JPH0738988A - Acoustic characteristic correction device - Google Patents

Abstract

PURPOSE:To prevent excess correction or irrational correction in the device correcting the response characteristic of a reproduction system so that the response characteristic of the reproduction system is made coincident with the desired characteristic. CONSTITUTION:An arithmetic operation means 142 calculates a correction characteristic based on a set desired characteristic and a measured characteristic. Correction such as an upper lower limit restriction of a correction level or restriction of a correction frequency range or the like is applied to the correction characteristic as required based on the operation of the operator.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acoustic characteristic correction device for correcting a response characteristic (frequency response or the like) of a reproduction system including a sound field of a listening room or the like to a desired characteristic. This is to prevent such correction.

[0002]

2. Description of the Related Art Conventionally, a graphic equalizer has been generally used as a device for correcting the response characteristic of the entire reproduction system including a room and a speaker. This is to divide the voice frequency band into several bands and adjust the gain for each of the divided bands. However, it was impossible to know how to adjust the reproduced sound to obtain the desired response characteristics.

Therefore, as an example in which the drawbacks of the conventional graphic equalizer are solved and the response characteristic of the entire reproducing system can be automatically set to a desired characteristic, for example, Japanese Patent Publication No. 61-
There was one described in Japanese Patent Publication No. 59004. This is because the user sets the desired characteristics, and the measurement signal such as white noise or impulse is reproduced by the speaker of the reproduction system in the sound field to be reproduced and the response characteristics are collected by the microphone. Measure, obtain the correction characteristic so that it matches the desired characteristic, set the filter characteristic of the equalizer that matches this correction characteristic, and play the music signal through this equalizer to adjust it to the desired characteristic. It is designed so that you can enjoy playing music.

[0004]

When a response characteristic is measured in a sound field to be reproduced, a large peak
The measurement characteristics with the dip may be observed. This peak dip is often caused by a slight change in the measurement environment, and if the correction characteristics are obtained using these measurement characteristics and equalization is performed, a slight change in the environment ( For example, a slight deviation in the frequency characteristics due to the influence of the temperature and humidity of the air) can no longer be a true correction, and conversely, a large correction error that normally cannot occur is generated, which is a rather characteristic characteristic. Become.

In addition, even if the reproduction frequency range of the speaker to be used is narrow, if the desired characteristics in which the low range and the high range are extended are set, the speaker will be subjected to an unreasonable correction. It may have a quirky characteristic or the speaker may be overloaded.

The present invention has been made in view of the above points, and it is an object of the present invention to provide an acoustic characteristic correction device which prevents excessive correction and unreasonable correction.

[0007]

The invention according to claim 1 is
At least one of the upper limit value and the lower limit value of the level of the correction characteristic is regulated.

According to the second aspect of the present invention, at least one of the upper limit value and the lower limit value of the frequency range of the correction characteristic is restricted.

[0009]

According to the first aspect of the present invention, at least one of the upper limit value and the lower limit value of the level of the correction characteristic is regulated, so that it is possible to prevent the characteristic from having a dull characteristic due to excessive correction. You can

According to the second aspect of the present invention, at least one of the upper limit value and the lower limit value of the frequency range of the correction characteristic is regulated, so that it is possible to prevent the characteristic from having a dull characteristic due to unreasonable correction. be able to.

[0011]

An embodiment of the present invention will be described below. FIG. 2 shows an outline of the hardware configuration of the entire apparatus. The acoustic characteristic correction device 10 is composed of a main body 12 and a remote controller 14, and the two are connected by a detachable signal cable 16.

When measuring the response characteristic, the main body 12 performs generation of a measurement signal, frequency characteristic calculation based on a microphone pickup signal, correction characteristic calculation, calculation of FIR filter coefficient corresponding to the correction characteristic, and the like. When used as an equalizer after measuring the response characteristic, the response characteristic is corrected by giving the set FIR filter characteristic to the acoustic signal to be reproduced. The remote controller 14 displays various operation instructions and various response characteristics (measurement characteristics, desired characteristics, correction characteristics, etc.) on the main body 12 during measurement and setting of desired characteristics.

In the main body 12, a microphone input terminal 18
, A measurement microphone is connected when measuring the response characteristics,
A microphone pickup signal is input. Also, the source input terminal 2
A source device such as a CD player is connected to 0, and a source signal reproduced from the source device when used as an equalizer is input. The input unit 22 performs A / D conversion of microphone input and source input. The output unit 24 is a source signal or a measurement signal (test tone signal) that has been equalized.
Is D / A converted and output from the output terminal 26. The patch bay unit 28 changes the connection of input / output and other various signals during measurement and during equalization. The waveform memory output unit 30 reads and outputs the measurement signal waveform (band signal waveform, TSP (Time Stretched Pulse) signal waveform) and TSP inverse filter waveform stored in the ROM.

The input waveform memory section 32 stores the A / D converted microphone input in the RAM. Convolution calculator 34
Is a real-time convolution circuit (for example, Yamaha Corporation LS
The IYM7309 is configured by a circuit in which a large number of stages are connected in cascade to form a convolution unit of several thousand stages. At the time of the equalizer, the filter coefficient of the equalizer is transferred to the equalizer to configure the equalizer by the FIR filter. Further, at the time of measurement when the TSP signal is used as the measurement signal, the TSP inverse filter is configured by transferring the TSP inverse filter coefficient to the convolution operation unit 34. The data processing calculation and other control unit 36 is composed of a CPU, and processes measurement data (measurement characteristic, desired characteristic, correction characteristic calculation, calculation of equalizer filter coefficient corresponding to correction characteristic (inverse Fourier transform), etc.) and patch bay unit 28. Connection switching, other necessary control of the main body 12 and CP of the remote controller 14
Exchanges signals with U42.

In the remote control section 14, the operation section 38 gives all necessary instructions to the main body section 12 at the time of measurement, desired characteristic setting, and correction characteristic setting. The display unit 40 displays various response characteristics and displays for operation. CPU4
2 exchanges data with the CPU 36 of the main body 12.

