KR20100069401A - Acoustic control method for line array speaker for automobile application - Google Patents

Abstract

PURPOSE: An acoustic sound controlling method of a line array speaker for a vehicle is provided to divide acoustic sound space between a driver and passengers without the use of the individual acoustic device by including an individual acoustic sound space inside a vehicle. CONSTITUTION: A first bright area and a first dark zone are set in the entire acoustic sound domain of the sound field system. The sound pressure of the sound field system is calculated. The sound field system is normalized by using the calculated sound pressure of the sound field system. A second bright area and a second dark area are set in the entire acoustic sound domain by using the sound pressure of the normalized sound field system. An eigen value and an eigen vector are calculated. The eigen value and the eigen vector maximize difference between the output energy compared to the input energy of the calculated second bright area and the output energy compared to the input energy of the second dark area. The eigen vector is determined to as the volume velocity of the sound field system.

Description

Acoustic control method for Line array speaker for automobile application

The present invention relates to an acoustic control method of an array speaker for allowing a driver and a non-driver to form different acoustic spaces in a vehicle interior space.

In general, an acoustic control method of a line array speaker refers to a technology for allowing a driver and a non-driver to form different acoustic spaces in a specific space, that is, an interior space of a vehicle.

A conventional technique for allowing a driver and a non-driver to form different acoustic spaces is a sound control method, which is a technique for collecting sound generated from a line array speaker to a desired position, for example, a driver's position. The location where sound sources are collected is called an acoustically bright area, and the location where the sound source should not reach is called a dark area. Therefore, the acoustic control method can maximize the acoustic energy in the bright region and minimize the acoustic energy in the dark region to achieve the desired purpose. In reality, however, the sound control method has a problem in that the dark area is more affected than the bright area when the sound control is performed through the ratio of energy, so that the sound control is not properly performed.

According to the present invention, the acoustic difference system (Acoustic Difference Algorithm) of the line array speaker that maximizes the light energy in the bright area and the sound energy in the dark area is minimized in the sound field system consisting of the interior space of the vehicle It is intended to provide a control method.

) 및 고유벡터(

)를 산출하여 상기 고유벡터(

)를 상기 음장시스템의 체적속도(q_c)로서 결정하는 단계를 포함한 것을 특징적 구성으로 한다.A sound control method for a line array speaker for a vehicle according to the present invention comprises the steps of: (a) setting a primary bright region (B region) and a primary dark region (D region) in the entire acoustic region T of the sound field system; (b) calculating a sound pressure (P) of the sound field system; (c) normalizing the sound field system using the calculated sound pressure P of the sound field system; (d) setting the secondary bright region (B region) and the secondary dark region (D region) in the entire acoustic region T using the sound pressure P of the normalized sound field system; And (e) an eigenvalue that maximizes the difference between the output energy compared to the input energy of the secondary bright region (region B) and the input energy to the input energy of the secondary dark region (region D).

) And eigenvectors (

) And the eigenvectors (

) Is determined as the volume velocity q _c of the sound field system.

) 및 고유벡터(

)를 산출하는 단계; (b-3) 음장시스템의 전체 음향 영역(T)의 전달함수(

)를 산출하는 단계; 및 (b-4) 상기 고유벡터(

) 및 상기 음장시스템의 전체 음향 영역(T)의 전달함수(

)를 이용하여 상기 음장시스템의 음압(P)을 산출하는 단계를 포함한다.Wherein step (b) of the present invention (b-1) is the distance between the x, y coordinates and the array speaker elements respectively present in the primary bright region (B region) and the primary dark region (D region) in consideration of the step of calculating the acoustical transfer impedance (R _D) of the acoustic transfer impedance (R _B) and the first dark area (D area) of the primary light region (B region); (b-2) A sound transmission impedance R _B composed of the ratio between the input energy and the output energy of the primary bright region B region and the ratio between the input energy and the output energy of the primary dark region D region Using the difference between the acoustic impedances (R _D ), the eigenvalues (maximum) that maximize the acoustic energy delivered to the primary bright (B area) and dark (D area)

) And eigenvectors (

Calculating c); (b-3) Transfer function of the entire sound field (T) of a sound field system (

