JP2015065540A - Acoustic space setting method, parametric speaker, and acoustic system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an acoustic space setting method using a parametric speaker, that can comparatively easily change the largeness of a listening area, and also to provide the parametric speaker, and an acoustic system.SOLUTION: An acoustic space setting method is the acoustic space setting method using a parametric speaker 1 that has multiple ultrasonic wave generation elements 11 arranged on a virtual curved surface S and radiating a modulation wave obtained by modulating the carrier wave of a sonic wave band with the use of the signal wave of an audible band. In this case, the multiple ultrasonic wave generation elements 11 are arranged on the virtual curved surface S. In the acoustic space setting method, the curvature t1 of the virtual curved surface S is set to allow the focal position F1 of the virtual curved surface S to exist between an element arrangement area AR10 where the multiple ultrasonic wave generation elements 11 are arranged on the virtual curved surface S and the listening area AR1 (AR2) of the parametric speaker 1. In this case, the listening area AR1 (AR2) becomes larger as separated from the element arrangement area AR10 on the opposite side of the element arrangement area AR10 with respect to the element arrangement area AR10 and the focal position F1.

Description

  The present invention relates to an acoustic space setting method using a parametric speaker, a parametric speaker, and an acoustic system, and more particularly to a listening area control technique.

  In recent years, a technique has been proposed in which sound is heard only by a listener existing in a specific listening area using a parametric speaker having superdirectivity (see, for example, Patent Document 1). This parametric speaker transmits sound using a parametric phenomenon in which sound is demodulated from an ultrasonic wave modulated by a sound signal due to nonlinear characteristics of a sound propagation medium such as air.

JP 2009-290357 A

  By the way, in the parametric speaker described in Patent Document 1, a plurality of ultrasonic generating elements are arranged on a plane, and the size of the listening area is approximately the size of the parametric speaker. Therefore, when it is attempted to change the listening area in order to cope with an increase or decrease in the number of listeners, for example, a single listening area may be configured by collecting listening areas of a plurality of parametric speakers. It is done. In this case, the size of the listening area can be changed by increasing / decreasing the number of parametric speakers used in accordance with the increase / decrease of the number of listeners.

  However, in order to collect the listening areas of a plurality of parametric speakers to form one listening area, it is necessary to set the direction of each parametric speaker while grasping the relative positional relationship of the plurality of parametric speakers. The setting work is complicated and the user may feel annoyed.

  The present invention has been made in view of the above reasons, and provides an acoustic space setting method, a parametric speaker, and an acoustic system using a parametric speaker that can change the size of a listening area relatively easily. Objective.

(1) An acoustic space setting method according to the present invention is an acoustic space setting method using a parametric speaker having a plurality of ultrasonic wave generating elements that emit a modulated wave obtained by modulating a carrier wave in a sound wave band with a signal wave in an audible band. The plurality of ultrasonic generating elements are arranged on the curved surface, and the focal position of the curved surface is between the element arrangement area where the plural ultrasonic generating elements are arranged on the curved surface and the listening area of the parametric speaker, and the element By setting the curvature of the curved surface so that it exists on either side opposite to the listening area side with respect to the arrangement area, the listening area becomes larger as it moves away from the focal position along the central axis of the parametric speaker. Like that.

  According to this configuration, the focal position of the curved surface is defined between the element arrangement area where a plurality of ultrasonic wave generating elements are arranged on the curved surface and the listening area of the parametric speaker, and the listening area side with respect to the element arrangement area. By setting the curvature of the curved surface so that it exists on either one of the opposite sides, the listening area is farther away from the element arrangement area on the side opposite to the element arrangement area side with respect to the element arrangement area and the focal position. I try to get bigger. This makes it easy to increase the size of the listening area on the side opposite to the element arrangement area side with respect to the element arrangement area and the focal position. Therefore, for example, the listening area of a plurality of parametric speakers is gathered to form one listening area, and the size of the listening area is larger than the method of changing the size of the listening area by increasing or decreasing the number of parametric speakers to be used. The thickness can be changed relatively easily.

(2) The acoustic space setting method according to the present invention may set the curvature of the curved surface based on the size of the listening area.
According to this configuration, if the curvature of the curved surface is set so that the region where the listener who should hear the sound is included is included in the listening region, the listener can be surely heard.

(3) The acoustic space setting method according to the present invention includes the curvature of the curved surface, the size of the listening area, the distance between the speaker listening areas between the parametric speaker and the listening area, and the size of the element arrangement area. The curvature of the curved surface may be set based on a relational expression established between them.
According to this configuration, the curvature of the curved surface can be set by performing a simple numerical analysis based on the above relational expression, so the curvature of the curved surface is actually set based on the hearing condition of the listener while trial and error. Compared to the case, the curvature of the curved surface can be set relatively easily.

(4) In the acoustic space setting method according to the present invention, the relational expression may be represented by the following expression (1).
... Formula (1)
A1: The size of the projection area on the plane perpendicular to the central axis of the parametric speaker in the element arrangement area, A2: The size of the projection area on the plane of the listening area, L1: The distance between the speaker listening areas, r1: Curvature radius of the curved surface According to the present configuration, the curvature of the curved surface can be set relatively easily as described above.

(5) In the acoustic space setting method according to the present invention, the relational expression may be represented by the following expression (2).
... Formula (2)
A1: The size of the projection area on the plane perpendicular to the central axis of the parametric speaker in the element arrangement area, A2: The size of the projection area on the plane of the listening area, L1: The distance between the speaker listening areas, r1: Curvature radius of the curved surface According to the present configuration, the curvature of the curved surface can be set relatively easily as described above.

(6) In the acoustic space setting method according to the present invention, the size of the listening area may be larger than the size of the element arrangement area.
According to this configuration, since the size of the listening area is larger than the size of the element arrangement area, for example, it is possible to hear sound to a plurality of listeners existing in a wider range than the element arrangement area. Become.

(7) A parametric speaker according to the present invention viewed from another viewpoint includes a plurality of ultrasonic generation elements that emit a modulated wave obtained by modulating a carrier wave in an ultrasonic band with a signal wave in an audible band, and a plurality of ultrasonic generation elements. And a support member that is attached in such a manner as to be disposed on the curved surface and that has a variable curvature of the curved surface.
According to this configuration, since the curvature radius of the curved surface can be changed, the focal position of the curved surface can be changed, so that the size of the listening area of the parametric speaker can be changed.

