JP7229679B2 - Speaker system and signal processing method - Google Patents

Description

The present disclosure relates to a speaker system capable of spot reproduction that allows only users located in a specific area to hear reproduced sounds.

2. Description of the Related Art There is known a speaker system that outputs a loud sound only in a specific direction by performing signal processing on a signal to be reproduced and reproducing it with a speaker array (see, for example, Patent Documents 1 and 2 and Non-Patent Document 1). Such speaker systems can provide sound only to those who need it. For example, in a space inside an automobile, sounds can be provided only to users seated in specific seats. Within a dwelling, sound can be provided only to specific locations. Alternatively, separate sounds can be provided at two locations within the same space.

JP 2008-252189 A JP 2015-231087 A

Yasushi Matsumoto, Kiyoshi Nishikawa, “Method for designing directional array loudspeaker with constant sidelobe amount” IEICE Technical Report 2004-74, pp.13-18

By the way, in the speaker system as described above, it is desirable to be able to control the directivity of signals in a wide frequency band.

The present disclosure provides a speaker system and signal processing method capable of directivity control for signals in a wide frequency band.

A speaker system according to the present disclosure includes a speaker array configured by a plurality of linearly arranged first speakers each receiving a first signal that has undergone first filtering and amplification processing; A first filter array that performs processing and a multi-channel amplifier that performs the amplification processing are provided, and the speaker array is arranged in a reproduction space having a wall surface that intersects the direction in which the plurality of first speakers are arranged. A peak in the arrangement direction of the directivity of the output reproduced sound corresponding to the first signal is shifted toward the wall surface side by the first filtering process.

According to the present disclosure, a speaker system and a signal processing method capable of directivity control for signals in a wide frequency band are realized.

FIG. 1 is a top view showing the interior of an automobile in which a speaker system according to Embodiment 1 is arranged. FIG. 2 is an enlarged view of area II of FIG. FIG. 3 is a side view showing the interior of an automobile in which the speaker system according to Embodiment 1 is arranged. FIG. 4 is a side view showing the interior of an automobile in which the speaker array according to Embodiment 1 is arranged on the dashboard. 5 is a block diagram showing the functional configuration of the speaker system according to Embodiment 1. FIG. FIG. 6 is a diagram showing the directivity of reproduced sound output from the speaker array according to the first embodiment. FIG. 7 is a diagram showing directivity of a speaker array according to a comparative example. FIG. 8 is a diagram showing the relationship between the length L of the speaker array and the effective distance according to the comparative example. FIG. 9 is a diagram for explaining the directivity of the speaker array according to Embodiment 1. FIG. 10 is a block diagram showing a functional configuration of a speaker system according to Embodiment 2. FIG. FIG. 11 is a diagram showing the directivity of reproduced sound output from the speaker array in the second embodiment. 12 is a block diagram showing a functional configuration of a speaker system according to a modification of Embodiment 2. FIG. 13 is a block diagram showing a functional configuration of a speaker system according to Embodiment 3. FIG. FIG. 14 is a diagram showing the directivity of reproduced sound output from the speaker array in the third embodiment. FIG. 15 is a diagram showing an application example of the speaker system according to the third embodiment.

A speaker system according to an aspect of the present disclosure includes a speaker array configured by a plurality of linearly arranged first speakers each receiving a first signal that has undergone first filtering and amplification processing; A first filter array that performs the first filtering process, and a multi-channel amplifier that performs the amplification process, wherein the speaker array is arranged in a reproduction space having a wall surface that intersects the direction in which the plurality of first speakers are arranged, A peak in the alignment direction of the directivity of the reproduced sound corresponding to the first signal output from the speaker array is shifted toward the wall surface side due to the first filter processing.

Thereby, the speaker system can lower the lower limit frequency of the frequency band in which the directivity can be controlled. In other words, a speaker system capable of directivity control for signals in a relatively wide frequency band is realized.

Also, for example, the peak is located on the wall surface.

As a result, in the speaker system, the lower limit frequency of the frequency band in which the directivity can be controlled can be reduced to half that of the speaker system according to the comparative example having the speaker array of the same length shown in FIG. 7 described later. can. In other words, a speaker system capable of directivity control for signals in a relatively wide frequency band is realized.

Further, for example, the plurality of first speakers are arranged at equal intervals with an interval D, and the interval between the first speaker positioned at the end of the plurality of first speakers on the wall surface side and the wall surface is D/ 2.

This makes it easy to locate the directivity peak of the reproduced sound corresponding to the first signal on the wall surface.

Further, for example, the first signal is a low frequency component of a signal to be reproduced, and the speaker system further converts the signal to be reproduced into the first signal and a high frequency component of the signal to be reproduced. a second filter array that performs a second filtering process on the second signal; and a third signal that is the first signal after the first filtering process. an addition unit that performs addition processing of a fourth signal that is the second signal after filter processing, and the multi-channel amplifier performs the amplification processing on the third signal that has been subjected to the addition processing; The third signal that has been subjected to the addition process and the amplification process is input to each of at least a portion of the first speakers of the second speaker, and output from at least a portion of the plurality of first speakers. A peak in the alignment direction of the directivity of the reproduced sound corresponding to the signal is positioned at the center of the speaker array by the second filtering process.