FIG. 3 shows a panel configuration example of the remote controller 14. The display unit 40 is composed of an LCD display or the like, and various response characteristics are graphically displayed. That is, the graph display section in the upper row has common graph axes (horizontal axis is frequency, vertical axis is level)
The bar graph 44 shows the measured characteristic and the line graph 46 shows the desired characteristic (an example of the flat characteristic) in an overlapping manner.
Also, cursors 62 and 64 indicating the frequency range are displayed as vertical lines. In addition, a correction characteristic calculated as a difference between the desired characteristic and the measured characteristic is displayed in the lower graph as a line graph 48. Further, a correction frequency range set by the operator's operation is displayed as a horizontal bar graph 50 between the upper and lower rows. In this case, the correction characteristic display 48 is not displayed outside the correction frequency range (or is displayed flat on the 0 dB line). Display portions 52 and 54 for displaying current setting items and setting contents are provided on the upper and lower portions of the graph display portion to assist the operation of the operator.

The operation section 38 is provided with a cursor key 56, a shuttle key (rotary encoder) 58, various key switches 60 and the like. Cursor keys 56 are up key 56a, down key 56b, left cursor selection key 5
6c and a right cursor selection key 56d. The left and right cursor selection keys 56c and 56d are used to select either one of the left and right cursors 62 and 64 of the display unit 40 when, for example, correcting a desired characteristic or setting a correction frequency range. When you press the left cursor select key 56c and turn the shuttle 58, the left cursor 6
2 moves to set the lower limit of the frequency range. When the right cursor selection key 56d is pressed and the shuttle 58 is rotated, the right cursor 64 moves in the rotated direction and the upper limit value of the frequency range is set. For example, a ∇ mark 65 is displayed at the selected position of the cursors 62 and 64, which makes it possible to know which is selected. The up and down keys 56a and 56b are used, for example, when modifying the desired characteristic. When the up key 56a is pressed for the specified frequency range, the level of the desired characteristic is smoothly and gradually increased with a curve, and the down key 56b is pressed. When pressed, the level of the desired characteristic is smoothly and gradually lowered with a curve. The key switch 60 is used to select setting items, measurement data,
It is used for execution instructions and other various instructions.

FIG. 4 shows an outline of the procedure from the measurement of the frequency characteristic using the acoustic characteristic correction apparatus 10 of FIG. 2 to the use as an equalizer. Each process is sequentially advanced by the mode advance operation by the operator (for example, every time one key switch is pressed, the next process is advanced). The outline of each step will be described.

Test As shown in FIG. 5 (a), a microphone 72 is arranged at a listening position 71 in a room 70 where music is reproduced, a measurement signal is output from the main unit 10 and reproduced through a power amplifier 74. Are reproduced from the speakers 76 and 78 used for
The sound is picked up by and the picked up sound waveform is stored in the memory in the apparatus 10.
This measurement is performed at each position by moving the microphone 72 to a plurality of points (for example, 5 points) centered on the receiving position 71 as shown on the right side of FIG.

Calculation of Measurement Characteristics The response characteristics are calculated based on the sound pickup signal taken in the memory. The obtained response characteristic (measurement characteristic) is displayed on the display unit 40 of the remote controller 14 in a bar graph as shown in FIG. 6A, for example.

Setting of Desired Characteristic On the remote control unit 14, while watching the display unit 40, the operation unit 38
Operate with to set the desired characteristics. The selected or set desired characteristic is displayed as a line graph 46 on the display unit 40 so as to be superimposed on the same graph axis as the measurement characteristic display 44 as shown in FIG. 6B. As a desired characteristic, for example, this FIG.
As shown in (b), when the measured characteristic 44 is set to a flattened characteristic, both characteristic displays are overlapped and displayed on the same graph axis. Easy to set because you can see at a glance if it becomes flat.

Calculation of Correction Characteristics When the desired characteristics are set, the correction characteristics are automatically calculated as the difference between the desired characteristics and the measurement characteristics, and the display section 40 displays
The line graph 50 is displayed as shown in FIG. Even when the desired characteristic is being corrected, the correction characteristic is always calculated and displayed.

Correction of Correction Characteristic A large peak of the correction characteristic causes an uncomfortable feeling in hearing, so the upper and lower limit values of the level of the correction characteristic are regulated as necessary. If the correction range is limited due to the limit of the reproduction frequency characteristic of the speaker used, the correction frequency range is restricted as necessary (that is, the correction amount outside the correction frequency range is set to 0 dB).

Calculation of Equalizer Filter Coefficients Once the correction characteristics have been determined, they are inversely Fourier transformed to obtain the corresponding impulse response. In this case, it is arbitrarily selected from the linear phase processing Fourier inverse transform, the minimum phase processing Fourier inverse transform, and the Fourier inverse transform of other algorithms according to the situation of use and the like. As a result,
The impulse response as shown in FIGS. 6D and 6E is obtained. The equalizer (FIR) filter coefficient is given as a level value at each position on the time axis of this impulse response. In this way, the equalizer characteristic over the entire frequency band is set.

Confirmation of correction effect The correction effect is confirmed as necessary. This is because the obtained equalizer filter coefficient is set in the convolution operation unit 34 to form an equalizer, and a correction characteristic is added to the measurement signal by this equalizer, reproduced from a speaker, and the response characteristic is measured again and displayed. The measurement characteristic and the desired characteristic are superimposed and displayed on the section 40 to confirm the correction effect. The closer the two characteristics are to each other, the more the correction is performed according to the desired characteristics. If the expected correction state cannot be obtained due to the limitations of the speaker characteristics, the desired characteristics are re-corrected as necessary.

When the music reproduction equalizer filter characteristic is finally determined, FIG.
As shown in (b), the source device 80 such as a CD player
Is connected and the main body portion 12 of the unit 10 is used as an equalizer to perform the final purpose of music reproduction.

