JP2020144185A - Sound creation method - Google Patents

Abstract

To provide a comfortable in-vehicle space by taking noise countermeasure irrespective of presence or absence of a sound insulation material.SOLUTION: A sound creation method comprises: a recording step for recording noise when a vehicle 10 travels; a measuring step for measuring brain waves of a subject while the subject is made to hear the noise recorded in the recording step; and a sound creation step for identifying a parameter of the noise which the subject desires on the basis of correlation relationship between a measurement result of an alpha wave in the brain wave measured in the measuring step and the noise, and creating sound on the basis of the identified parameter.SELECTED DRAWING: Figure 2

Description

The techniques disclosed herein relate to sound production methods.

Conventionally, it has been described that a sound insulating material obtained by laminating a soft material and a hard material is used as a noise countermeasure when the vehicle is running (Patent Document 1 below). By using the sound insulating material, it is possible to suppress the situation where noise enters the vehicle interior.

Japanese Patent No. 5194972

In the configuration using the sound insulating material as described above, it may be difficult to save space and weight by arranging the sound insulating material. Further, as a noise countermeasure, it is more preferable to combine various kinds of countermeasures. Under these circumstances, a method other than the method using a sound insulating material is required as a noise countermeasure.

The technology disclosed in the present specification has been completed based on the above circumstances, and provides a comfortable interior space by taking noise countermeasures regardless of the presence or absence of a sound insulating material in the vehicle interior space. The purpose is.

As a means for solving the above problems, the sound creation method disclosed in the present specification includes a recording step of recording the noise when the vehicle is traveling and the subject while listening to the noise recorded in the recording step. , The noise parameter preferred by the subject is specified and specified based on the measurement step of measuring the brain wave of the subject and the correlation between the measurement result of the alpha wave in the brain wave measured in the measurement step and the noise. It is characterized by including a sound creation step of creating a sound based on the above-mentioned parameters.

According to the above configuration, in the sound creation step, it is possible to create a sound preferred by the subject based on the noise when the vehicle is running. When the subject gets on the vehicle, the sound created in the sound creation step (the sound preferred by the subject) is played while the vehicle is running, so that the subject selectively hears the sound (so-called cocktail party effect). , It becomes difficult to hear other sounds. As a result, it is possible to take measures against noise regardless of the presence or absence of the sound insulating material, and further, it is possible to hear the sound preferred by the subject. As a result, a more comfortable vehicle interior environment can be provided. Further, since the sound created by the sound creation step is a sound created based on the noise when the vehicle is running, it is possible to suppress a situation in which the subject feels unnatural when the subject hears the sound while the vehicle is running.

Further, the parameter may include at least one of a parameter related to the explosion sound of the engine of the vehicle and a parameter related to the road noise. It is possible to create a sound that reflects the engine explosion sound and road noise, which are the main components of noise when the vehicle is running.

In addition, the subject can be assumed to be the owner of the vehicle. It is possible to create sounds that vehicle owners like.

According to the technology disclosed in the present specification, it is possible to provide a comfortable interior space by taking noise countermeasures regardless of the presence or absence of a sound insulating material in the vehicle interior space.

Block diagram showing the configuration of a recording device Block diagram showing the configuration of the sound creation device Graph showing an example of time change of overall value and noise level Graph showing an example of frequency characteristics of road noise component Graph showing an example of the frequency characteristics of the sound created in the sound creation step

An embodiment of the present invention will be described with reference to FIGS. 1 to 5. In the present embodiment, a sound creation method for creating a sound for output from an output device (speaker, etc.) mounted on the vehicle when the vehicle is running will be described. The sound creation method of the present embodiment includes a recording step, a measurement step, and a sound creation step.

(Recording step)
In the recording step, the noise when the vehicle travels is recorded, and is executed by using the recording device 11 mounted on the vehicle 10 as shown in FIG. As shown in FIG. 1, the recording device 11 includes a sound level meter 12 and a storage unit 13. The sound level meter 12 includes a microphone and an arithmetic processing unit (not shown), and can measure the noise level of sound (A characteristic sound pressure level). As the storage unit 13, for example, a data logger can be used.