As a result, the user hears the reproduced sound as if it is coming from the front. In other words, it is possible to prevent the user from feeling discomfort in how the reproduced sound is heard.

Further, for example, the third signal subjected to the addition processing and the amplification processing is input to each of a portion of the plurality of first speakers, and each of the other portions of the plurality of first speakers is input with the third signal that has undergone only the amplification process out of the addition process and the amplification process.

As a result, the speaker system outputs low tones corresponding to the first signal and high tones corresponding to the second signal from some of the plurality of first speakers, and outputs low tones corresponding to the second signal from the other portion of the plurality of first speakers. A low-pitched sound corresponding to one signal can be output.

Further, for example, another part of the plurality of first speakers are located at both ends of the speaker array in the arrangement direction.

As a result, only low-pitched sounds corresponding to the first signal are output from the first speakers positioned at both ends, and high-pitched sounds corresponding to the second signal are not output. Therefore, it is possible to make it difficult for other users to hear the high-pitched sound component of the reproduced sound output by the speaker array.

Also, for example, each of the plurality of first speakers receives the third signal that has been subjected to the addition processing and the amplification processing.

Thereby, the speaker system can output low-pitched sound corresponding to the first signal and high-pitched sound corresponding to the second signal from each of the plurality of first speakers.

Further, for example, the speaker array further includes a plurality of second speakers arranged linearly, and each of the plurality of second speakers is amplified by the multi-channel amplifier. four signals are input, at least a portion of the plurality of first speakers and the plurality of second speakers are alternately arranged, and at least a portion of the plurality of first speakers and the plurality of second speakers are arranged alternately; The peak in the alignment direction of the directivity of the reproduced sound corresponding to the second signal output from is positioned at the center of the speaker array by the second filtering process.

Thereby, the speaker system can raise the upper limit frequency of the frequency band in which the directivity can be controlled. In other words, a speaker system capable of directivity control for signals in a relatively wide frequency band is realized.

Further, for example, the plurality of first speakers are arranged at an equal interval D, and the plurality of second speakers are arranged at an equal interval D.

As a result, if the speakers are arranged at the interval D/2 with respect to the second signal (high-pitched sound component), the speaker system can control the directivity more than when the speakers are arranged at the interval D. The upper frequency limit of the band can be raised. In other words, a speaker system capable of directivity control for signals in a relatively wide frequency band is realized.

Further, for example, the speaker array is arranged on the ceiling of an automobile.

As a result, the distance from a user seated on a specific seat to the speaker array is much shorter than the distance from a user seated on a seat other than the specific seat to the speaker array. Therefore, the sound pressure difference caused by distance attenuation can be widened, and the reproduced sound output by the speaker array can be made difficult for users seated in other seats to hear.

Also, for example, the speaker array is arranged on the dashboard of an automobile.

As a result, the speaker array can be placed directly in front of the user seated in the driver's seat or the passenger's seat, so that the user can hear the reproduced sound from the front, thereby obtaining a natural sense of hearing.

These general or specific aspects may be realized by an apparatus, method, integrated circuit, computer program, or recording medium such as a computer-readable CD-ROM. and any combination of recording media.

For example, a signal processing method according to an aspect of the present disclosure is a signal processing method executed by a speaker system, wherein each of the speaker systems receives a first signal that has been subjected to first filtering and amplification processing. a speaker array composed of a plurality of first speakers arranged linearly, a first filter array that performs the first filtering process, and a multi-channel amplifier that performs the amplification process, wherein the speaker array includes The signal processing method is arranged in a reproduction space having a wall surface that intersects the direction in which the plurality of first speakers are arranged, and the signal processing method includes: A peak in the direction is moved toward the wall surface by the first filtering process.

Thereby, the signal processing method can lower the lower limit frequency of the frequency band in which the directivity can be controlled. In other words, a signal processing method capable of directivity control for signals in a relatively wide frequency band is realized.

Hereinafter, embodiments will be described with reference to the drawings. All of the embodiments described below are generic or specific examples. Numerical values, shapes, materials, components, arrangement positions and connection forms of components, steps, order of steps, and the like shown in the following embodiments are examples, and are not intended to limit the present disclosure. In addition, among the constituent elements in the following embodiments, constituent elements that are not described in independent claims representing the highest concept will be described as arbitrary constituent elements.

Each figure is a schematic diagram and is not necessarily strictly illustrated. Moreover, in each figure, the same code|symbol is attached|subjected with respect to substantially the same structure, and the overlapping description may be abbreviate|omitted or simplified.

