JP3273561B2 - Sound image localization loudspeaker method and loudspeaker system using distributed speakers - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and system for sound localization using a distributed loudspeaker, and more particularly to a technique for loudspeaking voices and performance sounds in a space used for lectures, ceremonies, conferences and other gatherings. .

[0002]

2. Description of the Related Art FIG. 16A shows a centralized loudspeaker system as an example of a conventional loudspeaker system, and FIG. 16B shows a distributed loudspeaker system as another example. In the centralized loudspeaker system, a microphone is installed near a sound source O such as a speaker or a performer, and a sound pressure change caused by vocalization or the like is amplified by a microphone amplifier and a power amplifier.
To transmit the sound from the sound source O to the listener 2. The speakers S are usually arranged on both sides of the stage. In the distributed arrangement loudspeaker system, the sound of the sound source O is simultaneously loudspeaked from a plurality of speakers S0 to S4 arranged at fixed intervals on a ceiling or the like. FIGS. 17A and 17B show the time when the loud sound from each speaker reaches the sound receiving point (hereinafter referred to as the loud sound arrival time) and the sound receiving point in the centralized loudspeaker system and the distributed loudspeaker system. An example of the relationship with the sound pressure level of the loudspeaker sound (hereinafter, referred to as loudspeaker arrival sound pressure level) will be described.

However, the conventional centralized loudspeaker system and the distributed loudspeaker system have the following problems.

(1) The viewing direction is different from the audible direction. In the centralized loudspeaker system with speakers on both sides of the stage, when the seat position is on the right side of the symmetry axis at the center of the stage, the voice of speaker O is heard from the right speaker and the speaker O comes to the center of the field of view. On the left, speaker O from the left speaker
Can be heard. Further, in the distributed arrangement and loudspeaker system, the voice of the speaker O on the stage can be heard from the overhead speaker above. In any of the methods, there is a problem that the recognition direction of the speaker O is different for the listener 2 between the sight and the hearing.

(2) Sound is blurred and heard. In the distributed arrangement loudspeaker system, as shown in FIG. 17 (B), the sound arriving at the sound receiving point from the plurality of speakers S0 to S4 is displaced in direction and time. As a result, many peaks and valleys occur in the frequency characteristic at the sound receiving point. As a result, the sound of the sound source is blurred and unclear at the sound receiving point.

(3) The volume of the sound becomes unnatural. In the concentrated diffusion method, by disposing the speaker S near the center of the stage, it is possible to eliminate the mismatch between the visual and auditory directions.
However, the intensity of the sound is significantly different between a place close to the stage and a place far from the stage, and there is a problem that the sound is noisy near and cannot be heard far away. On the other hand, if all the distributed speakers are loudspeaked at the same volume, a uniform sound field can be obtained, but there is a problem that the listener feels that the speaker's appearance and sound volume are unnatural. If you hear the sound at the same volume as the approached position even at a position away from the speaker, it is significantly different from the daily experience, that is, the experience that the voice decreases when you are away from the speaker,
The sound feels unnatural. It is said that this unnaturalness impairs the feeling (interactivity) being spoken by the speaker, and produces results such as being unable to concentrate on the talk and not being able to convey what they want to say.

As a loudspeaker method for solving the above-mentioned problem, as shown in FIG. 16C, a main sound source speaker (main speaker) S0 is arranged near a sound source O and distributed on a ceiling remote from the sound source. There is a semi-dispersed loudspeaker system in which speakers S1 to S3 are arranged. In this method, in order to obtain a feeling that sound comes from the speaker direction even at a sound receiving point close to the distributed speaker (sound image localization in a direction coinciding with the speaker direction), the sound emission time of the distributed speaker is compared with the sound time of the main speaker. Is controlled to delay. Each speaker S0 ~ by semi-dispersion loudspeaker system
FIG. 17C shows an example of the relationship between the arrival time and the reached sound pressure level at the sound receiving point of the loud sound from S3.

The direction of sound image localization is based on human auditory perception called a precedence effect. The precedence effect is described in, for example, FIG.
As shown in (B), when a sound (preceding sound) from the direction of the speaker A is heard at the sound receiving point, a certain range of time delay and a certain range of sound pressure level difference from the speaker B in another direction are heard. This is an psychoacoustic effect in which another sound (reinforcement sound) that arrives is localized in the direction of the speaker A (the direction of the preceding sound). FIG.
(A) is the arrival time difference between the preceding sound and the reinforcement sound at which the preceding sound effect is obtained at the sound receiving point (delay time, Tb−Ta = reception time of the sound receiving point of the reinforcement sound−the sound receiving point of the preceding sound). The relationship between the arrival time) and the arrival sound pressure level difference (Lb-La = the arrival sound pressure level at the sound receiving point of the reinforcement sound-the sound pressure level at the sound receiving point of the preceding sound) is shown. The hatched area in the figure is the area where the preceding sound effect can be obtained, that is, the sound image localization area. The precedence effect may be called the Haas effect or the first wavefront law.

In the half-dispersion loudspeaker system, as shown in FIG. 17C, control is performed so that the sound from the main speaker S0 reaches the listener 2 at the sound receiving point first. Distributed speakers S1 ~
Reinforcement sound from S3 (hereinafter sometimes referred to as subsequent sound)
Controls to reach the listener 2 at the sound receiving point with a time delay of about 10 ms from the preceding sound from the main speaker S0 and a sound pressure level difference within a certain range shown in FIG. 8A. By controlling the arrival time and arrival sound pressure level of the loudspeakers from the speakers S0, S1 to S3 in this manner, it is possible to localize the sound image in the direction of the main speaker at the sound receiving point.

[0010]

However, in the conventional semi-dispersion loudspeaker system, the main speaker S0 and the dispersion speakers S1 to S3
There is a problem that it is difficult to obtain the sound image localization at all the sound receiving points in the sound field due to the difference of the timbres. To obtain the preceding sound effect, it is necessary that the timbre of the preceding sound and the succeeding sound, that is, the frequency characteristics be close. Especially in the middle frequency range (250Hz-1kHz
In z), it is necessary that there is no difference in frequency characteristics between the preceding sound and the following sound. In the semi-dispersed loudspeaker system, the main speaker S0 and the dispersed loudspeakers S1 to S3 have different performances due to the difference in their roles, so that the loudspeakers from both speakers have the same frequency characteristics at all the sound receiving points in the sound field. It is difficult to convey the sound, and the occurrence of a sound receiving point where the preceding sound effect cannot be obtained is inevitable.

In addition, the half-dispersion loudspeaker method has a problem that it cannot cope with a change in the position of a sound source. In order to obtain the sound image localization, it is necessary that the difference between the direction of the speaker (sound source) viewed from the listener and the direction of the preceding sound speaker is within a certain allowable range.
Referring to FIG. 7, the speaker (sound source) and the listener (sound receiving point)
Assuming that the preceding sound speaker is on the XZ plane on the opposite side (positive side and negative side) of the origin on the Y axis on the XY plane (horizontal plane) and the speaker direction (Y A range of ± 10 degrees in the X-axis direction and ± 45 degrees in the Z-axis (vertical) direction with respect to the (axial direction) (the range indicated by oblique lines in the drawing) is the allowable arrangement range of the preceding sound speaker. When the position of the speaker changes in the semi-dispersed loudspeaker system, for example, when the stage position changes, the main speaker S0 must be moved within the permissible range in FIG. 7 in accordance with the position of the speaker. In this case, it is difficult to move the main speaker S0. Further, even when a questioner or the like appears at an unspecified position in the audience seat, it is impossible to localize the sound image to the questioner. For this reason, there have been problems such as the position of the questioner cannot be found in a large lecture hall or the like. It is desired to develop a loudspeaker method in which the direction of sound image localization changes according to the change in the position of a sound source or the appearance of a questioner.

