JP2022074680A - Noise reduction device - Google Patents

Abstract

To provide a new noise reduction device that reduces discomfort of noise entering a vehicle compartment.SOLUTION: A noise reduction device 10 includes: a sound reproduction unit 12 that reproduces sound to a passenger compartment based on reproduced sound signals; a vibration generation unit 16 that causes passenger compartment components to function as loudspeakers; and a vibration control unit 14 that controls the vibration generation unit 16 to cause the passenger compartment components to generate mitigation sound from the passenger compartment components to mitigate noise by vibrating the passenger compartment components. The vibration control unit 14 generates the mitigation sound so that, when a sound reproduction unit 13 is reproducing reproduced sound, sound pressure of some frequency components that overlap with the frequency components of the reproduced sound, of propagation noise propagating in the passenger compartment through the passenger compartment components is increased.SELECTED DRAWING: Figure 2

Description

The present invention relates to a noise reduction device.

Conventionally, in order to keep the vehicle interior comfortable, techniques for reducing various noises entering the vehicle interior have been proposed. As an example of such a technique, a passive method (for example, refer to Patent Document 1) in which a vehicle is provided with a sound absorbing material or a soundproofing material to suppress noise from entering the vehicle interior, and a sound wave extinguishing according to the target noise. Examples thereof include an active method (see, for example, Patent Document 2) in which (sound waves of opposite phases) are emitted to cancel the noise.

Japanese Unexamined Patent Publication No. 2020-106689 Japanese Unexamined Patent Publication No. 07-1997

In the above passive method, the volume of the sound absorbing material and the sound absorbing effect are approximately proportional to each other, and the mass of the sound insulating material is approximately proportional to the volume and the soundproofing frequency. At present, it has not been able to exert a sufficient sound insulation effect in vehicles that are limited in frequency or are required to be lightweight. In the above active method, it is difficult to control the speed of calculation, the position where the sound wave is generated, and the radiation direction in order to invert the phase of the noise acquired by the sensor or the like and accurately deliver it to the vehicle chamber. There is a problem that a muffling radiator (for example, a speaker) is required, and the sound pressure of noise is amplified depending on the location of the vehicle room, which causes discomfort to the occupants.

The technique disclosed herein has been made in view of the actual situation of the above-mentioned conventional technique, and it is an object of the present invention to provide a new noise reducing device for reducing the discomfort of noise entering the vehicle interior.

One of the purposes of noise reduction in a vehicle is to reduce the discomfort of the occupant due to the noise, and typical examples of this noise include road noise, wind noise, engine noise and the like. Although various techniques aimed at eliminating these noises have been difficult than before, the present inventor has made a diligent study and found that, for example, an occupant has a certain degree of perception in order to perceive the driving situation of a vehicle. It may be preferable for the noise to reach the ears. That is, the techniques disclosed herein provide noise mitigation devices. This noise reduction device is a noise reduction device that reduces the discomfort of the occupant due to the noise that enters the vehicle room, and is a sound reproduction unit that reproduces the reproduced sound that is the sound based on the reproduced sound signal to the vehicle room. By providing a plate-shaped vehicle chamber component that defines the vehicle chamber, a vibration generating portion that vibrates the vehicle chamber component, and controlling the vibration generating portion to vibrate the vehicle chamber component. A control unit for generating a mitigating sound for mitigating the noise from the vehicle chamber constituent member is provided. Then, when the sound reproduction unit reproduces the reproduced sound, the control unit overlaps with the frequency component of the reproduced sound among the frequency components of the propagated noise propagating into the vehicle chamber through the vehicle chamber constituent member. It is provided with a configuration for generating the relaxation sound so as to raise the sound pressure of the frequency component of the unit.

According to the above configuration, when the sound reproducing unit reproduces some reproduced sound, the vibration generating unit generates a relaxation sound from the vehicle chamber constituent member. As a result, the propagating noise propagating in the room through the vehicle chamber constituent members is recreated into a sound that is familiar to the reproduced sound by superimposing the mitigation sound. Further, since the mitigation sound is emitted into the vehicle room from the same vehicle room component that emits the propagating noise, it follows the same route as the noise before reaching the ears of the occupant. In other words, the mitigation sound and the propagating noise are affected by attenuation, reflection, amplification, etc. in exactly the same way while propagating in the vehicle chamber after being emitted. As a result, the mitigated sound is not affected differently from the propagated noise depending on the shape and size of the vehicle room, the position and material of equipment, etc., and the discomfort of the propagated noise is similarly reduced at any point in the vehicle room. can do.