(Embodiment 1)
[Speaker system configuration]
A speaker system according to Embodiment 1 will be described below with reference to the drawings. In Embodiment 1, an example in which a speaker system is arranged inside an automobile will be described. FIG. 1 is a top view showing the interior of an automobile in which a speaker system is arranged. FIG. 2 is an enlarged view of area II of FIG. FIG. 3 is a side view showing the interior of an automobile in which the speaker system is arranged.

The speaker system 100 shown in FIGS. 1 to 3 is used for spot reproduction that allows only users located in a specific area to hear the reproduced sound by outputting the reproduced sound with directivity. In Embodiment 1, speaker system 100 is arranged inside automobile 200 and gives directivity to the reproduced sound so that only a user sitting in driver's seat 230 can hear the reproduced sound. The speaker system 100 includes a speaker array 10 composed of a plurality of linearly arranged first speakers 10a. The number of first speakers 10a is not particularly limited.

As shown in FIG. 2, the plurality of first speakers 10a are arranged at equal intervals, for example, at intervals D. As shown in FIG. The distance between the wall surface 220a and the first speaker 10a positioned at the end on the wall surface 220a side among the plurality of first speakers 10a is D/2. The interval between the first speakers 10a means the distance between the sound output axes (center axes) of the first speakers 10a. The distance between the first speaker 10a and the wall surface 220a means the distance between the sound output axis of the first speaker 10a and the wall surface 220a.

Speaker array 10 is arranged in the interior space of automobile 200 . The interior space of automobile 200 is a closed space surrounded by ceiling 210 and side walls 220 including window glass and the like. The side wall 220 has a wall surface 220a that faces the user seated in the driver's seat 230 .

Specifically, the speaker array 10 is arranged on the ceiling portion 210 inside the automobile 200 . The speaker array 10 is arranged in front of the user seated in the driver's seat 230 of the automobile 200 so as to face the user, and outputs reproduced sound toward the user. The speaker array 10 is arranged such that the longitudinal direction of the speaker array 10, that is, the direction in which the plurality of first speakers 10a are arranged, is along the left-right direction of the user.

If the speaker array 10 is arranged on the ceiling portion 210 in this way, the distance from the user seated in the driver's seat 230 to the speaker array 10 is the same as the distance from the user seated in the front passenger seat or the rear seat to the speaker array 10. very close in comparison. Therefore, the sound pressure difference caused by distance attenuation can be widened, and the reproduced sound output by the speaker array 10 can be made difficult for a user seated in a seat other than the driver's seat 230 to hear.

Note that the speaker array 10 may be arranged on the dashboard 240 of the automobile 200, as shown in FIG. FIG. 4 is a side view showing the interior of automobile 200 in which speaker array 10 is arranged on dashboard 240. As shown in FIG. Also in this case, the speaker array 10 is arranged in front of the user seated in the driver's seat 230 of the automobile 200 so as to face the user, and outputs the reproduced sound toward the user. The speaker array 10 is arranged such that the longitudinal direction of the speaker array 10 is aligned with the left-right direction of the user.

If the speaker array 10 is arranged on the dashboard 240, the speaker array 10 can be arranged directly in front of the user sitting in the driver's seat, so that the user can hear the reproduced sound from the front and obtain a natural sense of hearing. can.

[Function configuration of speaker system]
Next, the functional configuration of the speaker system 100 will be described. FIG. 5 is a block diagram showing the functional configuration of the speaker system 100. As shown in FIG.

As shown in FIG. 5, the speaker system 100 includes a speaker array 10, a first filter array 21, and a multichannel amplifier 30. FIG.

The first filter array 21 performs first filtering. Specifically, the first filter array 21 is configured by a plurality of first filters 21a. The multiple first filters 21a correspond to the multiple first speakers 10a on a one-to-one basis. The first filter array 21 is, for example, a two-dimensional digital filter, and each of the plurality of first filters 21a is realized by, for example, a one-dimensional digital filter (a filter circuit that performs digital signal processing).

Each of the plurality of first filters 21a acquires a signal to be reproduced, and performs first filter processing on the acquired signal to be reproduced. In Embodiment 1, the signal to be reproduced is an example of the first signal. The specific processing content of the first filter processing differs, for example, for each first filter 21a. Each of the plurality of first speakers 10a outputs a sound based on the signal to be reproduced that has been subjected to the first filtering process, so that the reproduced sound output from the speaker array 10 is as shown in FIG. directivity is given. FIG. 6 is a diagram showing the directivity of reproduced sound output from the speaker array 10. As shown in FIG. In other words, the reproduced sound output from the speaker array 10 is the reproduced sound output from the speaker when the entirety of the plurality of first speakers 10a is regarded as one speaker.

As shown in FIG. 6, the directivity of the reproduced sound output from the speaker array 10 decreases as the distance from the wall surface 220a increases. The peak of the directivity of the reproduced sound in the arrangement direction of the plurality of first speakers 10a is closer to the wall surface 220a side than the central portion due to the first filtering process. The portion with low directivity is formed by, for example, canceling out sounds output from each of the plurality of first speakers 10a by the first filtering process. Effects obtained by such directivity of reproduced sound will be described later.

