JP3340763B2 - Apparatus and method for controlling equalizer characteristics in sound field correction - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound field correction system using an equalizer, which is used for calculating and controlling an optimum equalizer parameter necessary for performing correction so as to be closest to a target equalizer characteristic with a minimum equalizer control amount. Apparatus and method.

[0002]

2. Description of the Related Art FIG. 5 shows a conventionally proposed system for correcting a sound field using an equalizer circuit. In FIG. 5, 1 is a signal generator for measurement, 2 is a graphic equalizer circuit for sound field correction, 3 is an amplifier, 4 is a speaker, 5 is a microphone for measuring acoustic characteristics, and 6 is the frequency of a signal from the 5 microphone. A frequency characteristic analysis circuit for performing analysis, 7 is an arithmetic circuit for calculating a control amount of the graphic equalizer circuit 2 based on the measured value, and 8 is a control circuit for controlling the graphic equalizer. This sound field correction system operates as follows. Measurement signal generator 1
Measuring signal passes through a graphic equalizer circuit 2 which is set to the average equalizer characteristic, is amplified by the amplifier 3 is reproduced from the speaker 4 from.

Next, a measurement signal radiated from a speaker 4 is received by a microphone 5 placed at a listening position in a room to be corrected, and the received signal is input to a frequency characteristic analysis circuit 6. The level L _{1 to} L _n (n: the number of divided bands) of each frequency band is detected by each band pass filter in the circuit 2 divided into the same frequency band as the frequency point for controlling the graphic equalizer circuit 2. . The detected measurement data of each of the levels L _{1 to} L _n is transferred to the arithmetic circuit 7. The arithmetic circuit 7 receives the measurement data L _{1 to} L _n and calculates and determines the control amount of the graphic equalizer circuit 2. The calculation procedure in the arithmetic circuit 7 is shown in the flowchart of FIG.

First, the average level bar L = (L ₁ + L ₂ +... + L _n ) / n is obtained from the measured data L _{1 to} L _n prepared in step S 1, and the bar L = bar L in step S _{2. 1} = bar L ₂ =... = Bar L _n, and bars L ₁ to L _n are set as reference frequency characteristics to be corrected.

Next, in step S3, a level difference between the measured value for each band and the target value is obtained, and the value is set as gain control amounts G _{1 to} G _n of each band of the graphic equalizer. Gi = Li−Li (i = 1 to n) The graphic equalizer circuit 2 is controlled in accordance with the control amount transferred to the control circuit 8 in step S5 to perform sound field correction.

[0006]

However, in the arithmetic circuit of the above-described conventional sound field correction system, as a processing method, first, the average value level of each band of the measured data is set as a correction target. In the case where the frequency characteristics of the obtained space are as shown in FIG. 7, the amount of control of the equalizer can be reduced by performing the correction at the level (b) rather than at the average level (a) of each band. , Efficient. In general, when performing correction using an equalizer circuit,
It is said that it is better to adjust the control amount of the equalizer to be as small as possible in consideration of phase distortion when an equalizer is added, distortion S / N due to excessive input to the speaker, and the like.

Further, the conventional system attempts to perform correction by a graphic equalizer circuit having a fixed center frequency f and a fixed sharpness Q. The equalizer f in which the peak and dip of the measured frequency characteristic are set. If it occurs at a position deviated from the position or if Q is smaller than the set value, sufficient correction cannot be performed. Further, when it is necessary to correct the value of Q larger than the value set by the equalizer (FIG. 8), the correction must be performed by a plurality of equalizers, and the efficiency of the control amount of the equalizer described above is reduced. It will be worse and smooth correction cannot be done. For these reasons, there has been a problem that the equalizer sound field correction in the conventional system has not been performed optimally.

An object of the present invention is to solve the above-mentioned problems of the prior art and to propose a sound field correction system and method using an equalizer that can perform more efficient and optimum sound field correction.