FIG. 1 shows a control block configuration in the acoustic characteristic correction apparatus 10 for realizing each step of the above procedure.
FIG. 1 shows the connection state at the time of measurement. The microphone input terminal 18 and the source input terminal 20 have a measurement microphone 72,
The source devices 80 are respectively connected. The measurement signal input from the microphone input terminal 18 is amplified by the microphone amplifier 82. The switch 84 is used for measurement and calculation (from the above
Process) and during reproduction (the above process). The A / D converter 86 converts a microphone input or an analog source input into a digital signal. Switch 88
This is for passing the digital source input through the bypass 90, and can be switched between the digital source input reproduction and the other modes (analog input reproduction, measurement). The switch 92 is switched between measurement and reproduction. The waveform memory 32 is for taking in a microphone input during a test. The measurement signal generator 30 is composed of a ROM that stores the waveform of the measurement signal. In this embodiment, a band signal of the band signal method (described later) and a TSP signal of the TSP method (described later) are stored as the measurement signals, and either of them can be read according to the selection operation of the operator. Has been

The switch 94 is switched during reproduction, during calculation of response characteristics, and during testing. The switch 96 switches between a route passing through the convolution calculator 34 and a route 98 bypassing the convolution calculator 34. The bypass route 98 is selected at the time of test and response characteristic calculation in the band signal method.
A route passing through the convolution calculator 34 is selected when the response characteristic is calculated in the SP method, when the correction effect is confirmed, and when the music is reproduced. The use of the convolutional computing unit 34 can be switched by switching the switch 102. That is, at the time of calculating the response characteristic in the TSP method, the TSP inverse filter waveform read from the TSP inverse filter waveform memory 100 is set as a filter coefficient, and the TSP inverse filter performs time compression of the collected TSP signal to obtain an impulse response. Ask. Further, at the time of confirming the correction effect and at the time of reproducing music, an equalizer filter coefficient corresponding to the correction characteristic obtained by the calculation is set as a filter coefficient and operates as an equalizer. As a result, the convolution calculator 34 is used both as an inverse filter in the TSP method at the time of response characteristic calculation and as an equalizer at the time of confirming the correction effect and at the time of reproducing music, so that the hardware configuration is simplified. Even if it is used in this way, there is no problem because the response characteristic calculation, the correction effect confirmation and the music reproduction are not performed at the same time.

The output of the convolutional computing unit 34 or the output that has passed through the bypass path 98 is input to the switch 106 through the addition point 104. The switch 106 is switched between a test, a correction effect confirmation, a music reproduction, and a response characteristic calculation. During the test, the correction effect confirmation, and the music playback, the measurement signal or the music signal passed through the switch 106 is D
The analog signal is converted into an analog signal by the A / A converter 108 and the low-pass filter 110, output from the output terminal 26, and reproduced by the speakers 76 and 78 in the room 70 via the power amplifier 74.

The signal led from the switch 106 to the line 112 at the time of calculating the response characteristic is distributed by the switch 114 according to the measuring method. That is, in the case of the TSP method,
The frequency conversion means 116 Fourier transforms the impulse response signal to convert it into frequency information, and then the band division means 11
At 8, the signal is divided into a predetermined frequency band (for example, every 1/3 octave band). Further, in the case of the band signal method, since the measurement data is originally obtained in the state of being divided into frequency bands (for example, every 1/3 octave band), it is passed through the bypass path 120 as it is. The signals on both paths pass through an addition point 122 and a band power average calculation circuit 124 obtains a power average for each divided band. The obtained band power data of all frequency bands is stored in the band data memory 12
6 is stored. The band data memory 126 can store the measurement data of a plurality of times (for example, eight times). The measurement data of each time is displayed as a bar graph according to the display selection operation by the operator (measurement characteristic display 44 in FIG. 3).

The selection / weighting means 128 selectively outputs, out of the plurality of times of measurement data stored in the band data memory 126, one selected and instructed by the operator's selection operation. If necessary, the measurement data is weighted according to the positions (FIG. 5A) of the measurement points P1 to P5 with respect to the listening position 71. The collective averaging means 130
A set average of a plurality of selected and weighted measurement data is calculated. The interpolating means 132 treats the values of each band subjected to collective averaging as values at the center frequency of each band, interpolates between the center frequencies of each band, and connects all frequency bands with continuous and smooth curve data. Find characteristics.
The interpolation data thus obtained is stored in the RAM 134 as a final measurement characteristic.

The ROM 136 stores a desired characteristic such as an average characteristic and some other characteristics, and the one selected by the key switch 60 is read out. The selected desired characteristic is corrected to a desired characteristic by the calculating means 140 based on the operation of the cursor key 56, the shuttle key 58, etc. by the operator. The corrected desired characteristics are stored in the RAM 138 with a backup power supply and can be read out and used at any time in the same manner as the characteristics of the ROM 136.

The calculating means 142 calculates the correction characteristic from the set desired characteristic and measurement characteristic. As for the correction characteristic, corrections such as upper and lower limit values of the correction level and the restriction of the correction frequency range are added based on the operation of the operator. The equalizer filter coefficient calculation means 144 calculates an equalizer filter coefficient corresponding to the set correction characteristic. The calculated filter coefficient is set in the convolution calculator 34, and the equalizer characteristic at the time of reproducing music and at the time of confirming the correction effect is set. Further, the calculated filter coefficient is stored in the RAM 146 with backup power supply and can be read out and used at any time. The filter coefficient is also stored in the RAM card 148 so that the filter coefficient can be shared by inserting the RAM card 148 into another music characteristic correction device.

The display control means 150 displays the calculated measurement characteristics, desired characteristics, correction characteristics, etc. on the display section 4 of the remote control section 14.
Performs control for displaying 0. The CPU 36 (FIG. 2) of the main body 12 executes the switching control of each switch in FIG. 1 and various calculations other than the convolution calculator 34.

Next, the control of each step of the procedure of FIG. 4 by the control block of FIG. 1 described above will be described in detail. When the response characteristics are measured in the test room, the characteristics vary considerably depending on the location. This is because the reflected waves from the ceiling, floor, walls, etc. in the room interfere with each other and disturb the frequency characteristics. In addition, this phenomenon is remarkable even with a slight difference in the location as the frequency is shorter and higher. Therefore, when the correction characteristic is calculated based on the data of one measurement point and the filter coefficient of the equalizer is calculated, the best result is obtained at that point, but the area including the surrounding area (range where the listener's head moves, etc.) ), There may be extreme peak dips and the best results may not be obtained.

Therefore, in this embodiment, as shown in FIG.
As shown on the right of, a measurement area 73 centered on the listening position 71 in the room 70 is set, and a plurality of measurement points P1 to P5 including the listening position 71 are set in the area 73, and The microphone 72 is moved to the points P1 to P5 to perform measurement, and the correction characteristic is obtained from the spatial average thereof. As a result, good correction characteristics can be obtained on average at any position within the area, and the effective area for correction can be expanded.

