JP2021015207A - Speaker system and vehicle - Google Patents

Abstract

To improve sound environment by suppressing a standing wave.SOLUTION: A speaker system comprises: a speaker 7 which is attached to a partition member 6 for partitioning a first room 2 and a second room 3 and whose sound emitting surface faces the first room 2; and a sound absorption structure 10A which is installed in the first room 2 or the second room 3 and absorbs sound of a standing wave generated in a space 9 obtained by combining the first room 2 and the second room 3.SELECTED DRAWING: Figure 1

Description

The present invention relates to a speaker system and a vehicle equipped with the speaker system.

In a vehicle having a passenger compartment and a trunk compartment in which a person rides, there is a vehicle in which a sound absorbing structure is arranged in the trunk compartment as described in Patent Document 1 for the purpose of reducing noise in the passenger compartment. The sound absorbing structure of Patent Document 1 reduces road noise generated from tires and standing waves in the trunk room.

Japanese Patent No. 5359167

One of the problems of the present invention is to improve the sound environment in the space where the two chambers are combined in the speaker system in which a chamber having a narrow volume is formed inside and the speaker is installed in the partition member that separates the two chambers. The speaker.

In order to solve the above-mentioned problems, the speaker system according to one aspect of the present disclosure is attached to a partition member that separates the first chamber and the second chamber, and has a speaker whose sound emitting surface faces the first chamber and the first chamber. It is provided in one room or the second room, and includes a sound absorbing structure that absorbs the sound of a standing wave generated in the space where the first room and the second room are combined.

It is a side view which shows the vehicle provided with the speaker system of one Embodiment of this disclosure. It is a top view which shows the arrangement of the speaker of the speaker system. It is a side view which shows the waveform of the primary standing wave in the case which the vehicle is not provided with a sound absorbing structure. It is a figure which shows the change of the sound pressure with respect to the frequency of each next standing wave in the rear end part of a trunk room in a vehicle. It is a figure which shows the change of the sound pressure with respect to the frequency of each next standing wave in the front seat in a vehicle. It is a top view which shows the arrangement example of the sound absorption structure which is composed of the tube sound absorption body of the speaker system of this embodiment. It is a perspective view which shows an example of the sound absorption structure which is composed of the tube sound absorption body of this embodiment. FIG. 7 is a cross-sectional view taken along the line EE of FIG. It is a figure which shows the sound pressure distribution of the primary standing wave in the vehicle interior before and after the sound absorption structure is provided in the vehicle of this embodiment. It is a side view which shows another example of arrangement of the sound absorption structure which is composed of a tube sound absorption body of FIG. It is a side view which further shows another example of the arrangement of the sound absorbing structure composed of the tube sound absorbing body of FIG. It is a perspective view which shows the sound absorption structure composed by the Helmholtz resonator used in this embodiment. It is a side view which shows the mounting example of the sound absorption structure shown in FIG. It is a top view which shows the mounting example of the sound absorption structure shown in FIG. It is a side view which shows another example of the arrangement of the sound absorbing structure composed of a Helmholtz resonator. It is a side view which further shows another example of arrangement of a sound absorbing structure composed of a Helmholtz resonator. It is sectional drawing which shows another example of the Helmholtz resonator used in this embodiment. It is sectional drawing which further shows another example of the Helmholtz resonator used in this embodiment. It is a side view which shows an example of the room to which the speaker system of this disclosure is applied together with the waveform of the primary standing wave. It is a figure which shows the distribution of the sound pressure of the primary standing wave in the room before and after the sound absorption structure is provided in the room shown in FIG.

Hereinafter, embodiments according to the present disclosure will be described with reference to the drawings. In the drawings, the dimensions and scale of each part are appropriately different from the actual ones. In addition, the embodiments described below are preferred specific examples of the present disclosure. For this reason, the present embodiment is provided with various technically preferable limitations. However, the scope of the present disclosure is not limited to these forms unless otherwise stated in the following description to limit the present disclosure.