(8) Further, in the parametric speaker according to the present invention, the support member is formed in an elongated rod shape, and a plurality of fixing members in which a plurality of ultrasonic wave generating elements are fixed along the longitudinal direction thereof, and an elongated plate And two flexible members that support both ends in the longitudinal direction of the plurality of fixing members, and are arranged so that the one end faces in the short direction are opposed to each other. The curvature of the curved surface may be changed by bending the member.
According to this configuration, since the focal position can be changed by providing the mechanism for bending the flexible member, it is easy to mechanically change the listening area of the parametric speaker.

(9) The acoustic system according to the present invention viewed from another viewpoint includes a signal generation device that generates a signal wave in an audible band, a carrier wave generation unit that generates a carrier wave in an ultrasonic band, and the carrier wave generated by the signal wave. The size of the listening area corresponding to the parametric speaker is set by adjusting the curvature of the parametric speaker having a plurality of ultrasonic generating elements that emit modulated waves and the curved surface on which the plurality of ultrasonic generating elements are arranged. A curvature setting unit.
According to this configuration, the plurality of ultrasonic wave generating elements are arranged on the curved surface, and the curvature setting unit can set the size of the listening area by adjusting the direction of the parametric speaker and the curvature of the curved surface. . Thereby, the size of the listening area can be changed relatively easily.

(10) In the acoustic system according to the present invention, the curvature setting unit may adjust the curvature of the curved surface in accordance with a required size of the listening area.
According to this configuration, if the curvature of the curved surface is set so that the region where the listener who should hear the sound is included is included in the listening region, the listener can be surely heard.

(11) The acoustic system according to the present invention further includes a listener detection unit that detects the presence position of the listener and the number of listeners, and the curvature setting unit is detected by the listener detection unit. The curvature of the curved surface may be adjusted based on the location of the listener and the number of listeners.
According to this configuration, the position and size of the listening area can be appropriately set according to the position where the listener is present and the number of the listeners.

1 is a schematic configuration diagram of an acoustic system according to an embodiment. It is a schematic side view of the parametric speaker according to the embodiment. 1 is a block diagram of an acoustic system according to an embodiment. It is the schematic diagram which showed the relationship between an element arrangement | positioning area | region and a listening area | region in the acoustic space which concerns on embodiment. It is a schematic diagram which shows the sound pressure distribution evaluation method of the acoustic space which concerns on embodiment. It is a schematic diagram which shows the case where the focus exists between a parametric speaker and a listening area | region about the parametric speaker which concerns on embodiment. It is a figure which shows the sound pressure distribution of the acoustic space which concerns on embodiment. It is a figure which shows the sound pressure distribution of the acoustic space which concerns on embodiment. It is a schematic diagram which shows the case where the focus exists in the opposite side to the listening area side with respect to the parametric speaker about the parametric speaker which concerns on embodiment. It is a figure which shows the sound pressure distribution of the acoustic space which concerns on embodiment. It is a figure which shows the sound pressure distribution in the position spaced apart by 200 cm from the parametric speaker in the central axis direction of the parametric speaker in the parametric speaker according to the embodiment. It is a flowchart which shows operation | movement of the focus position control part of the acoustic system which concerns on embodiment. It is a figure which shows one usage example of the acoustic system which concerns on embodiment. It is a block diagram of the acoustic system which concerns on a modification. It is the schematic of the parametric speaker which concerns on a modification. It is a figure which shows the usage example of the acoustic system which concerns on a modification. It is a figure which shows an example of the table data which the focus position control part which concerns on a modification holds.

<Embodiment>
<1> Configuration First, the configuration of the acoustic system according to the present embodiment will be described.
FIG. 1 is a schematic configuration diagram of an acoustic system according to the present embodiment.
The acoustic system includes a parametric speaker 1, a focal position control unit (curvature setting unit) 2, a signal generation device 3, and a listener detection unit 4.
The parametric speaker 1 includes a plurality of ultrasonic wave generation elements 11, a support member 12 that supports the ultrasonic wave generation elements 11, and a support member variable unit 13 that changes the shape of the support member 12.

  The ultrasonic wave generation element 11 uses ultrasonic waves that cannot be perceived as sound by humans at a high frequency of 20 kHz or higher as a carrier wave, and modulates the modulated wave that has been widened and modulated by a signal wave in an audible band such as sound with a large amplitude that causes nonlinearity Radiates in. Since the modulated wave is distorted by the nonlinearity of air in the process of propagating in the air, the audible signal wave self-demodulates due to this distortion, and a highly directional sound field is formed. . As the ultrasonic wave generating element 11, for example, UT1007-Z325R manufactured by SPL (Hong Kong) Limited can be used. The ultrasonic wave generating element 11 has a resonance frequency of 40 kHz and an emission surface diameter of about 9.9 mm.

The support member 12 includes a plurality (9 in FIG. 1) of fixing members 12a and two flexible members 12b.
The fixing member 12a is formed in an elongated rod shape, and a plurality of (10 in FIG. 1) ultrasonic wave generating elements 11 are fixed along the longitudinal direction thereof. Here, the plurality of ultrasonic wave generating elements 11 are fixed to the fixing member 12a so that the emission direction of the ultrasonic waves faces one direction orthogonal to the longitudinal direction of the fixing member 12a.
The flexible member 12b is formed in an elongated rectangular plate shape, and is arranged so that one end surfaces in the short direction face each other. The two flexible members 12b support both end portions in the longitudinal direction of the plurality of fixing members 12a.

The support member variable portion 13 can change the focal position of the virtual curved surface (curved surface) S where the plurality of ultrasonic wave generating elements 11 are arranged by bending the flexible member 12 b of the support member 12.
Note that the “virtual curved surface” does not mean strictly one having an arcuate cross section, but includes, for example, a cross section having a polygonal shape, that is, a shape obtained by connecting a plurality of straight lines.

2A to 2C are schematic side views of the parametric speaker 1 according to the present embodiment.
The plurality of ultrasonic wave generating elements 11 are fixed to the support member 12 in a state of being arranged on the virtual curved surface S.
The support member variable portion 13 is a rectangular box-shaped main body portion 13a and a flexible body whose position can be changed in a direction perpendicular to the surface corresponding to the flexible member 12b of the main body portion 13a with respect to the main body portion 13a. And a plurality of flexible member support portions 13b that support the member 12b. The position of the flexible member support portion 13b can be changed by a motor (not shown) built in the main body portion 13a. Thereby, the protrusion amount to the flexible member 12b side from the main-body part 13a of the flexible member support part 13b can be changed.

