JP5611316B2 - filter - Google Patents

Description

  The present invention relates to a filter that adjusts at least phase frequency characteristics of frequency characteristics (amplitude frequency characteristics and phase frequency characteristics) of an audio signal.

  Conventionally, some acoustic devices use an FIR (finite impulse response) filter in order to equalize the amplitude frequency characteristic and phase frequency characteristic of the entire system so as to become a flat linear shape. The phase frequency characteristic is generally referred to as a phase characteristic or the like, and refers to a characteristic expressed by indicating the frequency on the horizontal axis and the phase on the vertical axis. The amplitude frequency characteristic is generally referred to as a frequency characteristic in the audio industry, and refers to a characteristic represented by indicating the frequency on the horizontal axis and the amplitude on the vertical axis.

  For example, Patent Document 1 describes a configuration in which an FIR filter is used and coefficients of the FIR filter are set so that the phase frequency characteristic of the sound output from a speaker has linearity.

  On the other hand, Patent Document 2 has a configuration in which at least three stages of 180-degree phase shift circuits configured using operational amplifiers are connected in cascade, and the phase of the audio input signal corresponds to a logarithmic increase in frequency in the audible frequency range. A sound quality improvement circuit having a phase frequency characteristic for generating a phase delay in the range of 450 to 600 degrees in the range of audible frequencies by gradually delaying the sound is shown.

JP 2000-91865 A JP 2005-143093 A

  In the technique disclosed in Patent Document 1, the phase frequency characteristic of the sound output from the speaker is set to have linearity. Further, the technique of Patent Document 2 is configured to delay the phase with a linear gradient in response to a logarithmic increase in frequency. In this way, these prior art, it is not suitable in advance for how to phase frequency characteristic is defined such, as a configuration for performing tone control in accordance with various applications.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a filter that can adjust sound quality according to various uses.

  In order to achieve the above object, a filter according to the present invention is a filter that inputs an audio signal, filters the audio signal, and outputs the filtered audio signal, and independent of its own phase frequency characteristic and its own amplitude frequency characteristic. The desired phase frequency characteristic curve and the desired amplitude frequency characteristic curve are displayed on the same screen of the display device, and based on the phase frequency characteristic represented by the desired phase frequency characteristic curve. The phase frequency characteristic of the audio signal is changed independently of the amplitude frequency characteristic of the self and the amplitude frequency characteristic of the audio signal is changed to the phase frequency based on the amplitude frequency characteristic represented by the desired amplitude frequency characteristic curve. It is configured to be changed independently of the characteristics.

  Further, by operating the operators corresponding to the center frequency, the frequency bandwidth, and the phase angle of the center frequency, which are operators on the phase frequency characteristic curve displayed on the screen of the display device. One or a plurality of sets of center frequency, frequency bandwidth, and phase angle of the center frequency are designated, and the desired phase frequency characteristic curve may be displayed by this designation.

  The desired phase frequency characteristic curve may be displayed by drawing on the screen of the display device.

  In addition, the desired phase frequency characteristic curve may be displayed by operating a phase frequency characteristic curve displayed in advance on the screen of the display device.

  Further, by operating the operators corresponding to the center frequency, the frequency bandwidth, and the phase angle of the center frequency, which are operators on the phase frequency characteristic curve displayed on the screen of the display device. One or more sets of center frequency, frequency bandwidth, and phase angle of the center frequency are designated, and the desired phase frequency characteristic curve is displayed by this designation, and the amplitude frequency characteristic displayed on the screen of the display device One or more sets of the center frequency, the frequency bandwidth, and the gain are designated by operating the operators corresponding to the center frequency, the frequency bandwidth, and the gain. The desired amplitude frequency characteristic curve may be displayed by designation.

  Also, the desired phase frequency characteristic curve is displayed by drawing on the screen of the display device, and the desired amplitude frequency characteristic curve is displayed by drawing on the screen of the display device. It may be.

  Further, the desired phase frequency characteristic curve is displayed by operating the phase frequency characteristic curve displayed in advance on the screen of the display device, and the amplitude frequency characteristic curve displayed in advance on the screen of the display device is displayed. The desired amplitude frequency characteristic curve may be displayed by operating.

  The present invention has an effect that it can provide a filter having the above-described configuration and capable of adjusting the sound quality according to various uses.

  The above object, other objects, features, and advantages of the present invention will become apparent from the following detailed description of the preferred embodiments with reference to the accompanying drawings.

FIG. 1 is a block diagram illustrating an example of an acoustic device using a filter according to an embodiment of the present invention. FIG. 2 is a circuit diagram showing an FIR filter which is a configuration example of the filter according to the embodiment of the present invention. FIG. 3 is a diagram showing a display screen of the input means of the first configuration example for independently changing the phase characteristic and the amplitude characteristic of the filter according to the embodiment of the present invention. FIG. 4 is a diagram showing a display screen of the input means of the second configuration example for independently changing the phase characteristic and the amplitude characteristic of the filter according to the embodiment of the present invention. FIG. 5 is a diagram showing a display screen of the input means of the sixth configuration example for independently changing the phase characteristic and the amplitude characteristic of the filter according to the embodiment of the present invention. FIG. 6 is a diagram showing a display screen of the input means of the seventh configuration example for independently changing the phase characteristic and the amplitude characteristic of the filter according to the embodiment of the present invention. FIG. 7 is a diagram showing a display screen of the input means of the eighth configuration example for independently changing the phase characteristic and the amplitude characteristic of the filter according to the embodiment of the present invention.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram illustrating an example of an acoustic device using a filter according to an embodiment of the present invention.