Calculating c); And (b-4) the eigenvector (

) And the transfer function of the entire acoustic region T of the sound field system (

Calculating a sound pressure (P) of the sound field system using;

On the other hand, in the step (d) of the present invention, the area B from the normalized sound pressure level (d-1) corresponds to each of the + and-coordinate values on all X axes at a distance where the Y coordinate of the array speaker is h = 1 meter. Finding a median value of the sound pressure level relative to the sound pressure level; (d-2) generating a first intermediate line and a second intermediate line by connecting intermediate values of sound pressure levels of the + coordinate value and the -coordinate value; (d-3) setting the inner points of the first middle line and the second middle line to the second bright area (area B): (d-4) all X-axis at a distance where the Y coordinate is a = 0.5 meter Finding a maximum value of the sound pressure level for each of the + and − coordinate values of the phase; (d-5) generating a third intermediate line and a fourth intermediate line by connecting the maximum values of sound pressure levels of the + coordinate value and the -coordinate value; And (d-3) setting outer points of the third middle line and the fourth middle line to the second dark area D area.

On the other hand, in the steps (b-2) and (e) of the present invention, the acoustic transmission impedance R _B of the bright area (area _B ) and the acoustic transmission impedance R _D of the dark area (area _D ) are respectively It is calculated through the equation of.

Equation

,

,

는 음장시스템의 입력에너지, V는 수음점이 형성되는 공간, R은 음향전달함수(

또는

)의 2차 다항식 형태(quadratic form)로 어레이의 각 요소 입력에 의해 관심 음향 영역(B 또는 D)에서 생성되는 음장 (Pressure Field)의 공간 상관관계 행렬,

여기서

는 각속도(Angular frequency), c는 음파의 속도,

는 공기의 밀도)(E _OUT is the output energy,

Is the input energy of the sound field system, V is the space where the sound absorption point is formed, and R is the sound transfer function (

or

Spatial correlation matrix of the pressure field generated in the acoustic region of interest (B or D) by the input of each element of the array in quadratic form

here

Is the angular frequency, c is the speed of sound waves,

Is the density of the air)

)는 아래의 수학식에서 (R_B-R_D)를 시스템 행렬로 하는 고유치(

)가 최대가 될 때의 해당 고유벡터 값이다.Meanwhile, the eigenvectors (b-2) and (e) of the present invention

) Is the eigenvalue of (R _B -R _D ) as the system matrix

Is the eigenvector value when) is maximum.

Equation

): 고유벡터,

: 고유치, E_in:입력에너지, E_B: 밝은 영역(B 영역)의 출력에너지, E_D :어두운 영역(D 영역)의 출력에너지)((

): Eigenvectors,

: Intrinsic value, E _in : Input energy, E _B : Output energy of bright area (B area), E _D : Output energy of dark area (D area))

The sound control method of the line array speaker of the present invention enables the creation of an effective personal sound space in the interior of a vehicle, thereby providing an effect of separating the sound space between the driver and the occupant without using personal sound listening means such as headphones.

Hereinafter, with reference to the accompanying drawings will be described specific details for the practice of the invention.

First, the basic theory of the sound control method of the present invention will be described.

1 is a photograph showing an acoustic space inside a vehicle of the present invention.

As shown in FIG. 1, the circle on the left is the driver's seat and the circle on the right is the passenger's seat in the interior space of the vehicle. The acoustic space of the driver's seat and the passenger's seat should be separated from each other to control the driver and the passenger to have different acoustic spaces. Here, if you describe an acoustic space that can only be heard by the driver, the driver's seat is a bright area with maximum directivity so that the sound can be heard, and the passenger's seat has a dark area with minimum directivity so that the sound is inaudible. Should be.

Figure 2a is a block diagram showing the configuration of the acoustic space of the present invention.

As shown in FIG. 2A, the acoustic space of the vehicle defines the entire acoustic space formed by a dotted line with respect to the position of the array speaker as T, and the bright zone where the acoustic energy is maximized is the B region and the acoustic energy. Defines the dark zone (Dark zone) to be minimized as D zone.