  As shown in FIG. 2A, it is assumed that the amount of protrusion from the main body portion 13a to the flexible member 12b side is substantially equal in the plurality of flexible member support portions 13b. In this case, the plurality of ultrasonic wave generating elements 11 are arranged in a flat virtual plane S.

  As shown in FIG. 2 (b), in the plurality of flexible member support portions 13b, the amount of protrusion from the main body portion 13a to the flexible member 12b side is such that the envelope shape of those tip portions protrudes toward the main body portion 13a side. It is assumed that the curved surface shape. In this case, the plurality of ultrasonic wave generating elements 11 are arranged on the inner surface of the virtual curved surface S that is curved so as to protrude toward the main body portion 13a.

  As shown in FIG.2 (c), in the some flexible member support part 13b, the protrusion amount from the main-body part 13a to the flexible member 12b side is the direction in which the envelope shape of those front-end | tip parts leaves | separates from the main-body part 13a side. It is assumed that the curved surface is convex. In this case, the plurality of ultrasonic wave generating elements 11 are arranged on the virtual curved surface S that is curved so as to protrude in the direction away from the main body portion 13a.

FIG. 3 is a block diagram of the acoustic system according to the present embodiment.
The parametric speaker 1 further includes a modulation unit 15, a carrier wave generation unit 16, and a plurality of amplification units 14 in addition to the ultrasonic wave generation element 11 and the support member variable unit 13 described above.

  The amplifying unit 14 is provided for each of the plurality of ultrasonic wave generating elements 11. The amplifying unit 14 is configured using, for example, an operational amplifier having good amplification characteristics in the ultrasonic band.

  The carrier wave generation unit 16 generates a carrier wave composed of ultrasonic waves having a predetermined frequency and outputs the carrier wave to the modulation unit 15. The carrier wave generation unit 16 includes a high-frequency oscillator using a crystal resonator, for example.

The modulation unit 15 widens and modulates the carrier wave input from the carrier wave generation unit 16 with the signal wave input from the signal generation device 3 to generate a modulated wave. The modulated wave is radiated from the ultrasonic wave generating element 11 in a state amplified by the amplifying unit 14.
Here, the modulation unit 15 and the carrier wave generation unit 16 are configured by a computer including a calculation unit such as a CPU, a storage unit such as a memory, and an input / output interface, for example. And the modulation | alteration part 15 and the carrier wave production | generation part 16 are implement | achieved when a calculating part runs the computer program read by the memory | storage part.

  The focal position control unit 2 inputs a control signal to the support member variable unit 13 to bend the flexible member 12b that constitutes a part of the support member 12, and the plurality of ultrasonic generating elements 11 are arranged. The curvature of the generated virtual curved surface S is adjusted. Specifically, the focus position control unit 2 appropriately sets the position of the flexible member support part 13b of the support member 12 by controlling a motor built in the main body part 13a of the support member variable part 13 by a control signal. By doing so, the shape of the virtual curved surface (virtual plane) where the plurality of ultrasonic wave generating elements 11 are arranged is changed.

The signal generation device 3 includes a signal source 31 and a filter processing unit 32.
The signal source 31 generates an audible signal wave such as an audio signal or an audio signal and outputs the signal wave to the filter processing unit 32.
The filter processing unit 32 gives a predetermined characteristic to the signal wave and outputs the signal wave to the parametric speaker 1.

  Returning to FIG. 1, the listener detection unit 4 includes an image processing unit 41 and a camera 42. Here, the image processing unit 41 acquires, for example, a scene image including the listener photographed by the camera 42 from the camera 42, and specifies the location of the listener, the number of listeners, and the like based on the acquired image. Here, for example, the image processing unit 41 calculates the feature amount in each part in the image, and if there is a portion where the calculated feature amount is close to the feature amount indicating the characteristics of the listener, the image of the listener is included in the portion. Authorize. Then, the image processing unit 41 identifies the positional relationship between the camera 42 and the listener based on the location identified as the listener's image in the image. In this way, the image processing unit 41 calculates information related to the location of the listener and the number of listeners. Thereafter, the image processing unit 41 sends information indicating the calculated location of the listener, the number of listeners, and the like to the focal position control unit 2.

  The image processing unit 41 constituting a part of the focal position control unit 2, the signal generation device 3, and the listener detection unit 4 includes an arithmetic unit such as a CPU, a memory, a storage unit such as an HDD, and other input / output interfaces. It is comprised from the personal computer provided with these. Then, by executing the computer program installed in the personal computer, the personal computer realizes each functional unit constituting the focal position control unit 2, the signal generation device 3, and the image processing unit 41.

<2> Acoustic Space Setting Method Next, an acoustic space setting method using the acoustic system according to the present embodiment will be described.
FIG. 4 is a schematic diagram showing the relationship between the element arrangement area AR10 and the listening areas AR1, AR2, AR3 in the acoustic space according to the present embodiment.
4A and 4B show a case where the focal position F1 of the parametric speaker 1 is located between the element arrangement area AR10 and the listening area AR1 (AR2). 4A and 4B, the distance (distance between speaker listening areas) L1 between the parametric speaker 1 (element arrangement area AR10) and the listening area AR1 (AR2) is the same.
In this case, the listening area AR1 (AR2) becomes larger as the focal length L21 (L22) of the parametric speaker 1 is shorter. Therefore, for example, when the number of listeners P increases and the listening area AR1 (AR2) needs to be widened, the focal length L21 (L22) may be shortened. The “size of the listening areas AR1 and AR2” corresponds to the area of the projection area on the plane orthogonal to the central axis of the parametric speaker 1.

FIG. 4C shows a case where the focal position F0 of the parametric speaker 1 is located on the side opposite to the listening area AR0 side with respect to the element arrangement area AR10.
In this case, as shown in FIGS. 4A and 4B, the listening area F1 is compared to the case where the focal position F1 of the parametric speaker 1 is located between the element arrangement area AR10 and the listening area AR1 (AR2). It is easy to increase AR0. When the number of listeners P increases and the listening area AR0 needs to be widened, the focal length L23 may be shortened.