In a preferred embodiment of the noise mitigation device, the control unit includes a configuration for generating the mitigation sound so as to increase the sound pressure of a frequency component between peaks in the frequency spectrum of the propagating noise. Propagation noise usually includes sounds of various frequency components, and peaks of various sizes may appear over a wide frequency range even in a frequency spectrum showing the relationship between the frequency and sound pressure. The psychological effect of sound (sound wave) on human hearing differs not only with sound pressure (typically, loudness) but also with the waveform of the frequency spectrum. According to the above configuration, in the propagated noise, the sound pressure between any two peaks in the frequency spectrum is increased (for example, evened to the same extent as the peak) by superimposing the relaxation sound, and the peaks are relative to each other. It will be changed to a broader one. As a result, the characteristics of the timbre of the propagating noise are reduced, and the discomfort of the propagating noise can be reduced.

In a preferred embodiment of the noise mitigation device, the control unit raises the sound pressure of a frequency component between the frequency of the fundamental tone in the propagating noise and the frequency of the second harmonic of the fundamental tone. It has a configuration to generate. Natural sounds are composed of a combination of a plurality of overtones, and by increasing the sound pressure between the peak of the fundamental tone and the peak of the second overtone, the timbre characteristics of the transmitted noise can be effectively reduced.

In a preferred embodiment of the noise mitigation device, the control unit raises the sound pressure of a harmonic frequency that is an integral multiple of the frequency of the base sound in the propagated noise among the frequency components of the reproduced sound. To generate. Natural sounds are composed of a combination of multiple overtones, and humans tend to find chords of the same scale, which differ by one octave, as "comfortable" because they are not accompanied by frequency shifts. According to the above configuration, in addition to the propagating noise, the vehicle chamber constituent member also reproduces the sound of the same scale as the propagating noise among the sounds included in the reproduced sound. As a result, the propagated noise and the reproduced sound become a consonant sound and are reproduced in the vehicle room, so that the discomfort of the noise can be reduced.

In a preferred embodiment of the noise mitigation device, the vehicle compartment component is at least selected from the group consisting of door trim, cowl side trim, instrument panel, deck side trim, pillar garnish, floor carpet, and window glass. There is one. The above-mentioned vehicle chamber constituent members are generally plate-shaped, and are arranged in a portion closely related to the causes of typical noises such as road noise, wind noise, and rain noise. Therefore, it is preferable to make these vehicle compartment components function as sub-speakers because the noise of the vehicle can be effectively reduced.

In a preferred embodiment of the noise mitigation device, the vehicle provided with the vehicle chamber is a land traveling vehicle, including a road surface grounding member, and the noise mitigation unit determines the frequency characteristics of the propagating noise, road surface conditions, and weather. , The traveling speed, and at least one element selected from the group consisting of the degree of deterioration of the road surface grounding member are stored in advance. The vehicle chamber constituent member has a frequency peculiar to the member depending on its material, shape, and relationship with a noise source, and emits noise peculiar to the member into the vehicle chamber. Therefore, the noise mitigation unit can generate more appropriate mitigation sound under each situation by investigating and storing the frequency characteristics of the propagating noise under various situations in advance for the target vehicle room constituent member. Can be done. This provides a noise mitigation device capable of more effectively reducing the noise of the vehicle.

In a preferred embodiment of the noise mitigation device, the control unit measures the frequency characteristics of the propagated noise in real time, and based on the measurement result, the vibration generating unit generates the mitigated sound from the vehicle chamber constituent member. It has a configuration to generate. The vehicle chamber constituent member has a frequency peculiar to the member depending on its material, shape, and relationship with a noise source, and emits noise peculiar to the member into the vehicle chamber. Therefore, by investigating the frequency characteristics of the propagated noise in real time for the target vehicle chamber constituent member, the noise mitigation unit can generate more appropriate mitigation sound in real time. This provides a noise mitigation device capable of more effectively reducing the noise of the vehicle.

According to the technique disclosed herein, it is possible to provide a new noise reducing device for reducing the discomfort of noise entering the vehicle interior.

The figure which shows the structure of the vehicle equipped with the noise reduction device which concerns on one Embodiment. Block diagram of noise reduction device according to one embodiment Frequency spectrum of door trim vibration during road noise FIG. 3 is a diagram in which the frequency spectrum of the reproduced sound according to the embodiment is superimposed on FIG. Frequency spectrum of the vibration of the door trim when the mitigation sound is generated from the door trim when the road noise is generated. The frequency spectrum of the reproduced sound according to another embodiment is superimposed on FIG. Frequency spectrum of the vibration of the door trim when the mitigation sound is generated from the door trim when the road noise is generated. The frequency spectrum of the reproduced sound according to another embodiment is superimposed on FIG. The frequency spectrum of the relaxed sound according to another embodiment is superimposed on FIG.