1. 1. Embodiment FIG. 1 is a side view showing a vehicle provided with a speaker system according to an embodiment of the present disclosure. As shown in FIG. 1, the vehicle 1 has a vehicle compartment 2 which is a first chamber and a trunk chamber 3 which is a second chamber. The passenger compartment 2 is a space for accommodating people. A front seat 5a and a rear seat 5b are installed inside the passenger compartment 2. The passenger compartment 2 and the trunk compartment 3 are separated by a rear seat 5b and a rear tray 6 on the back surface thereof. That is, the rear seat 5b and the rear tray 6 serve as partition members for partitioning the vehicle interior 2 and the trunk compartment 3.

As shown in the plan views of FIGS. 1 and 2, a speaker 7 is attached to the rear tray 6 with its sound emitting surface facing the passenger compartment 2. The speaker 7 is a speaker for bass reproduction, and is called a woofer unit or a subwoofer unit. In the present disclosure, in addition to the speaker 7 for bass reproduction, the rear tray 6 may be equipped with either or both speakers for midrange reproduction and treble reproduction. Armrests 5c are provided between the left and right seats of the rear seats 5b.

As shown in FIG. 1, the trunk room 3 acts as a cabinet forming a space behind the speaker 7 by partitioning the vehicle interior 2 and the trunk room 3 by the rear seat 5b and the rear tray 6. Normally, the passenger compartment 2 and the trunk compartment 3 are independent spaces. Therefore, standing waves due to the size of the respective spaces are generated in each of the passenger compartment 2 and the trunk compartment 3. However, when the speaker 7 for bass reproduction having a larger diameter than the speaker for midrange reproduction or treble reproduction is arranged on the rear tray 6, the passenger compartment 2 and the trunk room are provided via the diaphragm of the speaker 7. 3 is acoustically connected. As a result, since the passenger compartment 2 and the trunk compartment 3 act as one space 9, a standing wave having the waveform shown by the alternate long and short dash line 11 in FIG. 3 is generated. The reproduction frequency band of the speaker 7 includes the frequency of the primary standing wave among the frequencies of the standing wave. The reproduction frequency band means the effective frequency range specified in the Japan Electronics and Information Technology Industries Association standard JEITA RC-8124C "speaker system".

The standing wave shown in FIG. 3 is generated in the space 9 from the front end portion 2a of the passenger compartment 2 to the rear end portion 3a of the trunk room 3. Among the standing waves generated in the space 9, the lowest frequency primary standing wave is a frequency whose wavelength is twice the length L in the front-rear direction of the space 9 in the case of a general vehicle. It becomes. This frequency is about 60 Hz when the length L of the space 9 is 2.83 m. The frequency of the primary standing wave is the fundamental frequency of the standing wave.

The standing wave inside the vehicle is not only a primary standing wave, but also a standing wave having a higher order, that is, an integral multiple of the primary frequency (basic frequency of 60 Hz). FIG. 4 is a diagram showing changes in sound pressure with respect to frequencies of primary, secondary, and tertiary standing waves at the rear end portion 3a of the trunk room 3. The sound pressure at the rear end 3a of the trunk room 3 becomes the highest not only in the primary standing wave (60 Hz) but also in the secondary standing wave (120 Hz) and the tertiary standing wave (180 Hz). Also in the front end portion 2a of the vehicle interior 2, the sound pressure due to the standing wave becomes the highest as in the rear end portion 3a of the trunk room 3.

FIG. 5 is a graph showing the sound pressure of a standing wave at point 5a1 (see FIGS. 1 and 3) of the front seat 5a. As shown in FIG. 5, at this point 5a1, the sound pressure changes depending on the frequency of the standing wave. Such a change in sound pressure due to a standing wave causes deterioration in the quality of the sound generated by the speaker 7. That is, due to the generation of the standing wave, the sound pressure of the sound generated by the speaker 7 becomes extremely high or low depending on the position in the vehicle interior 2. For example, at the point 5a1 in the passenger compartment 2, the frequency characteristic is unintentionally changed, resulting in deterioration of sound quality. In particular, the effect on changes in sound pressure due to the primary standing wave becomes large.

