JP7286378B2 - Sound output device and sound output system - Google Patents

Description

TECHNICAL FIELD The present invention relates to a sound output device and a sound output system, and more particularly to a sound output device mounted on a moving object.

Hybrid vehicles and electric vehicles are known to be equipped with a speaker and output a warning sound to inform pedestrians of the approach, because the running noise is very low. Regarding notification sounds, it is necessary to warn pedestrians by emitting roughly the same sounds from various hybrid and electric vehicles. .

For example, in the technique described in Patent Document 1, regarding a notification sound composed of a plurality of frequency components, the frequency of each of the plurality of frequency components is shifted according to the speed of the vehicle, and the volume of each shifted frequency is adjusted. are changing.

JP 2013-205478 A

By the way, there is a demand for enabling users to change the content of notification sounds according to their preferences. However, as described above, regulations and standards are established for notification sounds.

In consideration of the above facts, the present invention generates and outputs a sound that can be changed by the user and a sound that cannot be changed by the user, so that the sound can be produced according to the taste of the user while considering safety. An object of the present invention is to provide a sound output device and a sound output system capable of outputting.

In order to solve the above-described problems, a sound output device according to one embodiment of the present invention is a sound output device mounted on a vehicle, comprising a warning sound generation unit that generates a warning sound including at least one sine wave; a background sound generating unit that generates a first background sound whose volume is adjusted based on the selected sound source; and control that selects the sound source of the first background sound based on selection information supplied from the outside. and a first synthesizing unit for synthesizing the warning sound and the first background sound and outputting it as a first notification sound, wherein the background sound generating unit generates the first background sound a sound source memory storing at least one sound source signal that is a sound source; a level measuring device for measuring the level of the sound source signal stored in the sound source memory; and a second volume adjuster that adjusts the volume of the first background sound based on the result of measurement by the level meter.

According to the present invention, by generating and outputting a sound that can be changed by the user and a sound that cannot be changed, it is possible to output a sound that matches the taste of the user while considering safety. .

1 is a block diagram showing an example of the configuration of a sound output system according to a first embodiment; FIG. It is a block diagram showing an example of the hardware constitutions of the sound output device concerning a 1st embodiment. 4 is a diagram showing an example of information stored in a speed control information memory according to the first embodiment; FIG. 4 is a diagram showing an example of information stored in a sound source memory according to the first embodiment; FIG. It is a block diagram showing an example of functional composition of a sound output device concerning a 1st embodiment. 3 is a block diagram showing an example of the configuration of a first sound generator according to the first embodiment; FIG. It is a block diagram showing an example of functional composition of a sound output device concerning a modification of a 1st embodiment. FIG. 7 is a diagram showing an example of information stored in a sound source memory according to a modification of the first embodiment; FIG. FIG. 11 is a block diagram showing an example of the configuration of a sound output system according to a second embodiment; FIG. FIG. 11 is a block diagram showing an example of a functional configuration of a sound output device according to a second embodiment; FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each drawing, the same reference numerals are given to the same or corresponding components.

[First Embodiment]
First, a sound output system 1 according to this embodiment will be described with reference to FIG. As shown in FIG. 1 , a sound output system 1 according to this embodiment has a sound output device 2 and a first speaker 3 . The sound output system 1 is mounted, for example, on a vehicle such as a hybrid vehicle or an electric vehicle.

As shown in FIG. 1, the sound output device 2 stores information about the speed of the vehicle (hereinafter referred to as "speed information") and at least one sound source signal stored in a sound source memory 207, which will be described later. Information about the selected sound source signal (hereinafter referred to as "selection information") is input. Further, the sound output device 2 outputs a first notification sound, which will be described later, to the first speaker 3, and the first speaker 3 emits the first notification sound toward the outside of the vehicle.