Further, in the semi-dispersion loudspeaker system, there is a problem that the difference between the transmission characteristics from the main speaker S0 and the transmission characteristics from the distributed speakers S1 to S3 to both ears of the listener 2 is out of an allowable range. In order to obtain the preceding sound effect, it is necessary that the transmission characteristics of the preceding sound speaker and the subsequent sound speaker to both ears of the listener 2 be similar. That is, the direction of the preceding sound speaker and the direction of the following sound speaker as viewed from the sound receiving point must be within a predetermined allowable range. The preceding sound speaker needs to be within the range indicated by the hatched area in FIG. 7, that is, within ± 10 degrees in the horizontal direction and ± 45 degrees in the vertical direction with respect to the sound source direction when viewed from the sound receiving point. It is desirable that the subsequent sound speaker is located within a cone having a vertical angle of 90 degrees with the central axis line immediately above (vertically) the sound receiving point. In the semi-variant loudspeaker system
It is difficult to arrange the main speaker S0 and the dispersed speakers S1 to S3 so that the transmission characteristics for the listener's both ears are within an allowable range, and a sound receiving point where a preceding sound effect cannot be obtained may occur.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a sound image localization loudspeaker using a distributed speaker and a loudspeaker system which can change the direction of sound image localization in accordance with the direction of a sound source.

[0014]

Referring to the embodiment of FIG. 1, a sound image localization and loudspeaker method using a distributed speaker according to the present invention will be described.
A plurality of loudspeakers Sj (1 ≦ j ≦ n) having substantially the same acoustic characteristics used for loudspeaking of the sound of the sound source O are distributed downward at predetermined positions above the sound receiving surface Ph by partially overlapping the cover areas of adjacent speakers. A portion on the sound receiving surface Ph vertically below each speaker Sj is set as a sound receiving point Pi (1 ≦ i ≦ n); a speaker closest to the sound source O among the speakers Sj is selected as a main speaker So; Surrounding speakers Sgx (x = 1, with the remaining speakers ranked in ascending order of distance from the main speaker So)
2, ..., (n-1)); sound source O from main speaker So
At the required input power at time zero with no time delay; for each of the peripheral speakers Sgx, in ascending order of the rank, a sound receiving point Pgx (for example, Pgx) below the peripheral speaker Sgx (for example, Sg ₁₅ ). _{In 15} ), the loudspeaker arrival time Txx from the peripheral speaker Sgx is the loudspeaker arrival time T from the main speaker So.
ox, the peripheral speaker Sgx (for example, Sxx) that is delayed by a delay time Δtx that gives a preceding sound effect (Txx = Tox + Δtx)
g ₁₅ ) is calculated, and the sound receiving point Pgx (eg, P
g ₁₅₎ in the peripheral speaker SGX (e.g. near a speaker of the lower rank arriving ahead amplified sound arrival time Txx from _{Sg 15) Sgk (k = 1,2} , ......, (x-1)) and the main The sum of the reached sound pressure levels of the loudspeakers from the speaker So is obtained as a function of the distance from each speaker Sgk and So to the sound receiving point Pgx and the input power and acoustic characteristics of each speaker Sgk and So. The sound pressure level Lxx at the sound receiving point Pgx (for example, Pg ₁₅ ) from the surrounding speaker Sgx (for example, Sg ₁₅ ) that is higher than the sum obtained by the sound pressure level difference ΔLx that gives a precedence effect. The input power of the peripheral speaker Sgx (for example, Sg ₁₅ ) corresponding to the determined arrival sound pressure level Lxx is calculated; the loud sound of the sound of the sound source O is calculated from each of the peripheral speakers Sgx at the calculated sounding time. With the calculated input power By sound, the localization direction of the sound image at each receiving point Pi sound O
It is the direction toward F.

[0015] Preferably, the predetermined target sound pressure level Lhc that the upper limit of the listening sound pressure level at each receiving point Pi provided, each peripheral speakers SGX (e.g. Sg ₁₅₎ below the receiving point Pgx (e.g. Pg _{1 5)} The listening sound pressure level at the surrounding speaker Sg
, and the lower-order peripheral speakers Sgk (k = 1, 2,...,
(X-1)) and the sum of the sound pressure levels reached by the main speakers So, and the peripheral speakers Pgx (eg, Sg) when the sum exceeds the target sound pressure level Lhc.
g ₁₅₎ of as inhibiting said sum coincides with the target sound pressure level Lhc within a precedence effect of the amplified sound reaching the sound pressure level Lxx is obtained.

More preferably, as shown in FIG. 5, the level of the predetermined target sound pressure level Lhc is reduced according to the distance from the sound source O, and the slope of the reduction with respect to the distance is smaller than the slope of the attenuation in the free sound field. With the inclination-type target sound pressure level Lhc, the listening sound pressure level at each sound receiving point Pi on the sound receiving surface Ph is gently reduced according to the distance from the sound source O.

Referring to the embodiment of FIG. 1, the sound image localization and loudspeaker system using the distributed loudspeaker of the present invention comprises a sound receiving surface Ph.
A loudspeaker Sj (1 ≦ j ≦ n) having substantially the same acoustic characteristics, in which a cover area of an adjacent speaker is partially overlapped with a cover area of an upper speaker at an upper predetermined position and distributed downward, and an acoustic signal from a sound source O is transmitted to each of the speakers Sj. Signal transmission device 10 for transmitting to a speaker Sj which is provided between the signal transmission device 10 and each speaker Sj and adjusts the sounding time and input power of an acoustic signal for each speaker Sj according to an instruction input. Signal conditioning device 2
0; speaker selection means 31 for selecting the speaker closest to the sound source O among the speakers Sj as the main speaker So; speakers Sj other than the main speaker So as peripheral speakers Sgx (x = 1,
2,..., (N-1)), a speaker ranking means 32 for ranking in ascending order of the distance from the main speaker So; a main speaker sound instructing means 33 for instructing a sounding time and an input power of the main speaker So; Vertically lower sound receiving surface of each speaker Sj
A sound receiving point Pi (1 ≦ i ≦ n) is defined on Ph, and the surrounding speakers Sg
x, the surrounding speakers S
gx (e.g. Sg ₁₅₎ below the receiving point Pgx (e.g. Pg ₁₅₎ by the delay time amplified sound arrival time Txx from the peripheral speaker Sgx gives precedence effect to amplified sound arrival time Tox from the main speaker So. Delta] tx Calculating the sounding time of the peripheral speaker Sgx (for example, Sg ₁₅ ), which is delayed only by (Txx = Tox + Δtx),
The surrounding speaker Sgx is placed at the sound receiving point Pgx (for example, Pg ₁₅ ).
(Eg, Sg ₁₅ ), the lower-order peripheral speakers Sgk (k = 1, 2,...) That arrive before the loudspeaker arrival time Txx.
, (X-1)) and the sum of the sound pressure levels reached by the main speakers So from the respective speakers Sgk and So.
gx as a function of the input power and acoustic characteristics of each speaker Sgk and So, and the surrounding speaker Sgx (eg, Sg) at the sound receiving point Pgx (eg, Pg ₁₅ ).
g ₁₅ ), the loudspeaker reaching sound pressure level Lxx is determined to be higher than the sum obtained by the sound pressure level difference ΔLx that gives the preceding sound effect, and the peripheral speakers corresponding to the determined reaching sound pressure level Lxx An input power of Sgx (for example, Sg ₁₅ ) is calculated, and peripheral loudspeaker sound instructing means 34 for instructing the calculated sounding time and input power is provided. By inputting the power instruction to the signal adjusting device 20, the localization direction of the sound image at each sound receiving point Pi becomes the direction toward the sound source O.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiment of FIG. 1 shows an embodiment in which 25 speakers Sj (1.ltoreq.j.ltoreq.25) are distributed downward above a sound receiving surface Ph. The sound receiving surface Ph is a virtual surface assumed at the height position h of the ear of the listener 2 on the floor surface 6, for example. Although FIG. 2 shows a horizontal sound receiving surface Ph parallel to the floor 6, the sound receiving surface Ph targeted by the present invention is not limited to a horizontal surface. It is desirable from the viewpoint of signal adjustment control described later that the speakers Sj are disposed above the sound receiving surface Ph at a certain height and downward so that the distance between them is constant.

