), generating a signal corresponding to the warning sound based on the sound signal acquired from the sound source for the warning sound (step S13), and outputting the generated signal to an exterior speaker mounted on the vehicle via the filter unit (step S14).

[0128] For example, the steps of the vehicle approach warning method may be executed by a computer (computer system). The present disclosure may be realized as a program for causing a computer to execute the steps included in the vehicle approach warning method.

[0129] Furthermore, the present disclosure can be realized as a non-transitory computer-readable recording medium, such as a CD-ROM on which the program is recorded.

[0130] For example, when the present disclosure is realized by a program (software), each step is executed by executing the program using hardware resources such as a computer's CPU, memory, input / output circuitry, etc. In other words, each step is executed by the CPU acquiring data from memory or input / output circuitry, etc., performing calculations, and outputting the calculation results to memory or input / output circuitry, etc.

[0131] Furthermore, each of the components included in the vehicle approach warning system of the above-described embodiment may be realized as a dedicated or general-purpose circuit.

[0132] Furthermore, each of the components included in the vehicle approach warning system according to the above-described embodiment may be realized as an LSI (Large Scale Integration) which is an integrated circuit (IC: Integrated Circuit).

[0133] Furthermore, the integrated circuit is not limited to an LSI, and may be realized by a dedicated circuit or a general-purpose processor. A programmable FPGA (Field Programmable Gate Array) or a reconfigurable processor in which the connections and settings of circuit cells within an LSI can be reconfigured may also be used.

[0134] Furthermore, if an integrated circuit technology that can replace LSI emerges due to advances in semiconductor technology or other derived technologies, it is natural that each component included in the vehicle approach warning system may be integrated into an integrated circuit using that technology.

[0135] In addition, the present disclosure also includes forms obtained by applying various modifications to the embodiments that a person skilled in the art may conceive, and forms realized by arbitrarily combining the components and functions of each embodiment within the scope that does not deviate from the spirit of the present disclosure. [Industrial Applicability]

[0136] The present disclosure can be applied to low-noise vehicles such as electric vehicles and hybrid vehicles. [Explanation of symbols]

[0137] 1, 1a, 2, 2a, 2b Vehicle proximity warning system 10, 10a, 10b, 20, 20a, 20b Vehicle proximity warning device 11 Setting section 12, 22, 31 Storage section 13, 23 Notification sound control section 14, 24 Filter section 15, 17, 25, 27, 34 Amplifier section 16, 26 Sound effect control section 30 In-vehicle sound system 32 Control section 33 Addition section 100, 200, 300 speakers 101 Speaker System

Claims

1. A filter section; an alert sound control unit that generates a signal corresponding to an alert sound that alerts an approach of a vehicle based on a sound signal acquired from a sound source for the alert sound, and outputs the generated signal to an exterior speaker mounted on the vehicle via the filter unit; The signal or sound transmission path from the sound source for the alert sound to the listening position for the alert sound has an acoustic characteristic in which at least two ⅓ octave band signals or sounds are formed, The filter section passes signals of the at least two 1 / 3 octave bands. Vehicle approach warning system.

2. A filter section, an alarm sound control unit that generates a signal corresponding to an alarm sound that notifies the driver of an approaching vehicle based on a sound signal acquired from the alarm sound source; a setting unit that acquires vehicle information of the vehicle and sets a filter characteristic to be applied to the filter unit in accordance with the vehicle information; a sound effect control unit that generates a signal corresponding to a sound effect to be output into a passenger compartment of the vehicle based on a sound signal obtained from a sound effect source different from the notification sound source, The notification sound control unit outputs the generated signal to an exterior speaker mounted in the vehicle via the filter unit. Vehicle approach warning system.