  The acoustic apparatus includes a filter 1, a D / A (digital / analog) converter 2 connected to an output terminal OUT thereof, an amplifier 3 connected to the D / A converter 2, and an amplifier 3. A speaker 4 and input means 5 such as push buttons are provided.

  The filter 1 performs digital signal processing. For example, an analog audio signal output from a microphone is output from an A / D converted digital audio signal or a recording medium playback device such as a CD player to an input terminal IN. Digital audio signal is input. A signal that has been processed by the filter 1 is input to the D / A converter 2 and converted to an analog signal, and further amplified by the amplifier 3 and output to the speaker 4. Is output.

  The filter 1 is configured to output a digital audio signal input from the input terminal IN by shifting a phase in a part of a predetermined frequency range within an audible frequency range (20 Hz to 20 kHz) by a predetermined angle.

The filter 1 is composed of, for example, a DSP (digital signal processor), and functions as, for example, an FIR (finite impulse response) filter as shown in FIG. This FIR filter includes n cascaded delay circuits 11, (n + 1) multipliers 12, and an adder 13. Each delay circuit 11 outputs each input signal after being delayed by the sampling period, and each multiplier 12 multiplies the input signal by a filter coefficient h _k (k = 0 to n) set correspondingly. The outputs of the multipliers 12 are added by the adder 13 and output. If such an FIR filter is used, an amplitude frequency characteristic (hereinafter referred to as “amplitude characteristic”) and a phase frequency characteristic (hereinafter referred to as “phase characteristic”) are set by setting a filter coefficient h _k (k = 0 to n). And can be set independently.

  Here, the phase characteristic refers to a characteristic expressed with the frequency on the horizontal axis and the phase on the vertical axis. The amplitude characteristic refers to a characteristic represented with a frequency as a horizontal axis and an amplitude (for example, gain) as a vertical axis.

  In addition, a memory (not shown) in which filter coefficients corresponding to various applications are stored in advance is built in the filter 1, and the filter coefficient corresponding to a certain application is selected by operating the input means 5. The selected filter coefficient is read from the memory and set as the gain of each multiplier 12. For example, when the audio signal from the microphone is input to the input terminal IN after being A / D converted, and when the microphone is used for speech or for making an emergency announcement, Filter coefficients corresponding to various applications such as a case where a digital audio signal output from a recording medium playback device such as a CD player is input to the input terminal IN are stored in the memory in the filter 1 in advance.

  In the present embodiment, the sound quality output from the speaker 4 is adjusted by the filter 1 by shifting the phase of the audio signal in a predetermined frequency range by a predetermined angle, for example, by delaying or advancing the phase of a certain frequency. It becomes possible. Further, a plurality of predetermined frequency ranges for shifting the phase may be set, and angles for shifting the phase may be set corresponding to the respective predetermined frequency ranges. Further, by operating the input means 5, the frequency range and angle for shifting the phase can be changed, and the sound quality can be adjusted according to various uses.

  Further, in adjusting the sound quality, it is sufficient that the angle for shifting the phase of the audio signal in the predetermined frequency range is within a range of less than ± 180 degrees.

  Further, by using an FIR filter for the filter 1, the amplitude characteristic and the phase characteristic can be set independently, so that the amplitude in a predetermined frequency range in which the phase is shifted may be configured to be unchanged. .

  In addition, when the above FIR filter is used, the phase characteristics can be changed independently of the amplitude characteristics, so that acoustic adjustment that has been impossible in the past is possible. In particular, by advancing the phase without changing the amplitude, it becomes possible to make adjustments that could not be realized in the past, such as making the sound of the band with the advanced phase more audible and noisy. . Furthermore, since the phase characteristics can be changed in combination with the change of the amplitude characteristics, effective settings can be made for each of them, and more complicated and free acoustic adjustment can be performed.

  Hereinafter, a configuration example in which the phase characteristics and the amplitude characteristics are changed independently will be described.

  Here, the filter 1 includes an FIR filter (hereinafter referred to as “FIR filter 1A”) and an operation control unit (hereinafter referred to as “operation control unit 1B”) functioning as a filter coefficient setting unit. Shall. The FIR filter 1A receives a digital audio signal from the input terminal IN and outputs a signal subjected to the filter process to the output terminal OUT.

  In the input means 5, for example, an operation for designating an amplitude characteristic and a phase characteristic set in the FIR filter 1 </ b> A is performed by the operator. In the case of first to third configuration examples described later, the input unit 5 is configured using, for example, a liquid crystal pen tablet that integrates a liquid crystal display and a pen tablet. In this case, a display screen for inputting amplitude characteristics and phase characteristics is displayed, and a stylus pen is used as a pointing device.

  Hereinafter, each configuration example will be described. In each configuration example, the configurations of the input unit 5 and the arithmetic control unit 1B are different, and the other configurations are the same.

(First configuration example)
FIG. 3 is a diagram showing a display screen of the input means 5 of the first configuration example.

  In the case of the display screen 31 shown in FIG. 3, the lower left area of the screen is an amplitude characteristic designation area for designating the amplitude characteristic, and the amplitude characteristic designated by the upper left area is displayed by the amplitude characteristic curve 34. This is an amplitude characteristic display area. The lower right area of the screen is a phase characteristic designation area for designating phase characteristics, and the upper right area is a phase characteristic display area for displaying the phase characteristics designated by the phase characteristic curve 35.