In the sound output device 2 according to the present embodiment, for example, a circuit for outputting a sound (hereinafter referred to as "warning sound") defined by the vehicle approaching notification standard and a sound that can be freely selected by the user. (hereinafter referred to as "background sound") is mounted in a single chip, and the warning sound and background sound are synthesized and output as a first notification sound. That is, a sound that can be freely selected by the user is synthesized as the background sound of the warning sound that cannot be changed, and is output as the first notification sound. The sound output device 2 is composed of, for example, one semiconductor integrated circuit, in other words, one chip.

Next, the hardware configuration of the sound output device 2 according to this embodiment will be described with reference to FIG. As shown in FIG. 2 , the sound output device 2 includes a CPU (Central Processing Unit) 20 , a memory 21 as a temporary storage area, a nonvolatile storage section 22 and an input/output port 23 . CPU 20 , memory 21 , storage unit 22 and input/output port 23 are connected to bus 24 .

The storage unit 22 is implemented by a non-volatile storage medium such as an HDD (Hard Disk Drive), SSD (Solid State Drive), and flash memory. A notification sound generation processing program 25, a speed control information memory 202, and a sound source memory 207 are stored in the storage unit 22 as a storage medium. The CPU 20 reads out the notification sound generation processing program 25 from the storage unit 22 , develops it in the memory 21 , and executes the expanded notification sound generation processing program 25 .

FIG. 3 shows an example of information stored in the speed control information memory 202. As shown in FIG. The information stored in the speed control information memory 202 is, for example, information stipulated by the vehicle approach notification standard. As shown in FIG. 3, the speed control information memory 202 stores the frequency f and the volume L of at least one sine wave constituting a warning sound indicated by a sine wave control signal for each speed information v, which will be described later. . The number of sine waves forming the warning sound may differ for each speed information v. For example, in the sine wave control signal, in speed information v1, the number of sine waves included in the warning sound is one (that is, the number of frequency components included in the warning sound is one), and the first sine wave has a frequency of f11 indicates that the volume is L11. Further, for example, in the sine wave control signal, in the speed information v2, the number of sine waves included in the warning sound is two (that is, the number of frequency components included in the warning sound is two), and the first sine wave has a frequency of is f21 and the volume is L21, and the second sine wave has a frequency of f22 and a volume of L22.

Further, as shown in FIG. 3, the speed control information memory 202 stores the frequency multiplier n and the maximum volume Lmax of the first background sound with respect to the first sound source signal indicated by the sound source control signal for each speed information v, which will be described later. remembered. For example, in velocity information v1, the sound source control signal indicates that the frequency magnification of the first background sound with respect to the first sound source signal is n1 and the maximum volume is Lmax1.

FIG. 4 shows an example of information stored in the tone generator memory 207. As shown in FIG. The sound source memory 207 stores, for example, at least one sound source signal that can be freely selected by the user. As shown in FIG. 4, the sound source memory 207 stores a sound source signal and an ID (IDentifier) as an example of identification information of the sound source signal in association with each other. The sound source signal may be uncompressed sound data or compressed sound data.

Next, a functional configuration of the sound output device 2 according to this embodiment will be described with reference to FIG. As shown in FIG. 5, the sound output device 2 includes a control section 11, a warning sound generation section 12, a background sound generation section 13 and a first synthesis section . By executing the notification sound generation processing program 25, the CPU 20 functions as the control section 11, the warning sound generation section 12, the background sound generation section 13, and the first synthesis section .

The control unit 11 performs control to select the sound source of the first background sound based on selection information supplied from the outside. Further, the control unit 11 may perform control to select one of at least one sound source signal stored in the sound source memory 207 based on the selection information. Further, based on the speed information, the control unit 11 supplies the warning sound generation unit 12 with a sine wave control signal including instructions regarding the frequency of the sine wave included in the warning sound and the volume of the warning sound, and based on the speed information, , a sound source control signal including instructions regarding the frequency and volume of the first background sound may be supplied to the background sound generator 13 .

The warning sound generator 12 generates a warning sound containing at least one sine wave. That is, at least one sine wave is at least one sine wave stored in speed control information memory 202 .