However, the distributed arrangement of the loudspeakers Sj of the present invention is not necessarily limited to the distributed arrangement at a fixed height and at an interval. For example, if there is a step on the ceiling, the height from the sound receiving surface Ph to each speaker Sj is not constant, but the sound receiving surface Ph is changed by changing the input power of each speaker Sj according to the difference in height. The difference in sound pressure of the loudspeaker above can be compensated. Also, as described later, if the overlap of the cover areas of the adjacent speakers Sj can be obtained, for example, about 20% or more, the intervals between the speakers Sj do not need to be constant.

In FIG. 1, a plurality of speakers Sj having substantially the same acoustic characteristics are used, and are arranged at a height H where a portion of the cover area of an adjacent speaker, for example, about 20%, overlaps on the sound receiving surface Ph. . Rather than using a main speaker different from a distributed speaker as in the semi-dispersive loudspeaker system,
For example, by using speakers Sj having substantially the same acoustic characteristics such as sound pressure frequency characteristics and directivity coefficients, each speaker Sj
, So that the precedence effect can be prevented from being hindered by a difference in tone on the sound receiving surface Ph. Also, for example, one octave band centered at 1 kHz, preferably 5 octave bands
By partially superimposing the cover area of the band of 00 Hz to 2 kHz, a region where the sound of the band does not reach on the sound receiving surface Ph is avoided, and the preceding sound effect is obtained at any position on the sound receiving surface Ph. To make things possible.

Generally, the characteristic A ₀ (f) of the speaker Sj is on the front axis of the speaker (horizontal direction 0 °, vertical direction 0 °) when a 1 (watt) signal is input at a frequency f (Hz). 1m
Is defined as the squared sound pressure P ² (the unit is the square of Pa (Pascal), that is, Pa ² ). Sound pressure level L
, As shown by the following equation (1) is defined as the square sound pressure P ² of the sound pressure P ₀ reference (Pa) of 20MyuPa. In the following description, the squared sound pressure P ² (P ² / P based on the sound pressure P _{0 of} 20 μPa)
P ₀ ² ) is represented as the squared sound pressure I.

The sound pressure frequency characteristic of the speaker is 1 (watt)
Sound pressure level L at 1 m point on the front axis of the speaker during signal input
Is defined as the frequency characteristic of Also, if the sound pressure in the horizontal directivity direction φ and the vertical directivity direction θ is represented by A (f, θ, φ) and A ₀ (f) is represented by A (f, 0, 0), the directivity coefficient D (f,
θ, φ) are defined as in the following equation (2). Distance R in the direction of horizontal pointing direction φ and vertical pointing direction θ with respect to the speaker
The squared sound pressure I of the loudspeaker reaching the sound receiving point separated by (m)
And the sound pressure level L are, as shown in the following equations (3) and (4), the distance R (m) from the speaker S to the sound receiving point, the directivity coefficient D (f, θ, φ) of the speaker. , And a function of the sound pressure frequency characteristic A (f) of the speaker and the input power W (watt).

[0023]

[Number 1] Sound pressure level ^{L = 10log (P 2 / P} 0 2) (dB) = 10logI (dB) ........................ (1) Oriented coefficient D (f, θ, φ) = A ( f, θ, φ) / A (f, 0, 0) (2) Squared sound pressure I of sound receiving point P = W · D (f, θ, φ) · A (f) / R ² (dB) ……………… (3) Sound pressure level of sound receiving point P = 10 · log ｛W · D (f, θ, φ) · A (f) / R ² ｝ (dB)… (4)

In FIG. 1, only speakers Sj having the same acoustic characteristics such as sound pressure frequency characteristics and directivity coefficients are used. FIG.
In the graph of (B), the sound pressure level L is -6 dB with respect to the front axis.
6 shows a directional frequency characteristic of an attenuating opening angle (directivity angle).
For example, when the speaker having the directional frequency characteristic shown in FIG. 9B is selected as the distributed speaker Sj of the present invention, since the directional angle at 1 kHz is about 85 to 90 degrees, the directional angle and the superimposition rate of the cover area are determined. The arrangement height of each speaker Sj from the sound receiving surface Ph can be designed in consideration of the above. The speaker arrangement shown in FIG. 1 is an example in which speakers having the directional frequency characteristics shown in FIG. 9 are dispersedly arranged.

However, the speakers Sj used in the present invention are not necessarily limited to the same type. For example, one octave band centered at 1 kHz, preferably 500 Hz to 2 kHz
When there is little difference in sound quality between the bands and the sound characteristics are substantially the same, different types of speakers can be used.

The distance between the distributed speakers Sj is determined so that the transmission characteristics of the two speakers Sj in the direction of the sound source O with respect to the sound receiving point are similar. As will be described later, in the present invention, the speaker Sj closest to the sound source O is set as the preceding sound speaker, and the sound source O
Speaker Sj in the direction from the sound to the sound receiving point (listener 2)
Is used as a subsequent sound speaker to localize the sound image. By appropriately designing the distance between the distributed speakers Sj in consideration of the relationship with the arrangement height, at any sound receiving point on the sound receiving surface Ph, the sound source direction with respect to both ears of the preceding sound speaker and the succeeding sound speaker The difference in transmission characteristics can be set within an allowable range in which sound image localization is possible.

Further, in the above-described arrangement of the speakers Sj, the deviation between the direction of the sound source O and the direction of the preceding sound speaker as viewed from the sound receiving point falls within the allowable range shown in FIG. For example, in FIG. 1, when the speaker O is below any of the other speakers Sj as viewed from the listener 2 below the speaker S5, the speaker Sj above the speaker with respect to the direction of the speaker O is shown in FIG. Since the speaker is located within the allowable range, a sound image localization can be obtained using the speaker above the speaker as a preceding sound speaker. That is, in the present invention, a plurality of speakers Sj are dispersedly arranged at predetermined positions that satisfy the height at which the cover area is superimposed, the mutual interval at which similar transmission characteristics are obtained, and the allowable range of the preceding sound speakers.

A sound signal from a sound source O is input to the dispersed speakers Sj by the signal transmission device 10. FIG.
The signal transmission device 10 includes a microphone 3, a mixer 11, and a signal transmission path. The microphone 3 is arranged near a speaker, a performer, or another sound source O in a sound field to directly collect sound. The collected direct sound is amplified by a microphone amplifier (not shown), then subjected to volume control of the entire sound field by the mixer 11, and sent to a signal adjusting device 20 described later. The microphone volume control in the mixer 11 can be manually controlled by an operator in consideration of the volume of the sound source O. However, the scope of application of the present invention is not limited to the loudness of the sound of the sound source O in the sound field. For example, the present invention can be applied to a case where a sound image is localized by a loud sound from a previously recorded sound source.

In the present invention, the signal transmission device 10 and each speaker
A signal adjusting device (effector) 20 for adjusting the acoustic delay and the sound pressure level of each speaker Sj is inserted between Sj and Sj. As shown in FIGS. 12 and 13, an example of the signal conditioning device 20 includes a speaker in response to an instruction signal input from a computer 30.
Acoustic delay circuit 21 and sound pressure level control circuit (volume control circuit) for adjusting the sounding time and input power of the acoustic signal for each Sj
22. Each signal conditioner 20 is connected to a computer 30, and each signal conditioner 20 is
And the adjustment of the input power are collectively controlled.

FIG. 6 shows an example of a flow chart of the control of the signal conditioner 20 by the computer 30 in the case where the sound image localization is obtained by loudspeaking the sound of the sound source O in the sound field. Hereinafter, the loudspeaker method of the present invention will be described with reference to the flowchart of FIG. First, in step 601, the position of the sound source O in the sound field is detected.
In FIG. 1, the position of the sound source O is detected based on the detection signal of the microphone position detecting device 37. Next, in step 602, the speaker S1 closest to the sound source O is selected as the main speaker So by the speaker selecting means 31. An example of the speaker selection means 31 is a computer built-in program that calculates the distance between the sound source O and each speaker Sj and selects the speaker S1 having the shortest distance. For detecting the position of the microphone 3, manual input by an operator or various automatic detection techniques belonging to the related art can be used. However, the microphone position detecting device 37 is not an essential requirement of the present invention.