로 정의 하면 음압(P)은 수학식 1과 같이 음향 전달 함수인 Green 함수(

)와 체적속도(q_c, Source Volume Velocity)의 곱으로 표현된다.Comparing the sound field system according to the acoustic space of the vehicle with the circuit system, the current of the circuit system corresponds to the volume volume velocity, the voltage corresponds to the sound pressure, and the transfer function between the two physical quantities

Sound pressure (P) is defined as the Green function (

) Is the product of volume velocity (q _c , Source Volume Velocity).

Equation 1

는 속도 음원이

위치(array위치)에 있을 때 체적속도 (q_c, Source Volume Velocity)와 x 위치들(네모 점선 전체 공 간)의 음압(P, Sound Pressure) 사이의 전달특성으로서 아래의 수학식2와 같이 표현된다.Where the green function, the sound transfer function

Has a sound source

It is expressed as the following Equation 2 as the transfer characteristic between the volume velocity (q _c , Source Volume Velocity) and the sound pressure (P, P) at the x positions (the entire dotted line) when in the position do.

Equation 2

는 각속도(Angular frequency), c는 음파의 속도,

는 공기의 밀도)(here

Is the angular frequency, c is the speed of sound waves,

Is the density of the air)

는 복수의 어레이 스피커 요소들 중 i번째 어레이 스피커 요소 입력들에 대한 수음점(Field Point)으로의 시스템 함수인 전달함수이므로 음장시스템의 입력에너지는

으로 나타낼 수 있고 출력에너지는 아래의 수학식3과 같이 나타낼 수 있다.here

Since is a transfer function that is a system function of the i-th array speaker element inputs among the plurality of array speaker elements, the input energy of the sound field system is

The output energy can be expressed as Equation 3 below.

Equation 3

,

,

또는

)의 2차 다항식 형태(quadratic form)이다.Where V is the space where the masturbation point forms, and R is the transfer function (

or

) Is the quadratic form of.

Hereinafter, a sound control method of the present invention will be described.

The difference in the volume of sound actually felt by the listener can be seen as the difference in sound pressure level between the bright region (hereinafter referred to as 'B region') and the dark region (hereinafter referred to as 'D region'). Based on this, the directivity of the sound can be set to the area B and the area D, and the difference between the equivalent sound pressures of the two areas can be evaluated as a level. Hereinafter, the present invention proposes an acoustic difference algorithm for maximizing the difference between the input energy in the region B and the output energy in the region D.

Figure 2b is a flow chart of the sound control method of the line array speaker of the present invention.

S100 (Setting the bright and dark areas of the entire sound field)

를 수학식2를 이용하여 산출한다. As shown in Figs. 2A and 2B, firstly, the primary bright region and the secondary dark region are set in the entire acoustic region (T, the square dotted overall space). First, the whole area T is viewed as the width (x) 2w meters and the length (y) h meters, and the center position coordinates of the array speaker are regarded as (0,0). Area B is centered on the (0, a) meter position, and area D is centered on the (-b, a) meter position, each of which has a diameter of 0.2 meters (diameter of human head diameter). In this case, the entire area T is divided by a spatial resolution of 0.01 meters to generate x and y coordinate values corresponding to the B area and the D area. That is, the x and y coordinates in the circle of area B are generated by the x and y coordinate values at 0.01 meter intervals. For example, if a is 0.5m, the x and y coordinates in the circle of area B can be (-0.49, 0.5), (-0.48,0.5), (-0.47,0.5). The transfer function considering the distance between the x and y coordinates and the array speaker in the B area and the D area

Is calculated using Equation 2.

S102 (Calculates the acoustic transmission impedance R _{D in the} bright area (area _B ) and the acoustic transmission impedance R _{D in the} dark area (area _D ))

는 벡터 값이 되며 이러한

를

의 정방 행렬(square matrix)로 형식을 바꾸고, B영역의 다른 점들에서 구한

행렬들을 수학식3과 같이 행렬 합을 한 후 B의 면적(3차원일 경우 체적)을 나누어 계산함으로써 B 영역의 음향전달임피던스인 R_B 및 D 영역 의 음향전달임피던스인 R_D를 산출한다.So calculated

Becomes a vector value and these

To

Is transformed into a square matrix of

Matrices are summed as shown in Equation 3, and then divided by calculating the area of B (volume in the case of 3D) to calculate R _D , which is the acoustic impedance of R _B and D, which are the acoustic impedance of _D.