The background sound generation unit 13 generates the first background sound whose volume is adjusted based on the selected sound source. That is, the selected sound source is at least one sound source signal stored in sound source memory 207 .

The first synthesizing unit 14 synthesizes the warning sound and the first background sound and outputs a first notification sound.

Next, the functions of the control section 11, the warning sound generation section 12, the background sound generation section 13 and the first synthesis section 14 will be described in detail.

First, the functions of the control section 11 will be described in detail. The control section 11 includes a reproduction control circuit 201 and a speed control information memory 202 .

When the speed information v is input, the reproduction control circuit 201 refers to the speed control information memory 202 to obtain the frequency f and the volume L of the sine wave corresponding to the speed information v, and obtains the frequency f and the volume L. A sine wave control signal including an instruction to generate a sine wave is output to the sine wave control circuit 203 .

Further, when the speed information v is input, the reproduction control circuit 201 refers to the speed control information memory 202 to acquire the frequency magnification n and the maximum volume Lmax corresponding to the speed information v, A sound source control signal including an instruction to generate the first background sound with the frequency magnification n and the maximum volume Lmax is output to the sound source control circuit 206 . Note that the reproduction control circuit 201 may control at least one of the frequency and volume of the first background sound generated by the background sound generator 13 .

Further, when the selection information is input, the reproduction control circuit 201 refers to the sound source memory 207 to output the sound source signal corresponding to the selection information (that is, the “first sound source signal”) to the first sound source generator 208 . To the sound source memory 207, a sound source selection signal including an instruction to output to the sound source memory 207 is output.

Next, the function of the warning sound generator 12 will be described in detail. The warning sound generation unit 12 generates a sine wave generation signal including an instruction to generate a sine wave having a frequency indicated by the sine wave control signal and a first volume control signal including an instruction regarding the volume of the warning sound indicated by the sine wave control signal. a sine wave control circuit 203 that outputs a sine wave generator 204 that outputs a sine wave based on the sine wave generation signal; and a first volume control that adjusts the volume of the warning sound based on the first volume control signal a device 205;

Based on the sine wave control signal, sine wave control circuit 203 outputs a sine wave generation signal including an instruction to generate a sine wave of frequency f to sine wave generator 204 . Further, the sine wave control circuit 203 outputs a first volume control signal including an instruction to adjust the volume of the sine wave signal to volume L to the first volume adjuster 205 based on the sine wave control signal. . When the sine wave control signal instructs generation of a plurality of sine waves, the sine wave control circuit 203 outputs a sine wave generation signal and a first volume control signal for each of them.

Sine wave generator 204 generates a sine wave of frequency f based on the sine wave generation signal, and outputs the generated sine wave (hereinafter referred to as “sine wave signal”) to first volume adjuster 205 . If the sine wave generation signal instructs generation of a plurality of sine waves, the sine wave generator 204 outputs a sine wave signal for each of them.

The first volume adjuster 205 adjusts the volume of the sine wave signal based on the first volume control signal, and outputs the volume-adjusted sine wave signal to the first synthesizer 211 as a warning sound. When the first volume control signal instructs adjustment of the volume of a plurality of sine waves, the first volume adjuster 205 outputs a sine wave signal whose volume is adjusted for each of them as a warning sound. do.

Next, the function of the background sound generator 13 will be described in detail. The background sound generation unit 13 generates a sound source generation signal including an instruction to generate a first background sound having a frequency indicated by the sound source control signal and a first background sound including an instruction to generate the first background sound having a volume indicated by the sound source control signal. 2, a sound source memory 207 storing at least one sound source signal to be the sound source of the first background sound, and a frequency of the first background sound based on the sound source generation signal. A sound source generator 208 to be adjusted, a level measuring device 209 for measuring the level of a sound source signal that is the source of the first background sound, and an adjustment so that the volume of the first background sound does not exceed a predetermined maximum volume. and a second volume control 210 that controls the volume. The second volume adjuster 210 may adjust the volume of the first background sound based on the result of measurement by the level meter 209 . Also, the second volume adjuster 210 may adjust the volume of the first background sound based on the second volume control signal.