The inventors have actually studied the acoustic space setting method using the acoustic system according to the present embodiment. Hereinafter, this result will be described.
FIG. 5 is a schematic diagram showing a sound pressure distribution evaluation method for an acoustic space according to the present embodiment. Here, the horizontal axis indicates the distance from the parametric speaker 1 to the measurement point in the direction orthogonal to the central axis of the parametric speaker 1. The vertical axis indicates the distance in the central axis direction of the parametric speaker 1 from the parametric speaker 1 to the measurement point.
Here, the sound pressure of the demodulated sound (0 to 20 kHz) is measured at 20 measurement points located around the parametric speaker 1 while changing the shape of the parametric speaker 1. Specifically, the evaluation is made for the case where the focal position of the parametric speaker 1 exists between the parametric speaker 1 and the listening area AR1, and the case where the focal position exists on the opposite side of the listening area AR1 with respect to the parametric speaker 1. doing.

FIG. 6 is a schematic diagram showing a case where the focal position F1 of the parametric speaker 1 according to the present embodiment is present between the parametric speaker 1 and the listening area AR1.
In FIG. 6, the distance between the positions B1 and C1 at both ends in the short direction of the parametric speaker 1 is x11, and the distance between the positions D1 and E1 at both ends of the listening area AR1 (AR2) is x12. Further, the distance from the position B1, C1 to the focal position F1 (the radius of curvature of the virtual curved surface S) is r1, and the distance from the position D1, E1 to the focal position F1 is r2. Then, it is assumed that the distance L1 between the speaker listening areas between the parametric speaker 1 and the listening area AR1 is equal to r1 + r2. In this case, the following relational expression (3) is established between x11, x12, r1, r2, and L1.
... Formula (3)

Further, the distance A11 of the projection area size A1 on the plane perpendicular to the central axis J1 of the parametric speaker 1 in the element arrangement area AR10 and the projection area size A2 on the plane of the listening area AR1 (AR2). , X12. In this case, the following relational expression (1) is established.
... Formula (1)
As shown in equations (1) and (3), when the distance x11 and the distance r1 are changed by changing the curvature of the virtual curved surface S of the parametric speaker 1, the length x12 of the listening area AR1 (AR2), the listening area It is possible to change the size of AR1 (AR2).

FIGS. 7A and 7B and FIG. 8 are diagrams showing the sound pressure distribution in the acoustic space according to the present embodiment. Here, (a) shows the result when the distance r1 is 30 cm, and (b) shows the result when the distance r1 is 10 cm. FIG. 7 shows a result when a plurality of ultrasonic wave generating elements 11 are arranged on a flat virtual plane S.
From the results of FIGS. 7A and 7B and FIG. 8, when the focal position of the parametric speaker 1 exists between the parametric speaker 1 and the listening area, a plurality of ultrasonic generators 11 are assumed to be flat. It can be seen that the directivity is broader than that in the case of being arranged on the plane S.
It can also be seen from the results of FIGS. 7A and 7B that the directivity increases as the distance r1 decreases.

In the configuration shown in FIG. 6, the listener is often present at a distance of at least 2 m from the parametric speaker 1. In consideration of this, in the above formula (3), it is preferable that the relational expression of the following formula (4) is established for the distance x11 and the curvature radius r1. Here, the distance x11 is a length serving as an index representing the size of the parametric speaker 1.
... Formula (4)
Here, the length of the radius of curvature r1 is preferably not more than 3 times the distance x11, and more preferably not more than 1.5 times the distance x11. The length of the curvature radius r1 is more preferably equal to the distance x11, and most preferably 0.7 times or less of the distance x11.
Further, the length of the curvature radius r1 is preferably 50 cm or less, and more preferably 25 cm or less. Further, the length of the curvature radius r1 is more preferably 20 cm or less, and most preferably 10 cm or less.
Here, for example, when the distance x11 is set to 0.15 m and the curvature radius r1 is set to 0.67 m, the distance r2 is 1.33 m and the distance x12 is 0.3 m. At this time, the distance r2 is three times the radius of curvature r1.
For example, if the distance x11 is set to 0.15 m and the radius of curvature r1 is set to 0.18 m, the distance r2 is 1.82 m and the distance x12 is 1.5 m. At this time, the distance r2 is 10 times the radius of curvature r1.
Further, for example, when the distance x11 is set to 0.15 m and the radius of curvature r1 is set to 0.09 m, the distance r2 is 1.91 m and the distance x12 is 3.31 m. At this time, the distance r2 is 21 times the radius of curvature r1. At this time, the angle of facing the virtual curved surface S from the focal position F1 is about 120 °.

  Thus, by setting the distance x11 and the radius of curvature r1, the focal position F1 of the virtual curved surface S of the parametric speaker 1 can be brought closer to the element arrangement area AR10 side, so that the element arrangement area AR10 from the focal position F1. The angle to face is increased. As a result, the spread angle of the modulated waves radiated from the plurality of ultrasonic wave generating elements 11 from the focal position F1 to the side opposite to the element arrangement area AR10 side is increased, so that the listening area AR1 (AR2) is increased. Can do.

FIG. 9 is a schematic diagram showing a case where the focal position F2 of the parametric speaker 1 according to the present embodiment is on the opposite side of the listening area AR1 with respect to the parametric speaker 1.
In FIG. 9, the distance between the positions B2 and C2 at both ends in the short direction of the parametric speaker 1 is x21, and the distance between the positions D2 and E2 at both ends of the listening area AR1 is x22. The distance from the positions B2 and C2 to the focal position F2 (the radius of curvature of the virtual curved surface S) is r1, and the distance from the positions D2 and E2 to the focal position F2 is r2. It is assumed that the distance L1 between the speaker listening areas between the parametric speaker 1 and the listening area AR1 is equal to r2-r1. In this case, the following relational expression (5) is established between x21, x22, r1, and r2.
... Formula (5)

Further, the size A1 of the projection area on the plane perpendicular to the central axis J2 of the parametric speaker 1 in the element arrangement area AR10 and the size A2 of the projection area on the plane of the listening area AR0 are distances x11 and x12. Suppose that it is proportional. In this case, the following relational expression (2) is established.
... Formula (2)
As shown in the equations (2) and (4), when the distance x21 and the distance r1 are changed by changing the curvature of the virtual curved surface S of the parametric speaker 1, the position D2, which is located at the distance r2 from the focal position F2. It is possible to change the length of the listening area AR0 defined by E2 and the size A2 of the listening area AR0.