In step 603, for example, the computer 30
The distributed speaker Sj other than the main speaker So is ranked in ascending order of the distance from the main speaker So by the speaker ranking means 32 which is a built-in program. In this specification, the ranked speakers Sj are referred to as peripheral speakers Sgx (x
= 1, 2, ..., (n-1)). For example, in FIG. 1, the speaker S2 in the distributed arrangement is the peripheral speaker Sg1 closest to the sound source O, and the speaker S3 is the peripheral speaker S4 closest to the fourth.
g4, the speaker S4 is ranked as the eighth nearest peripheral speaker Sg8, and the speaker S5 is ranked as the fifteenth nearest peripheral speaker Sg15.

As shown in steps 601 to 603, in the present invention, the position of the main speaker So is not fixed, the distributed speaker closest to the sound source O is set as the main speaker So, and the peripheral speakers Sgx are determined according to the distance from the main speaker So. Therefore, even when the sound source O moves, the position of the main speaker So and the order of the surrounding speakers Sgx can be changed according to the movement, and the sound image localization on the sound receiving surface Ph can be changed.

In step 604, the sounding time To and the input power Wo of the main speaker So are instructed by the main speaker sound instructing means 33 which is a program built in the computer 30, for example. FIG. 10 shows a method of determining the sounding time and input power of the main speaker So. For example, an acoustic signal from the signal transmission device 10 is generated by the main speaker So without time delay, and the sound generation time To is set to time zero (ms). However, the sound image localization of the present invention can be obtained even if a time delay is provided to the sounding time To of the main speaker So. Also, the input power Wo of the main speaker So
Is the level required for preventing the howling when the sound pressure level of the loud sound from the main speaker So in the microphone 3 is higher than the sound pressure level of the real voice from the speaker O (the sound pressure level at a point 1 m away), for example, 2 dB. Decide so that only the lower level. However, when no howling occurs, the input power Wo of the main speaker So can be set to a required level. In determining the input power Wo of the main speaker So, as shown in FIG.
Can be appropriately adjusted, and the attenuation of the attenuator of the amplifier 12 (hereinafter, sometimes referred to as attenuator position) at that time can be set to 0 (dB).

The method of determining the sounding time and input power of each peripheral speaker Sgx by the peripheral speaker sound instructing means 34 after step 605 will be described. This will be described with reference to FIG. Figure 2 shows the speaker closest to speaker O
S1 is the main speaker So, and speakers S2 to S5 are the peripheral speakers
This is a case where the listener 2 is ranked as Sg1 to Sg4 and the listener 2 is below the peripheral speaker Sg4. In step 605, sound receiving points P1 to P5 are first determined on the sound receiving surface Ph vertically below each of the speakers S1 to S5. In FIG. 2, a sound receiving point P1 is a sound receiving point Po vertically below the main speaker So, and sound receiving points P2 to P5 are peripheral speakers Sgx (Sg1
SSg4) below the sound receiving point Pgx (Pg1 to Pg4).

The loud sound from the main speaker So is the surrounding speakers
Assuming that the distance between the main speaker So and the sound receiving point Pgx is Rox, the time required to reach the sound receiving point Pgx below Sgx is given by (1)
0) can be calculated. In equation (10), the code C is the speed of sound (m
/ s). Normally, the sound speed at normal temperature and normal humidity (23 ° C., relative humidity 60%) is used as the sound speed C. Also, the sound pressure level Lox of the loud sound from the main speaker So that has reached the sound receiving point Pgx is expressed by the following equation.
With reference to (4), it can be expressed as the following equation (11). (1
In the equation (1), Wo represents the input power of the main speaker So, and Do represents the directivity coefficient of the main speaker So.

Further, the time required for the loud sound to reach from the surrounding speaker Sgx to the sound receiving point Pgx below the surrounding speaker Sgx and the reached sound pressure level Lxx are also set such that the distance between the surrounding speaker Sgx and the sound receiving point Pgx is Rxx. In the same way as the main speaker So, (12)
Equation (13) can be expressed. In Expression (13), Wx represents the input power of the peripheral speaker Sgx, and Dx represents the directivity coefficient of the peripheral speaker Sgx. In the illustrated example, since the main speaker So and the peripheral speaker Sgx have the same acoustic characteristics, A (f) in the equations (11) and (13) is the same.

Loud sounds from the main speaker and a plurality of peripheral speakers can reach each sound receiving point Pgx. A synthesized sound pressure level at a sound receiving point Pgx at which a loud sound from a plurality of speakers Sj (j = 1, 2, 3,...) Having the same characteristic A (f) reaches
It is called listening sound pressure level. ) Can be expressed by the following equation (14) based on the sum of the squared sound pressures I of the sound pressures reached from the respective speakers Sj.

[0038]

[Equation 2] Time required for the loud sound to reach the sound receiving point Pgx from the main speaker So = Rox / C (s) = 1000 · Rox / C (ms) ………………………………… (10) Loudspeaking sound arrival sound pressure level from the main speaker So to the sound receiving point Pgx Lox = 10logIox = 10 · log ｛Wo · Do (fo, θo, φo) · A (f) / Rox ² ｝ (dB) ... ………… (11) Time required for the loudspeaker to reach the sound receiving point Pgx from the surrounding speakers Sgx = Rxx / C (s) = 1000 · Rxx / C (ms) …………………………… ......... (12) amplified sound reaching the sound pressure level from the near speaker Sgx to receiving point Pgx Lxx = 10logIxx = 10 · log {Wx · Dx (fx, θx, φx) · a (f) / Rxx 2} ( dB) ………… (13) Listening sound level at sound receiving point Pgx = 10log (ΣIxx) = 10 · log [Σ ｛Wj · Dj (fj, θj, φj) · A (f) / Rkj ² ｝] (DB) …… (14)

In steps 605 to 612, each peripheral speaker Sg
The sounding time and input power of each peripheral speaker Sgx are determined according to the ascending order of x. First, the peripheral speaker Sg1 shown in FIG.
In step 605, the distance Ro1 from the main speaker So to the sound receiving point Pg1 below the peripheral speaker Sg1 and the distance R11 from the peripheral speaker Sg1 to the sound receiving point Pg1 are calculated. In the case of the peripheral speaker Sg1, there is no lower-order peripheral speaker Sgx, that is, the peripheral speaker Sgx closer to the main speaker So than the peripheral speaker Sg1. In step 606, the main speaker So at the sound receiving point Pg1 is obtained from the substitution result of the distance Ro1 from the main speaker So to the sound receiving point Pg1 to the expression (10) and the sounding time To = 0 (ms) of the main speaker So. Is calculated. Further, from the result of substituting the distance Ro1 from the main speaker So to the sound receiving point Pg1 and the input power Wo and the directivity coefficient Do of the main speaker So into the equation (11), the loud sound from the main speaker So at the sound receiving point Pg1 is obtained. Calculate the reached sound pressure level Lo1. However, the sound pressure frequency characteristic A (f) of the main speaker So is predetermined.

In step 607, the delay time Δt for giving the preceding sound effect to the loudspeaker sound arrival time To1 from the main speaker So
Ask for one. The delay time Δt1 is the shortest delay time Δtmin, for example, 3 ms at the peripheral speaker Sg1 closest to the main speaker So, and the longest delay time Δtmax, for example, 10 ms at the peripheral speaker Sg4 farthest from the main speaker So. In the peripheral speakers Sg2 and Sg3, the distance Ro from the main speaker So to the sound receiving points Pg2 and Pg3 below the peripheral speakers Sg2 and Sg3.
2. It can be determined as the time proportional to Ro3.

However, the method for determining the delay time Δt1 is not limited to the method based on the proportional distribution according to the distance. For example,
As shown in FIG. 11, the main speaker So to the peripheral speaker Sg
2. The distance between the shortest delay time and the longest delay time proportional to the logarithm (logRox) of the distance Ro2, Ro3 to the sound receiving points Pg2, Pg3 below Sg3. Table 1 below shows
1 shows the delay time Δtx of each of the peripheral speakers Sg1 to Sg4 determined from the graph of FIG. However, in Table 1, the delay time Δt1 of the peripheral speaker Sg1 which is the shortest delay time Δtmin is 6 ms, and the delay time Δt4 of the peripheral speaker Sg4 which is the longest delay time Δtmax is set.
Is set to 30 ms.