The sound source signals stored in the sound source memory 207 may vary in level. When the level of the signal that is the sound source of the first background sound is high, the warning sound contained in the first notification sound emitted from the first speaker 3 is drowned out by the first background sound, conforming to the standard. We need to make sure it doesn't go away. Therefore, the background sound generation unit 13 measures the level of the sound source signal, which is the source of the first background sound, by the level measuring device 209, and conforms to the standard by the second volume adjuster 210 based on the measurement result. The level of the sound source signal, which is the sound source of the first background sound, is adjusted within the range and output as the first background sound.

Based on the sound source control signal, the sound source control circuit 206 transmits a sound source generation signal including an instruction to adjust the frequency ratio of the first background sound to n times that of the first sound source signal to the first sound source generator 208 . output to Further, the sound source control circuit 206 performs second volume control including an instruction to adjust the volume of the first sound signal described later so that it does not exceed the volume Lmax based on the sound source control signal and the level signal described later. A signal is output to the second volume control 210 .

The sound source memory 207 outputs the first sound source signal to the first sound source generator 208 based on the sound source selection signal.

The first sound source generator 208 adjusts the frequency of the first sound source signal based on the sound source generation signal so that the frequency is multiplied by n times, and adjusts the frequency of the sound signal (hereinafter referred to as “first sound signal ) to the level meter 209 and the second volume adjuster 210 .

The level meter 209 measures the volume level of the first sound signal and outputs a level signal corresponding to the measured level to the sound source control circuit 206 . The level measuring instrument 209 measures sound volume such as sound pressure level (dB), amplitude (sound pressure) (Pa), sound power level (W), and sound intensity (W/m ² ) of the first sound signal, for example. measures the loudness level of the first sound signal.

The second volume adjuster 210 adjusts the volume of the first sound signal based on the second volume control signal so that the volume does not exceed the volume Lmax, and outputs the volume-adjusted first sound signal. It is output to the first synthesizer 211 as the first background sound. For example, the second volume adjuster 210 may adjust the volume by compressing only the portion of the first sound signal whose volume exceeds the volume Lmax to the volume Lmax, or may adjust the volume of the entire first sound signal. may be compressed and adjusted so that the maximum volume becomes volume Lmax.

Next, the function of the first synthesizing section 14 will be described in detail. The first combiner 14 includes a first combiner 211 and a first amplifier 212 . The first synthesizer 211 synthesizes the warning sound and the first background sound and outputs the synthesized sound to the first amplifier 212 as the first notification sound. The first amplifier 212 outputs the first notification sound to the first speaker 3 .

Before the volume level of the first sound signal is measured by the level measuring device 209, the sound source control circuit 206 sets the second volume so as not to generate the first background sound from the first speaker 3. A control signal may be defined. Also, the sound source control circuit 206 controls the first volume of the repeated reproduction of the first background sound to be zero, and during this time the level measuring device 209 measures the volume level of the first sound signal. can be

FIG. 6 is a block diagram showing the functional configuration of the first sound source generator 208. As shown in FIG. As shown in FIG. 6, the first sound source generator 208 is composed of a sound source data reproducing section 221, an FIR filter tap coefficient table 222, and an FIR filter 223. FIG.

The sound source data reproduction unit 221 reproduces the input first sound source signal and outputs it to the FIR filter 223 . When the first sound source signal is compressed sound data, the sound source data reproduction unit 221 decompresses and reproduces the first sound source signal.

The FIR filter tap coefficient table 222 is based on the input sound source generation signal so that the frequency of the first sound signal generated by the FIR filter 223 is n times the frequency of the first sound source signal. Determine tap coefficients.