In order to suppress the standing wave, in the present embodiment, as shown in FIG. 1, the sound absorbing structure 10A is attached to the trunk room 3. As shown in the plan view of FIG. 6 and the perspective view of FIG. 7, the sound absorbing structure 10A of this example attached to the trunk room 3 is an assembly of tubular tube sound absorbing bodies 10a to 10i. As shown in the cross-sectional view of FIG. 8, these tube sound absorbing bodies 10a to 10i are closed tubes in which one end of a tubular portion is a closed end portion 10x and the other end is an open end portion 10y. As shown in FIG. 6, the sound absorbing structure 10 is attached with the open end portion 10y of the pipe sound absorbing bodies 10a to 10i facing the rear end portion 3a of the trunk chamber 3. At the rear end 3a of the trunk room 3, the sound pressure of the standing wave becomes the highest. By mounting the open end 10y toward the rear end 3a, standing waves can be effectively suppressed. When the tube sound absorbing bodies 10a to 10i are composed of closed tubes as in this example, the tube sound absorbing bodies 10a to 10i resonate at the frequency of the odd-order standing wave, so that the odd-order standing wave can be efficiently suppressed. ..

In the sound absorbing structure 10A composed of the tube sound absorbing bodies 10a to 10i, the length A of the inner space shown in FIG. 8 has a wavelength λ (≈2L) at the frequency f1 (60Hz) of the primary standing wave in the space 9. The length is set as shown in Eq. (1) so as to resonate with the standing wave.

The resonance frequency f0 of the sound absorbing structure 10A composed of the tube sound absorbing bodies 10a to 10i is substantially equal to the frequency f1 of the primary standing wave. In this way, by setting the resonance frequency and locating the opening end portion 10y of the sound absorbing structure 10A near the rear end portion 3a of the trunk room 3, the sound of the standing wave is absorbed by the sound absorbing structure 10A. Therefore, as shown in FIG. 9, by installing the sound absorbing structure 10A, the sound pressure decreases at the end portion of the space 9 and increases at the central portion. Specifically, the sound pressure at the center increases by about 2 dB. That is, by suppressing the standing wave, the change in sound pressure is flattened before and after the position in the vehicle in the space 9. As a result, the sound environment is improved, and the sound quality reproduced by the speaker 7 is improved.

Since the standing wave is suppressed by installing the sound absorbing structure 10A in the trunk room 3, the influence of the standing wave of the sound in the low frequency range such as audio reproduced by the speaker 7 in the passenger compartment 2 where a person rides. Is reduced. As a result, the sound environment is improved, and the sound quality reproduced by the speaker 7 is improved.

Here, it is preferable that the fundamental frequency of the standing wave, that is, the frequency f1 of the primary standing wave is as close as possible to the resonance frequency f0 of the sound absorbing structure 10A. Specifically, if the frequency f1 of the primary standing wave is within the range of 90% to 110% of the resonance frequency f0 of the sound absorbing structure 10, a relatively good effect of suppressing the standing wave can be obtained.

As shown in FIGS. 1 and 6, the sound absorbing structure 10A is attached to the bottom surface of the trunk room 3 so as to be fixed to the trunk room 3 with a flat structure as shown in the illustrated example. As a result, the sound absorbing structure 10A can be easily attached.

FIG. 10 shows another mounting example of the sound absorbing structure 10B in the vehicle of the present embodiment. In the mounting example of the sound absorbing structure 10B, the sound absorbing structure 10B is arranged at a position corresponding to the rear end of the vehicle 1 inside the trunk room 3. The pipe sound absorbing body constituting the sound absorbing structure 10B is directed vertically, and the opening end portion 10y thereof is attached to the rear end portion 3a of the trunk room 3 at a position facing the bottom surface of the trunk room 3.

As described above, if the sound absorbing structure 10B is attached to the inside of the trunk room 3 at a position corresponding to the rear end of the vehicle 1, the sound absorbing structure 10B is not required to have high rigidity as compared with the case where the sound absorbing structure 10B is provided on the bottom surface of the trunk room 3. There is an advantage.

FIG. 11 further shows another mounting example of the sound absorbing structure 10C in the vehicle of the present embodiment. In this example, the sound absorbing structure 10C composed of the pipe sound absorbing body has its open end 10y located at the front end 2a of the passenger compartment 2, and at least a part thereof is in front of the front seat 5a which is the driver's seat. It is installed so that it is located in. More specifically, the sound absorbing structure 10C is provided from the bottom surface to the front surface of the passenger seat 2 in the front portion. The sound absorbing structure 10C may be attached to a dashboard provided at the front end of the vehicle interior 2. Further, the sound absorbing structures 10A to 10C composed of the pipe sound absorbing bodies may have a structure in which the pipes are curved in order to secure the required pipe length.