In step 607, the arrival time T11 (= To1 + Δt1) at which the loud sound from the surrounding speaker Sg1 should reach the sound receiving point Pg1 as the sum of the delay time Δt1 and the loud sound arrival time To1 from the main speaker So. ) Is calculated. If the time T11 to be reached by the loudspeaker is known, by substituting the distance R11 from the surrounding speaker Sg1 to the sound receiving point Pg1 into the equation (12),
In step 608, the sound generation time of the peripheral speaker Sg1 corresponding to the loudspeaker arrival time T11 can be determined.

[0043]

[Table 1]

In step 609, the total sum of the sound pressure levels of the lower-order peripheral speakers Sgk and the main speakers So that arrive at the sound receiving point Pg1 before the loudspeaker arrival time T11 from the peripheral speakers Sg1 is reached. . In this case, at the sound receiving point Pg1, since the loudspeaker sound that arrives before the loudspeaker arrival time from the surrounding speaker Sg1 is only the loudspeaker sound from the main speaker So, the arrival sound pressure of the loudspeaker sound from the main speaker So is reached. In step 610, a sound pressure level difference ΔL1 that gives a preceding sound effect to the loudspeaker reaching sound pressure level Lo1 from the main speaker So is calculated as the level Lo1 as the sum of the reaching sound pressure levels of the preceding loudspeakers. The sound pressure level difference ΔL1 is, for example, as shown in FIG. 8A, the delay time Δt from the preceding sound to the succeeding sound required to provide the preceding sound effect, and the sound pressure level difference ΔL between the preceding sound and the succeeding sound. (ΔL = f (Δt))
Is determined in advance by experiments or the like, and the delay time Δt1 required for calculating the sounding time of the peripheral speaker Sg1 is substituted into the relational expression of FIG.
L1 = f (Δt1)).

From the obtained sound pressure level difference ΔL1 and the sound pressure level Lo1 (= 10logIo1) of the loudspeaker reaching from the main speaker So,
At step 612, the loud sound from the surrounding speaker Sg1 should be shown at the sound receiving point Pg1 at the sound pressure level L11 (= 10logIo1 +
ΔL1) is calculated, and the calculated arrival sound pressure level L11 and the distance R11 from the surrounding speaker Sg1 to the sound receiving point Pg1 are substituted into the expression (13).
Determine the input power W1 of g1.

For example, in FIG. 8, when the delay time Δt1 of the arrival time of the peripheral speaker Sg1 is 6 ms,
If the difference between the sound pressure level reached from the main speaker So and the sound pressure level reached from the main speaker So is within 6 dB, it indicates that sound image localization can be obtained. The reached sound pressure level Lo1 at the sound receiving point Pg1 of the main speaker So is reduced due to distance attenuation or the like as shown in Expression (11). Based on the arrival sound pressure level Lo1 at the sound receiving point Pg1 of the main speaker So, the relative input level of the surrounding speaker Sg1 is set so that the sound pressure level from the surrounding speaker Sg1 at the sound receiving point Pg1 becomes (Lo1 + 6) (dB). The results determined by the attenuator position of the amplifier 12 are shown in Table 1 -3 (dB)
It is. Thus, the attenuator position of the amplifier 12 can be adjusted or corrected so that the input power of the peripheral speaker Sgx becomes the value calculated in step 611.

After the sounding time and input power of the peripheral speaker Sg1 are determined in step 612, the process proceeds to step 613.
It is determined whether the calculation of the sounding time and the input power has been completed for all the peripheral speakers. In this case, since the processing of the peripheral speakers Sg2 to Sg4 remains, the process returns to step 605, and the sounding time and input power are determined for the peripheral speaker Sg2 by repeating steps 605 to 612.
In the case of the peripheral speaker Sg2, since the lower-order peripheral speaker Sg1 exists, the distance Ro2 from the main speaker So to the sound receiving point Pg2 and the sound receiving point P from the peripheral speaker Sg2 in step 605.
In addition to calculating the distance R22 to g2, the distance R12 from the lower-order peripheral speaker Sg1 to the sound receiving point Pg2 is calculated. In step 606, the time at which the loud sound from the lower-order peripheral speaker Sg1 reaches the sound receiving point Pg2, and the loud sound reaching sound pressure level L12 are calculated based on the equations (12) and (13).

In step 607, a delay time Δt2 that gives a preceding sound effect to the loudspeaker sound arrival time To2 from the main speaker So is obtained. This calculation method is the same as the method described above for the peripheral speaker Sg1. From the sum of the delay time Δt2 and the loud sound arrival time To2 from the main speaker So, a time T22 (= To2 + Δt2) at which the loud sound from the surrounding speaker Sg2 should arrive at the sound receiving point Pg2 is obtained. If the time T22 at which the loud sound should arrive is known, the sound receiving point Pg2 can be obtained from the surrounding speaker Sg2.
By substituting the distance R22 to equation (12), the sounding time of the peripheral speaker Sg2 can be determined in step 608.

In step 609, at the sound receiving point Pg2, the loud sound arrival time T22 from the surrounding speaker Sg2 and the surrounding speaker Sg
Compare the loudspeaker arrival time T12 from 1 with the surrounding speaker Sg
If the loudspeaker arrival time T12 from 1 precedes, the sound receiving point Pg
Squared sound pressure of arriving loud sound from surrounding speaker Sg1
The sum (I12 + Io2) of I12 and the squared sound pressure Io2 of the arriving loud sound from the main speaker So is obtained, and the sum of the squared sound pressures (I12 + Io2)
By substituting into equation (14), the sum of the loudspeaker arrival sound pressure level L12 from the surrounding speaker Sg1 and the loudspeaker arrival sound pressure level Lox from the main speaker So (= 10log (I12 + Io2))
Is calculated.

The inventor of the present invention has determined that the lower-order peripheral speakers Sgk (k = 1, 2,..., (X−
If the loudspeaker sound from 1)) arrives before the loudspeaker sound from the peripheral speaker Sgx, not only the loudspeaker arrival sound pressure level Lox from the main speaker So but also the lower-order peripheral speakers Sgk Loudspeaker sound arrival pressure level Lkx (= 10log
ΣIkx) and the sound pressure level Lox reached by the loudspeaker from the main speaker So
(= 10logIox) and the total sound pressure level Lxx from the surrounding speaker Sgx above the sound receiving point Pgx so as to give a preceding sound effect to the sum (= 10log (ΣIkx + Iox)) On the sound receiving surface Ph, it has been found that the preceding sound effect can be reliably obtained at every sound receiving point on the sound receiving surface Ph. The present invention is based on this finding.

At step 610, for example, the delay time Δt2 of the sounding time of the peripheral speaker Sg2 is substituted into the relational expression of FIG. 8 (ΔL
2 = f (Δt2)) to determine the sound pressure level difference ΔL2. The obtained level difference ΔL2 is added to the sum (= 10 log (I12 +
Io2)), the sound pressure level L22 (= 10log (I
12 + Io2) + ΔL2). If the reached sound pressure level is obtained, in step 612, the input power W2 of the peripheral speaker Sg2 can be determined by substituting into the expression (13), as in the case of the peripheral speaker Sg1 described above.

After the sounding time and input power of the peripheral speaker Sg2 are determined at step 612, the process returns from step 613 to step 605, and repeats steps 605 to 612 for the peripheral speakers Sg3 and Sg4. Steps 605-6 of FIG.
By repeating 12 for all the peripheral speakers Sgx in the ascending order of the ranks, the sounding time and the input power of all the peripheral speakers Sgx can be determined. By inputting an instruction signal of the sounding time and input power of each peripheral speaker Sgx determined by the computer 30 to the signal adjusting device 20, the sounding time and input power of the sound signal from the signal transmission device 10 are adjusted for each speaker Sj. The adjusted audio signal to a power amplifier.
Input to each speaker Sj via 12 (see FIG. 1).