FIG. 10 is a diagram showing the sound pressure distribution in the acoustic space according to the present embodiment. Here, the result when the distance r1 is 30 cm is shown.
From the results of FIGS. 10 and 8, when the focal position F2 of the parametric speaker 1 is on the opposite side of the listening area AR2 with respect to the parametric speaker 1, the plurality of ultrasonic generating elements 11 are on the flat virtual plane S1. It can be seen that the directivity is broader than that in the case where the antennas are arranged in the.

  FIG. 11 is a diagram illustrating a sound pressure distribution at a position separated from the parametric speaker 1 by 200 cm in the central axis direction of the parametric speaker 1 according to the present embodiment. Here, “Def” indicates a case where the plurality of ultrasonic wave generating elements 11 are arranged on the flat virtual plane S. Moreover, (1) and (2) show a case where the focal position F1 of the parametric speaker 1 exists between the parametric speaker 1 and the listening area AR1. (3) shows a case where the focal position F2 of the parametric speaker 1 is on the side opposite to the listening area AR1 side with respect to the parametric speaker 1. (1) and (2) correspond to the case where the distance r1 is set to 30 cm and 10 cm, and (3) corresponds to the case where the distance r1 is set to 30 cm.

  As shown in FIG. 11, when the plurality of ultrasonic generating elements 11 are arranged on the flat virtual plane S, the sound pressure difference between the maximum sound pressure and the minimum sound pressure is 17.7 dB. On the other hand, when the focal position F1 of the virtual curved surface S of the parametric speaker 1 exists between the parametric speaker 1 and the listening area AR1, the sound pressure difference is reduced to 14.1 dB and 7.2 dB. . Furthermore, when the focal position F2 of the virtual curved surface S of the parametric speaker 1 is on the opposite side of the listening area AR1 with respect to the parametric speaker 1, the sound pressure difference is reduced to 7.7 dB. From these facts, when the shape of the parametric speaker 1 is curved, the directivity is broader than when the plurality of ultrasonic wave generating elements 11 are arranged on the flat virtual plane S1. I understand.

From the result of FIG. 11, when the focal position of the virtual curved surface S is located between the element arrangement area AR10 and the listening area AR1 (AR2), the loss of the modulated wave between the element arrangement area and the focal position F1 is reduced. can do.
On the other hand, when the focal position of the virtual curved surface S is located on the side opposite to the listening area AR0 side with respect to the element arrangement area AR10, the distance between the element arrangement area AR10 and the listening area AR0 (distance between speaker listening areas). Even if L1 is small, there is an advantage that the size of the listening area AR0 can be easily increased.

As described above, the relational expressions (1) and (2) are established among the sizes A1 and A2, the distance L1 between the listening areas of the speakers, and the curvature radius r1 of the virtual curved surface S. . Here, the size A1 is the size of the projection region onto a plane orthogonal to the central axis J1 (J2) of the parametric speaker 1 in the element arrangement region AR10. The size A2 is the size of the projection area of the listening area AR1 (AR2, AR0) onto the plane.
As described above, the radius of curvature r1 of the virtual curved surface S is set based on the sizes of the listening areas AR1, AR2, AR0. Thus, if the curvature of the curved surface is set so that the region where the listener to whom the sound should be heard exists is included in the listening region, the listener can be surely heard.

  As described above, if the curvature radius r1 of the virtual curved surface S is set based on the relational expressions (1) and (2), the virtual curved surface can be obtained by performing simple numerical analysis based on the relational expression. A radius of curvature r1 of S can be set. Therefore, it is possible to set the curvature of the curved surface relatively easily as compared with the case where the curvature of the curved surface is actually set based on trial and error based on the degree of hearing of the listener.

<3> Operation Next, the operation of the acoustic system according to the present embodiment will be described.
FIG. 12 is a flowchart showing the operation of the focal position control unit 2 of the acoustic system according to the present embodiment. FIG. 13 is a diagram illustrating an example of use of the acoustic system according to the present embodiment.
First, the focal position control unit 2 acquires the position information of the target area (step S1). Here, the focal position control unit 2 acquires position information indicating the regions (target regions) AR3 and AR4 where the listener P exists from the listener detection unit 4. As shown in FIGS. 13A and 13B, the “position information of the target area” corresponds to information indicating the positions of the central portions CE3 and CE4 of the target areas AR3 and AR4.

  Next, the focal position control unit 2 sets the direction of the parametric speaker 1 so as to face the center parts CE3 and CE4 of the target areas AR3 and AR4 (step S2). Here, as shown in FIGS. 13A and 13B, the focal position control unit 2 tilts the direction of the parametric speaker 1 from the specified direction J3 by an angle θ30 corresponding to the center portion CE3, or from the specified direction J3. It is inclined by an angle θ40 corresponding to the center part CE4.

  Subsequently, the focal position control unit 2 acquires information related to the spread of the target areas AR3 and AR4 (step S3). As shown in FIG. 13A, when there are six listeners P, the target area AR3 extends to an area including the six listeners P. On the other hand, as shown in FIG. 13B, when there are only two listeners P, the target area AR4 extends to an area including only the two listeners P.

  Thereafter, the focal position control unit 2 sets the curvature of the virtual curved surface S of the parametric speaker 1 so that the sound pressure in the target areas AR3 and AR4 is equal to or higher than the prescribed sound pressure (step S4). Here, as shown in FIGS. 13A and 13B, the focal position control unit 2 sets the curvature radius r1 of the virtual curved surface S of the parametric speaker 1 to a length R3 corresponding to the size of the target area AR3. It is set to a length R4 corresponding to the target area AR4. Here, the target area AR3 is larger than the target area AR4. Therefore, the curvature radius R3 is set smaller than the curvature radius R4.

  Next, the focal position control unit 2 determines whether or not there is a command to change the positions and spreads of the target areas AR3 and AR4 (step S5). This command is input from the listener detection unit 4.

If it is determined in step S5 that there is a command to change the position or spread of the target area (step S5: Yes), the focal position control unit 2 performs the process of step S1.
On the other hand, if it is determined in step S5 that there is no command to change the position or spread of the target region (step S5: No), the focal position control unit 2 determines whether there is an end command ( Step S6). This end command is input from, for example, a user interface (not shown) connected to the focal position control unit 2.