In the recording step, the vehicle 10 travels on a circuit (test course), and the noise during travel is acquired by the sound level meter 12. The circumferential circuit on which the vehicle 10 travels has a plurality of curves and undulations, and is considered to be rich in road surface changes. By traveling on such a circuit, the road noise (a part of the noise) during traveling changes with time. Further, the driver of the vehicle 10 adjusts the amount of depression of the accelerator pedal (accelerator opening degree) so that the vehicle 10 has a constant speed (for example, 60 km / h) when traveling on the circuit. As a result, the accelerator opening changes during driving, so that the engine explosion sound (a part of the noise) changes every hour. The noise data recorded in this way is stored in the storage unit 13.

(Measurement step)
In the measurement step, the subject's brain waves are measured while letting the subject hear the noise recorded in the recording step. The measurement step and the sound creation step described later are executed using, for example, the sound creation device 21 shown in FIG. Further, the subject referred to here is, for example, the owner of the vehicle 10 (or a vehicle of the same vehicle type as the vehicle 10).

The sound producing device 21 includes a control unit 22, a storage unit 25, a frequency analysis unit 26, headphones 27, and an electroencephalograph 28. The storage unit 25 stores noise data (noise data) recorded in the recording step. The storage unit 25 may be the same as the storage unit 13. The control unit 22 is electrically connected to the storage unit 25, the frequency analysis unit 26, the headphones 27, and the electroencephalograph 28, respectively.

The frequency analysis unit 26 can perform frequency analysis on the noise data stored in the storage unit 25. As a method of frequency analysis, for example, a Fast Fourier Transform (FFT) can be exemplified. The frequency analysis unit 26 can calculate the following four parameters (1) to (4) related to noise for each hour by performing frequency analysis on the noise data stored in the storage unit 25. There is.

Parameter (1): Noise overall value A1
The noise overall value A1 is the sum of the noise levels in all frequency bands.

Parameter (2): Ratio of engine explosion primary component to overall value A1 B1
The frequency of the primary explosion component of the engine (referred to as frequency F31 in the following description) can be calculated from the specifications of the engine mounted on the vehicle 10. Therefore, the ratio B1 can be calculated by referring to the noise level B2 at the frequency F31 in the noise data. FIG. 3 shows an example of the time change of the overall value A1 and the noise level B2 of the engine explosion primary component. The ratio B1 = B2 / A1.

Parameter (3): Ratio of road noise component to overall value A1 C1
Road noise is generally composed of sounds in the frequency band of 100 to 400 Hz. Therefore, in the present embodiment, the sum of the noise levels for each frequency band of the 1/3 octave band is used as the road noise component in the range of 100 to 400 Hz in the noise, and the ratio C1 of the road noise component to the overall value A1 is calculated. .. Note that FIG. 4 shows an example of the frequency characteristics of road noise. When the road noise component R2 is used, the ratio C1 = R2 / A1.

Parameter (4): Ratio of noise level in each frequency band of 1/3 octave band center frequency 160Hz, 250Hz, 315Hz D1
In general, most of the road noise often peaks in three frequency bands of 1/3 octave band, center frequencies 160 Hz, 250 Hz, and 315 Hz. Therefore, in the present embodiment, the ratio D1 of each noise level of the center frequencies 160 Hz, 250 Hz, and 315 Hz is calculated as a parameter that reflects the frequency characteristics of the road noise. When the noise level in the 160 Hz frequency band is X1, the noise level in the 250 Hz frequency band is X2, and the noise level in the 315 Hz frequency band is X3, the ratio D1 = X1: X2: X3.

The control unit 22 operates the headphones 27 based on the noise data stored in the storage unit 25. As a result, the headphone 27 outputs the noise during vehicle travel recorded in the recording step. The electroencephalograph 28 is capable of measuring the electroencephalogram of the subject. The electroencephalograph 28 is, for example, in the form of a headgear that can be worn by a subject, and the headphones 27 are provided on the headgear. In addition, the control unit 22 can perform frequency analysis on the electroencephalogram data measured by the electroencephalogram meter 28 using the frequency analysis unit 26. This makes it possible to measure the intensity of alpha waves (8 to 13 Hz components) among the subject's brain waves.

In the measurement step, the subject's electroencephalogram is measured by the electroencephalograph 28 while letting the subject hear the noise recorded in the recording step via the headphones 27. The control unit 22 stores the noise data (including the data of the above parameters (1) to (4)) of the noise heard by the subject and the measured alpha wave measurement data in the storage unit 25 while associating the time series with each other. ..

(Sound creation step)
The control unit 22 includes a sound creation unit 23 and a parameter determination unit 24. The parameter determination unit 24 is equipped with artificial intelligence (AI), and performs deep learning based on the correlation between the measurement data of the alpha wave (measured in the measurement step) stored in the storage unit 25 and the noise data. , The numerical value preferred by the subject (parameter of noise preferred by the subject) is determined for each of the parameters (1) to (4). Specifically, when the alpha wave exceeds a predetermined threshold value at a certain time, the numerical values of the parameters (1) to (4) at that time and the parameters (1) to (4) before and after that time. With reference to the tendency of change (time derivative value) and the like, the numerical values of the parameters (1) to (4) preferred by the subject are specified. For example, when only the overall value A1 is momentarily increased at the time point T1 when the alpha wave exceeds a predetermined threshold value, it is specified that the overall value A1 at the time point T1 is the overall value A1 preferred by the subject. Can be done.

If it is difficult to find the correlation between the alpha wave measurement data and the noise data in the data acquired in the recording step and the measurement step, return to the recording step and the measurement step and return to the recording step and the amount of the alpha wave measurement data and the noise data. Should be increased. Specifically, in the recording step, the circuit is driven at a constant speed at various speeds, and the amount of noise data is increased by acquiring noise data for each speed, and the amount of noise data to be heard by the subject is increased in the measurement step. This makes it possible to increase the amount of alpha wave measurement data.

Then, after the numerical values preferred by the subject are specified for each of the parameters (1) to (4), the sound creation unit 23 sets the overall value of the sound and the noise level in each frequency band of the 1/3 octave band. Create a sound that the subject likes by doing things such as. Specifically, the sound creation unit 23 creates a sound through the following procedures (1) to (5). FIG. 5 is a graph showing the frequency characteristics of an example of the created sound. As shown in FIG. 5, the sound creation unit 23 sets the noise level in the frequency band of 40 to 800 Hz, which mainly constitutes the noise inside the vehicle, for example. In the following description, the noise overall value A1 preferred by the subject is referred to as the overall value AL, and the ratio B1 of the primary explosion component preferred by the subject is referred to as the ratio BL (parameter related to the explosion sound of the vehicle engine). The ratio C1 of the preferred road noise component is referred to as the ratio CL (parameter related to the road noise), and the ratio D1 of each noise level preferred by the subject is referred to as the ratio DL (parameter related to the road noise).

Procedure (1) Determine the overall value of the sound to be created.
Overall value preferred by the subject The overall value of the sound that creates the AL is used (see F1 in FIG. 5).

Procedure (2) Calculate the noise level L1 of the frequency F31 (frequency of the primary explosion component) of the sound to be created.
(Noise level L1) = (overall value AL) * (ratio BL) (see F3 in FIG. 5).

Procedure (3) Calculate the road noise component R1 (sum of noise levels of 100 to 400 Hz).
(Road noise component R1) = (overall value AL) * (ratio CL) (see F2 in FIG. 5).

Procedure (4) Calculate the noise level of each frequency band of the center frequency 160Hz, 250Hz, 315Hz of the 1/3 octave band.
As for the noise level in each frequency band of the center frequencies 160 Hz, 250 Hz, and 315 Hz, 90% of the road noise component R1 is distributed by the ratio DL (see F4, F5, and F6 in FIG. 5). For example, when the ratio DL = 160 Hz frequency band noise level X1: 250 Hz frequency band sound level X2: 315 Hz frequency band sound level X3, the 160 Hz frequency band noise level is R1 for the sound to be created. * 0.9 * (X1 / (X1 + X2 + X3)). The noise level in the 250 Hz frequency band is R1 * 0.9 * (X2 / (X1 + X2 + X3)), and the noise level in the 315 Hz frequency band is R1 * 0.9 * (X3 / (X1 + X2 + X3)). is there.