3. A filter section, an alarm sound control unit that generates a signal corresponding to an alarm sound that notifies the driver of an approaching vehicle based on a sound signal acquired from the alarm sound source; a setting unit that acquires vehicle information of the vehicle and sets a filter characteristic to be applied to the filter unit in accordance with the vehicle information; a sound effect control unit that generates a signal corresponding to a sound effect to be output into a passenger compartment of the vehicle based on a sound signal acquired from the notification sound source; an in-vehicle audio system including an amplifier unit that drives an audio speaker mounted in the vehicle, and an external input unit to which an external signal is input, The notification sound control unit outputs the generated signal to an exterior speaker mounted in the vehicle via the filter unit, The sound effect control unit outputs the generated signal to the audio speaker via the external input unit of the in-vehicle sound system. Vehicle approach warning system.

4. the vehicle approach warning system includes a speaker for use outside the vehicle compartment, The speaker for the exterior of the vehicle has the acoustic characteristics. The vehicle approach warning system according to claim 1 .

5. The vehicle approach warning system includes a speaker for use outside the vehicle cabin, and a resonator that is mounted on the vehicle and through which the warning sound output from the speaker for use outside the vehicle cabin passes, The resonator has the acoustic characteristics. The vehicle approach warning system according to claim 1 .

6. The filter section is composed of a notch filter, a band elimination filter, or a band pass filter. The vehicle approach warning system according to claim 1 .

7. The sound signal obtained from the notification sound source has a frequency band including the at least two 1 / 3 octave bands.

7. A vehicle approach warning system according to claim 1, wherein the vehicle approach warning system is a vehicle approach warning system.

8. The vehicle approach warning system includes a sound effect control unit that generates a signal corresponding to a sound effect to be outputted into a passenger compartment of the vehicle based on a sound signal acquired from the warning sound source.

8. The vehicle approach warning system according to claim 1, wherein the vehicle approach warning system is a vehicle approach warning system.

9. The vehicle approach warning system includes a sound effect control unit that generates a signal corresponding to a sound effect to be output into a passenger compartment of the vehicle based on a sound signal obtained from a sound effect source different from the warning sound source.

8. The vehicle approach warning system according to claim 1, wherein the vehicle approach warning system is a vehicle approach warning system.

10. The informative sound control unit generates a signal corresponding to the informative sound based on a sound signal obtained from the informative sound source and a sound signal obtained from the sound effect sound source. The vehicle approach warning system according to claim 9.

11. The informative sound control unit generates a signal corresponding to the informative sound based on a sum signal obtained by adding a sound signal obtained from the informative sound source and a sound signal obtained from the sound effect sound source. The vehicle approach warning system according to claim 10.

12. At least one of the notification sound source and the sound effect sound source is rewritten.

12. The vehicle approach warning system according to claim 2, wherein the vehicle approach warning system is a vehicle approach warning system.

13. The sound source for the sound effects is stored in an external memory.

13. The vehicle approach warning system according to claim 2, wherein the vehicle approach warning system is a vehicle approach warning system.

14. The sound effect control unit outputs the generated signal to a speaker for use in a vehicle interior mounted in the vehicle. The vehicle approach warning system according to any one of claims 3 and 8 to 13.

15. The vehicle approach warning system includes an in-vehicle audio system including an amplifier unit that drives an audio speaker mounted in the vehicle, and an external input unit to which an external signal is input, The sound effect control unit outputs the generated signal to the audio speaker via the external input unit of the in-vehicle sound system. The vehicle approach warning system according to any one of claims 8 to 13.

16. A vehicle approach warning method executed by a vehicle approach warning system, comprising: The vehicle approach warning system has an acoustic characteristic in which at least two ⅓ octave band signals or sounds are formed in a signal or sound transmission path from a sound source for a warning sound to a listening position for the warning sound that warns of the approach of a vehicle, The vehicle approach warning method includes: generating a signal corresponding to the alert sound based on a sound signal acquired from the alert sound source, and outputting the generated signal to an exterior speaker mounted on the vehicle via a filter unit; Passing the at least two 1 / 3 octave band signals in the filter section A method for notifying approaching vehicles.

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