If it is determined in step S6 that there is no termination command (step S6: No), the focal position control unit 2 performs the process of step S5 again.
On the other hand, when it is determined in step S6 that there is an end command (step S6: Yes), the focal position control unit 2 ends the process.

  As described above, in the acoustic system according to the present embodiment, the plurality of ultrasonic wave generating elements 11 are arranged on the virtual curved surface S. The focal position control unit (curvature setting unit) 2 can set the sizes of the target areas (listening areas) AR3 and AR4 by adjusting the curvature radius r1 of the curved surface of the parametric speaker. As a result, the sizes of the target areas (listening areas) AR3 and AR4 can be changed relatively easily.

  The focal position control unit 2 adjusts the radius of curvature r1 of the virtual curved surface S in accordance with the required target areas (listening areas) AR3 and AR4. Thus, if the curvature of the curved surface is set so that the region where the listener to whom the sound should be heard exists is included in the listening region, the listener can be surely heard.

  In the acoustic system according to the present embodiment, the listener detection unit 4 detects the presence position of the listener P and the number of listeners P. Then, the focal position control unit 2 adjusts the radius of curvature r1 of the virtual curved surface S of the parametric speaker 1 based on the presence position of the listener P detected by the listener detection unit 4 and the number of the listeners P. Accordingly, the sizes of the target areas AR3 and AR4 can be appropriately set according to the position where the listener P exists and the number of the listeners P.

<4> Summary After all, the acoustic space setting method according to the present embodiment changes the radius of curvature R1 (R2, R0) of the virtual curved surface S on which the plurality of ultrasonic wave generating elements 11 are arranged, thereby increasing the size of the listening area. To change. Therefore, for example, the size of the listening area can be changed relatively easily compared to an acoustic space setting method in which the size of the listening area is changed using a plurality of parametric speakers. Note that the radius of curvature R1 (R2, R0) of the virtual curved surface S is a relational expression established between the distance L1 between the speaker listening areas, the size of the element placement area AR10, and the size of the listening area AR1 (AR2, AR0) ( It sets based on Formula (1)).

  In addition, since the size of the listening area AR1 (AR2, AR0) is larger than the size of the element arrangement area AR10, for example, it is possible to make sounds to a plurality of listeners existing in a wider range than the element arrangement area AR10. It becomes possible.

  In addition, the parametric speaker 1 according to the present embodiment includes a support member 12 to which a plurality of ultrasonic wave generating elements 11 are attached in a form arranged on the virtual curved surface S, and the curvature of the virtual curved surface S can be changed. Thereby, the focal position F1 (F2) of the virtual curved surface S can be changed by changing the radius of curvature r1 of the virtual curved surface S, so that the size of the listening area AR1 (AR2, AR0) of the parametric speaker 1 is increased. It becomes possible to change.

  Further, in the parametric speaker 1 according to the present embodiment, the support member 12 includes a plurality of fixing members 12a and two flexible members 12b that support both end portions in the longitudinal direction of the plurality of fixing members 12a. . Then, as the two flexible members 12b are bent, the focal position F1 (F2) of the modulated wave emitted from the plurality of ultrasonic wave generating elements 11 is changed. Thus, since the focal position F1 (F2) can be changed by providing a mechanism for bending the flexible member 12b, the listening area AR1 (AR2, AR0) of the parametric speaker 1 can be mechanically changed. It becomes easy.

<Modification>
(1) In the embodiment, the example in which the curvature of the virtual curved surface S on which the plurality of ultrasonic generating elements 11 are arranged has been described. However, for example, a plurality of super members are respectively provided on a plurality of types of support members having different curvatures of the virtual curved surface. The structure to which the sound wave generating element 11 is attached may be used.
FIG. 14 is a block diagram of an acoustic system according to this modification.
The acoustic system according to this modification includes a parametric speaker 201, a direction control unit 202, and a signal generation device 3. In addition, about the structure similar to embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted suitably.
The parametric speaker 201 includes a plurality of sub-speakers 211A to 211C, one main support member 213 to which all of the plurality of sub-speakers 211A to 211C are attached, and a switching unit 217, according to the embodiment. 1 is different.

  The sub-speaker 211A (211B, 211C) includes a plurality of ultrasonic generation elements 11 and a sub-support member 212A (212B, 212C) that supports the plurality of ultrasonic generation elements 11. The plurality of sub-speakers 211A to 211C have different radii of curvature R21A to R21C of the virtual curved surfaces SA to SC on which the plurality of ultrasonic wave generating elements 11 are arranged. For example, the radius of curvature R21A of the virtual curved surface SA corresponding to the sub speaker 211A is the smallest, and the radius of curvature R21C of the virtual curved surface SC corresponding to the sub speaker 211C is the largest. The curvature radius of the virtual curved surface corresponding to each of the plurality of sub-speakers including the sub-speaker 211B is set to a size between the curvature radii R21A to R21C.

The switching unit (curvature setting unit) 217 switches the sub-speakers 211 </ b> A to 211 </ b> C that receive the modulated wave input from the modulation unit 15. Specifically, when receiving the command information for enlarging the listening area, the switching unit 217 inputs the modulated wave to the sub-speaker having a small curvature radius. On the other hand, when receiving the command information for reducing the listening area, the switching unit 217 inputs the modulated wave to the sub-speaker having a large curvature radius.
The orientation control unit 202 controls the orientation of the attachment surfaces of the plurality of sub-speakers 211A to 211C in the main support member 213.

  According to this configuration, a mechanism such as the support member variable portion 13 that changes the radius of curvature of the support member 12 to which the plurality of ultrasonic wave generating elements 11 are fixed, such as the acoustic system according to the embodiment, is not necessary. Therefore, the structure of the parametric speaker 201 can be simplified.

(2) In the embodiment, the example in which the curvature of the virtual curved surface S on which the plurality of ultrasonic wave generating elements 11 are arranged is changed by changing the shape of the support member 12 is described. However, the curvature of the virtual curved surface S is changed. The configuration to be made is not limited to this. For example, when a parametric speaker body is attached to a mold member having a predetermined curvature, the parametric speaker body may be deformed along the mold member.