The multi-channel amplifier 30 performs amplification processing. The multi-channel amplifier 30 is specifically composed of a plurality of amplifiers 30a. The plurality of amplifiers 30a correspond to the plurality of first speakers 10a and the plurality of first filters 21a on a one-to-one basis. Each of the plurality of amplifiers 30a amplifies the output signal of the corresponding first filter 21a and outputs it to the corresponding first speaker 10a. Each of the plurality of amplifiers 30a is implemented by, for example, an operational amplifier.

In this way, a signal to be reproduced that has been subjected to the first filter processing and the amplification processing is input to each of the plurality of first speakers 10a. The speaker array 10 is configured by arranging such a plurality of first speakers 10a in a straight line. The speaker array 10 outputs a reproduced sound corresponding to the signal to be reproduced.

[Effect obtained by the directivity of the speaker array]
Next, the effect obtained by the directivity realized by the first filtering process (hereinafter also referred to as the directivity of the speaker array 10) as shown in FIG. 6 will be described with reference to a comparative example. FIG. 7 is a diagram showing directivity of a speaker array according to a comparative example.

The directivity peak of the speaker array 90 according to the comparative example is located at the central portion in the direction in which the plurality of speakers forming the speaker array 90 are arranged. The directivity of the speaker array 90 according to the comparative example becomes lower toward the ends in the direction in which the plurality of speakers forming the speaker array 90 are arranged. As a result, only a user seated in a specific seat (for example, the driver's seat) can hear loud sounds from the speaker array 90 inside the vehicle. A specific technique for forming such directivity is disclosed in Non-Patent Document 1, for example. In Non-Patent Document 1, a spatial window is designed in the spatial domain (or spatial frequency domain) for each temporal frequency in the frequency domain, and the higher the temporal frequency, the narrower the window width of the spatial window (the wider the passband in the spatial frequency domain ) is disclosed.

However, the directivity of the speaker array 90 according to the comparative example is based on the assumption that there is no sound reflection in the space where the speaker array 90 is arranged. When the speaker array 90 according to the comparative example is arranged in a space having the wall surface 220a, there is a problem that the sound field is disturbed by the sound reflected from the wall surface 220a, and desired directivity cannot be obtained.

Another problem is that when the length of the speaker array 90 is restricted, the lower limit frequency of the frequency band in which the directivity can be controlled (hereinafter also referred to as the control band) is limited. . This is because the lower limit frequency of the control band is inversely proportional to the length L of the speaker array 90 in the longitudinal direction. FIG. 8 is a diagram showing the relationship between the length L of the speaker array 90 and the effective distance.

In FIG. 8, the effective distance is a parameter indicating that the longer the effective distance, the easier the directivity control. As shown in FIG. 8, if the frequency is the same, the longer the length L of the speaker array 90, the easier the directivity control, and the lower limit frequency of the control band can be lowered. In a narrow space such as a space inside a vehicle, the length of the speaker array 90 is restricted, so the lower limit frequency of the control band is restricted.

Here, as shown in FIG. 9, the first filtering process for realizing the directivity of the speaker array 10 includes the virtual speaker array 10v of length L with the wall surface 220a as the plane of symmetry. The speaker array is designed to have directivity with a peak located in the central portion (on the wall surface 220a) as shown in FIG. FIG. 9 is a diagram for explaining the directivity of the speaker array 10. FIG.

Specifically, regarding the directivity of the speaker array 10, considering the reflection of the reproduced sound on the wall surface 220a, the sound output from the virtual speaker array 10v is reflected by the sound output from the speaker array 10 on the wall surface 220a. Realized. The directivity of the speaker array 10 is indicated by a solid line in FIG. 9, and the peak in the alignment direction of the directivity is positioned on the wall surface 220a by the first filter processing.

As a result, although the length of the speaker array 10 is L, the lower limit frequency of the control band of the speaker array 10 is the same as that of a speaker array having a length of 2L. As described above, since the lower limit frequency of the control band is inversely proportional to the length of the speaker array, the lower limit frequency of the control band of speaker array 10 is half that of speaker array 90 according to the comparative example. Therefore, the speaker array 10 can give desired directivity to sounds in a relatively wide frequency band even if it is arranged in a narrow space.

In addition, since the reflection of the reproduced sound on the wall surface 220a is taken into consideration for the directivity of the speaker array 10, the sound field is less likely to be disturbed due to the reflection of the reproduced sound on the wall surface 220a, and the desired directivity can be easily achieved. There are advantages.

Note that, in the speaker system 100, the first filter processing may be performed assuming a speaker array longer than the length of the speaker array 10 including the virtual speaker array 10v. That is, the length of the virtual speaker array 10v may not be the same as the length of the speaker array 10, and may be shorter than the length of the speaker array 10. FIG. In other words, the directivity of the speaker array 10 should be such that the peak in the alignment direction of the directivity is shifted toward the wall surface 220a by the first filter processing.