<< Embodiment >>
An embodiment of the technique disclosed herein will be described by taking a noise reduction device 10 mounted on a vehicle 1 as an example of a vehicle as an example with reference to FIGS. 1 to 9. The symbols F, Rr, U, and D shown in each figure indicate the front, rear, and above and below in the vertical direction (vertical direction), respectively. However, the above direction is only for convenience and should not be interpreted in a limited way.

As shown in FIG. 1, the vehicle 1 is a floor that forms a part of the skeleton of the vehicle 1 and the wheels 2 and 2 that drive the vehicle 1 by being rotationally driven, and constitutes the floor surface of the vehicle interior. It includes a panel 3, a roof panel 4 that constitutes the ceiling surface, a pillar 5 that supports the ceiling surface with respect to the floor surface, and the like. By attaching a vehicle door 6, a window glass 7, or the like to these vehicle skeletons, a vehicle interior space is defined inside the vehicle 1. In the passenger compartment, for vehicles such as cowl side trim 2A, floor carpet 3A, roof trim 4A, pillar garnish 5A, door trim 6A, instrument panel (not shown), and deck side trim to enhance comfort and design. Interior materials are provided. These interior materials for vehicles form the design surface of the vehicle interior by surrounding the vehicle interior, enhance the heat retention of the vehicle interior, and also have a function as a passive sound absorbing / insulating material.

Here, the member (for example, an interior material for a vehicle) that defines the vehicle interior has a plate shape formed into various shapes, and is subject to impact and vibration when the vehicle 1 travels on land. It vibrates by propagating, and the vibration is radiated into the vehicle interior as noise. For example, in the vehicle 1, vibration and contact noise (road noise) generated by the tire 2B (an example of a road surface contact member) mounted on the wheels 2 and 2 coming into contact with the road surface are generated by the cowl side trim 2A and the floor carpet. It is easily radiated into the vehicle interior through 3A, door trim 6A, deck side trim (not shown), etc. Further, the engine sound is likely to be radiated into the vehicle interior through an instrument panel (not shown) arranged between the gasoline engine room in front of the vehicle 1 and the vehicle interior. Then, wind noise, rain noise, etc. due to air, rain, etc., which hit the traveling vehicle 1, are likely to be radiated into the vehicle interior as noise through the door trim 6A, the pillar garnish 5A, the window glass 7, and the like. The vibration mode of the vehicle interior components may differ depending on the structure of the vehicle, the shape, material, etc. of each vehicle interior component, but as a typical example, the frequencies due to external impacts and vibrations of the vehicle interior components shown below are shown below. Is roughly as follows.

Therefore, the vehicle 1 is provided with a noise reducing device 10 for reducing the discomfort caused by such noise. The noise reduction device 10 is generally configured to include an audio device 12 (an example of a sound reproduction unit), a vibration control unit 14, and a vibration generation unit 16, and the above-mentioned vehicle interior component is a sub-speaker. When the sound such as music is reproduced from the audio device 12, a mitigation sound that alleviates the noise propagating into the vehicle interior through the vehicle interior component (hereinafter referred to as “propagated noise”) is also generated from the vehicle interior component. I'm trying to make you. Hereinafter, each part of the noise reduction device 10 and its operation will be described.

The audio device 12 is a device capable of reproducing the reproduced sound to the vehicle interior based on the digital or analog reproduced sound signal, and the audio device 12 of this example is a general device as shown in FIG. 2, for example. It can be configured by an analog device (also referred to as a stereo device or the like). Although not limited to this, the audio device 12 typically includes a conversion unit 12A that converts the sound to be transmitted into an electric signal capable of digital processing, and the converted electric signal as needed. The processing unit 12B to be processed, the amplifier 12C that amplifies the processed or unprocessed electric signal, the speaker unit 12D that converts the electric signal amplified by the amplifier into acoustic vibration and radiates it into the vehicle interior, and each of these parts. It is provided with a control unit 12E that controls and reproduces a sound.

The conversion unit 12A is an element that generates an electric signal corresponding to a sound to be transmitted (radiated) to the outside in the audio device 12, a microphone that converts various sounds and the like into an electric signal, and sound information including a reproduced sound signal. It may be a player that converts a recorded medium into an electric signal, a receiving device that receives a reproduced sound signal transmitted by wire or wirelessly from an external device or the like, and converts it into an electric signal as needed.

For example, the processing unit 12B has a gain function for amplifying or mixing (mixing) a plurality of input electric signals (reproduced sound signals in the state of electric signals) with respect to sound components divided by sound quality (for example, frequency). It has a mixer function, an equalizer function for correcting tone color, and a panning function for outputting electric signals to a plurality of speakers and changing their ratios. The processing unit 12B can convert, for example, a plurality of reproduced sound signals transmitted from the conversion unit 12A in the state of an electric signal into a sound quality of the user's preference.