)및 고유벡터(

) 산출)S104 (using R _B and R _D , the eigenvalue that maximizes the difference between the input energy in the area _B and the output energy in the area D)

) And eigenvectors (

) Calculation)

Equation 4 for maximizing the difference between the input energy in the region B and the output energy in the region D is as follows.

Equation 4

을 시스템 행렬로 하는 고유치(

)및 고유벡터(

) 문제에 해당되며, B영역에서 계산되는 음압과 D영역에서 계산되는 음압의 차이를 최대화 하는 표현이다. 이에 상기 S102에서 산출된 R_B 및 R_D를 상기 수학식4에 대입 하여 고유치 문제를 풀면 N개의 고유치

와 고유 벡터(

)를 구하는데, 각각의 고유 벡터(

)는 N개로 구성된 벡터로 각 어레이 스피커 요소들의 입력이 되는 체적속도

로 복소 해(Complex Solution)이다. 여기서 각 고유치는 수학식4의 "or" 왼쪽편의 표현과 같이 입력에너지에 대한 B영역의 출력에너지와 D영역의 출력에너지들 간의 차이를 나타내므로, 최대 고유치

에 해당되는 고유벡터(

)가 빔포밍(Beamforming) 해가 된다. 즉 상기 고유벡터(

)가 수학식 1의 체적속도(q_c)가 된다. 여기서 상기

의 시스템 행렬을 이용하여 고유치(

)및 고유벡터(

)를 산출하는 것은 널리 알려진 기술이므로 상세한 산출과정은 생략한다.Equation 4 is

Eigenvalues where

) And eigenvectors (

) Is a problem, and maximizes the difference between the sound pressure calculated in the B area and the sound pressure calculated in the D area. Thus, by substituting R _B and R _D calculated in S102 into Equation 4 to solve the eigenvalue problem, N eigenvalues are solved.

And eigenvectors (

), Each eigenvector (

) Is the N-vector, the volume velocity that is input to each array speaker element.

It is a complex solution. Here, each eigenvalue represents the difference between the output energy of the B region and the output energies of the D region, as shown in the left side of "or" in Equation 4,

Eigenvectors corresponding to

) Becomes a beamforming solution. In other words, the eigenvector

) Is the volume velocity q _c of Equation 1. Where above

Using the system matrix of

) And eigenvectors (

) Is a well-known technique, so detailed calculation is omitted.

S106 (calculates the sound pressure (P) of the sound field system)

)와 S100에서 산출한

을 수학식1에 대입하여 본 발명의 음장시스템의 음압(P)을 산출한다.This is the eigenvector

) And from S100

Is substituted into Equation 1 to calculate the sound pressure P of the sound field system of the present invention.

S108 (normalization of the sound field system using sound pressure (P) of the sound field system)

The sound field at the individual frequencies is normalized based on the sound pressure P calculated in S106. FIG. 3 shows a sound pressure level (SPL) of -50 dB to 0 dB at 1,2,3 kHz by applying an acoustic difference algorithm from the line array speaker of FIG. 2A (for example, 9 speakers and a center distance of 4 cm) and spatial definition. The results of simulations are shown by normalizing. Since the normalization of the sound field system using the sound pressure P is a known technique, detailed description thereof will be omitted.

S110 (Resetting new B area and new D area using normalized sound field system)

4 is a configuration diagram showing the configuration of the acoustic space of the present invention.