[Modification]
Although the length L of the speaker array 10 is, for example, 600 mm, it may be appropriately set according to the size of the space in which the speaker array 10 is arranged. Also, the number (number of channels) of the plurality of first speakers 10a constituting the speaker array 10 and the width of the interval D are not particularly limited. The narrower the interval D, the higher the upper limit frequency of the control band.

Also, in FIG. 1, the speaker system 100 is applied only to the driver's seat 230, but a similar speaker system 100 may be applied to the passenger's seat or rear seats instead of the driver's seat. In addition to the driver's seat 230, a similar speaker system 100 may be applied to the front passenger seat and rear seat. When the speaker system is applied to the rear seat, the speaker array 10 may be arranged on the ceiling of the rear seat, or may be arranged on the backrest of the driver's seat or the front passenger's seat.

(Embodiment 2)
Human beings are more sensitive to the direction of arrival of high-pitched sound, which has relatively sharp directivity, than the direction of arrival of low-pitched sound. Therefore, in the speaker system 100 according to Embodiment 1, since the peak of the directivity in the entire frequency band of the reproduced sound is close to the wall surface 220a side, there is a possibility that high-frequency sound may be heard from the wall surface 220a side. . In other words, there is a possibility that the user will feel uncomfortable with how high-pitched sounds are heard.

Therefore, in the speaker system 100, the directivity shown in FIG. 6 may be given to the low frequency component of the reproduced sound, and the directivity shown in FIG. 7 may be provided to the high frequency component of the reproduced sound. FIG. 10 is a block diagram showing the functional configuration of such a speaker system according to the second embodiment.

It should be noted that in the following description of the second embodiment, the description will focus on the differences from the first embodiment, and the description of the previously mentioned matters will be omitted as appropriate. In the second embodiment, the first signal is the low-pitched sound component of the signal to be reproduced, and the second signal is the high-pitched sound component of the signal to be reproduced.

As shown in FIG. 10, a speaker system 100a according to Embodiment 2 includes a speaker array 10, a first filter array 21, and a multi-channel amplifier 30, similarly to the speaker system 100. FIG. The speaker system 100 a further includes a frequency filter section 40 , an addition section 50 and a second filter array 22 .

The frequency filter unit 40 divides the signal to be reproduced into a first signal that is a low frequency component of the signal to be reproduced and a second signal that is a high frequency component of the signal to be reproduced. Specifically, the frequency filter unit 40 extracts the first signal from the signal to be reproduced and outputs it to the first filter array 21, and the LPF 41 extracts the second signal from the signal to be reproduced and outputs it to the second filter array. and an HPF 42 that outputs to 22.

Each of the plurality of first filters 21a forming the first filter array 21 acquires the first signal from the LPF 41 and performs the first filtering process on the acquired first signal. The specific processing content of the first filter processing differs, for example, for each first filter 21a. Each of the plurality of first speakers 10a outputs a sound based on the signal to be reproduced that has been subjected to such first filtering, thereby reproducing a sound corresponding to the first signal output from the speaker array 10 ( The bass component of the reproduced sound) is given directivity as shown in FIG. 11(a). FIG. 11 is a diagram showing the directivity of reproduced sound output from speaker array 10 in the second embodiment.

The second filter array 22 performs second filtering that is different from the first filtering. Specifically, the second filter array 22 is composed of a plurality of second filters 22a. The multiple second filters 22a correspond to the multiple first speakers 10a on a one-to-one basis. The second filter array 22 is, for example, a two-dimensional digital filter, and each of the plurality of second filters 22a is realized by, for example, a one-dimensional digital filter (a filter circuit that performs digital signal processing).

Each of the plurality of second filters 22a acquires a second signal from the HPF 42 and performs second filtering on the acquired second signal. The specific processing content of the first filter processing differs for each second filter 22a, for example. Each of the plurality of first speakers 10a outputs a sound based on the signal to be reproduced that has been subjected to the second filtering process, thereby reproducing the sound corresponding to the second signal output from the speaker array 10. Directivity is given as shown in FIG. 11(b).

The adder 50 adds the fourth signal, which is the second signal after the second filter processing, to the third signal, which is the first signal after the first filter processing. The adder 50 is specifically an adder array composed of a plurality of adders 50a. The multiple adders 50a correspond to the multiple first speakers 10a on a one-to-one basis. Each of the multiple adders 50a adds the fourth signal output from one second filter 22a to the third signal output from one first filter 21a. The adder 50a is specifically realized by a digital arithmetic circuit or the like.

The multi-channel amplifier 30 performs amplification processing on the third signal that has undergone addition processing by the addition section 50 . The amplified third signal is input to the speaker array 10 .

Each of the plurality of first speakers 10a receives the third signal that has undergone addition processing by the addition section 50 and amplification processing by the multi-channel amplifier 30. FIG. That is, the plurality of first speakers 10a are shared for outputting high-pitched sound and low-pitched sound. As a result, as shown in FIG. 11(a), the peak of the directivity of the reproduced sound corresponding to the first signal output from the speaker array 10 in the direction in which the plurality of first speakers 10a are arranged is Due to one filtering process, it is closer to the wall surface 220a.