The amplifier 12C is an element that amplifies the electric signal processed by the processed unit 12B or the unprocessed electric signal, and amplifies the electric signal so as to achieve the sound pressure level desired to be output from the speaker unit 12D. The amplifier 12C may be integrated with the speaker unit 12D or may be separate from the speaker unit 12D. The speaker unit 12D is an element that returns an electric signal amplified by the amplifier 12C to a raw sound and radiates it into the vehicle interior, and one audio device 12 is provided with one or a plurality of two or more.

The control unit 12E is an element that controls the operation of each unit of the audio device 12, and is mainly composed of a microcomputer or the like having a CPU, RAM, ROM, or the like. It is connected so that it can communicate. The control unit 12E basically converts the reproduced sound signal into an electric signal by the conversion unit 12A, then amplifies the electric signal by the amplifier 12C so as to realize a predetermined sound pressure (volume), and the speaker. The electric signal amplified in the unit 12D is radiated into the vehicle interior as acoustic vibration and reproduced. In the control unit 12E, for example, when the sound reproduction unit 13 includes a plurality of speaker units 12D, for example, the processing unit 12B divides the reproduced sound signal into a plurality of sound components for each sound quality, and then the plurality of speaker units 12D. The types of output sound components and their ratios can be changed for each of the above. Further, the control unit 12E can change the sound pressure of the output sound, in other words, the amplification factor of the amplifier 12C, for each of the plurality of speaker units 12D. Further, the control unit 12E can, for example, emit high-quality sound according to the size, shape, configuration, etc. of the vehicle interior, the processing content of the processing unit 12B, the sound quality of the reproduced sound radiated from each speaker unit 12D, and the sound quality of the reproduced sound. The sound pressure may be stored in advance as a plurality of control modes, and the sound may be reproduced from each speaker unit 12D based on the control mode selected by the user.

The vibration generation unit 16 is provided in a plate-shaped vehicle compartment component that defines the vehicle interior, and is an element that vibrates the vehicle compartment component, and is an example of a control unit in the technique disclosed herein. .. The vehicle interior components are not limited to this, but are not limited to, for example, the vehicle interior materials (typically, cowl side trim 2A, floor carpet 3A, roof trim 4A, pillar garnish) surrounding the vehicle interior described above. 5A, door trim 6A, instrument panel, deck side trim, window glass 7, etc.) are examples. Further, as the vibration generating unit 16, for example, a vibration generating device capable of generating mechanical vibration based on an electric signal can be adopted. As such a vibration generating unit 16, for example, a piezo film speaker, an exciter, a vibration motor, an electromagnetic vibration device, or the like that can convert electric energy into kinetic energy can be adopted. The vibration generating unit 16 can make the vehicle chamber component function as a speaker by vibrating the vehicle chamber component to which it is attached. The vibration generating unit 16 may be attached to any one of the interior materials for vehicles, or may be attached to each of two or more interior materials for vehicles. When the vehicle interior member is an interior material for a vehicle, the vibration generating unit 16 may be attached to the back surface side (outside surface of the vehicle interior) with respect to the interior material for the vehicle. Further, when the storage chamber component is the window glass 7, the vibration generating portion 16 is exposed to the appearance such as the mounting frame of the window glass 7 and the inside of the skeleton panel (the portion sandwiched between the inner panel and the outer panel). It is better to install it in a position where it will not be installed.

The vibration control unit 14 is an element that controls the operation of the vibration generation unit 16 to vibrate the vehicle chamber components, and imparts an electric signal corresponding to the relaxation sound for alleviating the above-mentioned propagating noise to the vibration generation unit 16. do. The vibration control unit 14 may be provided inside the audio device 12, or may be provided at a position different from the audio device 12 (for example, in the vicinity of the vibration generation unit 16). When the vibration control unit 14 is provided inside the audio device 12, the vibration control unit 14 may be an element of the control unit 12E. When the vibration control unit 14 is provided separately from the audio device 12, the vibration control unit 14 is mainly composed of, for example, a microcomputer having a CPU, RAM, ROM, etc., and generates vibration via wire or wireless. It is communicably connected to the unit 16 and the audio device 12. For example, the vibration control unit 14 sends an electric signal corresponding to the relaxation sound to the vibration generation unit 16, so that the vibration generation unit 16 vibrates the vehicle chamber constituent member, and the above-mentioned electricity is transmitted from the vehicle chamber constituent member together with the above-mentioned electricity. The sound corresponding to the signal (that is, the relaxation sound) will be reproduced. The vibration generation unit 16 may appropriately use the conversion unit 12A of the audio device 12, the processing unit 12B, the amplifier 12C, and the like when creating an electric signal corresponding to the relaxed sound.