The FIR filter 223 adjusts the frequency of the first sound source signal reproduced by the sound source data reproduction unit 221 based on the tap coefficients determined by the FIR filter tap coefficient table 222 .

Specifically, the FIR filter tap coefficient table 222 determines tap coefficients so that the sampling timing for the waveform data of the first sound signal matches the sampling timing for the waveform data of the first sound signal. That is, the tap coefficients of the FIR filter 223 are not fixed, but change at each sampling timing.

With such a configuration, the waveform data of the sound source signal stored in the sound source memory 207 can be output as it is as the first background sound. By contracting, it becomes possible to raise or lower the frequency of the entire sound information.

As described above, the sound output device 2 according to the present embodiment generates a warning sound including at least one sine wave, and generates the first background sound with the volume adjusted based on the selected sound source. . Therefore, by generating and outputting a sound that can be changed by the user and a sound that cannot be changed, it is possible to output a sound that matches the taste of the user while considering safety.

In some cases, the first background sound does not have to meet the frequency requirements defined by the vehicle approaching notification standards. In that case, it is not necessary to adjust the frequency of the first sound source signal by the first sound source generator 208 .

Further, when the level of the first sound signal measured by the level measuring device 209 is lower than the maximum volume Lmax, the background sound generation unit 13 may not adjust the volume, or may not adjust the volume. The volume may be increased so that the maximum volume of the sound signal level is Lmax.

[Modification of First Embodiment]
Next, a modification of the first embodiment will be described with reference to FIG. This modification achieves simplification of the circuit configuration by omitting the level measuring device 209 in the first embodiment.

FIG. 8 shows an example of information included in the tone generator memory 213 according to this modification. The sound source memory 213 stores, for example, one or more sound source signals that can be freely selected by the user and volume level information for each sound source signal. The volume level is the maximum volume of the sound source signal measured in advance by other hardware or software, and is stored in association with the ID and the sound source signal.

The sound source control circuit 206 acquires volume level information for each sound source signal from the sound source memory 213 instead of the level signal output from the level measuring device 209 . By storing the sound volume level information of the sound source signal together with the sound source signal in advance in the sound source memory 213 in this way, it is possible to adjust the sound volume within a range that conforms to the standard by a simpler method.

[Second embodiment]
The sound output device 5 according to the second embodiment outputs a second notification sound together with the first notification sound output by the sound output device 2 according to the first embodiment. The second notification sound is, for example, a sound that is not subject to the vehicle proximity notification standard, such as a sound emitted from a speaker directed into the vehicle. That is, the second notification sound does not have to comply with the vehicle approach notification standard, and the degree of freedom of the background sound can be increased. For example, it is possible to send a voice message to the operator.

First, the sound output system 4 according to this embodiment will be described with reference to FIG. As shown in FIG. 9, the sound output system 4 according to this embodiment has a sound output device 5, a first speaker 3, and a second speaker 6. As shown in FIG. The sound output system 4 is mounted, for example, on a vehicle such as a hybrid vehicle or an electric vehicle.

As shown in FIG. 9, the sound output device 5 stores speed information and information about a sound source signal selected by the user (hereinafter referred to as "first (hereinafter referred to as "second selection information") and information about the sound source signal to be added only to the second notification sound (hereinafter referred to as "second selection information"). The first selection information is the same information as the selection information in the first embodiment.

Further, the sound output device 5 outputs the first notification sound to the first speaker 3, and the first speaker 3 emits the first notification sound toward the outside of the vehicle. The sound output device 5 outputs the second notification sound to the second speaker 6, and the second speaker 6 emits the second notification sound into the vehicle.

Next, with reference to FIG. 10, the functional configuration of the sound output device 5 according to this embodiment will be described. As shown in FIG. 10 , the sound output device 5 includes a control section 11 , a warning sound generation section 12 , a background sound generation section 16 , a first synthesis section 14 and a second synthesis section 15 . By executing the notification sound generation processing program 25, the CPU 20 functions as the control unit 11, the warning sound generation unit 12, the background sound generation unit 16, the first synthesis unit 14, and the second synthesis unit 15. The configurations of the control unit 11, the warning sound generation unit 12, and the first synthesis unit 14 are the same as those of the first embodiment, and thus description thereof is omitted.