  In the amplitude characteristic designation area, for example, a gain adjustment operator 32 for setting a gain (gain) at each of a plurality of preset frequencies within a range of audible frequencies (20 Hz to 20 kHz) is displayed. Similarly, in the phase characteristic designation area, a phase adjustment operator 33 for setting the phase at each of a plurality of preset frequencies within the above audible frequency range is displayed. For example, when the above-described plurality of preset frequencies are 10, the gain adjusting operator 32 and the phase adjusting operator 33 arranged from left to right in FIG. For example, it corresponds to the frequencies of 31 Hz, 62 Hz, 125 Hz, 250 Hz, 500 Hz, 1 kHz, 2 kHz, 4 kHz, 8 kHz, and 16 kHz. Moreover, although the numerical value of these frequencies is displayed on the display screen 31, the illustration is abbreviate | omitted in FIG.

  Using the stylus pen, the operator moves (drags) the position of each gain adjustment operator 32 up and down so as to obtain a desired amplitude characteristic, and sets the gain at each frequency. Similarly, the phase at each frequency is set by moving the position of each phase adjustment operator 33 up and down so as to obtain the desired phase characteristics. Then, an amplitude characteristic curve 34 corresponding to the position of each gain adjustment operator 32 is displayed, and a phase characteristic curve 35 corresponding to the position of each phase adjustment operator 33 is displayed. Each gain adjusting operator 32 and each phase adjusting operator 33 are displayed as an initial state in which the gain or phase at each frequency is set to 0, for example, as an initial state where setting has never been performed. The

In the input means 5 on which the display screen 31 shown in FIG. 3 is displayed as described above, for example, each “adjustment” button 32 (not shown) on the display screen 31 is touched with a stylus pen to adjust each gain adjustment operator 32. The display information indicating the position of the phase and the display information indicating the position of each phase adjustment operator 33 are output to the arithmetic control unit 1B. Thereby, the amplitude characteristic and the phase characteristic to be set in the FIR filter 1A are designated by the input means 5. In the arithmetic control unit 1B, the display information of each gain adjustment operator 32 is converted into amplitude characteristic information and the display information of each phase adjustment operator 33 is converted into phase characteristic information. Based on the characteristic information, a filter coefficient h _k is obtained by performing an inverse FFT or the like, and is set in the FIR filter 1A. The display information of each gain adjustment operator 32 is information about a wide interval frequency (for example, 31 Hz, 62 Hz,..., 8 kHz, 16 kHz as described above). Amplitude characteristic information is obtained by interpolating amplitude information (gain) regarding the frequency of the gap between these frequencies. Similarly, the display information of each phase adjustment operator 33 is also information on a wide interval frequency (for example, 31 Hz, 62 Hz,..., 8 kHz, 16 kHz as described above). Then, the phase characteristic information is obtained by interpolating the phase information regarding the frequency between these frequencies.

  When the gain or phase is set once and then the setting is changed next, before the change, each gain adjusting operation element 32 and each phase adjusting operation element 33 are in the state when they are set immediately before. The state before the change is displayed. From this state, the operating elements 32 and 33 are moved up and down to change the setting. At this time, in addition to the amplitude characteristic curve 34 and the phase characteristic curve 35 displayed corresponding to the positions of the operation elements 32 and 33, the amplitude characteristic curve 34a and the phase characteristic curve 35a before the change are displayed. Also good. This facilitates comparison between the amplitude characteristic and phase characteristic before the change and the amplitude characteristic and phase characteristic to be newly set.

  Each gain adjusting operator 32 and each phase adjusting operator 33 are not displayed on the screen as described above, but are configured by hardware that is actually operated by an operator by hand. May be.

  Note that the amplitude characteristic information is data of a numerical string representing the amplitude characteristic as shown in the graph of the amplitude characteristic curve 34, for example, and the phase characteristic information is the phase as shown in the graph of the phase characteristic curve 35, for example. It is data of a numerical sequence representing the characteristics.

(Second and third configuration examples)
FIG. 4 is a diagram showing a display screen of the input means 5 of the second configuration example.

  In the case of the display screen 41 shown in FIG. 4, the upper area of the upper half is an area for specifying the amplitude characteristic (amplitude characteristic display area), and the lower area of the lower half is for specifying the phase characteristic. This is an area (phase characteristic display area).

  In the upper amplitude characteristic display area, for example, a line (amplitude characteristic line) 42 for displaying the amplitude characteristic set in the range of the audible frequency is displayed. The line 42 is in a state where the gain is set to 0 in the entire range of the audible frequency as an initial state, for example. Alternatively, it may be set to a state other than this. The operator uses the stylus pen to drag an arbitrary portion of the line 42 to form the line 42 showing a desired amplitude characteristic.

  In the lower phase characteristic display area, for example, a line (phase characteristic line) 43 for displaying the phase characteristic set within the range of the audible frequency is displayed. The line 43 is in a state where the phase is set to 0 in the entire range of the audible frequency as an initial state, for example. Alternatively, it may be set to a state other than this. The operator uses the stylus pen to drag an arbitrary portion of the line 43 to form the line 43 showing a desired phase characteristic.

  In the input means 5 of the second configuration example described above, the arbitrary lines 42 and 43 are deformed to form the lines 42 and 43 showing the desired characteristics. For example, the display screen 41 in the initial state is displayed. In FIG. 4, a screen other than the lines 42 and 43 is displayed and only the lines 42 and 43 are not displayed, and the operator draws the lines 42 and 43 indicating desired characteristics using a stylus pen. (This may be referred to as the input means 5 of the third configuration example).

In the input means 5 of the second and third configuration examples in which the display screen 41 shown in FIG. 4 described above is displayed, for example, by touching a “confirm” button (not shown) on the display screen 41 with a stylus pen. The display information of the line 42 and the display information of the line 43 are output to the arithmetic control unit 1B. Thereby, the amplitude characteristic and the phase characteristic to be set in the FIR filter 1A are designated by the input means 5. In the arithmetic control unit 1B, the display information of the line 42 is converted into amplitude characteristic information and the display information of the line 43 is converted into phase characteristic information. Then, based on the amplitude characteristic information and the phase characteristic information, an inverse FFT or the like is performed. A filter coefficient h _k is obtained by performing an operation, and is set in the FIR filter 1A.