In this embodiment, the test method is as follows.
As described above, one of the band signal method and the TSP method can be selected according to the selection operation by the operator. The TSP method has an advantage that the measurement time is short and continuous measurement data can be obtained instead of discrete measurement data for each divided band. However, in this embodiment, as described above, since the convolution calculator 34 for the equalizer is also used as the TSP inverse filter used in the TSP method, there is a limit to the length of the measurement TSP signal. There is a limit to the power of the entire TSP signal, and when used for measurement in a noisy environment, the SN ratio of the measurement result may deteriorate.

Therefore, the band signal method is used in a noisy environment or when the measurement time is not restricted, and in a noisy environment or when the measurement time is limited (for example, in a reproduction system in a hall or the like). There are many (speaker systems), and the band signal method requires time for measurement, etc.)
The TSP method is used for the above, and both methods are used properly.

Test methods using the band signal method and the TSP method will be described respectively. (A) Band Signal Method The band signal method is to sequentially output band signals obtained by dividing a frequency band into a plurality of parts at different times, and measure the response for each band. Here, the band width of each band uses a 1/3 octave band method (that is, a division method in which each band has a 1/3 octave band width) which is said to be relatively close to the auditory characteristics. In this case, it is possible to obtain continuous data with a high division ability by finely dividing the division pitch, but it takes a huge amount of time to generate the band signal of the entire band. Therefore, here, the division pitch is set by either the 1/3 octave of FIG. 7A or the 1/6 octave of FIG. 7B by the operator's selection operation, and the measurement data is obtained. Interpolated to obtain continuous data. If the division pitch is 1/3 octave pitch, the band width will not overlap,
If the pitch is 1/6 octave, the band width will change while overlapping by 1/3 octave. If they overlap, the connection between the bands in the measurement data will be good.

FIG. 8 shows an example in which the 1/3 octave band is divided into 1/3 octave pitches. (A) is the band signal waveform center frequency, (b) is the band signal waveform (when the center frequency is 100 Hz), and (c) is the output flow of the band signal waveform. The band signal waveform of (b) is shown in FIG.
Stored in the measurement signal generator 30 (ROM) of
By changing the read speed, a measurement signal for each band is generated. Speaker 7 with staggered time
The band signals emitted from 6, 78 are picked up by the microphone 72 for each band, and the picked-up sound waveform is stored in the waveform memory 32 of FIG.

(B) TSP method In general, a single pulse is used to measure the impulse response of a hole or the like. However, since the signal power is small, the SN ratio cannot be sufficiently obtained even if a method such as synchronous addition is used together. Often. On the other hand, when the TSP signal is used, the signal power is large and it is easy to obtain the SN ratio. In addition, an inverse filter can be easily obtained, and in order to convert the response of the TSP signal into an impulse response, convolution calculation with this inverse filter can be performed. Therefore, if a convolver can be used, conversion is easy. Therefore, the TSP signal has a characteristic convenient for measurement.

The TSP signal used in the TSP method is shown in FIG.
It has a waveform as shown in. This TSP waveform is stored in the measurement signal generator 30 shown in FIG. 1, and is read once by one measurement and reproduced from the speakers 76 and 78.
The reproduced TSP signal is picked up by the microphone 72, and the picked up sound waveform is stored in the waveform memory 32.

Calculation of Measurement Characteristic The calculation of the response characteristic based on the collected sound waveform stored in the waveform memory 30 is performed as follows according to the test method.

(A) Band Signal Method In the band signal method, the collected sound waveform for each divided band stored in the waveform memory 30 of FIG.
4, 96, bypass path 98, addition point 104, switch 1
After passing through 06, 114, the bypass path 120, and the addition point 122, the band power average calculation means 124 calculates the band power average for each divided band and stores it in the band data memory 126. The band data memory 126 can store a plurality of measurement data, for example, as shown in FIG.
The measurement data of five points P1 to P5 shown on the right of (a) are stored. The selection weighting means 128 selects or discards data by the operator looking at the individual measurement characteristics on the display unit 40 and excluding data that is extremely different from the others. In addition, the remaining data is weighted as necessary. Specifically, when the measurement points are, for example, five points P1 to P5 shown on the right side of FIG.
The other points P2 to P5 are set to 0.5 respectively, or the point P1 at the center position is set to 1 and the other points P are set.
2 to P5 are summed to 1 and so on.

The selected and weighted measurement data is set averaged by the set averaging means 130. As a result, average measurement data of the area where the measurement is performed can be obtained. Since the measurement data subjected to collective averaging is discrete data for each divided band, this is interpolated by the interpolating means 132 to be converted into continuous smooth curve data. As the interpolation method, a spline interpolation method that can perform interpolation in a short time is suitable. In the interpolation, as shown in FIG. 10, data obtained as a power average for each divided band is treated as a value at the center frequency of each band, and spline interpolation is performed between the points based on the values of several points before and after. Then 40
Interpolation data of 96 points is obtained and this is used as a measurement characteristic.

As described above, the power average for each divided band is obtained, and this is used as the value at the center frequency to perform spline interpolation between the points, whereby useful and practical averaging of the obtained measurement characteristic results is achieved. As it is possible to prevent large peak dips due to phase interference in the measurement characteristics as in the past, it is uncomfortable to hear due to the extreme correction when using the measurement characteristics as they are to obtain the correction characteristics and using them for the characteristic correction. Is prevented. The data of the measurement characteristic thus obtained is stored in the RAM 134 of FIG. 1 and displayed on the display unit 40 as a bar graph (measurement characteristic display 4 of FIG. 3).
4) Is done.

(B) TSP method The collected sound waveform stored in the waveform memory 32 of FIG. 1 in the TSP method is immediately stored in the TSP inverse filter coefficient memory 100 by the convolution calculator 34 via the switches 94 and 96. The inverse TSP waveform (FIG. 9 (b)) and the convolution operation (time compression) are performed to obtain an impulse response (FIG. 9 (c)). The inverse TSP waveform is a waveform obtained by temporally inverting the TSP waveform (FIG. 9A). When the number of stages of the convolutional computing unit 34 is insufficient as a time compression filter for the TSP signal, the time compression can be performed separately.