The background sound generation unit 16 generates a first background sound whose volume is adjusted based on the selected sound source, and generates a second background sound. The second synthesizing unit 15 synthesizes the warning sound, the first background sound, and the second background sound, and outputs a second notification sound.

Next, the functions of the control section 11, the background sound generation section 16 and the second synthesis section 15 will be described in detail.

First, the functions of the control section 11 will be described in detail. The control section 11 includes a reproduction control circuit 301 and a speed control information memory 202 . In addition to the functions of the reproduction control circuit 201 in the first embodiment, the reproduction control circuit 301 refers to the sound source memory 307 when the second selection information is input, and generates a sound source signal corresponding to the second selection information. (that is, the “second sound source signal”) to the second sound source generator 308 is output to the sound source memory 307 .

Next, the function of the background sound generator 16 will be described in detail. The background sound generator 16 includes a sound source control circuit 306, a sound source memory 307, a first sound source generator 208, a level measuring device 209, a second volume adjuster 210, a second sound source generator 308, and a third volume adjuster. including vessel 310 . The functions of the first sound source generator 208, the level measuring device 209, and the second sound volume adjuster 210 are the same as those of the first embodiment, so description thereof will be omitted.

In addition to the information of the sound source memory 207 in the first embodiment, the sound source memory 307 further stores a sound source signal used for the second background sound and its ID. The sound source memory 307 outputs the second sound source signal to the second sound source generator 308 based on the second sound source selection signal, in addition to the functions of the sound source memory 207 in the first embodiment.

The second sound source generator 308 outputs a sound signal (hereinafter referred to as “second sound signal”) obtained by reproducing the second sound source signal to the third volume adjuster 310 . The third volume adjuster 310 outputs the second sound signal to the second synthesizer 313 as the second background sound.

As indicated by the dotted line in FIG. 10, the sound source control circuit 306 has the functions of the sound source control circuit 206 in the first embodiment, as well as the second sound source generation including an instruction to adjust the frequency of the second sound source signal. The signal may be output to a second sound source generator 308 . In this case, the second sound source generator 308 adjusts the frequency of the second sound source signal based on the second sound source generation signal, and outputs the frequency-adjusted sound signal as the second sound signal. good too. For example, similar to the sound source generation signal, the frequency of the second sound source signal may be adjusted so as to have a frequency magnification of n times.

10, the sound source control circuit 306 may output a third volume control signal including an instruction to adjust the volume of the second sound signal to the third volume adjuster 310. . In this case, the third volume adjuster 310 adjusts the volume of the second sound signal based on the third volume control signal, and outputs the volume-adjusted second sound signal as the second background sound. It is good also as a mode to carry out. For example, like the second volume control signal, the volume of the second sound signal may be adjusted so as not to exceed the volume Lmax. Also, for example, the volume of the second background sound may be adjusted so that the warning sound and the first background sound are not inaudible.

Next, the function of the second synthesizing section 15 will be described in detail. The second combiner 15 includes a second combiner 313 and a second amplifier 312 . The second synthesizer 313 synthesizes the warning sound, the first background sound, and the second background sound, and outputs the second notification sound to the second amplifier 312 . The second amplifier 312 outputs the second notification sound to the second speaker 6 .

As described above, the sound output device 5 according to the present embodiment generates a warning sound including at least one sine wave, and generates the first background sound with the volume adjusted based on the selected sound source. , to generate a second background sound. Therefore, by generating and outputting a sound that can be freely changed by the user and a sound that cannot be changed, it is possible to output a sound that matches the taste of the user while considering safety.

It should be noted that the second speaker 6 may be used for outputting sound to the outside of the vehicle if the second notification sound satisfies the conditions stipulated by regulations and regulations.