  When the input means 5 of the first, second, and third configuration examples configured to display the display screen as shown in FIGS. 3 and 4 is used, the operator can display the display screen on the display screen. It is possible to easily specify the desired amplitude characteristic and phase characteristic of the FIR filter 1A.

(Fourth configuration example)
Next, a fourth configuration example will be described. In the fourth configuration example, the arithmetic control unit 1B has a storage unit including, for example, an internal memory of a microcomputer that constitutes the arithmetic control unit 1B. Are stored (stored) in advance. Then, by operating the input means 5, desired amplitude characteristic information and phase characteristic information are selected from those stored in the storage unit. The input means 5 in the case of the fourth configuration example is provided with, for example, an amplitude characteristic designation button corresponding to each of a plurality of amplitude characteristics and a phase characteristic designation button corresponding to each of the plurality of phase characteristics. These designation buttons may be a push button type that is actually selected and operated by a human hand, or may be displayed on the touch panel and selected by touching with a finger or a stylus pen. In either case, the operation for specifying the amplitude characteristic and the phase characteristic is easy. The input means 5 outputs an amplitude characteristic selection signal corresponding to the selected amplitude characteristic designation button and a phase characteristic selection signal corresponding to the selected phase characteristic designation button to the arithmetic control unit 1B. The arithmetic control unit 1B reads out the amplitude characteristic information and the phase characteristic information corresponding to each selection signal from the storage unit, and performs a computation such as inverse FFT based on the amplitude characteristic information and the phase characteristic information. A coefficient h _k is obtained and set in the FIR filter 1A.

  In the fourth configuration example, the input unit 5 may be configured so that information stored in the storage unit in the arithmetic control unit 1B can be rewritten. For example, when the storage unit of the arithmetic control unit 1B stores the amplitude characteristic information and the phase characteristic information of the FIR filter 1A corresponding to the acoustic output device configured by the amplifier 3 and the speaker 4, the acoustic output device May be rewritten to the phase characteristic information and the amplitude characteristic information of the FIR filter 1A corresponding to the other acoustic output device. In this case, the input means 5 is provided with a reading means for reading information on a recording medium such as a flash memory and a CD, and new amplitude characteristic information and phase characteristic information read from the recording medium are stored (stored) in the storage unit. What is necessary is just to comprise. The recording medium may be distributed from an acoustic adjustment device or an acoustic device manufacturer, or a host computer such as an acoustic adjustment device or an acoustic device manufacturer by a user operating a personal computer (personal computer). Then, a new amplitude characteristic information and phase characteristic information file may be downloaded and recorded on a recording medium.

(Fifth configuration example)
Next, a fifth configuration example will be described. In this fifth configuration example, the input means 5 increases, for example, the gain at each of a plurality of preset frequencies from the initial state (for example, gain is 0) of the FIR filter 1A or the amplitude characteristic set immediately before. An amplitude increase frequency designation button for reducing the gain and an amplitude decrease frequency designation button for decreasing the gain are provided corresponding to each frequency, and the initial state of the FIR filter 1A (for example, the phase is 0) or set immediately before From the phase characteristics, a phase advance frequency designation button for advancing the phase at each of a plurality of preset frequencies and a phase delay frequency designation button for delaying the phase are provided corresponding to each frequency. When the above-mentioned plurality of preset frequencies are ten, ten amplitude increase frequency designation buttons, amplitude decrease frequency designation buttons, phase advance frequency designation buttons, and phase delay frequency designation buttons are provided. Each designation button corresponds to, for example, ones having frequencies of 31 Hz, 62 Hz, 125 Hz, 250 Hz, 500 Hz, 1 kHz, 2 kHz, 4 kHz, 8 kHz, and 16 kHz. These designation buttons may be actually selected by a human hand, such as a push button type, or may be displayed on the touch panel and selected by touching with a finger or a stylus pen. .

  In this case, when a certain amplitude increase frequency designation button is selected n times, the input means 5 outputs a selection signal corresponding to the selected amplitude increase frequency designation button n times to the arithmetic control unit 1B, and a certain amplitude decrease. When the frequency designation button is selected n times, a selection signal corresponding to the selected amplitude decrease frequency designation button is output n times to the arithmetic control unit 1B. When a certain phase advance frequency designation button is selected n times, a selection signal corresponding to the selected phase advance frequency designation button is output n times to the arithmetic control unit 1B. When n is selected n times, a selection signal corresponding to the selected phase delay frequency designation button is output n times to the arithmetic control unit 1B.

  The arithmetic control unit 1B increases the gain of the frequency corresponding to the amplitude increase frequency designation button for which the selection signal is output n times by a predetermined value × n with respect to the amplitude characteristic of the FIR filter 1A set immediately before. In addition, information for determining the changed amplitude characteristic is obtained by decreasing the gain of the frequency corresponding to the amplitude reduction frequency designation button for which the selection signal is output n times by a predetermined value × n, and the amplitude characteristic is based on the information. Ask for information. The predetermined value is a predetermined value. The information for determining the changed amplitude characteristics obtained by the selection signal of each amplitude increase frequency designation button and amplitude decrease frequency designation button is a frequency with a wide interval (for example, 31 Hz, 62 Hz,..., 8 kHz, 16 kHz as described above. ), The arithmetic control unit 1B interpolates amplitude information (gain) relating to the frequency gap between these frequencies to obtain amplitude characteristic information.