FIG. 3 shows the sound pressure generated at the sound receiving point Sg4 by the loudspeakers from the speakers So and Sg1 to Sg4 determined as described above. That is, in this case, the real voice from the speaker O arrives as the earliest preceding sound, and the main speaker So that is closest to the speaker O.
Loudspeakers followed by the surrounding speakers Sg1, Sg2, Sg3
Loudspeakers arrive in order. Finally, the loud sound from the peripheral speaker Sg4 arrives. Since the relationship between the real voice and the loud sound from each speaker and the mutual relation between the loud sounds from the speakers satisfy the condition where the preceding sound effect works, the sound field perception of the listener 2 at the sound receiving point Sg4 is synthesized. It is considered that the subjective level of the sound pressure is as shown by the solid line in FIG. That is, the solid line in FIG. 4 indicates that the loudspeakers from a plurality of distributed speakers are perceived by the listener 2 as one sound.

According to the present invention, since the speakers having substantially the same acoustic characteristics are used, there is no difference in the timbre of the speakers, and the difference in the transmission characteristics with respect to both ears of the listener can be kept within an allowable range by appropriately setting the speaker interval. Moreover, since the sounding time and input power of each peripheral speaker are controlled such that the loud sound from the main speaker becomes the preceding sound, the sound image can be localized in the direction toward the sound source O at any position on the sound receiving surface. In addition, since the main speaker can be selected and the peripheral speakers can be ranked according to the movement of the position of the sound source, the sound image can be localized on the moving sound source. It is also possible to localize the sound image to a questioner or the like appearing at an unspecified position.

Thus, it is possible to achieve the object of the present invention, that is, "a sound image localization loudspeaker method and a loudspeaker system using a distributed speaker capable of changing the direction of the sound image localization in accordance with the direction of the sound source".

Preferably, the listening sound pressure level at each sound receiving point Pi is suppressed to a predetermined target sound pressure level Lhc, so that the listener 2 can be at any predetermined sound receiving point Pi on the sound receiving surface Ph. Be able to listen at the level. In this case, in step 611 of FIG. 6, for example, the listening sound pressure level at the sound receiving point Pg4 reaches the sound pressure level L44 (= 10logI44) of the loudspeaker reaching the sound from the surrounding speaker Sg4 at the sound receiving point Pg4 in advance. The sum of the sound pressure levels reached by the surrounding speakers Sgk (k = 1, 2, 3) in the lower rank and the main speaker So (= 10 lo)
g (ΣIk4 + Io4)) (= 10logΣ (I44 + ΣIk4 +
Io4)). When the obtained listening sound pressure level exceeds the target sound pressure level Lhc, the total (= 10logΣ (I44 + Ik4 + Io4)) of the arrival sound pressure level L44 of the peripheral speaker Pg4 within the range where the preceding sound effect can be obtained is the target sound pressure level.
Suppress until it matches Lhc.

More preferably, the target sound pressure level Lhc is determined as shown by the solid line in FIG. 5, and the sound pressure level of the synthesized sound field on the sound receiving surface Ph created by each speaker Sj decreases as the distance from the sound source O increases. Control. This attenuation control enables the formation of a sound field that matches the daily experience that the sound becomes smaller when the sound source is separated from the sound source O, and acts so that the sound field is perceived by the listener with a natural feeling. For this reason, in a lecture or the like, the listener can listen while feeling that the speaker is talking to the speaker, and the speaker can give psychological feedback such as developing the topic while feeling the audience's reaction well It can be expected that participants will be able to communicate with each other.

The target sound pressure level Lhc shown in FIG.
The level decreases in accordance with the distance Rh from, but the slope of the decrease with respect to the distance Rh is smaller than the slope of the sound attenuation in the free sound field. According to the target sound pressure level Lhc, it is possible to increase the sound volume with a sufficiently large sound pressure while giving the listener a natural perception. The black portion of 40 dB or less in the figure indicates a range in which the sound is too low and hinders the listener's hearing. In the free sound field, even if the speaker utters a little loud voice, it may be difficult for a listener at a distance of about 100 m to hear. However, according to the loudspeaker method using the target sound pressure level Lhc in FIG. 100
It is possible to hear the speaker's utterance at a sufficient sound pressure even at a distance of m.

As shown in FIG. 5, the present inventor sets the target sound pressure level Lhc to be the maximum sound pressure level Loo from the main speaker So at the sound receiving point Po below the main speaker So, Logarithm of distance Rh from So (logRh)
By using the inclined target sound pressure level Lhc = Loo−3.0 × logRh such that the level is reduced in proportion to the distance from the speaker without any unnatural deviation between sound and distance, However, it was experimentally confirmed that a sound field where clear and refreshing natural sound could be heard as if the speaker were nearby was formed. However, the inclined target sound pressure level
The proportional constant of the attenuation of Lhc is not limited to the illustrated example.

[0060]

FIG. 12 shows an embodiment of a block diagram in which the present invention is realized by using a commercially available monaural signal conditioner 20a. In this embodiment, the signal conditioning device
20a and the main amplifier 12 need to be provided separately for each speaker Sj. For this reason, the audio signal distributor 13 for distributing the signal from the signal transmission device 10 to each speaker Sj
And the signal conditioner 20a. Also, the computer 30 needs to have a control line for each signal conditioning device 20a.

FIG. 13 shows the signal conditioner 20 and the amplifier 24.
FIG. 14 shows another embodiment of the present invention using a composite amplifier 20b integrating the same.
FIG. In the illustrated example, the composite amplifiers 20b are connected in tandem, and one digital audio signal line 27 and one control signal line 28 are used to connect the composite amplifiers 20b.
Are supplied with an acoustic signal and a control signal. The composite amplifier 20b has two sound delay units 21L and 21R and two volume control units 22L and 22R, and can simultaneously process two-channel digital sound signals.

The sounding time (delay time) and input power (volume) of the main speaker So and each peripheral speaker Sgx calculated by the computer 30 (see FIG. 15) are transmitted to the CPU 25 of the composite amplifier 20b via the interface 14 and the control line 28.
Sent to The CPU 25 is connected to the sound delay units 21L and 21R and the volume control units 22L and 22R, and adjusts the sounding time and input power of the two-channel digital sound signal in accordance with the processing pattern stored in the pattern memory 26. The adjusted digital audio signal is mixed by the mixer 23 and
4, sent to the speaker via output line 29. By using the composite amplifier 20b shown in the figure, sounds from two sound sources can be processed simultaneously, and sound images directed to two sound sources on the sound receiving surface Ph can be simultaneously localized.

FIG. 15 shows still another embodiment of the present invention using the composite amplifier 20b. 5m x 3 at 3.5m height from floor.
Fourteen speakers Sj were dispersedly arranged in a grid at intervals of 5 m, and a composite amplifier 20 was attached to each speaker Sj. As shown in the figure, the first sound source below the speaker S1 and the speaker
The sound of the second sound source below S4 was picked up by the microphones 3 and 4, respectively, and input to the interface 14 via the mixer 11. On the other hand, the computer 30 calculates control signals necessary for localization of sound images to the two sound sources in accordance with the flowchart of FIG. The digital audio signal from the mixer 11 and the control signal from the computer 30 are transferred to the composite amplifier 20 of each speaker Sj via the interface 14.
Transmitted to Each composite amplifier 20 was connected in tandem as shown in FIG. In the composite amplifier 20b, the digital audio signal from the microphone 3 sent to the right channel and the digital audio signal from the microphone 4 sent to the left channel are simultaneously processed and sent to each speaker Sj via the mixer 23 and the main amplifier 24. Output.

Table 2 shows an example of the control signals used in the embodiment of FIG. The present inventor has confirmed that the sound image heading to the first sound source and the sound image heading to the second sound source can be simultaneously localized on the sound receiving surface Ph by the control signals in Table 2. FIG. 15 and Table 2
As can be understood from the embodiment of the present invention, even when two sound sources O exist in the sound field, for example, a speaker on the stage and a prisoner in the hall, the speaker according to the present invention It is possible to perform sound image localization as the first sound source and simultaneously perform sound image localization using the interlocutor as the second sound source. By simultaneously performing the two sound image localizations, the speaker and the questioner can hear each other's voices well, making it easy to talk. Furthermore, the interaction between the two can be heard with a natural feeling anywhere in the venue. Can create a place.

[0065]

[Table 2]

[0066]

As described above in detail, the sound image localization loudspeaker method and the loudspeaker system using the distributed loudspeakers according to the present invention cover a plurality of loudspeakers Sj having substantially the same acoustic characteristics over a sound receiving surface in one area. The speakers closest to the sound source O among the speakers Sj are set as the main speakers So, and the remaining speakers are set as the peripheral speakers Sgx ranked in ascending order of the distance from the main speakers So. The sounding time and input level of each peripheral speaker are controlled so that the loud sound from the main speaker gives a preceding sound effect at the sound receiving point below the peripheral speaker, and the sound image localization direction toward the sound source O on the sound receiving surface is controlled. Since the direction is set, the following remarkable effects are obtained.

(A) Since the speaker closest to the sound source is selected as the main speaker from among the distributed speakers,
Even when the sound source moves, the sound image can be localized in the direction toward the sound source according to the movement by reselecting the main speaker. (B) Since speakers having substantially the same acoustic characteristics are used,
The sound image localization in the direction of the sound source can be obtained regardless of where on the sound receiving surface the sound image localization does not hinder the sound image localization from the speaker.

(C) A plurality of sound images can be simultaneously localized in a sound field by processing a sound signal of a different sound source for each channel using a signal adjustment device or the like corresponding to multiple channels. For example, by localizing the sound image using the speaker as the first sound source and localizing the sound image using the interlocutor as the second sound source, it is possible to smoothly exchange the interlocutor on the stage with the interlocutor in the hall. (D) The speaker closest to the sound source is the main speaker, and the sound of the sound source is returned to the vicinity of the sound source, so that the main speaker can be a so-called “rebound speaker”. Since the speaker can always hear the rebound sound regardless of the position on the sound receiving surface, he / she can always speak while confirming his / her own voice, so that the user feels comfortable speaking.

(E) Adjusting the listening sound pressure level at each sound receiving point so that attenuation corresponding to the distance from the sound source is obtained, thereby creating a natural sound field in accordance with the listener's daily experience. And the presence of the sound field can be enhanced. (F) Because it is possible to create a natural and highly realistic sound field, it is possible to expect the effect that the emotional expression through the music of the performer can be felt with a sense of realism at concerts, etc.
In lectures and the like, it can be expected that the audience will listen while feeling that the audience is speaking from the speaker. In addition, the speaker can naturally receive the response of the audience such as the questioner, and can be expected to be used to improve communication between the speaker, the participants, and the participants.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of one embodiment of the present invention.

FIG. 2 is an explanatory diagram showing the principle of sound image localization according to the present invention.

FIG. 3 is an explanatory diagram of a sound reached from each speaker at a sound receiving point in FIG. 2;

FIG. 4 is an explanatory diagram of a sound intensity at a sound receiving point in FIG. 2;

FIG. 5 is an explanatory diagram of a target sound pressure level at a sound receiving point.

FIG. 6 is an example of a flowchart of a method of calculating a sounding time and input power of each speaker.

FIG. 7 is an explanatory diagram of an arrangement allowable range of a preceding sound speaker for obtaining a preceding sound effect.

FIG. 8 is an explanatory diagram of a relationship between a preceding sound at which a preceding sound effect is obtained and a reinforcement sound.

FIG. 9 is a diagram illustrating an example of acoustic characteristics of a speaker.

FIG. 10 is an explanatory diagram showing a method of determining a sounding time and an input power of a main speaker.

FIG. 11 is an explanatory diagram of one calculation method of a delay time of a sounding time of a peripheral speaker.

FIG. 12 is an explanatory diagram of an embodiment of the present invention using a signal distributor.

FIG. 13 is an explanatory diagram of an embodiment of the present invention using a two-channel composite amplifier.

FIG. 14 is an explanatory diagram of a two-channel composite amplifier.

FIG. 15 is an explanatory diagram of another embodiment of the present invention.

FIG. 16 is an explanatory diagram of a conventional centralized loudspeaker system, a distributed loudspeaker system, and a semi-dispersed loudspeaker system.

FIG. 17 is an explanatory diagram of a reaching sound level at a sound receiving point in the conventional concentrated loudspeaker system, distributed loudspeaker system, and semi-dispersive loudspeaker system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Talker 2 ... Listener 3 ... Microphone 4 ... Second microphone 5 ... Ceiling surface 6 ... Floor surface 10 ... Signal transmission device 11 ... Mixer 12 ... Amplifier 13 ... Signal distributor 14 ... Interface 20 ... Signal adjustment device 20a ... Monaural Signal conditioner 20b ... 2 channel type signal conditioner 21 ... Sound delay unit 22 ... Volume control unit 23 ... Mixer 24 ... Amplifier 25 ... CPU 26 ... Pattern memory 27 ... Digital audio input line 28 ... Control input line 29 ... Output line 30 ... Computer 31 ... Speaker selecting means 32 ... Speaker ranking means 33 ... Main speaker sound indicating means 34 ... Surround speaker sound indicating means 37 ... Microphone position detecting device A ... Sound pressure C ... Sound speed f ... Frequency H ... Ceiling height h ... Sound receiving surface height I ... Square sound pressure Jh ... Speaker direction Js ... Sound image direction L ... Sound pressure level Lh ... Listening sound pressure level Lhc ... Target sound pressure level Lp ... Sound intensity O ... Sound source Pi ... Sound receiving point Ph … Sound receiving surface R: distance S, Sj: speaker So: main speaker Sgx: peripheral speaker T: time Δt: delay time w: sound source input power φ: elevation angle (vertical plane) θ: azimuth angle (horizontal plane)

Claims (12)