On the other hand, as shown in (b) of FIG. 11, the directionality of the reproduced sound (high-pitched sound component of the reproduced sound) corresponding to the second signal output from the speaker array 10 is the direction in which the plurality of first speakers 10a are arranged. The peak at is located in the center of the speaker array 10 by the second filtering process.

As described above, in the speaker system 100a, the signal to be reproduced is divided by the frequency filter unit 40 (LPF 41 and HPF 42) into the first signal, which is the low frequency component of the signal, and the second signal, which is the high frequency component of the signal. be done. As described in Embodiment 1, the first signal (bass component) requires a long speaker array length in order to widen the control band. Therefore, the first signal is subjected to the first filtering described in the first embodiment. This lowers the lower limit frequency of the control band.

On the other hand, unlike the first signal, the second signal (high frequency component) does not require the length of the speaker array. Therefore, the second signal is subjected to a second filter process different from the first filter process so that the directivity peak is located in the central portion in the direction in which the plurality of first speakers 10a are arranged.

As described above, humans are more sensitive to the direction of arrival of high-frequency sound with relatively sharp directivity than the direction of arrival of low-frequency sound. In the speaker system 100a, the directivity peak of the reproduced sound corresponding to the second signal, which is the high-frequency component, is in the center, so the user feels as if the reproduced sound is coming from the front. In other words, it is possible to prevent the user from feeling discomfort in how the reproduced sound is heard. Moreover, in the speaker system 100a, the first signal, which is a bass component, is processed in the same manner as in the first embodiment, so the lower limit frequency of the control band can be lowered.

[Modification]
As described above, since the second signal (high-pitched sound component) does not require the length of the speaker array, only the low-pitched sound corresponding to the first signal is emitted from the first speakers 10a located at both ends of the speaker array 10. may be output. 12 is a block diagram showing a functional configuration of a speaker system according to a modification of Embodiment 2. FIG.

In the speaker system 100b according to the modified example of the second embodiment shown in FIG. is input. In other words, both the sound of the high frequency component and the sound of the low frequency component are output from each of the part 11 of the plurality of first speakers 10a. A portion 11 of the plurality of first speakers 10a is positioned in the central portion in the alignment direction of the plurality of first speakers 10a. In addition, the number of the first speakers 10a included in the part 11 of the plurality of first speakers 10a is not particularly limited.

On the other hand, each of the other part 12 of the plurality of first speakers receives the third signal that has been subjected to only the amplification process among the addition process and the amplification process. That is, only the low-pitched sound among the high-pitched sound and the low-pitched sound is output from each of the other portions 12 of the plurality of first speakers 10a. Other portions 12 of the plurality of first speakers are positioned at both ends in the direction in which the plurality of first speakers 10a are arranged. The number of first speakers 10a included in the other part 12 of the plurality of first speakers 10a is not particularly limited. From the viewpoint of symmetry, the number of first speakers 10a positioned at one end should be equal to the number of first speakers positioned at the other end.

Thus, in the speaker system 100b, the first speakers 10a located at both ends output only low-pitched sounds corresponding to the first signal, and do not output high-pitched sounds corresponding to the second signals. As a result, it is possible to make it difficult for a user sitting in a seat other than the driver's seat 230 to hear the high-pitched sound component of the reproduced sound output by the speaker array 10 .

Like the speaker system 100b described above, in the speaker system 100a, the third signal subjected to addition processing and amplification processing is input to each of at least some of the plurality of first speakers 10a included in the speaker array 10. I wish I could. As a result, the peak of the directivity of the reproduced sound corresponding to the second signal output from at least a part of the plurality of first speakers in the arrangement direction of the plurality of first speakers 10a is reduced by the second filter processing. located in the center of

(Embodiment 3)
As described above, the narrower the distance D between the plurality of first speakers 10a constituting the speaker array 10, the higher the upper limit frequency of the control band. Therefore, the speaker array 10 included in the speaker system 100b may further include a plurality of second speakers that output high-pitched sounds corresponding to the second signals. The plurality of first speakers 10a and the plurality of second speakers may be arranged alternately to narrow the substantial speaker spacing with respect to the second signal. FIG. 13 is a block diagram showing the functional configuration of such a speaker system according to the third embodiment.

It should be noted that in the following description of the third embodiment, the description will focus on the differences from the speaker system 100b according to the modified example of the second embodiment, and the description of the previously mentioned matters will be omitted as appropriate.

As shown in FIG. 13, unlike the speaker array 10, the speaker array 10c included in the speaker system 100c according to the third embodiment includes a plurality of linearly arranged second speakers 10b. The number of multiple second speakers 10b is not particularly limited.