In the above example, the sound absorbing structures 10A, 10B, and 10C are attached individually, but two or more of the sound absorbing structures 10A, 10B, and 10C may be attached in combination.

Even when the sound absorbing structure 10C is provided in the vehicle interior 2, standing waves can be suppressed and the sound quality in the low frequency range is improved.

In the present disclosure, as the sound absorbing structure, not only a tube sound absorbing body but also a Helmholtz resonator 14A as shown in FIG. 12 can be used. The Helmholtz resonator 14A of FIG. 12 has a rectangular flat plate-shaped sound absorbing structure formed by combining plate materials.

That is, in this Helmholtz resonator 14A, one side side of the Helmholtz resonator 14A having a rectangular shape in order to communicate one or more (three in the illustrated example) resonance air chambers 14a with each resonance air chamber 14a and the outside air. It has a neck 14b as a communication portion for communicating the outside air and the resonance air chamber 14a, respectively. Here, for convenience of explanation, the resonance air chamber 14a side is the rear part and the neck 14b side is the front part. The resonance air chamber 14a includes a bottom plate 15a, an upper plate 15b, a rear plate 15c that closes the rear ends of the bottom plate 15a and the upper plate 15b, and left and right side plates 15d and 15e that close the left and right side surfaces of the bottom plate 15a and the upper plate 15b. And a partition plate 15f provided at the center of the bottom plate 15a and the top plate 15b in the front-rear direction. The neck 14b is formed by a partition plate 15g and 15h provided between the bottom plate 15a, the top plate 15b, and the bottom plate 15a and the top plate 15b in the front-rear direction.

The resonance frequency f0 of the sound absorbing structure composed of the Helmholtz resonator 14A can be expressed by Eq. (2). In equation (2), c is the speed of sound, s is the opening area of the neck 14b, V is the volume of the resonance air chamber 14a, l is the length of the neck 14b, and δ is the correction value of the opening end of the neck 14b.

As shown in FIGS. 13 and 14, the sound absorbing structure composed of the Helmholtz resonator 14A is located in the trunk chamber with a ventilation interval between the neck 14b and the rear end portion 3a of the trunk chamber 3. It is attached to the bottom of 3. The Helmholtz resonator 14A can be configured more compactly than the sound absorbing structures 10A to 10C composed of the tube sound absorbing body. Therefore, the arrangement of the sound absorbing structure becomes easy.

As shown in FIG. 15, the Helmholtz resonator 14B may be attached to the rear end portion 3a side in the trunk chamber 3. Further, the Helmholtz resonator 14B may be provided from the trunk chamber 3 along the rear end portion 3a of the trunk chamber 3. In this case, the Helmholtz resonator 14B positions at least the neck 14b at the rear end 3a of the trunk chamber 3. Further, as shown in FIG. 16, the Helmholtz resonator 14C may be mounted in front of the driver's seat, which is the front seat 5a. In this case, the neck of the Helmholtz resonator 14B may be attached sideways so that the open end thereof is located at the front end portion 2a of the vehicle interior 2.

In the above example, the Helmholtz resonators 14A, 14B, and 14C are attached individually, but two or more of them may be attached in combination.

FIG. 17 shows another example of a Helmholtz resonator. The Helmholtz resonator 14D includes a neck 14b that communicates the resonance air chamber 14a and the resonance air chamber 14a, which are formed in a rectangular box shape, with the outside air. The neck 14b is composed of a through hole 14e provided in the front plate 14d formed to have a thickness.

FIG. 18 further shows another example of a Helmholtz resonator. The Helmholtz resonator 14E is composed of a tubular portion 14g provided on the front plate 14d with a neck 14b for communicating the resonance air chamber 14a formed in a rectangular box shape with the outside air.