The impulse response output from the convolution calculator 34 is Fourier transformed by the frequency conversion means 116 via the addition point 104 and the switches 106 and 114 to obtain the frequency response characteristic (FIG. 9 (d)). The obtained frequency response characteristic is band-divided by the band dividing means 18 into the same state as in the band signal method (1/3 octave band width, 1/3 or 1/6 octave pitch). The band-divided measurement data is subjected to the same processing as in the band signal method. That is, the measurement data for each band divided by the band dividing unit 118 passes through the addition point 122, the band power average for each divided band is calculated by the band power average calculating unit 124, and the band power average is stored in the band data memory 126. It The band data memory 126 stores measurement data for multiple points and multiple times. The selection weighting means 128 selects or discards data by the operator looking at the individual measurement characteristics on the display unit 40 and excluding data that is extremely different from the others. In addition, the remaining data is weighted as necessary. The selected and weighted measurement data is subjected to collective averaging by the collective averaging means 130. As a result, average measurement data of the area where the measurement is performed can be obtained. Since the measurement data subjected to collective averaging is discrete data for each divided band, this is spline-interpolated by the interpolating means 132 to be converted into continuous smooth curve data. The interpolated measurement data is stored in the RAM 34 as a measurement characteristic and is displayed on the display unit 40 as a bar graph.

As described above, also in the TSP method, the measured data is once band-divided, the power average is taken for each band, and interpolation is performed to obtain continuous data. Since the occurrence of the peak dip is prevented, an uncomfortable feeling due to the extreme correction when the correction characteristic is obtained by using the measurement characteristic as it is and used for the characteristic correction is prevented.

FIG. 11 shows an example of the operation procedure in the calculation of the test and measurement characteristics described above. First, the microphone position is set (S1), and either the band signal method or the TSP method is selected as the test method (S2).
Further, either 1/3 octave band pitch or 1/6 octave band pitch is selected as the band division pitch (S3). Then, when the test start button is pressed (S4), the test sound is reproduced from the speakers 76 and 78, picked up by the microphone 72 and stored in the waveform memory 32 (S5). The measurement result is immediately displayed on the display unit 40 as a bar graph (S6), and the operator can confirm it by looking at it. If the measurement result seems to be abnormal (for example, if a large amount of noise is present), retest is performed at that point (S7, S8). If the measurement result is good, move the microphone position to another point and repeat the test (S
9).

When the test is completed for all the points (S10), the collected data is sequentially displayed on the display unit 40, and the data is selected (S11). The selected data is weighted for each measurement point by automatic or manual setting as needed (S1).
2). Then, for the data of each weighted point, the set average value and the interpolation value are automatically calculated, and R
It is stored in the AM 134 as one final measurement characteristic data (S13), and the measurement is completed.

Setting of Desired Characteristics FIG. 12 shows an example of the setting flow of desired characteristics. When the desired characteristic setting mode is selected on the remote controller 14 (FIG. 3), the graph scale is displayed on the display unit 40 (S2
2), the measurement characteristics stored in the RAM 134 are displayed in the bar graph 44 (S23). Next, when the desired characteristic is selected (S24), the corresponding desired characteristic is stored in the ROM.
136 or the RAM 138 and read from the display unit 4.
A line graph 46 is displayed at 0 (S25).

By the way, the transmission characteristic of the speaker in the listening room or the hall changes depending on the directivity of the speaker and the reverberation characteristic of the room, and the desirable characteristic in hearing does not always coincide with the flattening of the measurement characteristic. do not do. Therefore, it is convenient if desired characteristics in the room can be easily set. For example, in a large speaker system, desired characteristics desired for PA (Public Address) in the hall, desired characteristics when listening with a small speaker in a home listening room, and the like can be easily prepared in advance. It is possible to correct the characteristic.

Therefore, the ROM 136 has, as a general pattern of desired characteristics, a characteristic C1 which is flat over the entire band as shown in FIG. 13, a characteristic C2 in which the low and high frequencies of the flat characteristic are attenuated, and bass emphasis. It is convenient to prepare in advance a characteristic C3, a mid-tone emphasis characteristic C4, a bass / high-pitched sound emphasis characteristic C5, and the like. In this case, by displaying the characteristic pattern name on the display unit 40, the operator refers to this, moves the cursor to the desired characteristic pattern and performs a selection operation, reads the corresponding characteristic data from the ROM 136, and outputs the desired characteristic. Can be used as In addition, characteristic data classified by various speakers (PA for hall PA, outdoor PA, small speaker for studio monitor, etc.) and various rooms (Japanese-style listening room, Western-style listening room, etc.) is stored in the ROM 136, and the display unit 40 is stored. By displaying the speaker type name or room type name on the screen, the operator can refer to this and move the cursor according to the speaker type or room to use to select the speaker type or room type. The desired characteristic data can be read from the ROM 136 and used as a desired characteristic. Once the desired characteristics are set,
The calculation unit 142 automatically calculates [measurement characteristic]-[desired characteristic] to obtain the correction characteristic, and the display unit 40
Is displayed as a line graph 48 (S27). ROM
The characteristic data read from 136 can be used as it is as a desired characteristic, but it can be partially modified and used.

As a characteristic adjusting method in the case of the conventional graphic equalizer or parametric equalizer, FIG.
, The center frequency F, the gain G, and the sharpness Q
It was common to adjust by changing the value of. In this case, as the order of adjustment, first determine the center frequency F,
Then, the value of Q is set, and finally the gain G is raised or lowered, but it is necessary to adjust the three parameters independently to match the target characteristics, and the adjustment operation is not easy. In addition, when Q is changed, its effect extends to the entire frequency range, so it is difficult to understand how the characteristics actually change when Q is changed.
It was difficult to adjust.

Therefore, here, the center frequency is not determined, but the frequency range from where to where is set,
By raising and lowering the characteristic within the specified range while maintaining the smooth connection of the characteristics at both ends, it is possible to easily set the characteristic curve of the desired characteristic that is smooth and close to the human sense. Step S28 of FIG. 12 showing this setting procedure.
The following steps will be described.

When the desired characteristics are initially set, the display unit 40
Either the lower limit value or the upper limit value of the frequency range designated by the cursors 62 and 64 is selected so that it can be corrected (the ∇ mark 65 is displayed on the selected side). When the shuttle key 58 is operated in this state (S28), the selected one of the upper limit value and the lower limit value of the frequency range changes in the direction in which the shuttle key 58 is turned (S29, S30, S31). Display unit 4
The cursor 62 or 64 with the ∇ mark 65 on the 0 also moves in the same direction (S32).

When the left and right cursor keys 56c or 56d are pressed to switch to the other cursor (S3
4) Either the lower limit value or the upper limit value of the frequency range that has been switched can be corrected, and the position of the ∇ mark 65 on the display unit 40 is also moved to the other cursor side. When the shuttle key 58 is operated in this state (S28), the corresponding value changes in the direction in which the shuttle key 58 is rotated (S28).
29, S30, S31), and accordingly the ∇ mark 65 on the display unit 40 also moves in the same direction (S32).

By pressing the up key 56a or the down key 56b after setting the frequency range in this way (S39), as shown in FIG. 15A, the level of the desired characteristic is set for the set frequency range. Depending on the number of pressings or the pressing time, while maintaining continuity with the outside of the set frequency range, the center position of the frequency range peaks and increases or decreases with a curve (S40,
S41), the display of the desired characteristic on the display unit 40 also changes accordingly. According to such a correction method, since it is only necessary to specify the frequency range and the level increase / decrease amount, the operation is easy. Further, since the increase / decrease of the level does not affect the outside of the designated frequency range, it is easy to understand how the characteristic actually changes due to the increase / decrease operation, and it is easy to correct the characteristic as desired. The calculation for correcting the desired characteristic is performed by the calculation means 10 shown in FIG.

As a concrete algorithm of the correction processing in the calculating means 10, for example, by considering what kind of correction curve should be increased / decreased according to the frequency range, the operation feeling and the change in the actual characteristic should be examined to determine the frequency. A correction curve corresponding to the range can be set in advance in a table, and a correction curve corresponding to the set frequency range can be read out from the table and a gain corresponding to the increase / decrease instruction amount can be given and used. . By doing so, the feeling of the level increasing / decreasing operation matches the actual change state of the characteristic, and the correction operation to the desired desired characteristic becomes easy.

If the up key 56a or the down key 56b is pressed with the lower limit value of the frequency range set to the lowest frequency of the entire frequency band, the desired characteristic is one-sided up on the low frequency side as shown in FIG. 15 (b). Or it changes to a one-sided state. Similarly, when the up key 56a or the down key 56b is pressed in a state where the upper limit value of the frequency range is set to the highest frequency of the entire frequency band, the desired characteristic is ascending or rising on the high frequency side as shown in FIG. 15 (c). It changes to a downhill state. In these cases as well, for example, a correction curve for one-sided or one-sided-down according to the frequency range and the increase / decrease amount is set in advance in the table, and the correction curve corresponding to the set frequency range is read from the table and the increase / decrease instruction is given. A gain according to the amount (the number of times the up / down keys 56a and 56b are pressed) can be given and used.

After modifying the desired characteristics as described above,
By pressing the key switch 60 (S42), the characteristic setting routine is exited, and at this time, the characteristic determination and setting are completed (S43). The determined characteristic can be stored and stored in the designated area of the RAM 138 with backup power supply as correction desired characteristic information by instructing to store the characteristic as needed, and can be read out and used at any time. Therefore, it is not necessary to readjust each time the desired characteristic is switched.

Another modification method for modifying the desired characteristic will be described. When the desired characteristic is set, if the correction characteristic is obtained and the equalizing is performed as it is, the correction may be overcorrected. Therefore, as shown in FIG. 16, an intermediate characteristic between the initially set desired characteristic (which may be the desired characteristic modified as shown in FIG. 15) and the measured characteristic is calculated by the calculating means 140.
It is possible to automatically calculate and use this as a new desired characteristic for correction. Specifically, for example, the difference between the initially set desired characteristic and the measured characteristic at each frequency (that is, the correction value of each frequency) is divided into 20 equal parts, and the desired value is set each time the up key 56a or the down key 56b is pressed according to this step. When a desired characteristic is obtained by calculating and displaying a characteristic change that gradually brings the characteristic closer to the measured characteristic or vice versa, sets this as the new desired characteristic. To do. FIG. 17 shows the calculation process at this time. First, the difference between the measured characteristic Nb and the initially set desired characteristic Db is obtained (S51), and this difference Eb is obtained.
Is multiplied by [the number of times the up key 56a or the down key 56b is pressed] ÷ 20 to obtain a correction amount ΔEb of the desired characteristic (S52), and the correction amount ΔEb is added to the desired characteristic Db to obtain Db + ΔEb (S53). This is used as a new desired characteristic (S54). By doing so, an intermediate correction value that is not corrected as much as the desired characteristic Db at the beginning can be set in a good balance in a simple operation in the entire frequency band. The intermediate characteristic created in this way can also be stored in the RAM 136.

Calculation of Correction Characteristics The correction characteristics can be calculated by setting desired characteristics.
At 42, it is automatically calculated as a difference from the measurement characteristic and displayed on the display unit 40.

Correction Property Correction If, for example, a desired property of 0 dB flat is set for the measurement property shown in FIG. 18A, the correction property is the same as in FIG.
As shown in, a large peak dip has occurred. This peak dip is often caused by a slight change in the measurement environment, and if equalization is performed using such a correction characteristic as it is, the portion that is greatly corrected (the portion indicated by ○ in (b) above) ), A slight change in the environment (for example, a slight shift in the frequency characteristic due to the influence of the temperature and humidity of air) can no longer be a true correction, and conversely cannot occur normally. As shown in (c), the correction error becomes large, and the characteristic becomes rather odd. Therefore, the upper and lower limits of the level of the correction characteristic can be set to an arbitrary value (for example, ± 10 dB) by the operation of the operator.
Set to. As a result, the correction characteristic calculation means 14 of FIG.
In No. 2, the upper and lower limit values of the correction characteristic are restricted to the set values as shown in FIG. 18 (d) to prevent unnecessary correction, thereby preventing an increase in correction error. Further, as a result, the maximum value on the + side of the correction characteristic is limited, so that the maximum input can be suppressed and the distortion of the entire system such as the power amplifier and the speaker can be suppressed.