[0009]

In order to achieve the above object, a first aspect of the present invention is to convert a predetermined measurement signal into a measurement reproduction signal by using an equalizer characteristic based on a predetermined equalizer control amount of the equalizer means. The reproduction output signal is reproduced by the reproduction output means, and the reproduced reproduction signal for measurement is fetched by reproduction signal input means provided at an arbitrary listening position in the space to be corrected, and the measurement reproduction signal is reproduced by the frequency analysis means. the frequency level analyzed in correspondence with the control frequency band of the equalizer means, the equalizer control amount calculation means, based on the result of the frequency-level analysis, the apparatus for controlling operation of the equalizer control amount, for the measurement
From the plurality of values of the reproduction signal,
So that the equalizer control amount of the riser control means is minimized
Correction control amount calculating means for calculating the level of the correction target curve; and equalizer parameter correction control means for controlling parameters f, Q, and G of the equalizer characteristic based on the equalizer control amount of the equalizer means by the correction control amount. It is characterized by having.

According to a second aspect of the present invention, a predetermined measuring signal is
The signal is converted into a measurement signal by an equalizer characteristic based on a predetermined equalizer control amount of the equalizer means, reproduced and output by the reproduction output means, and the reproduced reproduction signal for measurement is set at an arbitrary listening position in the space to be corrected. The reproduced signal for measurement is fetched by the reproduced signal input means provided in the apparatus, and the reproduction signal for measurement is analyzed by the frequency analysis means in correspondence with the control frequency band of the equalizer means, and the result of the frequency level analysis is obtained by the equalizer control amount calculating means. A method of calculating and controlling the equalizer control amount based on the correction target curve such that the equalizer control amount of the equalizer control means required for correction is minimized from a plurality of values of the reproduction signal for measurement. A correction target bell calculating step of calculating the level of the signal; Equalizer parameters f for,
Determining an optimum value of an equalizer parameter for determining a Q and a G, and calculating an optimum value of an equalizer parameter that minimizes a deviation between the correction target curve and the measurement value curve based on the measurement reproduction signal from the combination thereof; It is characterized by including.

[0011]

[0012]

In the first and second aspects of the present invention, the level of the target curve for minimizing the equalizer control amount for correction is calculated from a plurality of values of the reproduction signal for measurement. An equalizer parameter for correction is determined from these levels and a plurality of values of the reproduction signal for measurement, and an optimum value of the equalizer parameter from which a deviation between the correction target curve and the measurement value curve based on the reproduction signal for measurement is minimized. Is calculated.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention shown in the drawings will be described below. FIG. 1 shows an embodiment of a control device for equalizer characteristics in sound field correction according to the present invention. In the figure, 11 is a signal generation circuit for measurement, 12 is a parametric equalizer for sound field correction, 13 is an amplifier, 14 is a speaker, 15 is a microphone, 16 is a frequency analysis circuit that performs frequency analysis of a signal from the microphone 15, Reference numeral 17 denotes an arithmetic circuit for calculating the control amount of the parametric equalizer based on the measurement data, 18 a control circuit for controlling the parametric equalizer 12 according to the calculation result, and 19 a control circuit (CP) for automatically operating the entire system.
U). In this embodiment, as the parametric equalizer 12, a 6-band digital parametric equalizer constituted by a digital filter is used.
Six independent digital filters, each with a center frequency f ₀ of 20 Hz to 20 kHz, variable in 1/3 octave steps, and a gain amount of ± 12 dB in 1 dB steps,
Q can be varied in 0.5 steps from 0.5 to 7.

The operation of the above embodiment is controlled by the control circuit 19 in the following procedure. Measurement signal generation circuit 1
From 1 to a predetermined measurement signal (in this embodiment, pink noise is used, but other wavetones or the like may be used depending on the purpose) by the parametric equalizer 12 set to an average equalizer characteristic. As described above, the signal is amplified by the amplifier 13 and reproduced from the speaker 14. Next, the microphone 15 placed at the listening position in the room to be corrected receives the measurement signal radiated from the speaker 14 and inputs the signal to the frequency analysis circuit 16, where the signal is input. 1/3 for each band-pass filter which is divided into a frequency band of an octave step detects the level L ₁ ~L ₃₁ of each frequency band, obtaining the frequency characteristics of the space to be corrected. In response to the frequency characteristic data, the arithmetic circuit 17 determines the optimal correction control amount of the parametric equalizer. In the process of obtaining the optimum control amount performed in the present invention, first, the level value of the optimum correction target curve that reduces the equalizer control amount is obtained,
By applying the equalizer to the measured data, a combination of parametric equalizer parameters f, Q, and G that is closest to the target value is obtained. First, a procedure for obtaining the level value of the target curve will be described with reference to FIG.