The Helmholtz resonator 14E also includes one or more resonant air chambers 14ax on the side surface of the Helmholtz resonator 14E. Each resonant air chamber 14ax includes a neck 14bx that allows outside air to communicate with each resonant air chamber 14ax on the side of the Helmholtz resonator 14E, that is, in a direction orthogonal to the neck 14b. The resonance air chamber 14ax is provided for the purpose of suppressing a standing wave or the like having a frequency other than the standing wave generated in the space 9 of the vehicle 1. For example, the resonance air chamber 14ax is provided in the trunk room 3 or the vehicle compartment 2 in order to exert a function of suppressing standing waves generated only in the trunk room 3 or the vehicle compartment 2 and road noise generated in the tires. Be done.

As shown in FIG. 18, the Helmholtz resonator 14E is provided with a function of suppressing not only the standing wave of the space 9 including the passenger compartment 2 and the trunk room 3 but also other standing waves and noise. Further, the sound environment of the passenger compartment 2 can be improved.

2. 2. Modified Example FIG. 19 is a side view showing an example of a room to which the speaker system of the present disclosure is applied, together with a waveform of a primary standing wave. The room 20 includes a floor portion 21, a ceiling portion 22, front and rear wall portions 23 and 24 including fittings such as doors between the floor portion 21 and the ceiling portion 22, and side wall portions (not shown). Is configured as a small space. The partition member 25 is provided between the front and rear wall portions 23 and 24. The partition member 25 divides the room 20 into a first room 26 and a second room 27. A speaker 7 for reproducing a low frequency range is attached to the partition member 25 with its sound emitting surface facing the first chamber 26 side.

The room 20 is configured as, for example, a karaoke room, a living room, or the like. In this case as well, the speaker 7 acts to acoustically connect the first room 26 and the second room 27 as in the case of the vehicle 1. .. Then, with the first chamber 26 and the second chamber 27 as one space, a standing wave having a waveform as shown by the alternate long and short dash line 28 is generated.

FIG. 20 shows changes in the sound pressure distribution before and after installing the sound absorbing structure that suppresses the primary standing wave in the second room 27 of the room 20 shown in FIG. As shown in FIG. 20, by installing a sound absorbing structure that generates the first chamber 26 and the second chamber 27 as one space, standing waves can be suppressed and the sound quality in the bass range can be improved. Can be done. The sound absorbing structure may be installed in the first chamber 26. Further, as the sound absorbing structure, the above-mentioned tube sound absorbing body, Helmholtz resonator, or the like can be used. The room 20 having this sound absorbing structure is more preferably effective in a relatively narrow room of about 8 tatami mats or less where a standing wave in a low frequency range of 150 Hz or less is a problem, but is a room larger than this. May be adopted for. The first room 26 may be a living room and the second room 27 may be, for example, a walk-in closet.

It should be noted that the above-described examples merely show a typical form of the present disclosure, and the present disclosure is not limited to the above-mentioned examples, and various types are provided without departing from the gist of the present disclosure. It can be changed and added.

3. 3. Aspects grasped from at least one of the embodiments and each modification The following aspects are grasped from at least one of the above-described embodiment and each modification.

One aspect of the speaker system described above is attached to a partition member that separates the first chamber and the second chamber, and is provided in the first chamber or the second chamber with a speaker whose sound emitting surface faces the first chamber. A sound absorbing structure that absorbs the sound of a standing wave generated in the space where the first chamber and the second chamber are combined is provided. By providing the sound absorbing structure in the first room or the second room, the standing wave is suppressed, so that the sound environment in a small space such as a vehicle interior can be improved.

In one aspect of the speaker system described above, the reproducible band of the speaker includes the frequency of the primary standing wave generated in the space. In this case, the sound environment in a small space such as a vehicle interior can be satisfactorily improved by suppressing the primary standing wave, which has a particularly large influence on the reproduced sound.

In one aspect of the speaker system described above, the fundamental frequency of the standing wave is preferably in the range of 90% to 110% of the resonance frequency of the sound absorbing structure. In this case, since the resonance frequency of the sound absorbing structure is within the range of 90% to 110%, the standing wave is well suppressed.

In one aspect of the speaker system described above, the partition member is provided between the end of the first chamber and the end of the second chamber, and the fundamental frequency of the standing wave is the same as that of the first chamber. It is preferable that the frequency is one wavelength, which is twice the length from the end to the end of the second chamber. In this case, the standing wave of the resonance frequency is suppressed, so that the sound quality in the low frequency range is improved.