  In addition, the arithmetic control unit 1B sets the phase of the frequency corresponding to the phase advance frequency designation button for which the selection signal is output n times to a predetermined angle × n with respect to the phase characteristic of the FIR filter 1A set immediately before. In addition to determining the phase characteristic after the change by delaying the phase of the frequency corresponding to the phase delay frequency designation button for which the selection signal is output n times by a predetermined angle × n, Obtain phase characteristic information. The predetermined angle is a predetermined value. Information for determining the phase characteristics after change obtained by the selection signal of each phase advance frequency designation button and phase slow frequency designation button is a frequency with a wide interval (for example, 31 Hz, 62 Hz,..., 8 kHz as described above) , 16 kHz), the arithmetic control unit 1B obtains phase characteristic information by interpolating phase information relating to the frequency gap between these frequencies.

Further, the arithmetic control unit 1B obtains a filter coefficient h _k by performing an inverse FFT or the like based on the amplitude characteristic information and the phase characteristic information obtained as described above, and sets it in the FIR filter 1A. .

  When the input means 5 of the fifth configuration example is used, the amplitude characteristic of the FIR filter 1A is changed by a simple operation such as pressing an amplitude increase frequency designation button and an amplitude decrease frequency designation button corresponding to the frequency whose amplitude is to be changed. be able to. Further, the phase characteristics of the FIR filter 1A can be changed by a simple operation such as pressing a phase advance frequency designation button and a phase delay frequency designation button corresponding to the frequency whose phase is to be changed.

(Sixth configuration example)
FIG. 5 is a diagram showing a display screen of the input means 5 of the sixth configuration example.

  Here, the input means 5 is comprised using the liquid crystal display which has the display screen 101, a keyboard, a mouse | mouth, etc., for example.

  In the case of the display screen 101 shown in FIG. 5, an amplitude characteristic display area for displaying the amplitude characteristic curve 102 or the like is arranged in the left area of the screen, and the phase characteristic for displaying the phase characteristic curve 103 or the like in the right area of the screen. A display area is arranged.

  Below the amplitude characteristic display area, respective operation buttons 104a, 104b for designating a set point number (No.), a center frequency (f), a frequency bandwidth (Q), and a gain (G) at the center frequency, 105a, 105b, 106a, 106b, 107a, and 107b and boxes 104, 105, 106, and 107 in which designated values are displayed are displayed. Similarly, below the phase characteristic display area, each operation button 108a for designating a set point number (No.), a center frequency (f), a frequency bandwidth (Q), and an angle (D) at the center frequency. , 108b, 109a, 109b, 110a, 110b, 111a, 111b and boxes 108, 109, 110, 111 in which designated values are displayed.

  The operator sets the center frequency, the frequency bandwidth, and the gain at the center frequency for each set point number (for example, 1, 2, 3,...) So as to obtain a desired amplitude characteristic. The operator can increase and decrease the set point number displayed in the box 104 by clicking the increase button 104a and the decrease button 104b using a mouse, for example. The center frequency displayed in the box 105 can be increased and decreased by clicking the increase button 105a and the decrease button 105b. Further, by clicking the increase button 106a and the decrease button 106b, the frequency bandwidth displayed in the box 106 can be increased or decreased. Further, the gain displayed in the box 107 can be increased and decreased by clicking the increase button 107a and the decrease button 107b.

  The input means 5 outputs each amplitude setting information including the center frequency, the frequency bandwidth, and the gain for each setting point number set by the above operation to the arithmetic control unit 1B. The arithmetic control unit 1B obtains amplitude characteristic information based on each amplitude setting information. Display information for displaying the amplitude characteristic curve 102 is created based on the amplitude characteristic information, and the amplitude characteristic curve 102 is displayed on the display screen 101 of the input means 5.

  Further, the operator sets the center frequency, the frequency bandwidth, and the angle at the center frequency for each set point number (for example, 1, 2, 3,...) So as to obtain a desired phase characteristic. The operator can increase and decrease the set point number displayed in the box 108 by clicking the increase button 108a and the decrease button 108b using, for example, a mouse. The center frequency displayed in the box 109 can be increased and decreased by clicking the increase button 109a and the decrease button 109b. Further, by clicking the increase button 110a and the decrease button 110b, the frequency bandwidth displayed in the box 110 can be increased and decreased. Further, by clicking the increase button 111a and the decrease button 111b, the angle displayed in the box 111 can be increased and decreased.

  The input means 5 outputs each phase setting information including the center frequency, the frequency bandwidth and the angle for each set point number set by the above operation to the arithmetic control unit 1B. The arithmetic control unit 1B obtains phase characteristic information based on each phase setting information. Display information for displaying the phase characteristic curve 103 is created based on the phase characteristic information, and the phase characteristic curve 103 is displayed on the display screen 101 of the input means 5.

Further, the arithmetic control unit 1B calculates a filter coefficient h _k by performing an inverse FFT or the like based on the obtained amplitude characteristic information and phase characteristic information, and sets it in the FIR filter 1A.

  Further, during the operation for changing the setting, the amplitude characteristic curve 102a and the phase characteristic curve 103a before the change may be displayed. This facilitates comparison between the amplitude characteristic and phase characteristic before the change and the amplitude characteristic and phase characteristic to be newly set.

  Further, during the operation for changing the setting, the target amplitude characteristic curve is displayed in the amplitude characteristic display area of the display screen 101, and the target phase characteristic curve is displayed in the phase characteristic display area. Also good. This makes it easy to create the amplitude characteristic curve and the phase characteristic curve so as to overlap the target amplitude characteristic curve and the target phase characteristic curve.

  Operation buttons (104a, 104b), (105a, 105b), (106a, 106b), (107a, 107b) for setting amplitude characteristics, and operation buttons (108a, 108b) for setting phase characteristics , (109a, 109b), (110a, 110b), (111a, 111b), for example, a slide bar or the like as shown by the operation elements 32, 33 in FIG. 5 may be used. Further, these operation buttons, slide bars, and other controls are not displayed on the screen as described above, and may be configured by hardware that is actually operated by the operator's hands. .

(Seventh configuration example)
FIG. 6 is a diagram showing a display screen of the input means 5 of the seventh configuration example.

  In the case of the display screen 131 shown in FIG. 6, this is an amplitude characteristic drawing area for creating an amplitude characteristic curve indicating the amplitude characteristic specified by the upper area, and a phase characteristic curve indicating the phase characteristic specified by the lower area. This is a phase characteristic drawing area for creating

  The input unit 5 is configured using, for example, a liquid crystal display having a display screen 131, a keyboard, a mouse, and the like.

  When an operation start command is given by the input means 5, a mountain-shaped amplitude characteristic curve 141 having a predetermined shape and size is displayed at a predetermined frequency position on the frequency axis in the amplitude characteristic drawing area of the display screen 131. In the same manner, a mountain-shaped phase characteristic curve 151 having a predetermined shape and size is also displayed in the phase characteristic drawing area.

  The amplitude characteristic curve 141 has two operators 142 and 143. The operation element 142 is provided at the peak position in the center of the amplitude characteristic curve 141, and the operation element 143 is provided in the middle of the amplitude characteristic curve 141. The operator 142 can move (drag) the cursor in the vertical and horizontal directions of the screen by moving the cursor to the operator 142 with the mouse. In addition, the operator 143 can move (drag) the cursor in the horizontal direction of the screen by using the mouse to align the cursor with the operator 143.

  The peak gain of the amplitude characteristic curve 141 can be adjusted by moving the operation element 142 in the vertical direction. For example, when the operator 142 of the amplitude characteristic curve 141 is dragged upward, it expands to a similar state as shown by the amplitude characteristic curve 141a, for example, and when the mouse button is released, that is, when it is dropped, the enlargement is performed at that position. Stop. Further, when the operation element 142 is dragged downward, although not shown, the amplitude characteristic curve 141 is reduced in a similar shape.

  Further, the frequency (center frequency) that becomes the gain of the peak of the amplitude characteristic curve 141 can be changed by moving the operation element 142 in the left-right direction. For example, when the operator 142 of the enlarged amplitude characteristic curve 141a is dragged to the right, the amplitude characteristic curve 141a moves in the horizontal direction as indicated by, for example, the amplitude characteristic curve 141b, and the movement stops at the point where it is dropped.

  The frequency bandwidth of the amplitude characteristic curve 141 can be changed by moving the operator 143 in the left-right direction. For example, when the operator 143 of the amplitude characteristic curve 141b whose maximum gain and its frequency are moved is dragged horizontally toward the right direction, the slope of the amplitude characteristic curve becomes gentle as shown as the amplitude characteristic curve 141c. That is, the frequency bandwidth is increased. When the operator 143 is dragged leftward, the slope of the amplitude characteristic curve 141 becomes steep. That is, the frequency bandwidth is reduced. Such a change in inclination continues until dropping.

  By creating the amplitude characteristic curve by the operation as described above, the amplitude setting information including the center frequency, the frequency bandwidth, and the gain at one set point is determined. Further, by repeating the above-described operation a plurality of times, for example, an amplitude characteristic curve in an audible frequency range is created (drawn), and a center frequency, a frequency bandwidth, and a center frequency at each of a plurality of setting points corresponding thereto are drawn. Amplitude setting information including the gain at is determined.

  The phase characteristic curve 151 also has two operators 152 and 153. The operation element 152 is provided at the peak position in the center of the phase characteristic curve 151, and the operation element 153 is provided in the middle of the phase characteristic curve 151. The operator 152 can move (drag) the cursor in the vertical and horizontal directions of the screen by moving the cursor to the operator 152 with the mouse. In addition, the operator 153 can move (drag) the cursor in the horizontal direction of the screen by using the mouse to align the cursor with the operator 153.

  The peak angle (phase) of the phase characteristic curve 151 can be adjusted by moving the operation element 152 in the vertical direction. For example, if the operator 152 of the phase characteristic curve 151 is dragged upward, it expands to a similar state as shown by the phase characteristic curve 151a, for example, and if it is dropped, the expansion is stopped at that position. Further, when the operator 152 is dragged downward, the phase characteristic curve 151 is reduced in a similar state, although not shown.

  Further, the frequency (center frequency) that becomes the angle of the peak of the phase characteristic curve 151 can be changed by moving the operation element 152 in the left-right direction. For example, when the operator 152 of the enlarged phase characteristic curve 151a is dragged in the right direction, the phase characteristic curve 151a moves in the horizontal direction, for example, as indicated by the phase characteristic curve 151b, and the movement stops at the point where it is dropped.

  The frequency bandwidth of the phase characteristic curve 151 can be changed by moving the operator 153 in the left-right direction. For example, when the operator 153 of the phase characteristic curve 151b whose maximum angle and its frequency have been moved is dragged horizontally toward the right direction, the slope of the phase characteristic curve becomes gentle as shown by the phase characteristic curve 151c. That is, the frequency bandwidth is increased. Further, when the operator 153 is dragged to the left, the slope of the phase characteristic curve 151 becomes steep. That is, the frequency bandwidth is reduced. Such a change in inclination continues until dropping.