[0015] Step S11: measurement data (measurement reproduced signal) maximum value Lmax of L ₁ ~L _31, obtains the minimum value Lmin (Figure 3 (a)). Step S12: The level range from Lmax to Lmin is set to n
It is divided into equal parts (in the present embodiment, n = 15 as an initial value), and the respective ranges are Do to D
n (FIG. 3B).

[0016]

Table 1 Lmin ≦ Do <Lmin + (Lmax−Lmin) / n Lmin + (Lmax−Lmin) / n ≦ D1 <Lmin + (Lmax−Lmin) / n × 2: Lmin + (Lmax−Lmin) / n × (n−) 1) ≦ Dn <Lmax

Step S13: Level L _{1 of} measured data
~L ₃₁ it is checked if there in which range each Do～Dn, obtains a frequency distribution of the scope Do～Dn.

Step S14: In the frequency distribution, Do
Of -Dn, what was often the most power and D _R.

[0019] Step S15: If the D _R is not limited to one (if one with maximum frequency of Do~Dn there were two or more), or, the frequency of D _R 10
If a there was less than the value of n by 1 small (the width of the division by one step larger) again processing S12 to S14 D _R
Is repeated until the above condition is not satisfied.

[0020] Step S16: When the D _R is something other than the condition of step S15, takes out those that are present in the range of D _R among the measurement values L ₁ ~L _31, it l ₁ ~lLmax
(FIG. 3D). (Lmax = D power of _R) Step S17: l ₁ ~lLmax average bar _{l = (l 1 + ...... +} lLmax) data / seek Lmax.

The bar l obtained by the above procedure is the optimum target curve level value. The level of the target curve obtained by the above procedure is assumed to be constant regardless of the frequency band, and is assumed to be corrected to a flat target curve.However, if it is desired to correct the frequency characteristics with any weight, the minus the weighting in the frequency curve of the target from the measured data and L ₁ ~L _31, S contrast
The processing from 15 to S17 is performed, the obtained bar l is weighted again as a target, and the level for each frequency component may be set as bar l ₁ to bar l ₃₁ .

Next, a description will be given of a processing procedure for obtaining a combination of parameters f, Q, and G of the parametric equalizer 12 which is closest to a target characteristic when an equalizer is applied to the measurement data. FIG. 4 shows this processing procedure.

Step S21: For each of the terms corresponding to the measured data L _{1 to} L ₃₁ and the target curve bars l ₁ to l ₃₁ , the respective deviations αi = bar li−Li (i = ₁ to ₃₁ ) are obtained. The largest value αn of α31 is obtained.

Step S22: Parameter values f, Q, and 1 of the first band of the 6-band parametric equalizer
Let G be the center frequency of the frequency band corresponding to n of αn to αn obtained in S21, let G be the value of αn, and let the value of Q be a controllable parameter range (0.5 to 7 in this embodiment). It is set to the median (3 in this embodiment) and these are set to f ₀ , G ₀ ,
Let it be Q ₀ .

Step S23: When equalizer control is performed with the parameter values set in S22, how much the level of each frequency band at 1/3 octave intervals changes, and the amount of change EQ ₁ -EQ ₃₁ is determined by the equalizer filter. Is calculated on the circuit from the transfer function of

In one example of this embodiment, the equalizer 12 is constituted by using a digital filter. This digital filter uses a second-order IIR filter, and its transfer function is

[0027]

(Equation 1)

(Equation 2)

(Equation 3)

Is as follows. The equation for obtaining the frequency characteristic from this transfer function is

(Equation 4)

In the present embodiment, from the above equations, EQ ₁ to EQ
Seeking ₃₁ .

Step S24: Measured data L _{1 to} L
And _31, added together and variation EQ ₁ ~EQ ₃₁ by the equalizer determines the estimated value L ₁ '~L _31' of the frequency characteristics when multiplied by the equalizer to the measured value.

(Equation 5)

Step S25: L ₁ '-L ₃₁ ' and bar l ₁
~ Bar l ₃₁ Take the deviation for each corresponding one,
The sum is S.

[0032]

(Equation 6)

Step S26: The value of Q that is currently set is varied in magnitude, and the processing of S23 to S25 is repeated for each of them, so that Q is set so that S is minimized.
Find the value of

Step S27: With respect to the value of Q obtained in S26, next, the values of f and G are changed in magnitude, and
Steps S25 to S25 are repeated for each, and the values of f and G that minimize S are obtained.