Further, when the correction range is limited by the limit of the reproduction frequency characteristic of the speaker to be used, if the speaker is driven as it is based on the calculated correction characteristic, the speaker may be overloaded. The frequency range is set by the operator's operation, the correction characteristic is used only within the range, and the correction is not performed by making the range 0 dB flat outside the range. The frequency range to be corrected is displayed in the horizontal bar graph as the corrected frequency range display 50 on the display unit 40 of FIG.

FIG. 19 shows an example of a concrete calculation process in each stage from the measurement data being obtained to the final determination of the correction characteristic as described above. Data to be used for calculation of measurement characteristics is selected and weighted from the plurality of times of measurement data stored in the band data memory 126 of FIG. 1 (S61) and weighted. The selected data The divided band numbers are b = 1 to B. B is 31 or 61 in this example.

When a plurality of data are selected, the set average means 130 calculates the set average for each band. Is calculated (S62). And as the average value of all bands of this collective average Is calculated (S63). In addition, as a normalized average measurement data Is calculated (S64), and this is displayed on the display unit 40 as a measurement characteristic. This measurement characteristic Nb is spline-interpolated into continuous data. By normalization, the average value of the measurement characteristic Nb is adjusted to always be 0 dB, and even if the sound collection level is small, the measurement characteristic display on the display unit 40 will always be substantially on the same level. It becomes easier to compare with the characteristic display.

[0069] If desired characteristic Db is set by operation of the operator _{(S65), E b = N} b -D b is obtained as the correction characteristic in the calculation unit 142 (S66). The measurement characteristic Nb here is data after spline interpolation. Then, as the average value of all bands of this correction characteristic Is calculated (S67). Further, the calculation means 142 uses the normalized correction characteristics as Is calculated (S68). By the normalization, the average value of the correction characteristic Fb is adjusted so as to always be 0 dB, and as a whole, the sound quality before and after correction only changes the sound quality but does not change the sound volume.

With respect to the obtained correction characteristic Fb, a process of regulating the upper limit value and the lower limit value of the level shown in FIG. 18 (d) is performed (S69). In addition, steps S66 to S6
Step 9 is performed only within the designated frequency range of FIG. 18 (e). Outside the designated frequency range, a process of flattening the correction characteristic to 0 dB is separately performed (S70). The correction characteristic finally determined in this way goes to a routine for calculating a convolutional (equalizer) filter coefficient (S71).

Calculation of Equalizer Filter Coefficient The FIR filter algorithm for acoustic characteristic correction includes:
Each has advantages and disadvantages, and may not be usable depending on the intended purpose. Therefore, here, as the FIR filter, either one of a linear phase filter (Linear Phase Filter) and a minimum phase filter (Minimum Phase Filter) can be selected in accordance with an operator's selection operation. The impulse responses of the linear phase filter and the minimum phase filter are, for example, as shown in FIGS. 6 (d) and 6 (e), and their advantages and disadvantages are as follows.

Transmission characteristics Delay amount filter Ease of calculation Linear phase filter ◎ × (large) ○ Minimum phase filter △ ◎ (small) △ According to this, the linear phase filter has good transmission characteristics and filter coefficient is easy to calculate. However, since the delay is too large (see FIG. 6D), it cannot be used when real-time characteristics such as PA and mixdown are required (because the raw sound and the equalized sound are deviated in time). Further, the minimum phase filter is inferior to the linear phase filter in terms of transmission characteristics and ease of calculation of filter coefficients, but since it has almost no delay (see FIG. 6 (e)), it is suitable for the case where real-time property is required. Therefore, the operator can select one of the algorithms according to the purpose of use.
One device can be used in various situations.

In any case, since the FIR characteristic using the digital convolution operation is used for the correction characteristic addition, the linear phase filter, the minimum phase filter, or other special characteristics can be added only by switching the algorithm. It is extremely easy to change the specifications according to the purpose, and the correction accuracy can be arbitrarily set by arbitrarily increasing the calculation accuracy as necessary. In this kind of acoustic characteristic correction device, the FIR correction means is practically used. The effect is great.

An example of a procedure for calculating the impulse response of the linear phase filter and the impulse response of the minimum phase filter from the correction characteristic by using the inverse Fourier transform in the equalizer filter coefficient calculating means 144 will be described.

(A) Calculation of impulse response of linear phase filter i) The correction characteristic is once band-divided (for example, 1/3 to 1).
/ 12 octave pitch), and obtain the power average for each band. ii) The obtained power average value is used as a value at the center frequency of each band to interpolate 4096 points of data capable of Fourier transform by spline interpolation or the like. iii) The data obtained in ii) is used as the real part (corresponding to the amplitude term), and the imaginary part (corresponding to the phase term) is subjected to inverse Fourier transform on all the complex format data set to zero. iv) Since the real part of the complex data obtained as a result becomes a linear phase impulse response as it is, these are converted into FIR
It is set as a coefficient of the filter (convolution operator 34).

(B) Calculation of impulse response of minimum phase filter i) The correction characteristic is once divided into bands (for example, 1/3 to 1).
/ 12 octave pitch), and obtain the power average for each band. ii) The obtained power average value is used as a value at the center frequency of each band to interpolate 4096 points of data capable of Fourier transform by spline interpolation or the like. iii) Apply the Hilbert transform to the complex format data with the data obtained in ii) as the real part and all the imaginary parts as 0, and calculate the complex format data that matches the correction characteristic curve and becomes the minimum phase shift system. To do. This complex format data has a necessary phase component added to the imaginary part. iv) Inverse Fourier transform is performed on the complex format data obtained in iii). v) Since the real part of the resulting complex format data is the minimum phase impulse response, these are set as the coefficients of the FIR filter (convolution operator 34).

In addition to the linear phase filter and the minimum phase filter, a filter having an intermediate characteristic may be prepared and any one of them may be selected.