In one aspect of the speaker system described above, the speaker system for a vehicle is configured by the first room being a vehicle compartment and the second room being a trunk room. In this case, by suppressing the standing wave, the sound pressure distribution in the bass range such as audio in the vehicle interior is homogenized, and as a result, the sound quality is improved.

In one aspect of the speaker system described above, the sound absorbing structure is attached to the rear end of the vehicle in the trunk room to form the speaker system. In this case, since the sound absorbing structure is attached to the trunk room, it is easier to secure the mounting space as compared with the case of mounting the sound absorbing structure in the passenger compartment.

In one aspect of the speaker system described above, the sound absorbing structure is attached to the bottom surface in the trunk room to form the speaker system. In this case, since the sound absorbing structure is attached to the bottom surface of the trunk room, it can be easily attached as compared with the case where it is attached to the side surface.

In one aspect of the speaker system described above, the speaker system is configured by at least a part of the sound absorbing structure being attached to the front of the driver's seat in the passenger compartment. In this case as well, by suppressing the standing wave, the sound pressure distribution in the low frequency range such as audio in the vehicle interior is homogenized, and the sound quality is improved.

In one aspect of the speaker system described above, the sound absorbing structure is a tubular tube sound absorbing body having a closed portion closed at one end and an opening opened at the other end, or a hollow chamber and the chamber and the outside. A speaker system is configured with a Helmholtz resonator having an communicating part. In this case, by providing a tube sound absorber or a Helmholtz resonator as a sound absorbing structure, standing waves can be suppressed well.

In order to solve the above-mentioned problems, the vehicle according to one aspect of the speaker system comprises the above-mentioned speaker system for a vehicle. As described above, by providing the vehicle with the speaker system having the above-mentioned sound absorbing structure, it is possible to provide a vehicle in which the standing wave in the vehicle internal space is reduced and the sound quality reproduced by the speaker is improved.

1 ... Vehicle, 2 ... Car room, 3 ... Trunk room, 5a ... Front seat, 5b ... Rear seat, 6 ... Rear tray, 7 ... Speaker, 9 ... Space, 10A-10C ... Sound absorbing structure (tube sound absorbing body), 11, 12 ... Primary standing wave waveform, 14A-14E ... Sound absorbing structure (Helmholtz resonator), 20 ... Room, 21 ... Floor, 22 ... Ceiling, 23, 24 ... Wall, 25 ... Partition member, 26 ... 1st room, 27 ... 2nd room, 28, 29 ... Standing wave waveform, 30 ... Sound absorbing structure.

Claims (10)

A speaker attached to a partition member that separates the first room and the second room, and the sound emitting surface faces the first room.
A sound absorbing structure provided in the first chamber or the second chamber and absorbing the sound of a standing wave generated in the space where the first chamber and the second chamber are combined.
Speaker system with. The speaker system according to claim 1, wherein the reproduction frequency band of the speaker includes the frequency of a primary standing wave generated in the space. The speaker system according to claim 1 or 2, wherein the fundamental frequency of the standing wave is in the range of 90% to 110% of the resonance frequency of the sound absorbing structure. The partition member is provided between the end of the first chamber and the end of the second chamber.
The fundamental frequency of the standing wave is a frequency whose wavelength is twice the length from the end of the first chamber to the end of the second chamber, according to claims 1 to 3. The speaker system according to any one item. The speaker system according to any one of claims 1 to 4, wherein the first room is a vehicle compartment and the second room is a trunk room. The speaker system according to claim 5, wherein the sound absorbing structure is attached to a rear end of a vehicle in the trunk room. The speaker system according to claim 5, wherein the sound absorbing structure is attached to a bottom surface in the trunk room. The speaker system according to claim 5, wherein at least a part of the sound absorbing structure is mounted in front of the driver's seat in the passenger compartment. The sound absorbing structure is
1 to claim 1 comprising a tubular tube sound absorber having a closed portion with one end closed and an opening with an open end, or a Helmholtz resonator having a hollow chamber and a communicating portion that communicates the chamber with the outside. The speaker system according to any one of up to 4. A vehicle provided with the speaker system according to any one of claims 5 to 9.

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