Procedure (5) Determine each noise level in a frequency band other than the center frequencies 160 Hz, 250 Hz, and 315 Hz in the 1/3 octave band.
Each frequency band (see F7 to F17 in FIG. 5) other than the center frequencies 160 Hz, 250 Hz, and 315 Hz in the 1/3 octave band is determined based on the following procedures (A) to (C).
(A): Each average value of each noise level of the frequency bands F7 to F17 in the noise data is calculated.
(B): Let each average value of each noise level of the frequency bands F7 to F17 be the ratio of each frequency band F7 to F17.
(C): Each noise level of each frequency band F7 to F17 so that the total noise level of each frequency band F7 to F17 is 10% of the road noise component R1 while maintaining the ratio defined in the above (B). To set.

The sounds created based on the above procedures (1) to (5) are the parameters preferred by the subject (overall value AL, explosion primary component ratio BL, road noise component ratio CL, 160Hz, 250Hz, 315Hz noise levels. It is a sound including the ratio DL) of, and is a sound preferred by the subject (a sound that generates an alpha wave when the subject hears it).

Next, the effect of this embodiment will be described. According to the present embodiment, in the sound creation step, a sound preferred by the subject can be created based on the noise when the vehicle 10 is running. When the subject gets on the vehicle 10, the sound created in the sound creation step (the sound preferred by the subject) is played while the vehicle 10 is running, so that the subject selectively listens to the sound (so-called cocktail party). Effect), it becomes difficult to hear other sounds. As a result, noise countermeasures can be taken regardless of the presence or absence of the sound insulation material, and the subject can be made to hear a favorite sound. As a result, a more comfortable vehicle interior environment can be provided. Further, since the sound created by the sound creation step is a sound created based on the noise when the vehicle is running, it is possible to suppress a situation in which the subject feels unnatural when the subject hears the sound while the vehicle is running.

Further, the noise parameters preferred by the subject include parameters related to the explosion sound of the engine of the vehicle 10 and parameters related to road noise. It is possible to create a sound that reflects the engine explosion sound and road noise, which are the main components of noise when the vehicle is running. The subject is the owner of the vehicle 10. It is possible to create a sound preferred by the owner of the vehicle 10.

<Other embodiments>
The present invention is not limited to the embodiments described in the above description and drawings, and for example, the following embodiments are also included in the technical scope of the present invention.
(1) In the above embodiment, the subject and the owner of the vehicle may be different persons.
(2) The sound created in the sound creation step is not limited to that shown in FIG.
(3) The sound creation procedures (1) to (5) by the sound creation unit 23 are not limited to the order, and the order may be changed as much as possible.

10 ... Vehicle, BL ... Ratio of primary explosion component B1 (parameters related to the explosion sound of the vehicle engine, noise parameters preferred by the subject), CL ... Ratio of road noise components (parameters related to road noise, noise preferred by the subject) Parameters), DL ... Ratio of each noise level of 160Hz, 250Hz, 315Hz (parameters related to road noise, noise parameters preferred by the subject)

Claims (3)

A recording step that records the noise when the vehicle is running, and
A measurement step of measuring the brain wave of the subject while letting the subject hear the noise recorded in the recording step,
A sound that identifies the noise parameter preferred by the subject based on the correlation between the alpha wave measurement data in the brain wave measured in the measurement step and the noise, and creates a sound based on the specified parameter. A sound creation method that includes a creation step. The sound creation method according to claim 1, wherein the parameter includes at least one of a parameter related to an explosion sound of the engine of the vehicle and a parameter related to road noise. The sound creation method according to claim 1 or 2, wherein the subject is the owner of the vehicle.

Images