(57) [Claims] A plurality of loudspeakers Sj (1 ≦ 1) having substantially the same acoustic characteristics used for loudspeaking of the sound of a sound source O at a predetermined position above a sound receiving surface Ph.
j ≦ n) are arranged in a downward direction by partially overlapping the cover areas of the adjacent speakers; portions of the sound receiving surface Ph vertically below each of the speakers Sj are respectively assigned to sound receiving points Pi (1 ≦ i ≦
n); among the speakers Sj, the speaker closest to the sound source O is selected as the main speaker So, and the remaining speakers are ranked in the ascending order of the distance from the main speaker So. The peripheral speakers Sgx (x = 1, 2) ,..., (N-1)); a loud sound of the sound of the sound source O is produced from the main speaker So at a time zero without a time delay at a required input power; and for each of the peripheral speakers Sgx, In ascending order, the peripheral speaker Sg at the sound receiving point Pgx below the peripheral speaker Sgx.
The delay time Δt at which the loudspeaker arrival time Txx from x gives the preceding sound effect to the loudspeaker arrival time Tox from the main speaker So
Peripheral speaker S that is delayed by x (Txx = Tox + Δtx)
The onset time of gx is calculated, and the lower-order peripheral speakers Sgk (k = 1, 2,..., (x) that reach the sound receiving point Pgx earlier than the loudspeaker sound arrival time Txx from the peripheral speaker Sgx.
-1)) and the sum of the reached sound pressure levels of the loudspeakers from the main speaker So and the distance from each speaker Sgk and So to the sound receiving point Pgx and the input power and acoustic characteristics of each speaker Sgk and So. Calculated as a function and the sound receiving point Pgx
In the loudspeaker arrival sound pressure level Lxx from the peripheral speaker Sgx is determined to be higher than the sum obtained by the sound pressure level difference ΔLx that gives a precedence effect to the obtained sum, and the sound pressure level Lxx corresponding to the determined arrival sound pressure level Lxx Calculating the input power of the peripheral speakers Sgx; generating the loudspeaker sound of the sound of the sound source O from each of the peripheral speakers Sgx at the calculated onset time at the calculated input power, so that the sound at each of the sound receiving points Pi is obtained. A sound image localization method using a distributed loudspeaker in which a sound image localization direction is a direction toward the sound source O. 2. The method according to claim 1, wherein said sound source O
Including the microphone below the main speaker So,
The input power of the main speaker So is determined such that the loudspeaker arrival sound pressure level of the microphone from the main speaker So is lower than the arrival sound pressure level of the sound from the sound source O by a level required for preventing howling from occurring. A method of sound image localization using a distributed speaker. 3. The loudspeaker method according to claim 1, wherein the delay time Δtx required for calculating the loudspeaker arrival time Txx of each of the peripheral speakers Sgx is set to be the shortest time in the peripheral speaker Sgx closest to the main speaker So. Δtmin and the main speaker S
The longest time Δtmax with the peripheral speaker Sgx furthest from o
In the other peripheral speakers Sgx, the time between the shortest time Δtmin and the longest time Δtmax according to the distance Rox from the main speaker So to the sound receiving point Pgx below the peripheral speaker Sgx (Δtmin ≦ Δtx ≦ Δtmax) A sound image localization method using a distributed speaker. 4. The loudspeaker method according to claim 3, wherein the delay time Δtx required for calculating the loudspeaker arrival time Txx of said another peripheral speaker Sgx is changed from said main speaker So to said peripheral speaker Sgx.
A sound image localization loudspeaker using a distributed speaker, which is a time between the shortest time Δtmin and the longest time Δtmax proportional to the logarithm (logRox) of the distance Rox to the sound receiving point Pgx below x. 5. A loudspeaker method according to claim 1, wherein a delay time Δt from a preceding sound to a succeeding sound necessary for giving a preceding sound effect and a sound pressure level difference ΔL between the preceding sound and the succeeding sound.
(ΔL = f (Δt)) is experimentally determined, and the sound pressure level difference ΔLx required for calculating the loudspeaker arrival sound pressure level Lxx of each of the peripheral speakers Sgx is determined by the loudspeaker arrival time of the corresponding peripheral speaker Sgx. A sound image localization loudspeaker method using a distributed speaker, which is determined by substituting a delay time Δtx required for calculating Txx into the relational expression (ΔLx = f (Δtx)). 6. A method according to claim 1, wherein a predetermined target sound pressure level Lhc which is an upper limit of a listening sound pressure level at each of said sound receiving points Pi is provided, and said peripheral speakers S
The listening sound pressure level at the sound receiving point Pgx below gx is defined as the loudspeaker reaching sound pressure level Lxx from the surrounding speaker Sgx and the preceding surrounding speaker Sgk (k = 1,
,..., (X−1)) and the sum of the sound pressure levels reached by the main speakers So, and when the sum exceeds the target sound pressure level Lhc, The total sound pressure level Lxx is within the range in which the preceding sound effect can be obtained.
A sound image localization and loudspeaker method using a distributed loudspeaker suppressed to match Lhc. 7. The loudspeaker method according to claim 6, wherein said predetermined target sound pressure level Lhc is reduced in level according to a distance from said sound source O, and a slope of reduction with respect to the distance is smaller than a slope of attenuation in a free sound field. Small inclined target sound pressure level Lhc
A sound image localization method using a distributed speaker, wherein the listening sound pressure level at each sound receiving point Pi on the sound receiving surface Ph is gently reduced according to the distance from the sound source O. 8. A method according to claim 7, wherein said predetermined target sound pressure level Lhc is set to a sound receiving point Po under the main speaker So.
Sound pressure level reached by the main speaker So at
Loo to the maximum level and distance R from the main speaker So
Slope-type target sound pressure level Lhc whose level decreases in proportion to the logarithm of h (logRh) (= Loo−a × logRh, a is a proportional constant)
A sound image localization method using a distributed speaker. 9. A loudspeaker Sj (1.ltoreq.j.ltoreq.n) having substantially the same acoustic characteristics in which a cover area of an adjacent loudspeaker is partially overlapped at a predetermined position above a sound receiving surface Ph and dispersed downward.
A signal transmission device for transmitting an audio signal from a sound source O to each of the speakers Sj; a sound transmission time provided between the signal transmission device and each of the speakers Sj and for each of the speakers Sj in response to an instruction input; Signal adjusting device for adjusting the input and the input power to output to each of the speakers Sj; each of the speakers
Speaker selection means for selecting the speaker closest to the sound source O as the main speaker So among Sj; speakers Sj other than the main speaker So as peripheral speakers Sgx (x = 1, 2,...,
(N-1)) speaker ranking means for ranking in ascending order of distance from the main speaker So; the main speaker
Main speaker sound instructing means for instructing the sound generation time and input power of So; and a sound receiving point Pi (1 ≦ i ≦ n) is defined on the sound receiving surface Ph vertically below each of the speakers Sj, and the peripheral speakers Sgx are determined. For each of the above, the loudspeaker arrival time Txx from the peripheral speaker Sgx at the sound receiving point Pgx below the peripheral speaker Sgx gives a precedence effect to the loudspeaker arrival time Tox from the main speaker So. The peripheral speaker Sgx that is delayed by the delay time Δtx (Txx = Tox + Δtx)
, And the lower-order peripheral speakers Sgk (k = 1, 2,..., (X−1) that arrive at the sound receiving point Pgx earlier than the loudspeaker arrival time Txx from the peripheral speaker Sgx.
1)) and the sum of the reached sound pressure levels of the loud sounds from the main speaker So as a function of the distance from each speaker Sgk and So to the sound receiving point Pgx and the input power and acoustic characteristics of each speaker Sgk and So. And the loudspeaker reaching sound pressure level Lxx from the surrounding speaker Sgx at the sound receiving point Pgx is determined to be higher by the sound pressure level difference ΔLx that gives the preceding sound effect to the sum obtained above, and is determined. Calculating the input power of the peripheral speaker Sgx corresponding to the reached sound pressure level Lxx, including peripheral speaker sound instruction means for instructing the calculated sounding time and input power, the main speaker sound instruction means and the peripheral speaker sound instruction means By inputting the instruction of the sound generation time and the input power according to the above to the signal adjusting device, the localization direction of the sound image at each of the sound receiving points Pi is determined as the direction toward the sound source O. Distributed speaker use sound localization loudspeaker system. 10. A loudspeaker system according to claim 9, wherein a delay time Δt from a preceding sound to a succeeding sound required for giving said preceding sound effect to said peripheral speaker sound indicating means and a sound pressure level between the preceding sound and the succeeding sound. The relational expression (ΔL = f (Δ
t)) is stored, and the delay time Δtx required to calculate the loudspeaker arrival time Txx of each of the peripheral speakers Sgx is determined by the main speaker S.
The distance R from o to the sound receiving point Pgx below the surrounding speaker Sgx
ox, and the sound pressure level difference ΔLx required for calculating the loudspeaker arrival sound pressure level Lxx of each of the peripheral speakers Sgx is the delay time Δtx required for calculating the loudspeaker arrival time Txx of the peripheral speaker Sgx. Substitution into the equation (ΔLx = f (Δt
x)) A sound image localization loudspeaker system using distributed speakers obtained by 11. A speaker system according to claim 9, wherein said peripheral speaker sound indicating means stores a target sound pressure level Lhc which is an upper limit of a listening sound pressure level at each of said sound receiving points Pi. The listening sound pressure level at the sound receiving point Pgx below Sgx is defined as the loudspeaker reaching sound pressure level Lxx from the surrounding speaker Sgx and the preceding lower-order surrounding speaker Sgk (k = 1, 2,..., ( x-1)) and the sum of the loudspeaker arrival sound pressure levels from the main speaker So, and when the total exceeds the target sound pressure level Lhc, the loudspeaker arrival sound pressure level of each of the peripheral speakers Pgx. A sound image localization loudspeaker system using a distributed speaker, wherein Lxx is suppressed so that the total sum coincides with the target sound pressure level Lhc within a range where the preceding sound effect can be obtained. 12. The loudspeaker system according to claim 11, wherein said predetermined target sound pressure level Lhc is reduced in level according to a distance from said sound source O, and a slope of reduction with respect to the distance is smaller than a slope of attenuation in a free sound field. A sound image localization loudspeaker using a distributed loudspeaker, which has a small inclined target sound pressure level Lhc, and gradually reduces the listening sound pressure level at each sound receiving point Pi on the sound receiving surface Ph according to the distance from the sound source O. system.