Some of the plurality of first speakers 10a and the plurality of second speakers 10b are alternately arranged. At least some of the plurality of first speakers 10a and the plurality of second speakers 10b may be alternately arranged. For example, all of the plurality of first speakers 10a and the plurality of second speakers 10b They may be arranged alternately.

The speaker array 10c includes a first speaker group 11a positioned at the center in the direction in which the plurality of first speakers 10a are arranged, and a group of first speakers 11a positioned at both ends in the direction in which the plurality of first speakers 10a are arranged. A second speaker group 11b is included. The first speaker group 11a includes a plurality of first speakers 10a and a plurality of second speakers 10b. The second speaker group 11b includes a plurality of first speakers 10a.

Each of the first speakers 10a included in the first speaker group 11a receives the third signal that has undergone addition processing by the addition section 50 and amplification processing by the multi-channel amplifier 30. FIG. In other words, both high-pitched sound and low-pitched sound are output from each of the first speakers 10a included in the first speaker group 11a.

On the other hand, the fourth signal amplified by the multi-channel amplifier 30 is input to each of the second speakers 10b included in the first speaker group 11a. That is, from each of the second speakers 10b included in the first speaker group 11a, only the high-pitched sound of the high-pitched sound and the low-pitched sound is output.

Then, each of the first speakers 10a included in the second speaker group 11b receives the third signal which has not been subjected to addition processing by the addition unit 50 and has been subjected to amplification processing by the multi-channel amplifier 30. be done. That is, from each of the first speakers 10a included in the first speaker group 11a, only the sound of the low frequency component among the sound of the high frequency component and the sound of the low frequency component is output.

Here, the plurality of second speakers 10b are arranged at regular intervals of D, like the plurality of first speakers 10a. Then, the plurality of speakers (the plurality of first speakers 10a and the plurality of second speakers 10b) included in the first speaker group 11a are arranged at intervals of D/2 for the second signal (high-pitched sound component). It is supposed to be This raises the upper limit frequency of the control band.

As shown in FIG. 14(b), the peak of the directivity of the reproduced sound corresponding to the second signal output from the second speaker group 11b in the arrangement direction of the plurality of first speakers 10a is the second filter It is positioned at the center of the speaker array 10c by processing. FIG. 14 is a diagram showing the directivity of reproduced sound output from speaker array 10c in the third embodiment.

On the other hand, the plurality of first speakers 10a included in the speaker array 10c are arranged at intervals D with respect to the first signal (bass component). Therefore, as shown in FIG. 14(a), the peak of the directivity of the reproduced sound corresponding to the first signal output from the speaker array 10c in the arrangement direction of the plurality of first speakers 10a is Similar to 1 and 2, the first filter processing is closer to the wall surface 220a.

Thus, in the speaker system 100c, the upper limit frequency of the control band can be increased by adding the second speaker 10b that outputs high-pitched sounds corresponding to the second signal.

(Embodiment 4)
Embodiment 4 describes an application example of the speaker system 100c according to Embodiment 3 with reference to FIG. FIG. 15 is a diagram showing an application example of the speaker system 100c.

As shown in FIG. 15, the speaker system 100c is installed in the living room 250. As shown in FIG. The right end of speaker system 100c is placed in contact with wall surface 260a of living room 250, and the left end thereof is placed in contact with wall surface 260b. play a role. Since the configuration of the operation and the like is the same as that of the third embodiment, description thereof will be omitted.

In Embodiment 4, the screen 280 is installed or projected onto the wall surface 270 . In the screen 280, the same signal can be reproduced from all the speakers when one screen is displayed, and different sounds can be provided to areas 290a and 290b when two screens are displayed. At this time, since areas 290a and 290b are adjacent to wall surfaces 260a and 260b, control can be performed down to a lower frequency range as in the case of the third embodiment.

It should be noted that depending on the shape of the living room, only one side wall may be provided. In that case, it becomes possible to control the bass reproduction band down to low frequencies only in one area. Moreover, although the living room is described as an example in the fourth embodiment, other rooms may be used. Also, the screen 280 may be omitted.

(Other embodiments)
Although the embodiments have been described above, the present disclosure is not limited to such embodiments.

For example, the speaker systems according to the above embodiments are applied to spaces in automobiles or houses, but may be applied to other spaces having walls. The speaker system according to the above embodiment may be applied to spaces inside moving bodies other than automobiles, and may be used in commercial facilities such as art museums and department stores, exhibition spaces, signage in public spaces, and the like.

Also, the configuration of the speaker system according to the above embodiment is an example. The speaker system may further include components such as, for example, D/A converters, low pass filters (LPF), high pass filters (HPF), amplifiers (power amplifiers), or A/D converters. Further, the signal processing executed in the speaker system is mainly digital signal processing, but part of it may be analog signal processing.

In addition, forms obtained by applying various modifications that a person skilled in the art can think of to the above embodiments, and arbitrarily combining the components and functions described in the above embodiments within the scope of the present disclosure is also included in the present disclosure.

For example, the present disclosure may be implemented as a signal processing method performed by a speaker system. Further, the present disclosure may be implemented as a signal processing device (integrated circuit) that outputs signals that have undergone signal processing to a speaker array.