  By creating the phase characteristic curve by the operation as described above, phase setting information including the center frequency, the frequency bandwidth, and the gain at one setting point is determined. In addition, by repeating the above-described operation a plurality of times, for example, a phase characteristic curve in an audible frequency range is created (drawn), and the center frequency, frequency bandwidth, and center frequency at each of a plurality of setting points corresponding thereto are drawn. Phase setting information consisting of an angle at is determined.

The input means 5 outputs the amplitude setting information at each setting point and the phase setting information at each setting point set by the above operation to the arithmetic control unit 1B. In the calculation control unit 1B, amplitude characteristic information is obtained based on each amplitude setting information, phase characteristic information is obtained based on each phase setting information, and calculation such as inverse FFT is performed based on the obtained amplitude characteristic information and phase characteristic information. To obtain the filter coefficient h _k and set it in the FIR filter 1A.

  In addition, during the operation for changing the setting, the amplitude characteristic curve before the change is displayed in the amplitude characteristic drawing area of the display screen 131, and the phase characteristic curve before the change is displayed in the phase characteristic drawing area. Also good. This facilitates comparison between the amplitude characteristic and phase characteristic before the change and the amplitude characteristic and phase characteristic to be newly set.

  Further, during the operation for changing the setting, the target amplitude characteristic curve is displayed in the amplitude characteristic drawing area of the display screen 131, and the target phase characteristic curve is displayed in the phase characteristic drawing area. Also good. This makes it easy to create the amplitude characteristic curve and the phase characteristic curve so as to overlap the target amplitude characteristic curve and the target phase characteristic curve. In this case, information for displaying the target amplitude characteristic curve and the target phase characteristic curve is stored, for example, in the storage unit of the arithmetic control unit 1B.

(Eighth configuration example)
FIG. 7 is a diagram showing a display screen of the input means 5 of the eighth configuration example.

  Here, the input means 5 is comprised using the liquid crystal display which has the display screen 161, a keyboard, a mouse | mouth, etc., for example.

  In the case of the display screen 161 shown in FIG. 7, a tabular amplitude characteristic setting file and a phase characteristic setting file are displayed. The set point numbers (No.) of both of these files are displayed in advance in the order of 1, 2, 3,.

  The operator operates a keyboard or the like, for example, and inputs desired values in the center frequency (f), frequency bandwidth (Q), and gain (G) at the center frequency of the amplitude characteristic setting file. Similarly, a desired value is entered in the center frequency (f), frequency bandwidth (Q), and angle (D) at the center frequency field of the phase characteristic setting file.

In the input means 5, for each setting point number input to the amplitude characteristic setting file, each amplitude setting information including the center frequency, frequency bandwidth and gain, and each setting point number input to the phase characteristic setting file. The phase setting information including the center frequency, the frequency bandwidth, and the angle is output to the arithmetic control unit 1B. The arithmetic control unit 1B obtains amplitude characteristic information based on each amplitude setting information and obtains phase characteristic information based on each phase setting information. Further, the arithmetic control unit 1B calculates a filter coefficient h _k by performing an inverse FFT or the like based on the obtained amplitude characteristic information and phase characteristic information, and sets it in the FIR filter 1A.

  In the eighth configuration example, the input unit 5 creates the amplitude characteristic setting file and the phase characteristic setting file. However, for example, the amplitude characteristic setting file and the phase characteristic setting file are created using a personal computer or the like. If uploaded to the filter, it is not necessary to provide a display or the like for displaying the display screen 161 on the input means 5 of the filter.

  Further, in the personal computer or setting device, the display screen as shown in FIGS. 5 and 6 can be displayed, and amplitude setting information and phase setting information set in the same manner as in the sixth and seventh configuration examples are filed. Alternatively, the amplitude characteristic setting file and the phase characteristic setting file may be created and uploaded to a filter.

Further, in the storage unit of the arithmetic control unit 1B, information on a plurality of amplitude characteristic setting files corresponding to a plurality of amplitude characteristics (a plurality of amplitude characteristic specifying information) and a plurality of phase characteristic setting files corresponding to the plurality of phase characteristics are stored. Information (a plurality of phase characteristic specifying information) is stored in advance, and the input means 5 is set to a desired amplitude characteristic specifying information and phase characteristic from those stored in the storage unit as in the above-described fourth configuration example. You may comprise so that specific information may be selected. In this case, the arithmetic control unit 1B reads the amplitude characteristic specifying information and the phase characteristic specifying information from the storage unit according to the operation of the input unit 5, and reads the read amplitude characteristic specifying information (information including one or a plurality of amplitude setting information). ) Based on the phase characteristic specifying information (information consisting of one or a plurality of phase setting information), and filter based on the amplitude characteristic information and the phase characteristic information. A coefficient h _k is obtained and set in the FIR filter 1A.

  As described above, in any case of the first to eighth configuration examples, for example, a button or a menu for flattening the phase characteristics may be provided in the set frequency range. This facilitates setting of flat phase characteristics (for example, the angle is 0 in the entire frequency range to be set). Similarly, in the frequency range to be set, for example, buttons and menus for flattening the amplitude characteristics may be provided. This facilitates the setting of flat amplitude characteristics (amplitude is constant in the set frequency range).

  In the present embodiment, the FIR filter 1A that can individually set the amplitude characteristic and the phase characteristic by setting the filter coefficient is used, and the amplitude characteristic and the phase characteristic of the FIR filter 1A are individually set. Therefore, it is possible to easily adjust the sound quality output from the speaker 4 according to the listener's preference and various uses. In particular, it is possible to adjust the sound quality output from the speaker 4 by delaying or advancing the phase of a certain frequency.

  As described above, in the present embodiment, the FIR filter 1A is used for acoustic adjustment. That is, digital signal processing technology is used.