Hereinafter, as shown in FIG. 2, the relaxation sound generated by the vibration control unit 14 will be described by taking the case where the vehicle compartment component is the door trim 6A as an example.
FIG. 3 schematically shows a frequency spectrum of the vibration of the door trim 6A due to the impact and vibration of the moving vehicle 1, the horizontal axis is an octave band display of the frequency, and the vertical axis is sound. It shows the pressure level. The door trim 6A itself vibrates based on the impact between the tire and the road surface while the vehicle is running, so that, for example, as shown in Table 1, propagation noise over a frequency range of about 100 to 1000 Hz is generated. do. Here, the door trim 6A has a natural frequency, and the vibration of the door trim 6A when the vehicle 1 travels on a general paved road surface (in other words, road noise propagating in the vehicle interior via the door trim 6A). The center frequency of is about 160 Hz. The natural sound including the propagated noise is composed of a combination of the fundamental tone and its overtones, and the door trim 6A of this example also has a fundamental tone of about 160 Hz (scale; Les # (D # 3)) and about 315 Hz. It can be confirmed that the 2nd harmonic of (scale; Les # (D # 4)) is included. In the present technique, when the term "frequency of vibration of door trim 6A" is simply referred to, it means the frequency of the fundamental tone. Further, since the loudness of the sound perceived by humans is not proportional to the multiple of the reference sound pressure but to the logarithm thereof, the unit of the sound pressure on the vertical axis in FIGS. 3 to 9 is decibel [dB] (logarithm). Display).

Here, in a known active noise canceller (ANC), a cancel vibration (cancellation sound) that cancels such road noise is applied to, for example, a door trim. On the other hand, the present inventor states that the road noise may not necessarily be eliminated because it includes information related to the driving of the vehicle 1, such as the road surface, the surface condition of the tire, the installation condition, and the traveling speed. I'm paying attention. However, when listening to music or the like by the audio device 12 of the vehicle 1, for example, the road noise may hinder the music and the road noise may feel unpleasant. Therefore, the present inventor, when listening to music or the like by the audio device 12, produces a mitigating sound that reduces the discomfort of noise propagating through the door trim 6A for each vehicle room component to which the vibration generating unit 16 is attached (here). Then, for example, by preparing the door trim 6A) and reproducing the mitigation sound from the door trim 6A together with the noise, the noise reaches the ears of the occupant as if the discomfort is reduced. For example, music is reproduced from the speaker unit 12D of the audio device 12, and the door trim 6A is used as a sub-speaker so that the reduced sound is reproduced from the door trim 6A (sub-speaker) in addition to the propagated noise. The mitigation sound reproduced in addition to the propagating noise from the door trim 6A (sub-speaker) may include only the sound corresponding to the frequency component for mitigating the noise (mitigation sound itself), or the mitigation sound and the reproduction target. It may include music that is. The technique disclosed herein proposes an unprecedented new technical idea from the viewpoint of reducing discomfort from noise rather than eliminating noise.

More specifically, the vibration control unit 14 overlaps with the frequency component of the reproduced sound among the frequency components of the propagated noise propagating in the vehicle room through the door trim 6A when the audio device 12 reproduces some reproduced sound. The relaxation sound is generated so as to raise the sound pressure of the frequency component of the part. The solid line in FIG. 4 schematically shows the frequency spectrum (relationship between frequency and sound pressure) of the music (reproduced sound) reproduced by the audio device 12. This reproduced sound generates a sound having a frequency including the frequency region (about 100 to 1000 Hz) of the propagated noise from the door trim 6A. Then, as shown in FIG. 4, for example, when the sound pressure of the music reproduced by the audio device 12 is larger than the sound pressure of the road noise, the mitigated sound is in the frequency spectrum of the propagated noise as shown in FIG. It can be such that the sound pressure of the frequency component between peaks is increased. The relaxed sound is, for example, in the frequency spectrum of road noise, a frequency component (that is, about 160 Hz) between the frequency of the base sound in the propagated noise (here, about 160 Hz) and the frequency of its second harmonic (here, about 315 Hz). The sound can be produced to have an effect of increasing the sound pressure (~ 315 Hz) (hatching portion). Such a relaxation sound has an effect as if the space between the basic sound and the second harmonic of the transmitted noise is smoothly filled with white noise or various colored noises having a substantially constant sound pressure. This makes it possible to reduce the discomfort of noise.

Further, for example, when the sound pressure of the music reproduced by the audio device 12 is smaller than the sound pressure of the propagating noise as shown in FIG. 6, the mitigated sound is the frequency spectrum of the road noise as shown in FIG. In, the frequency component (that is, about 160 to 315 Hz) between the frequency of the base sound of the propagated noise (here, about 160 Hz) and the frequency of the second harmonic overtone (here, about 315 Hz) is included, and these base sounds are included. It can be a sound in which the sound pressure is increased (hatched portion) so as to fill the low sound pressure region formed in a valley shape between the second harmonics. In addition, the mitigation sound may be one that suppresses a rapid decrease in sound pressure in the high frequency side portion of the spectrum of propagated noise and compensates for the sound pressure to decrease smoothly in inverse proportion to the frequency. .. Such a relaxation sound has an effect as if the sound at the high frequency side end of the spectrum of the propagated noise is smoothly filled with colored noise such as Brownian noise. Such propagated noise and mitigation noise are reproduced from the door trim 6A in the vehicle interior as sounds having frequency components along the outer shape shown in FIG. 7. As a result, the dissonance between the noise and the reproduced sound can be eliminated, and the discomfort of the noise can be reduced.

The frequency of the propagating noise propagating from the door trim 6A is low, that is, the so-called bass, while the music (sound) reproduced by the audio device 12 is sufficiently high-pitched with respect to the road noise, as shown in FIG. Therefore, it is possible that the sound has a high frequency. Further, although not specifically shown, it is conceivable that the music (sound) reproduced by the audio device 12 does not include the sound corresponding to a wide frequency range, as shown in FIGS. 4 and 6. Furthermore, it is known that in the chord relationship of two different sounds, the fundamental tone and its overtones are in the best harmony to form a chord. Therefore, among the sounds constituting the music reproduced by the audio device 12, the frequency of the road noise (here, about 160 Hz) may be used as the fundamental tone, and the sound corresponding to at least one of the fundamental tone and its overtones may be used as the relaxation tone. For example, specifically, as shown in FIG. 9, a sound having a frequency (here, about 630 Hz) that is a harmonic overtone of the road noise among the reproduced sounds can be used as a relaxation sound. At this time, the vibration control unit 14 uses the sound of the frequency of noise (here, about 160 Hz) propagating in the vehicle interior through the door trim 6A as the basic sound among the sounds corresponding to the reproduced sound signal of the music to be reproduced, and is this basic sound. Alternatively, by extracting the frequency component of the sound that is the harmonic (here, the component of about 630 Hz), an electric signal corresponding to the relaxed sound can be generated, and this electric signal is output to the vibration generation unit 16 for reproduction. can do. If the relaxation sound is only harmonics (for example, only the sound having a frequency of 630 Hz), such a sound is artificial and gives a sense of discomfort to the human ear. Therefore, the relaxation sound is, for example, about the harmonic frequency ± 10 Hz. It may be a sound over a wide frequency range (see FIG. 9). The sound pressure of the relaxed sound in this case is not particularly limited, but is 0.5 times or more (for example, 0.7 times or more) and 1.5 times or less (for example, 0.7 times or more) the sound pressure of the base sound of the noise. It should be about 1.2 times or less). Such noise and mitigation sound are reproduced from the door trim 6A in the vehicle interior as a sound having a frequency component indicated by the outer shape of FIG. As a result, the noise and the reproduced sound form a consonant sound, and the discomfort of the noise is reduced.

It should be noted that such a relaxation sound can be easily created by the vibration control unit 14 using the audio device 12. That is, the audio device 12 has a function of extracting and processing a specific frequency component from the sound corresponding to the reproduced sound signal. Therefore, the vibration control unit 14 has a signal component of the same frequency F1 as the frequency F1 of the propagating noise propagating in the vehicle interior through the vehicle compartment constituent members, and a signal component of the harmonic frequency F2 which is an integral multiple of the frequency F1 of the propagating noise. It may be configured so that the relaxation sound including at least one of the frequency components of the above can be sent as an electric signal to the vibration generating unit 16 described later, and the relaxation sound can be generated from the vehicle chamber constituent member. Although not limited to this, the vibration control unit 14 of this example may be functionally realized by the control unit 12E described above controlling the operation of the processing unit 12B. .. In that case, the control unit 12E is configured to generate an electric signal corresponding to the relaxation sound in the vibration control unit 14 and send the electric signal corresponding to the generated relaxation sound to the vibration generation unit 16.

Such a relaxation sound harmonizes the music or the like reproduced by the audio device 12 with the road noise, and among the sounds of the reproduced music (that is, the sound corresponding to the reproduced sound signal), the sound corresponding to the reproduced sound signal is entered into the vehicle interior through the door trim 6A. It is a sound including a harmonic frequency F2 (here, about 630 Hz) of the frequency F1 (here, about 160 Hz) of the base sound of the propagating road noise. By reproducing such a relaxation sound from the door trim 6A, the propagating noise propagated through the door trim 6A and the music are harmonized by the action of the relaxation sound, and the discomfort of the noise perceived by the occupant is alleviated. At this time, the noise and the mitigation sound emitted from the door trim 6A follow the same path, in other words, are equally subjected to alteration actions such as reflection and attenuation, and are delivered to the ears of the occupant. As a result, it is also preferable in that the balance between noise and mitigation sound is kept equal at any position in the vehicle interior.

The above-mentioned effects of the present embodiment will be described. The noise reducing device 10 in the present embodiment reduces the discomfort of the occupant due to the noise entering the vehicle interior (vehicle compartment), and is music (reproduced sound) which is a sound based on the reproduced sound signal to the vehicle interior. ), An audio device 12 (sound reproduction unit), a vibration generating unit 16 provided on a plate-shaped door trim 6A (an example of a vehicle compartment component) that defines the vehicle interior, and a vibration generating unit 16 that vibrates the door trim 6A. A vibration control unit 14 (control unit) that generates a mitigating sound for alleviating noise from the door trim 6A by controlling the generation unit 16 to vibrate the door trim 6A is provided. When the audio device 12 is playing music, the vibration control unit 14 determines the sound pressure of a part of the frequency components of the propagating noise propagating in the vehicle interior through the door trim 6A, which overlaps with the frequency component of the music. It is equipped with a configuration that generates a relaxing sound so as to raise it. According to such a configuration, the noise propagated in the room through the door trim 6A is superposed with the relaxation sound generated from the door trim 6A by the vibration generating unit 16, and the road noise can be recreated into a sound familiar to the reproduced sound. Further, since the relaxation sound is emitted into the vehicle interior from the same door trim 6A as the road noise, it will follow the same route as the road noise before reaching the ears of the occupants. In other words, the relaxation sound and the road noise are affected by attenuation, reflection, amplification, etc. in exactly the same way while propagating in the vehicle interior after being emitted. As a result, the mitigated sound is not affected differently from the noise depending on the shape and size of the passenger compartment, the position and material of the equipment, etc., and the discomfort of the road noise is similarly reduced at any point in the passenger compartment. be able to.

Further, in the above embodiment, the vibration control unit 14 has a configuration for generating a relaxation sound so as to increase the sound pressure of the frequency component between peaks in the frequency spectrum of the propagated noise. The vibration control unit 14 preferably generates a relaxation sound so as to raise the sound pressure of the frequency component between the frequency of the fundamental tone in the propagated noise and the frequency of the second harmonic of the fundamental tone. In such a configuration, the sound pressure of the reproduced sound corresponding to the frequency range is divided between the sound of the frequency component having the highest sound pressure of the propagated noise and the sound of the frequency component having the second highest sound pressure. It is filled with a relaxed sound with a raised shape. The transmitted noise is changed so that the peak of the frequency is relatively broad. As a result, the characteristics of the timbre of the propagating noise are reduced, and the discomfort of the propagating noise can be reduced.

Further, in the above embodiment, the vibration control unit 14 has a configuration for generating a relaxation sound so as to raise the sound pressure of the harmonic frequency, which is an integral multiple of the frequency of the basic sound in the propagated noise, among the frequency components of the reproduced sound. ing. Natural sounds are composed of a combination of multiple overtones, and humans tend to find chords of the same scale, which differ by one octave, as "comfortable" because they are not accompanied by frequency shifts. According to the above configuration, the vehicle room constituent member such as the door trim 6A reproduces the sound having the same scale as the propagated noise among the sounds included in the reproduced sound in addition to the propagated noise. As a result, the propagated noise and the reproduced sound become a consonant sound and are reproduced in the vehicle room, so that the discomfort of the noise can be reduced.

<About other configurations>
The techniques disclosed herein are not limited to those disclosed in the above embodiments, and for example, the following aspects are also included in the technical scope disclosed herein. In addition, the techniques disclosed herein can be implemented in various modified embodiments without departing from their essence.

(1) In the noise reduction device 10 of the above embodiment, the vibration control unit 14 is functionally realized by the control unit 12E of the audio device 12 (sound reproduction unit) controlling the operation of the processing unit 12B. Or it was mechanically configured by a microprocessor. However, the configuration of the vibration control unit 14 is not limited to this, and may be mechanically realized by another structure such as a digital signal processor (DSP).
(2) In the above embodiment, a configuration is disclosed in which the door trim 6A as a vehicle compartment component reduces noise having a frequency of about 160 Hz based on vibration and noise generated by the installation of the tire 2B of the vehicle 1 traveling on land and the road surface. However, the techniques disclosed herein are not limited to such embodiments. For example, the noise reduction device 10 may have a configuration in which a vehicle room component other than the door trim 6A can be used as a sub-speaker to generate a mitigation sound, or two or more vehicle room components can be used as sub-speakers for each vehicle. It may be provided with a configuration capable of generating a relaxing sound suitable for the vehicle chamber constituent member from the chamber constituent member.

(3) In the noise reduction device 10, the vibration control unit 14 sets the noise frequency determined for each vehicle room component for each environmental condition such as road surface conditions, weather, traveling speed, and deterioration degree of the road surface grounding member. It may be checked in advance and stored as a frequency table or the like for each of these environmental conditions. Further, these environmental conditions may be complex environmental conditions in which the above elements are combined in various ways. At this time, it is possible to acquire a more appropriate noise frequency of the vehicle compartment constituent member according to the environmental conditions of the vehicle 1, and it is possible to more effectively reduce the discomfort of the noise.
(4) Further, the noise reduction device 10 may additionally include a vibration sensor for measuring the vibration frequency of the vehicle chamber constituent member. Then, the vibration control unit 14 measures the frequency characteristic of the noise based on the vibration of the vehicle chamber component in real time, and generates an electric signal corresponding to the mitigated sound that alleviates the discomfort of the noise based on the measurement result. The relaxation sound may be generated from the vehicle chamber constituent member by the vibration generating unit 16. As a result, it is possible to obtain a more appropriate noise frequency according to the environmental conditions of the vehicle 1 at any time for the vehicle compartment constituent members, and it is possible to more effectively reduce the discomfort of the noise.
(5) The vehicle exemplified in the above embodiment is a vehicle, but the noise reduction device 10 is not limited to the one provided for the vehicle, and may be provided in various vehicles. For example, the noise reduction device 10 can be applied to vehicles such as trains and amusement vehicles as ground vehicles, airplanes and helicopters as flight vehicles, ships and submersibles as marine and underwater vehicles.

1 ... Vehicle, 2 ... Wheel (road surface grounding member), 6 ... Vehicle door, 6A ... Door trim (Vehicle room component), 10 ... Noise reduction device, 12 ... Audio device, 14 ... Noise reduction unit, 16 ... Vibration generator

Claims (7)

It is a noise reduction device that reduces the discomfort of the occupants due to the noise that enters the vehicle room.
A sound reproduction unit that reproduces the reproduced sound, which is the sound based on the reproduced sound signal, to the vehicle room,
A vibration generating portion provided on a plate-shaped vehicle chamber component that defines the vehicle chamber and vibrates the vehicle chamber component, and a vibration generating portion.
A control unit that generates a mitigating sound for alleviating the noise from the vehicle chamber constituent member by controlling the vibration generating portion to vibrate the vehicle chamber constituent member.
Equipped with
The control unit is a part of the frequency component of the propagating noise propagating in the vehicle chamber through the vehicle chamber component, which overlaps with the frequency component of the reproduced sound when the sound reproduction unit reproduces the reproduced sound. A noise reduction device having a configuration for generating the relaxation sound so as to raise the sound pressure of the frequency component of the above. The noise mitigation device according to claim 1, wherein the control unit has a configuration for generating the mitigation sound so as to raise the sound pressure of a frequency component between peaks in the frequency spectrum of the propagating noise. The noise according to claim 2, wherein the control unit generates the relaxation sound so as to raise the sound pressure of the frequency component between the frequency of the fundamental tone in the propagating noise and the frequency of the second harmonic of the fundamental tone. Mitigation device. The first or second aspect of the present invention, wherein the control unit generates the relaxation sound so as to raise the sound pressure of the harmonic frequency which is an integral multiple of the frequency of the basic sound in the propagated noise among the frequency components of the reproduced sound. Noise reduction device. The vehicle compartment component is at least one selected from the group consisting of a door trim, a cowl side trim, an instrument panel, a deck side trim, a pillar garnish, a floor carpet, and a window glass, according to claims 1 to 4. The noise reduction device according to any one of the items. The vehicle provided with the vehicle chamber is a land-running vehicle, and includes a road surface grounding member.
The control unit pre-stores the frequency characteristics of the propagated noise for at least one element selected from the group consisting of road surface conditions, weather, traveling speed, and deterioration degree of the road surface grounding member. Item 5. The noise reduction device according to any one of Items 1 to 5. The control unit measures the frequency characteristic of the propagated noise in real time, and based on the measurement result, the vibration generation unit generates the relaxation sound from the vehicle chamber component member, according to any one of claims 1 to 6. The noise reduction device according to item 1.

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