Confirmation of Correction Characteristics FIG. 20 shows the result of confirming the correction effect by setting the coefficient of the FIR filter 34 in the above procedure.
(A) is an initial (that is, without equalizing) measurement result at each of the measurement points P1 to P5 (see FIG. 5). (B) is a measurement characteristic obtained by collectively averaging the measurement data of the points P1 to P5 with the same weighting and a desired characteristic arbitrarily set by the operator. (C) is a correction characteristic obtained as a difference from the desired characteristic of (b). The FIR filter coefficient calculated based on this correction characteristic is set in the convolution calculator 34 to form an equalizer, and the measurement signal (band signal or TSP signal) is reproduced through this equalizer and measurement is performed again. Each measurement point P
The results measured in 1 to P5 are shown in FIG. According to this, as compared with the case before the correction of (a), the corresponding characteristic correction was performed at every measurement point, and it was confirmed that the optimum correction was performed for the area including these points.

Music Playback By inputting a music source instead of the measurement signal and playing it back through the equalizer (convolution operation unit 34),
You can enjoy listening to music with the playback characteristics that you want.

[0080]

[Modification] In the above-described embodiment, in calculating the measurement characteristics, the average value obtained for each divided band is subjected to spline interpolation or the like to calculate the measurement characteristics in both the band signal method and the TSP method. Although band division is performed again when the FIR filter coefficient that realizes the correction characteristic is calculated while being calculated, the present invention is not limited to this.

That is, when displaying the obtained measurement characteristics with high accuracy or when separately using the measurement characteristics, it is slightly difficult to use the divided band data as it is, but in other cases, By performing the spline interpolation when calculating the correction characteristic, it is possible to omit or simplify the interpolation processing before the calculation of the measurement characteristic.
For example, the correction information is calculated as the correction value for each frequency-divided band based on the measurement characteristic calculated for each frequency-divided band and the desired characteristic set for each frequency-divided band, and is calculated for each band. It is also possible to obtain a correction characteristic by setting the correction value as a value at approximately the center frequency of each band and calculating values between them by interpolation. By doing so, it is of course possible to prevent a large peak dip in the correction characteristic and to prevent an unpleasant sensation due to the extreme correction, and the correction characteristic is directly calculated based on the 4096-point interpolated measurement characteristic. This is effective because the amount of calculation can be markedly reduced as compared with the case etc., and the correction characteristics finally obtained do not cause so much accuracy deterioration.

[0082]

As described above, according to the first aspect of the invention, at least one of the upper limit value and the lower limit value of the level of the correction characteristic is regulated, so that there is a habit of excessive correction. It is possible to prevent the characteristics.

According to the second aspect of the present invention, at least one of the upper limit value and the lower limit value of the frequency range of the correction characteristic is regulated, so that it is possible to prevent the characteristic from having a dull characteristic due to an unreasonable correction. be able to.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and shows a control configuration of an acoustic characteristic correction device 10 of FIG.

FIG. 2 is an acoustic characteristic correction device 10 to which the present invention is applied.
3 is a block diagram showing the internal hardware configuration. FIG.

3 is an external view showing a panel configuration of a remote control unit 14 of FIG.

FIG. 4 is a flowchart showing an outline of a procedure from characteristic measurement by the music characteristic correction device of FIG. 1 to use as an equalizer.

5A and 5B are diagrams showing a connection state and a microphone arrangement of a device when an acoustic characteristic is measured using the acoustic characteristic correction device of FIG. 2, and a connection state of a device when the device is used as an equalizer for reproducing music.

6 is a diagram showing various characteristics in the process of FIG.

FIG. 7 is a diagram showing a band division state at the time of measurement.

FIG. 8 is a diagram showing a band signal used in the band signal method.

FIG. 9 is a diagram showing an outline of the TSP method.

FIG. 10 is a diagram illustrating a method of obtaining continuous measurement characteristics by interpolating between bands based on divided data for each band.

FIG. 11 is a flowchart showing an example of an operation procedure in a test and calculation of measurement characteristics.

FIG. 12 is a flowchart showing a procedure for setting desired characteristics.

FIG. 13 is a diagram showing various patterns of desired characteristics prepared in a ROM.

FIG. 14 is a diagram showing a characteristic adjustment method in a conventional graphic equalizer or parametric equalizer.

FIG. 15 is a diagram showing a method of correcting a desired characteristic.

FIG. 16 is a diagram showing another method for correcting a desired characteristic.

FIG. 17 is a flowchart showing a calculation process for realizing the method of FIG.

FIG. 18 is a diagram showing a method of correcting a correction characteristic.

FIG. 19 is a flowchart showing an example of a calculation process in each stage from the acquisition of measurement data to the determination of the correction characteristic.

FIG. 20 is a diagram showing measured values of measurement characteristics, correction characteristics, and correction effects.

[Explanation of symbols]

10 Acoustic Characteristic Correction Device 34 Convolution Operation Unit (Correction Characteristic Providing Means) 38 Operation Unit (Desired Characteristic Setting Means) 70, 76, 78 Room, Speaker (Playback System Including Sound Field) 134 RAM (Measurement Characteristic Outputting Means) 142 Correction characteristic calculation means (correction characteristic level regulation means,
Correction frequency range regulation means)

Claims (2)

[Claims] 1. A desired characteristic setting means for setting a desired characteristic of a response characteristic of a reproduction system including a sound field based on an operation of an operator, and information of a measured characteristic of a response characteristic of the reproduction system including a sound field. Measurement characteristic output means for outputting, correction characteristic calculation means for calculating a correction characteristic for realizing the desired characteristic based on the desired characteristic and the measured characteristic, and upper and lower limits of the level of the calculated correction characteristic. An acoustic characteristic correction device comprising: a correction characteristic level regulating unit that regulates at least one of the values; and a correction characteristic imparting unit that imparts a correction characteristic whose level is regulated to an acoustic signal to be reproduced. 2. A desired characteristic setting means for setting a desired characteristic of a response characteristic of a reproducing system including a sound field based on an operation of an operator, and information on a measured characteristic of a response characteristic of the reproducing system including a sound field. Measurement characteristic output means for outputting, correction characteristic calculation means for calculating a correction characteristic for realizing the desired characteristic based on the desired characteristic and the measured characteristic, and an upper limit value of a frequency range of the calculated correction characteristic, Acoustic characteristic correction comprising correction frequency range regulating means for regulating at least one of the lower limit values, and correction characteristic imparting means for imparting to the acoustic signal to be reproduced the correction characteristic in which the compensation frequency range is regulated. apparatus.