  Since the phase characteristic of the FIR filter 1A can be set by using the input means 5 as described above, various acoustic adjustments that could not be realized by the conventional acoustic adjustment methods. Is possible. Since the FIR filter 1A is used as described above, an arbitrary phase characteristic can be set. That is, an arbitrary phase characteristic can be given for each frequency. Moreover, it is possible to adjust the phase characteristics only in an arbitrary frequency range. For example, it is possible to change the phase of the input audio signal only in the frequency range from 100 Hz to 200 Hz and not to change the phase in other frequency ranges.

  Further, since the phase characteristic and the amplitude characteristic of the FIR filter 1A can be set using the input means 5 as described above, the phase characteristic and the amplitude characteristic can be set independently. it can. That is, only the phase characteristic can be changed from the already set characteristic (phase characteristic) to another characteristic (phase characteristic) without changing the amplitude characteristic already set in the FIR filter 1A.

  On the contrary, only the amplitude characteristic is changed from the already set characteristic (amplitude characteristic) to another characteristic (amplitude characteristic) without changing the phase characteristic already set in the FIR filter 1A. You can also.

  Furthermore, both the phase characteristic and amplitude characteristic already set in the FIR filter 1A can be changed to different characteristics.

  Also, an amplitude characteristic that gives a constant gain regardless of the frequency is set for the FIR filter 1A, and the phase characteristic of the FIR filter 1A is set so that only the phase characteristic of the audio signal is changed. It is also possible to change the phase characteristics set in the FIR filter 1A in various ways.

  In particular, by advancing the phase without changing the amplitude, it becomes possible to make adjustments that could not be realized in the past, such as making the sound of the band with the advanced phase more audible and noisy. . Furthermore, since the phase characteristics can be changed in combination with the change of the amplitude characteristics, effective settings can be made for each of them, and more complicated and free acoustic adjustment can be performed.

  From the foregoing description, many modifications and other embodiments of the present invention are obvious to one skilled in the art. Accordingly, the foregoing description should be construed as illustrative only and is provided for the purpose of teaching those skilled in the art the best mode of carrying out the invention. The details of the structure and / or function may be substantially changed without departing from the spirit of the invention.

  The filter according to the present invention is useful as a filter for adjusting the sound quality.

1 Filter 2 D / A Converter 3 Amplifier 4 Speaker

Claims (10)

A filter that inputs an audio signal, filters the audio signal, and outputs the filtered signal.
It is configured to be able to change its own phase frequency characteristic and its own amplitude frequency characteristic independently.
A phase frequency characteristic curve and an amplitude frequency characteristic curve are displayed on the same screen of the display device, and the own phase frequency characteristic is expressed based on the phase frequency characteristic represented by the phase frequency characteristic curve. And independently changing the own amplitude frequency characteristic based on the amplitude frequency characteristic represented by the amplitude frequency characteristic curve, independently of the own phase frequency characteristic,
A first graph display area having a horizontal axis as a frequency and a vertical axis as a phase is displayed on the screen, and the phase frequency characteristic curve is displayed in the first graph display area. Displaying on the screen first changing means used for changing the phase frequency characteristic curve displayed in the area ;
A filter configured to change the phase frequency characteristic curve displayed in the first graph display area in accordance with an operation of the first changing means .   The filter according to claim 1, wherein the filter is configured to display the first changing unit in the first graph display area.   The first changing means is an operator displayed in the first graph display area, and includes an operator corresponding to each of a center frequency, a frequency bandwidth, and a phase angle of the center frequency, The center frequency, the frequency bandwidth, and the phase angle of the center frequency are designated by operating one or more sets, and the phase frequency characteristic curve is displayed by the designation. The filter described.   The filter according to claim 2, wherein the phase frequency characteristic curve itself displayed in the first graph display area is the first changing unit. A filter that inputs an audio signal, filters the audio signal, and outputs the filtered signal.
It is configured to be able to change its own phase frequency characteristic and its own amplitude frequency characteristic independently.
A phase frequency characteristic curve and an amplitude frequency characteristic curve are displayed on the same screen of the display device, and the own phase frequency characteristic is expressed based on the phase frequency characteristic represented by the phase frequency characteristic curve. And independently changing the own amplitude frequency characteristic based on the amplitude frequency characteristic represented by the amplitude frequency characteristic curve, independently of the own phase frequency characteristic,
A first graph display area having a horizontal axis as a frequency and a vertical axis as a phase is displayed on the screen, and the phase frequency characteristic curve is displayed in accordance with a drawing operation in the first graph display area . A filter configured to A second graph display area with the horizontal axis as frequency and the vertical axis as gain is displayed on the screen, and the amplitude frequency characteristic curve is displayed in the second graph display area. the second change means used for the operation for changing the amplitude-frequency characteristic curve displayed on the area is displayed on the screen,
2. The filter according to claim 1, wherein the filter is configured to change the amplitude frequency characteristic curve displayed in the second graph display area in accordance with an operation of the second changing unit .   The filter according to claim 6, wherein the filter is configured to display the second changing unit in the second graph display area.   The second changing means is an operation element displayed in the second graph display area, and includes an operation element corresponding to each of a center frequency, a frequency bandwidth, and a gain, and operates the operation element. The filter according to claim 7, wherein one or a plurality of sets of center frequency, frequency bandwidth, and gain are designated, and the amplitude frequency characteristic curve is displayed by the designation.   The filter according to claim 7, wherein the amplitude-frequency characteristic curve itself displayed in the second graph display area is the second changing unit. A second graph display area having a horizontal axis as a frequency and a vertical axis as a gain is displayed on the screen, and the amplitude frequency characteristic curve is displayed according to a drawing operation in the second graph display area . The filter according to claim 5, which is configured as follows.

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