As shown in FIG. 4, first, from the normalized sound pressure level, the area B is the + coordinate value and the -coordinate value on all X axes at a distance where the Y coordinate is h meters when the center of the array speaker is (0,0) meters. Find the median of the sound pressure level for each of. For example, in (a) to (c) of FIG. 3, when the X coordinate has a + coordinate value at the point where the Y coordinate is h = 1 meter, the far right end is expressed in blue color so that the sound pressure level is the lowest and the center. The part is colored green and the sound pressure level is highest. At this point where the Y coordinate is 1 meter, find the point where the sound pressure level between the rightmost end and the center point has an intermediate value (upper right red line point) at a point having a + coordinate value and Y up to a point of 0.5 meters. The coordinates are continuously reduced by one spatial resolution (the Y coordinate is divided by 51 spatial resolution in the interval, and thus the same value as the median value is continuously found for each spatial resolution), thereby generating a first intermediate line. In this way, at the point where the Y coordinate is 1 meter, the median value of the sound pressure levels for the -coordinate values is found, and the points representing the same value are connected to generate a second intermediate line. Accordingly, the inner points of the first middle line and the second middle line become new, that is, secondary B regions. That is, it can be seen that there is a difference in the design method from the B area set in S100.

On the other hand, the D area finds the maximum value of the sound pressure level for each of the + and-coordinate values on all the X axes at a distance of 0.5 meters from the Y coordinate. For example, in (a) to (c) of FIG. 3, when the X coordinate has a + coordinate value at the point where the Y coordinate is 0.5 meters, the far right end is expressed in blue color so that the sound pressure level is the lowest and Expressed in red, the sound pressure level is the highest. At the point where the Y coordinate is 0.5 meters, the point with the + coordinate value is found at the point where the sound pressure level between the rightmost end and the center point is maximum (the upper right blue line) and the Y coordinate to the point where Y is 0 meters. And continue to decrease as much as 1 spatial resolution (the Y coordinate is divided by 51 spatial resolution in the above intervals, and thus continue to find the same value as the maximum value for each spatial resolution) to generate a third intermediate line. In this way, the fourth intermediate line is generated by finding the maximum value of the sound pressure level for the -coordinate values at the point where the Y coordinate is 0.5m and connecting the points representing the same value. Accordingly, the outer points of the third intermediate line and the fourth intermediate line are new, that is, secondary D regions. That is, it can be seen that there is a difference in the design method from the D area set in S100.

S112 (Calculate R _B and R _D of new B area and new D area)

를 수학식2를 이용하여 산출하고, S102와 동일한 방법으로 새로운 B영역 및 D영역의 음향전달임피던스인 R_B 및 R_D를 각각 산출한다. In this way, using the newly reset B area and D area in S110, the sound transfer function is the same as that of S100 of the present invention.

Is calculated using Equation 2, and R _B and R _D, which are acoustic transfer impedances of the new B area and the D area, are respectively calculated in the same manner as in S102.

)및 고유벡터(

) 산출)S114 (using R _B and R _D , the eigenvalue that maximizes the difference between the output energy of the input area and the output energy of the new area.

) And eigenvectors (

) Calculation)

)를 산출한다. 이에 산출된 고유벡터(

) 즉 체적속도를 음장시스템에 새로운 입력 수학식 1의 체적속도(q_c, Source Volume Velocity)로서 결정할 수 있다(이때 수학식1의 음향 전달 함수인 Green 함수(

)는 상기 S112에서 새로이 산출한

를 이용).R _B and R _D of the new B region and D region calculated in S112 Substituting Equation 4 as in S104, the eigenvector (

) Is calculated. The eigenvectors

In other words, the volume velocity can be determined as the volume velocity (q _c , Source Volume Velocity) of the new input equation 1 to the sound field system (in this case, the Green function (

) Is newly calculated in S112.

).

FIG. 5A is a configuration diagram in which the sound pressure level SPL is normalized by the conventional sound collation method, and FIG. 5B is a configuration diagram in which the sound pressure level SPL is normalized by the acoustic difference method of the present invention.

As shown in FIGS. 5A and 5B, while the acoustic contrast method simultaneously reduces the energy of the bright region together with the energy of the dark region, the acoustic difference method can visually identify that the energy of the dark region is reduced while maintaining the energy of the bright region. . It can also be observed that the acoustic difference method provides better representation of acoustic dark areas.

As mentioned above, although the present invention has been described by means of a limited configuration and drawings, the technical idea of the present invention is not limited to the above, and by those skilled in the art to which the present invention pertains, Various modifications and variations may be made without departing from the scope of the appended claims.