15A and 15B show a parametric speaker 301 according to the present modification, in which FIG. 15A is a schematic perspective view showing an operation for changing the shape of the parametric speaker main body 301a, and FIG. 15B shows the shape of the parametric speaker main body 301a. It is a schematic perspective view which shows the state.
A parametric speaker 301 according to this modification includes a parametric speaker main body 301a and a mold member 301b. Here, the mold member 301b includes a first part 323 where the parametric speaker main body 301a is disposed, and a second part 324 which is continuous with the first part 323 and guides the parametric speaker main body 301a to the first part 323. . The contact surface with which the parametric speaker main body 301a contacts in the first part 323 is curved in an arch shape. The radius of curvature of the contact surface at the first portion 323 is set in advance based on the size of the listening area and the distance from the parametric speaker 301 to the listening area.

In addition, holding portions 321 that hold both ends of the parametric speaker main body 301a in the width direction are provided at both ends in the width direction of the mold member 301b.
As shown in FIG. 15A, before use, first, the parametric speaker body 301a is held at both ends in the width direction by the holding portions 321 from the second portion 324 side of the mold member 301b to the first portion 323. Slide in the state.
And as shown in FIG.15 (b), the parametric speaker main body 301a is arrange | positioned in the 1st site | part 323 of the type | mold member 301b.

  According to this configuration, if a plurality of types of mold members having different shapes are prepared, the size of the listening area can be changed.

(3) In the sound system according to the embodiment, for example, when the seat position can be grasped in advance as in a movie theater or the like, the focal position control unit 2 determines the direction of the parametric speaker 1 based on the seat position. The focal length may be controlled. Specifically, the focal position control unit 2 may hold table data indicating the relationship between the seat identification information of each seat and the direction of each seat when viewed from the parametric speaker 1. Then, the focal position control unit 2 may control the direction of the parametric speaker 1 with reference to the table data.

FIG. 16 is a diagram illustrating a usage example of the acoustic system according to the present modification. FIG. 17 is a diagram illustrating an example of table data held by the focal position control unit 2 according to the modification.
Here, it is assumed that the focal position control unit 2 can change the direction of the parametric speaker 1 into a vertical direction (longitudinal direction) and a direction orthogonal to the vertical direction (lateral direction), for example. Then, the focal position control unit 2 can change only the radius of curvature of the cross section perpendicular to the vertical direction of the parametric speaker 1.

In this case, as shown in FIG. 17, the table data indicates the relationship between the seat identification information of each seat and two types of angles that specify the direction of each seat (for example, the direction of the center of each seat). And it is sufficient.
Then, the focal position control unit 2 refers to the table data and calculates the direction (lateral angle) of the parametric speaker 1 based on, for example, the relational expression shown in the following formula (6).
... Formula (6)
Here, θs is an angle indicating the lateral position of the central portion of the listening area, θj is an angle indicating the lateral position of the seat of the identification number j, and m1 and m2 are lateral directions of both ends of the listening area. It is an identification number indicating the position of.
That is, the focal position control unit 2 sets the direction of the parametric speaker 1 to the direction represented by the angle coordinates (θs, φk).
The focal position control unit 2 also has a virtual curved surface S on which the plurality of ultrasonic generating elements 11 in the parametric speaker 1 are arranged according to the number of seats included in the listening area based on the relational expression of the above formula (1). Set the radius of curvature.

  For example, as indicated by a one-dot chain line in FIG. 16, it is assumed that sound is delivered from the parametric speaker 1 to a person sitting in three seats “3-C” to “3-E”. In this case, the focal position control unit 2 sets the direction of the parametric speaker 1 to the direction represented by the angle coordinates ((θ3 + θ4 + θ5) / 3, φ3) based on the table data and the above equation (6). In addition, the focal position control unit 2 sets the curvature radius R41 of the virtual curved surface S so that the three seats “3-C” to “3-E” are within the listening area AR41.

  Further, as indicated by a broken line in FIG. 16, it is assumed that sound is delivered from the parametric speaker 1 only to a person sitting on one seat “5-B”. In this case, the focal position control unit 2 sets the direction of the parametric speaker 1 to the direction represented by the angle coordinates (θ2, φ5) based on the table data and the above equation (6). Further, the focal position control unit 2 sets the curvature radius R42 of the virtual curved surface S so that one seat “5-B” enters the listening area AR42.

In this modification, the focal position control unit 2 may be able to change only the radius of curvature of the cross section parallel to the vertical direction of the parametric speaker 1. In this case, the focal position control unit 2 may calculate the vertical angle of the parametric speaker 1 based on, for example, the relational expression shown in the following formula (7) with reference to the table data.
... Formula (7)
Here, φs is an angle indicating the vertical position of the central portion of the listening area, φk is an angle indicating the horizontal position of the identification number k, and n1 and n2 are horizontal positions of both ends of the listening area. Is an identification number.

  According to this configuration, for example, when the scheduled listening area planned to be included in the listening area is known in advance, if the information indicating the planned listening area is registered in the table data, the focal position control unit 2 The table data can be referred to and included in the listening area. Therefore, since the focal position control unit 2 can omit the process of calculating the direction of the parametric speaker 1, the processing load on the focal position control unit 2 can be reduced.

(4) In the parametric speaker 1 according to the embodiment, the example in which the virtual curved surface S on which the plurality of ultrasonic generating elements 11 are arranged is a cylindrical side surface has been described. However, the shape of the virtual curved surface S is limited to this. It is not something. For example, the shape of the virtual curved surface S may be a parabolic curved surface or a spherical shape. Further, the shape of the virtual curved surface S may be a conical side surface.
In particular, when the virtual curved surface S has a conical side surface shape, the listening area of the parametric speaker is selected by selecting the ultrasound generating element 11 that generates a modulated wave from the plurality of ultrasound generating elements 11 based on the position thereof. Can be changed.

  Specifically, it is assumed that the distance between the parametric speaker 1 and the listening area (distance between the speaker listening areas) is constant. In this case, if a modulated wave is generated only from the ultrasonic wave generating element 11 positioned on the conical tip portion side of the virtual curved surface S, the focal position of the virtual curved surface S is set to a position relatively close to the parametric speaker 1, The listening area becomes large. On the other hand, if the modulated wave is generated only from the ultrasonic wave generating element 11 located on the cone base end side of the virtual curved surface S, the focal position of the virtual curved surface S is set at a position relatively far from the parametric speaker 1, The listening area becomes smaller.