In each of the above-described embodiments, the notification sound generation processing program 25, the speed control information memory 202, and the sound source memories 207 and 307 are pre-stored (installed) in the storage unit 22, but the present invention is not limited to this. The notification sound generation processing program 25, the speed control information memory 202, and the sound source memory 207 are CD-ROM (Compact Disc Read Only Memory), DVD-ROM (Digital Versatile Disc Read Only Memory), USB (Universal Serial Bus) memory, etc. may be provided in a form recorded on a recording medium. Also, the notification sound generation processing program 25, the speed control information memory 202 and the sound source memory 207 may be downloaded from an external device via a network.

1, 4 sound output system 2, 5 sound output device 3, 6 speaker 11 control unit 12 warning sound generation unit 13 background sound generation unit 14 first synthesis unit 15 second synthesis unit 20 CPU
21 memory 22 storage unit 23 input/output port 24 bus 201, 301 reproduction control circuit 202 speed control information memory 203 sine wave control circuit 204 sine wave generator 205 first volume controller 206, 306 sound source control circuit 207, 212, 307 Sound source memory 208 First sound source generator 209 Level measuring device 210 Second sound volume adjuster 211 First synthesizer 212 First amplifier 221 Sound source data reproducing unit 222 FIR filter tap coefficient table 223 FIR filter 312 Second Amplifier 313 Second combiner

Claims (6)

A sound output device mounted on a vehicle,
a warning sound generator for generating a warning sound comprising at least one sine wave;
a background sound generator that generates a volume-adjusted first background sound based on the selected sound source;
a control unit that performs control to select the sound source of the first background sound based on selection information supplied from the outside;
a first synthesizing unit that synthesizes the warning sound and the first background sound and outputs a first notification sound;
including
The background sound generation unit includes a sound source memory that stores at least one sound source signal that is the sound source of the first background sound, a level measuring device that measures the level of the sound source signal stored in the sound source memory, a second volume adjuster that adjusts the volume of the first background sound so that it does not exceed a predetermined maximum volume;
The second volume adjuster adjusts the volume of the first background sound based on the result of measurement by the level meter.
sound output device. The control unit supplies a sine wave control signal including instructions regarding the frequency of the sine wave included in the warning sound and the volume of the warning sound to the warning sound generation unit based on the speed information indicating the speed of the vehicle. , based on the speed information, supplies a sound source control signal including instructions regarding the frequency and volume of the first background sound to the background sound generation unit;
The warning sound generation unit comprises a sine wave generation signal including an instruction to generate a sine wave having a frequency indicated by the sine wave control signal, and a first signal including an instruction regarding the volume of the warning sound indicated by the sine wave control signal. a sine wave control circuit that outputs a volume control signal; a sine wave generator that outputs a sine wave based on the sine wave generation signal; and a first volume control signal that adjusts the volume of the warning sound based on the first volume control signal 1 volume control;
The background sound generation unit generates a sound source generation signal including an instruction to generate the first background sound having a frequency designated by the sound source control signal and the first background sound having a volume designated by the sound source control signal. a sound source control circuit that outputs a second volume control signal including an instruction; and a first sound source generator that adjusts the frequency of the first background sound based on the sound source generation signal;
The second volume adjuster adjusts the volume of the first background sound based on the second volume control signal.
The sound output device according to claim 1 . 3. The sound output device according to claim 1, wherein the control unit selects one of at least one sound source signal stored in the sound source memory based on the selection information. The background sound generation unit generates a second background sound,
4. The method according to any one of claims 1 to 3, further comprising a second synthesizing unit that synthesizes the warning sound, the first background sound, and the second background sound and outputs a second notification sound. A sound output device as described. a sound output device according to any one of claims 1 to 3 ;
a speaker to which the first notification sound is input;
sound output system including a sound output device according to claim 4 ;
a first speaker to which the first notification sound is input;
a second speaker to which the second notification sound is input;
sound output system including

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