1 is a photograph showing the acoustic space inside the vehicle of the present invention.

Figure 2a is a block diagram showing the configuration of the acoustic space of the present invention.

Figure 2b is a flow chart of the sound control method of the line array speaker of the present invention.

3 is a block diagram showing the results of performing a simulation by normalizing the sound pressure level (SPL) at 1,2,3 kHz by applying an acoustic difference algorithm from a line array speaker and a space definition under the same conditions.

Figure 4 is a block diagram showing the configuration of the acoustic space of the present invention.

5A is a configuration diagram in which the sound pressure level SPL is normalized by a conventional sound collation method.

5B is a configuration diagram in which the sound pressure level SPL by the acoustic difference method of the present invention is normalized.

Claims (5)

A sound control method for a line array speaker for a vehicle, (a) setting a primary bright region (region B) and a primary dark region (region D) in the entire acoustic region T of the sound field system; (b) calculating a sound pressure (P) of the sound field system; (c) normalizing the sound field system using the calculated sound pressure P of the sound field system; (d) setting the secondary bright region (B region) and the secondary dark region (D region) in the entire acoustic region T using the sound pressure P of the normalized sound field system; And (e) An eigenvalue that maximizes the difference between the output energy compared to the input energy of the second bright region (region B) and the input energy of the second dark region (region D).

) And eigenvectors (

) And the eigenvectors (

) Is determined as the volume velocity (q _c ) of the sound field system. The method of claim 1, Step (b) is (b-1) Sound of the primary bright region (region B) in consideration of the distance between the x and y coordinates and the array speaker in the primary bright region (region B) and the primary dark region (region D) Calculating the acoustic impedance R _{D of the} transmission impedance R _B and the primary dark region D region; (b-2) wherein the primary light regional acoustic transfer impedance (R _B) and the first dark region acoustic transfer impedance input at the B area by using the difference between the (R _D) of (D area) of (B area) Eigenvalues that maximize the difference between the ratio between energy and output energy and the ratio between input and output energy

) And eigenvectors (

Calculating c); (b-3) Transfer function of the entire sound field (T) of a sound field system (

Calculating c); And (b-4) The eigenvector

) And the transfer function of the entire acoustic region T of the sound field system (

Calculating a sound pressure (P) of the sound field system using a). The method of claim 1, Step (d) (d-1) from the normalized sound pressure level, the area B finds an intermediate value of the sound pressure level for each of the + and − coordinate values on all X axes at a distance at which the Y coordinate of the array speaker is set; (d-2) generating a first intermediate line and a second intermediate line by connecting intermediate values of sound pressure levels of the + coordinate value and the -coordinate value; (d-3) setting inner points of the first middle line and the second middle line to a second bright area (area B): (d-4) finding the maximum value of the sound pressure level for each of the + and-coordinate values on all X axes from the midpoint of the set distance, wherein the Y coordinate; (d-5) generating a third intermediate line and a fourth intermediate line by connecting the maximum values of sound pressure levels of the + coordinate value and the -coordinate value; And and (d-3) setting outer points of the third middle line and the fourth middle line to a second dark area (D area). The method of claim 2, In the steps (b-2) and (e) The light areas acoustic transfer impedance (R _B) and the acoustic transfer impedance of the dark area (D area) (R _D) is the sound control of the line array speaker, characterized in that for calculating from the equation below, each of the (B area) Way. Equation

,

(E _OUT is the output energy,

Is the input energy of the sound field system, V is the space where the sound absorption point is formed, R is the transfer function of the entire acoustic region (T) of the sound field system (

or

Quadratic form of

here

Is the angular frequency, c is the speed of sound waves,

Is the density of the air) The method of claim 4, wherein In the steps (b-2) and (e) The eigenvector

) Is the eigenvalue of (R _B -R _D ) as the system matrix

) Is the value when the maximum is the acoustic control method of the line array speaker. Equation

((

): Eigenvectors,

: Intrinsic value, E _in : Input energy, E _B : Output energy of bright area (B area), E _D : Output energy of dark area (D area))

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