(5) In the parametric speaker 1 according to the embodiment, the support member variable portion 13 flexes the flexible member 12b to have a predetermined radius of curvature by appropriately changing the position of the flexible member support portion 13b. An example of forming the virtual curved surface S has been described. However, the mechanism for forming the virtual curved surface S is not limited to this. For example, the flexible member 12b may be made of bimetal. In this case, the parametric speaker adjusts the voltage applied to the flexible member 12b made of the bimetal, thereby deforming the flexible member 12b into a predetermined shape to form a virtual curved surface S (see FIG. (Not shown).

  According to this configuration, the structure of the parametric speaker can be simplified.

(6) In the acoustic system according to the embodiment, an example has been described in which the listener detection unit 4 acquires information on the location and number of listeners from an image obtained by capturing with the camera 42. However, the configuration of the listener detection unit 4 is not limited to this. For example, the location of the listener, the number of the listeners, and the like are detected by detecting a radio signal transmitted from the tag device held by each listener. The information regarding may be acquired.

In this case, the listener detection unit 4 may be configured to include, for example, a plurality of wireless receivers and a signal analysis device. Here, the plurality of wireless receivers are installed at a plurality of locations within a range where sound radiated from the parametric speaker 1 can reach. The signal analysis device acquires the strength of the radio signal received by each radio receiver and analyzes the radio signal received by each radio receiver to obtain identification information given to each tag device.
Here, the signal analysis device acquires information on the location and number of tag devices based on the position information of each of the plurality of wireless receivers and the radio wave intensity received by each wireless receiver.

  According to this configuration, it is possible to accurately grasp the position and the number of the listeners who possess the tag device, so that the sound can be reliably delivered to the listeners.

<Appendix>
The present invention is not limited to the above embodiment, and can be appropriately changed within the scope described in the claims.

  The acoustic space setting method according to the present invention is suitable for an acoustic system used for transmitting audio information only to a listener who exists in a specific listening area, for example, in an exhibition hall or a concert hall.

1,201,301 Parametric speaker 2 Focus position control unit (curvature setting unit)
DESCRIPTION OF SYMBOLS 3 Signal generation apparatus 4 Hearing person detection part 11 Ultrasonic wave generation element 12 Support member 12a Fixing member 12b Flexible member 13 Support member variable part 13a Main body part 13b Flexible member support part 14 Amplification part 15 Modulation part 16 Carrier wave generation part 31 Signal Source 32 Filter processing unit 41 Image processing unit 42 Camera 202 Orientation control unit 211A, 211B, 211C Sub speaker 212A, 212B, 212C Sub support member 213 Main support member 217 Switching unit (curvature setting unit)
301a Parametric speaker body 301b Mold member 321 Holding part 323 First part 324 Second part AR0, AR1, AR2, AR41, AR42 Listening area AR3, AR4 Target area (listening area)
AR10 element arrangement area F1, F2, F0 focal position J1, J2 central axis L1 distance between speaker listening areas L21, L22, L23 focal distance R0, R1, R2, R3, R4, R21A, R21B, R21C, R41, R42 radius of curvature S, SA, SB, SC Virtual curved surface

Claims (11)

An acoustic space setting method using a parametric speaker having a plurality of ultrasonic wave generating elements that emit a modulated wave obtained by modulating a carrier wave in a sound wave band with a signal wave in an audible band,
The plurality of ultrasonic generating elements are arranged on a curved surface,
The focal position of the curved surface is defined between the element arrangement area where the plurality of ultrasonic wave generating elements are arranged on the curved surface and the listening area of the parametric speaker, and the listening area side with respect to the element arrangement area. By setting the curvature of the curved surface so that it exists on either one of the opposite sides, the listening area becomes larger as the distance from the focal position along the central axis of the parametric speaker increases. Method. The acoustic space setting method according to claim 1, wherein the curvature of the curved surface is set based on the size of the listening area. Based on the relational expression established between the curvature of the curved surface, the size of the listening area, the distance between the speaker listening areas between the parametric speaker and the listening area, and the size of the element arrangement area, The method for setting an acoustic space according to claim 2. The acoustic space setting method according to claim 3, wherein the relational expression is represented by the following expression (1).
... Formula (1)
A1: The size of the projection area on the plane perpendicular to the central axis of the parametric speaker in the element arrangement area, A2: The size of the projection area on the plane of the listening area, L1: The distance between the speaker listening areas, r1: radius of curvature of the curved surface The acoustic space setting method according to claim 3, wherein the relational expression is represented by the following expression (2).
... Formula (2)
A1: The size of the projection area on the plane perpendicular to the central axis of the parametric speaker in the element arrangement area, A2: The size of the projection area on the plane of the listening area, L1: The distance between the speaker listening areas, r1: radius of curvature of the curved surface The acoustic space setting method according to any one of claims 1 to 5, wherein a size of the listening area is larger than a size of the element arrangement area. A plurality of ultrasonic wave generating elements that emit a modulated wave obtained by modulating a carrier wave in an ultrasonic band with a signal wave in an audible band;
A parametric speaker, comprising: a support member in which the plurality of ultrasonic wave generating elements are attached in a form arranged on a curved surface, and the curvature of the curved surface is variable. The support member is
A plurality of fixing members formed in the shape of an elongated bar and having a plurality of ultrasonic generating elements fixed along the longitudinal direction thereof;
Two flexible members that are formed in an elongated plate shape and are arranged so that one end faces in the short-side direction face each other and support both ends in the longitudinal direction of the plurality of fixing members,
The parametric speaker according to claim 6, wherein the curvature of the curved surface changes when the two flexible members bend. A signal generator for generating an audible signal wave;
A carrier generation unit that generates a carrier wave in an ultrasonic band, and a parametric speaker having a plurality of ultrasonic wave generation elements that radiate modulated waves obtained by modulating the carrier wave with the signal wave;
And a curvature setting unit that sets a size of a listening area corresponding to the parametric speaker by adjusting a curvature of a curved surface on which the plurality of ultrasonic generation elements are arranged. The acoustic system according to claim 9, wherein the curvature setting unit adjusts the curvature of the curved surface according to a required size of the listening area. A listener detection unit for detecting the location of the listener and the number of listeners;
The acoustic system according to claim 10, wherein the curvature setting unit adjusts the curvature of the curved surface based on the presence position of the listener detected by the listener detection unit and the number of listeners.