The speaker system according to the present disclosure is useful as a speaker system capable of spot reproduction that allows only users located in a specific area to hear the reproduced sound by outputting the reproduced sound with directivity.

10, 10c, 90 speaker array 10a first speaker 10b second speaker 10v virtual speaker array 11 part 11a first speaker group 11b second speaker group 12 other part 21 first filter array 21a first filter 22 second filter Array 22a Second filter 30 Multi-channel amplifier 30a Amplifier 40 Frequency filter section 41 LPF
42HPF
50 adder 50a adder 100, 100a, 100b, 100c speaker system 200 automobile 210 ceiling 220 side wall 220a wall 230 driver's seat 240 dashboard 250 living room 260a, 260b side wall of living room 270 wall of living room 280 screen 290a, 290b Play area in living room

Claims (9)

A speaker system,
a speaker array composed of a plurality of linearly arranged first speakers each receiving a first signal that has undergone first filtering and amplification processing;
a first filter array that performs the first filtering;
A multi-channel amplifier that performs the amplification process,
The speaker array is arranged in a reproduction space having a wall surface that intersects the direction in which the plurality of first speakers are arranged,
A peak in the alignment direction of the directivity of the reproduced sound corresponding to the first signal output from the speaker array is shifted toward the wall surface side by the first filtering process,
the first signal is a bass component of a signal to be reproduced;
The speaker system further comprises:
a frequency filter unit that divides the signal to be reproduced into the first signal and a second signal that is a high-pitched component of the signal to be reproduced;
a second filter array for performing a second filtering process on the second signal;
an addition unit that performs addition processing of a fourth signal that is the second signal that has been subjected to the second filter processing to a third signal that is the first signal that has been subjected to the first filter processing;
The multi-channel amplifier performs the amplification process on the third signal subjected to the addition process,
The third signal subjected to the addition process and the amplification process is input to each of at least some of the plurality of first speakers,
A peak in the alignment direction of the directivity of the reproduced sound corresponding to the second signal, which is output from at least some of the plurality of first speakers, is positioned at the center of the speaker array by the second filtering process. speaker system. The third signal that has undergone the addition process and the amplification process is input to each of a portion of the plurality of first speakers,
2. The speaker system according to claim 1 , wherein the third signal that has undergone only the amplification process out of the addition process and the amplification process is input to each of the other part of the plurality of first speakers. 3. The speaker system according to claim 2 , wherein another part of the plurality of first speakers are positioned at both ends in the row direction of the speaker array. The speaker system according to claim 1 , wherein each of the plurality of first speakers receives the third signal that has been subjected to the addition processing and the amplification processing. The speaker array further includes a plurality of second speakers arranged linearly,
Each of the plurality of second speakers receives the fourth signal amplified by the multi-channel amplifier,
At least some of the plurality of first speakers and the plurality of second speakers are arranged alternately,
A peak in the arrangement direction of the directivity of the reproduced sound corresponding to the second signal, which is output from at least a part of the plurality of first speakers and the plurality of second speakers, is obtained by the second filtering process. 2. The speaker system according to claim 1 , located in the center of said speaker array. The plurality of first speakers are arranged at equal intervals with an interval D,
The speaker system according to claim 5 , wherein the plurality of second speakers are arranged at equal intervals of the interval D. The speaker system according to any one of claims 1 to 6 , wherein the speaker array is arranged on the ceiling of an automobile. The speaker system according to any one of claims 1 to 6 , wherein the speaker array is arranged on a dashboard of an automobile. A signal processing method performed by a loudspeaker system, comprising:
The speaker system is
a speaker array composed of a plurality of linearly arranged first speakers each receiving a first signal that has undergone first filtering and amplification processing;
a first filter array that performs the first filtering;
A multi-channel amplifier that performs the amplification process,
The speaker array is arranged in a reproduction space having a wall surface that intersects the direction in which the plurality of first speakers are arranged,
In the signal processing method, the peak in the alignment direction of the directivity of the reproduced sound corresponding to the first signal output from the speaker array is shifted to the wall surface side by the first filtering process,
the first signal is a bass component of a signal to be reproduced;
The speaker system further comprises:
a frequency filter unit that divides the signal to be reproduced into the first signal and a second signal that is a high-pitched component of the signal to be reproduced;
a second filter array for performing a second filtering process on the second signal;
an addition unit that performs addition processing of a fourth signal that is the second signal that has been subjected to the second filter processing to a third signal that is the first signal that has been subjected to the first filter processing;
The multi-channel amplifier performs the amplification process on the third signal subjected to the addition process,
The third signal subjected to the addition process and the amplification process is input to each of at least some of the plurality of first speakers,
In the signal processing method, the peak in the arrangement direction of the directivity of the reproduced sound corresponding to the second signal, which is output from at least some of the plurality of first speakers, is detected by the speaker array through the second filtering process. signal processing method.

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