Step 28: Further, the processes of S26 and S27 are sequentially performed, and a combination of f, Q, and G that minimizes the value of S is obtained.

The parameter value obtained by the above processing is the optimum control amount of the first band of the parametric equalizer. To find the optimum value after the second band, L ₁
~L ₃₁ to change the frequency characteristic estimated value L ₁ '~L _31' when subjected to the optimum value parametric equalizer optimal parameters obtained by the above process, successively performs processing of S21 to S28.

Thus, the parametric equalizer 1 shown in FIG.
When the optimal control amounts of all the bands included in step 2 are obtained, the control circuit 18 of FIG. 1 controls the parametric equalizer 12 according to the values to complete the correction of the sound field.
The parametric equalizer circuit shown in the present embodiment is not limited to the one using a digital filter, but may use an analog one if the transfer function can be obtained by calculation. Further, specific numbers such as the number of bands of the equalizer described in the present embodiment are not limited thereto, and may be used after being changed according to conditions such as the degree of disturbance of the sound field in the space to be corrected. It is possible.

[0038]

As described above, according to the present invention, by correcting the sound field, efficient and optimum sound field correction can be performed with a minimum amount of equalizer.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present embodiment.

FIG. 2 is a flowchart for explaining a procedure for obtaining a level value of a target curve in the embodiment.

FIG. 3 is a characteristic diagram corresponding to each step of the procedure of FIG. 2;

FIG. 4 is a flowchart showing a procedure for obtaining a combination of equalizer parameters that is closest to a target characteristic in the embodiment.

FIG. 5 is a block diagram showing a conventional sound field correction system.

FIG. 6 is a flowchart showing a calculation procedure of an arithmetic circuit in FIG. 5;

FIG. 7 is a frequency characteristic diagram of a measured space.

FIG. 8 is a diagram illustrating a measured f characteristic curve and a graphic equalizer characteristic required for correction.

[Explanation of symbols]

 Reference Signs List 11 Measurement signal generator 12 Parametric equalizer 16 Frequency characteristic analysis circuit 17 Operation circuit 18 Equalizer control circuit 19 Control circuit

Claims (2)

(57) [Claims] 1. A predetermined measurement signal is converted into a measurement reproduction signal by an equalizer characteristic based on a predetermined equalizer control amount of the equalizer means, and the reproduction output signal is reproduced and output by the reproduction output means. The reproduction signal is captured by a reproduction signal input means provided at an arbitrary listening position in the space to be corrected, and the frequency analysis means performs a frequency level analysis on the measurement reproduction signal corresponding to the control frequency band of the equalizer means, By the equalizer control amount calculation means,
In the device for calculating and controlling the equalizer control amount based on the result of the frequency level analysis , it is necessary to correct a plurality of values of the reproduction signal for measurement for correction.
The equalizer control amount of the equalizer control means is minimized.
Correction control amount calculating means for calculating the level of the correction target curve so as to obtain the equalizer parameter correction control means for controlling the equalizer characteristic parameters f, Q, and G based on the equalizer control amount of the equalizer means by the correction control amount. A control device for equalizer characteristics in sound field correction, comprising: 2. A predetermined measurement signal is converted into a measurement signal by an equalizer characteristic based on a predetermined equalizer control amount of the equalizer means, and is reproduced and output by a reproduction output means. A signal is fetched by a reproduction signal input means provided at an arbitrary listening position in a space to be corrected, and the reproduction signal for measurement is frequency-analyzed by a frequency analysis means in accordance with a control frequency band of the equalizer means. A method for calculating and controlling the equalizer control amount based on a result of the frequency level analysis by a control amount calculating unit, wherein a plurality of values of the measurement reproduction signal are used to correct the equalizer control unit necessary for correction. A correction target bell calculation step of calculating the level of the correction target curve so that the equalizer control amount is minimized; The equalizer parameters f, Q, and G for correction are determined from the signal and the plurality of values of the level, and the deviation between the correction target curve and the measurement value curve based on the reproduction signal for measurement from the combination thereof is minimized. An equalizer parameter optimum value calculating step of calculating an optimum value of the equalizer parameter. A method for controlling equalizer characteristics in sound field correction, comprising: