Patent Translate Powered by EPO and Google Notice This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate, complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or financial decisions, should not be based on machine-translation output. DESCRIPTION JP2000023299 [0001] BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound image localization control device and a sound image localization control system that make it feel as if a sound image is localized at a desired arbitrary position different from the position of an actual speaker. [0002] 2. Description of the Related Art A sound image forming method for controlling a sound image by controlling signal levels (amplitudes) and phases of both ears has conventionally been disclosed in, for example, Japanese Patent Application Laid-Open No. 2-298200. That is, in this sound image forming method, the signal from the sound source is subjected to frequency analysis, and the level difference and the phase difference (time difference) depending on the frequency are given to both left and right channel signals to digitally control the localization of the sound image. [0003] In order to localize a sound image, generally, a method of controlling a head-related transfer function (HRTF) with a digital filter is used. The basic principle is shown in FIGS. 1 (a) and 1 (b). As shown in FIG. 1 (a), this method is a method of collecting a sound image generated in the 10-05-2019 1 original sound field using a simulated head simulating a listener and supplying it to the listener. As shown in FIG. 1 (b), the head related transfer functions (HRTF-R, HRTF-L) measured at each incident angle of the sound wave are replaced with the electric filters 101 and 102, and the direct sound collected in the original sound field is obtained. By processing the sound and the reflected sound with the filters 101 and 102, it is possible to provide the listener with a sound image equivalent to the system using the artificial head of FIG. 1 (a). In this case, control is performed using sound image localization filters as the filters 101 and 102 in order to approximate head transfer functions (HRTF-R, HRTF-L). At this time, in order to move the sound image localization position, the transfer characteristics of all the necessary sound image localization positions are measured in advance, this is held as a coefficient set of the sound image localization filter, and the coefficients of the sound image localization filter (digital filter) are an angle Switch by unit and use. [0004] First, the method of setting the characteristic value of the sound image localization filter will be described. In general, the transfer function of the sound image localization filter is obtained by generating white noise in an environment given to the system and measuring its impulse response by arithmetic processing. : Shingaku Technical Report EA 93-1 1993-04 "). FIG. 2 shows an example of the head related transfer function obtained in this manner. The coefficient value of the digital filter that realizes the characteristics of FIG. 2 can be held as a coefficient set to realize the sound image localization filter. [0005] FIG. 3 is a view showing an example of the arrangement of a conventional sound image localization control apparatus. Referring to FIG. 3, the sound image localization control device includes a CPU 201 that controls the whole, a coefficient ROM 202 that stores a coefficient set of the sound image localization filter, an interface unit 203 that receives a position control signal, and Rch (R And a sound image localization filter unit 205 for Lch (L-channel). [0006] Here, the Rch sound image localization filter unit 204 converts the Rch sound source input signal (analog signal) into a digital signal, an A / D converter 211, a sound image localization filter (digital filter) 212, and a sound image The coefficient buffer 213 is stored by loading coefficients of the localization filter 212 from the coefficient ROM 202 and stored, and a D / A converter 214 10-05-2019 2 that converts an output signal (digital signal) from the sound image localization filter 212 into an analog signal. . [0007] The Lch sound image localization filter unit 205 converts an Lch sound source input signal (analog signal) into a digital signal, an A / D converter 221, a sound image localization filter (digital filter) 222, and a sound image localization. A coefficient buffer 223 stores coefficients of the filter 222 loaded from the coefficient ROM 202 and a D / A converter 224 which converts an output signal (digital signal) from the sound image localization filter 222 into an analog signal. [0008] In such a configuration, the coefficient set of the sound image localization filters 212 and 222 is stored in the coefficient ROM 202, loaded from the coefficient ROM 202 to the coefficient buffer 213 and 223 in accordance with the position control instruction from the CPU 201, I have control. Therefore, in this conventional method, the characteristic values of the sound image localization filters 212 and 222 are determined by the coefficient set of the digital filter that realizes the frequency characteristic obtained from the impulse response in a certain environment stored in the coefficient ROM in advance. The coefficient set of the sound image localization filter for realizing the characteristic value could not be changed. [0009] Also, after converting previously measured spatial impulse responses of a large number of people and real ear headphone responses into feature parameter vectors corresponding to human auditory characteristics, clustering is performed to use a reduced number of reduced data. There is also a method (Japanese Patent Laid-Open No. 5-252598), but in this method, the characteristic value of the sound image localization filter actually depends on the environment in which the coefficient is set and the ear canality of the individual. Sometimes good characteristics were not obtained. [0010] 10-05-2019 3 Also, as a sound image localization filter, it is necessary to realize a complex frequency characteristic as shown in FIG. 2, and for that purpose, a high-order FIR filter is required, and a large scale hardware is required for its operation. In addition, storage capacity for a large amount of filter coefficients was required. On the other hand, if an IIR filter is used for this sound image localization filter, there is an advantage that the change of characteristics is easy and versatile, and the coefficient memory can be reduced. However, IIR filters are difficult to design for realizing complicated frequency characteristics, and tend to be unstable such as limit cycle oscillation. [0011] For example, when a transfer function having complex frequency characteristics as shown in FIG. 2 is designed with an IIR filter, it has been reported that a simple arbitrary characteristic can be designed with a bi-quad digital filter (by Kasuga Masao) Literature "Real-time processing method of digital equalizer The Institute of Electronics and Communication Engineers Information System National Convention, pp 228, 1979"). This method is to design a target transfer function by cascading bi-quad transfer functions having two zeros and poles described later. On the other hand, there is also a method of designing an IIR filter by sampling frequency characteristics (the document by Ochi Hiroshi "Design of an IIR filter Interface 206-213, (1996.11)"), but a large number of filter orders are required. There are also problems such as not being of a certain order. [0012] The above-mentioned system is basically a method of designing an analog transfer function and Z-converting it (US Pat. No. 4,188.504). expressed. [0013] [Equation 1] [0014] 10-05-2019 4 In the case of designing in this method, three parameters of fc (center (cutoff) frequency), Q (sharpness) and L (gain) which are design parameters are appropriately changed in order to approximate the target frequency characteristics. Then, a method of approximating to the design characteristic is taken. However, this method is a trial and error method that approximates while minimizing the difference between the target characteristics and the characteristics of the frequency characteristics of the design filter at appropriate frequency points, without clear guidelines, and many frequency points. They have to be calculated over time, and have the disadvantage of being inefficient. Furthermore, in the case where the poles are close to each other, design problems such as difficulty in changing parameters by Q are practically significant. [0015] Also, when changing the localization position of the sound image as described above, conventionally, a position control signal is issued from the CPU 201, and the coefficient set of the sound image localization filter is stored in memory in advance to switch the position. This is done as needed by calling and switching, or by downloading coefficients to a designated memory area (Japanese Patent Laid-Open No. 5-252598). [0016] However, when changing the coefficients of the sound image localization filter, it takes a certain time for the filter characteristic to reach the desired characteristic value, so that switching noise occurs when switching the sound image localization position. It had happened. [0017] SUMMARY OF THE INVENTION In order to avoid these problems, two sound image localization filters are prepared, and when switching the localization angle, a fixed time until the operation of the above filter becomes stable There is a method to switch after the elapse of. Further, there is a system in which a variable attenuator is prepared and a cross fade is 10-05-2019 5 performed in order to move the localization position smoothly at the time of the switching (Japanese Patent Application Laid-Open No. 6-245300). An example of this circuit configuration is shown in FIG. Referring to FIG. 4, the sound image localization control device includes a CPU 301 that controls the whole, a coefficient ROM 302 that stores a coefficient set of a sound image localization filter, an interface unit 303 that receives a position control signal, and Rch (R And a sound image localization filter unit 305 for Lch (L-channel). [0018] Here, the Rch sound image localization filter unit 304 converts the Rch sound source input signal (analog signal) into a digital signal, an A / D converter 311, and two sound image localization filters (FIR filters) 312a. , 312b and the coefficients of each of the sound image localization filters 312a and 312b are loaded from the coefficient ROM 302 and stored respectively from the coefficient buffers 313a and 313b and the output signals (digital signals) from the sound image localization filters 312a and 312b as analog signals It has D / A converters 314 a and 314 b to convert and a fader 315. [0019] Also, the Lch sound image localization filter unit 305 converts the Lch sound source input signal (analog signal) into an A / D converter 321, and two sound image localization filters (FIR filters) 322a, Coefficient buffers 322a and 323b in which the coefficients of the sound image localization filters 322a and 322b are loaded from the coefficient ROM 302 and stored, respectively, and output signals (digital signals) from the sound image localization filters 322a and 322b are converted to analog signals And D / A converters 324 a and 324 b and a fader 325. [0020] Each of the faders 315 and 325 is configured as a cross fade means by two variable attenuators and an addition means. [0021] In such a configuration, the CPU 301 reads out the required coefficient set from the coefficient ROM 302 according to the position control signal of the sound image, and the two coefficient 10-05-2019 6 buffers possessed by the two FIR filters 312a and 312b of the sound image localization filter unit 304 for Rch. In one of the coefficient buffers 313a and 313b, and in one of the two coefficient buffers 323a and 323b possessed by the two FIR filters 322a and 322b of the sound image localization filter unit 305 for Lch. Therefore, the two FIR filters 312a and 312b of the sound image localization filter unit 304 for Rch operate with the coefficient for the old position and the coefficient for the new position, and the two FIR filters 322a of the sound image localization filter unit 305 for Lch. , 322 b operate with the coefficients relating to the old position and the coefficients relating to the new position, by performing fade-in (new position) and fade-out (old position) processing for a certain time using the faders 315 and 325 Even when the position of the sound image changes, smooth replacement from the old position to the new position is possible with respect to the output signal from the sound image localization filter. [0022] FIG. 5 is a diagram for explaining the timing of the cross fading process. For example, consider the case where the sound image localization process is currently performed at a position of 60 degrees, and the sound image localization process is performed at a position of 90 degrees. Now, it is assumed that one of the FIR filters 312a and 322a is in operation with a coefficient for 60 degrees supplied and the other FIR filters 312b and 322b are in non-operation. In this state, as shown in FIG. 5 (e), if there is an instruction to switch the sound image localization position from the position of 60 degrees to the position of 90 degrees in the CPU 301, the CPU 301 executes the timing shown in FIG. The coefficients for 90 degrees are supplied to the other FIR filters 312b and 322b. Furthermore, the cross fade control signal is output from the CPU 301 at the timing shown in FIG. [0023] Then, according to the cross fade control signal, the outputs of one of the FIR filters 312a and 322a are faded out as shown in FIG. 5 (d) by the faders 315 and 325, and the other FIR filters 10-05-2019 7 312b and 322b. The output of is faded in as shown in FIG. 5E and switched while crossfading from one of the FIR filters 312a and 322a to the other of the FIR filters 312b and 322b. If switching is performed while crossfading is performed over several tens of milliseconds, switching coefficients can be switched to smoothly change the sound image localization position without generating switching noise. [0024] However, although the FIR filters 312a, 312b, 322a and 322b in this case require high-order filters depending on their impulse response times, their coefficient memory capacity is also large and the hardware scale is large. . Therefore, preparing a plurality of sound image localization filters for each of Rch and Lch (two for Rch and two for Lch) as described above has a disadvantage that the circuit scale becomes very large. [0025] According to the present invention, a small-sized sound image localization filter is used, and for each of Rch and Lch, the sound image localization position is smoothly controlled with a small hardware scale by preparing only one small-sized sound image localization filter. It is an object of the present invention to provide a possible sound image localization control device and a sound image localization control system. [0026] SUMMARY OF THE INVENTION In order to achieve the above object, the invention according to claim 1 comprises A / D conversion means for converting an input sound source signal into a digital signal, each sound image localization position Of the sound image localization filter simulating the head related transfer function measured for the above, the coefficient storage means for storing the coefficients of the sound image localization filter, and the characteristics of the sound image localization filter by changing the coefficients stored in the coefficient storage means Control means for controlling the auditory position of the sound source signal, and D / A conversion means for converting the digital output signal of the sound image localization filter into an analog signal, wherein the sound image localization filter comprises For the sound image localization filter simulating the head transfer function, the control means uses characteristic parameter values for approximating the frequency characteristics of the given target head transfer function. It is characterized in that it comprises a coefficient calculating means for calculating a coefficient value of the sound image localization filter I. 10-05-2019 8 [0027] The invention according to claim 2 is characterized in that, in the sound image localization control apparatus according to claim 1, the coefficient calculating means changes the characteristic value of the sound image localization filter by changing the characteristic parameter value. And [0028] The invention according to claim 3 is the sound image localization control apparatus according to claim 1 or 2, wherein the control means further causes the head to change the auditory position of the sound source signal. Parameter interpolation value calculation means for calculating an interpolation value between the characteristic parameter value at the position before change and the characteristic parameter value at the position after change for the characteristic parameter value approximating the frequency characteristic of the partial transfer function; It is characterized by being equipped. [0029] According to the fourth aspect of the present invention, a single sound image localization filter, coefficient switching means for switching the coefficients of the sound image localization filter to change the characteristics of the single sound image localization filter, and coefficient switching means Coefficient holding means for storing switched coefficients, input buffer means for storing a sound source signal as an input signal of a sound source localization filter, output buffer means for storing an output signal of a sound image localization filter for a fixed time, fade in / fade out of output buffer means A fade-in / fade-out control means for controlling a function, and when switching coefficients of a single sound image localization filter, an output signal before switching coefficients in a single sound image localization filter and an output after switching the coefficients It is characterized in that control is performed to cross fade the signal. [0030] DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. The present invention provides a design method for realizing complex frequency characteristics using an IIR filter as a sound image localization filter in order to achieve the above object, and a sound image localization control apparatus is configured using this method. . 10-05-2019 9 Furthermore, when moving (changing) the position of the characteristic value of the sound image localization filter, interpolation operation between the reference position is performed based on the characteristic parameter (characteristic parameter value approximating the frequency characteristic of the head transfer function). By doing this, it is made to move smoothly between positions. [0031] FIG. 6 is a view showing an example of the arrangement of a sound image localization control apparatus according to the present invention. Referring to FIG. 6, the sound image localization control device includes a control unit 1 for controlling the whole, a sound image localization filter unit 4 for Rch (R-channel), and a sound image localization filter unit 5 for Lch (L-channel). And have. [0032] Here, the Rch sound image localization filter unit 4 converts the Rch sound source input signal (analog signal) into a digital signal, the sound image localization filter (digital filter) 12 and the sound image A coefficient buffer 13 in which the coefficients of the localization filter 12 are stored, and a D / A converter 14 for converting an output signal (digital signal) from the sound image localization filter 12 into an analog signal. [0033] The Lch sound image localization filter unit 5 converts an Lch sound source input signal (analog signal) into a digital signal, an A / D converter 21, a sound image localization filter (digital filter) 22, and a sound image localization. A coefficient buffer 23 in which the coefficients of the filter 22 are stored, and a D / A converter 24 for converting an output signal (digital signal) from the sound image localization filter 22 into an analog signal. [0034] FIG. 7 is a view showing a specific example of the control means 1 of FIG. 6. In the example of FIG. 7, the control means 1 of FIG. 6 is an interface unit 33 to which a position control signal is input, a CPU 31, and parameters. Sound image localization based on the parameters calculated by the parameter generation unit 34 that generates the parameter, the initial setting parameter 10-05-2019 10 storage unit 35 in which the parameter generated by the parameter generation unit 34 is initialized, the parameter operation unit 36, and the parameter operation unit 36 A coefficient generation calculation unit 37 that generates and calculates coefficients of the filters 11 and 22 and a parameter interpolation value calculation unit 38 that performs interpolation calculation of parameter values are included. [0035] Here, the parameter generating unit 34 is an initial parameter based on the impulse response measuring unit 41 for measuring the frequency characteristic of the head related transfer function, and the frequency characteristic of the head related transfer function measured by the impulse response measuring unit 41. And a parameter extraction unit 42 for extracting the [0036] The initial parameters extracted by the parameter extraction unit 42 are characteristic values of a sound image localization filter forming a head transfer function measured in advance as shown in FIG. Have parameters (fc, Q, L). Here, fc is the center (cutoff) frequency of the sound image localization filter, Q is the sharpness, and L is the gain. [0037] The initial parameters are sent to the parameter calculator 36 through the CPU 31, and the parameter calculator 36 performs parameter calculations to obtain frequency characteristics, and the frequency characteristics calculated by the parameter calculator 36 are coefficients. It is sent to the generation operation unit 37. Then, the coefficient generation calculation unit 37 calculates the coefficient values of the sound image localization filters 12 and 22 to generate necessary coefficient sets, sends the generated coefficient sets to the coefficient buffers 13 and 23, and outputs the sound image localization filters 12 and 22. It is supposed to work. 10-05-2019 11 [0038] Further, when changing the position, the parameter interpolation value calculation unit 38 uses the interpolation value obtained by dividing the two positions at a certain interval for the abovementioned parameters (fc, Q, L), and changes its frequency characteristics. It is obtained and given to the coefficient generation operation unit 37. [0039] Next, the processing operation of the sound image localization control apparatus having such a configuration will be described. First, an outline of the processing operation of the sound image localization control device of FIGS. 6 and 7 will be described. For example, when a position control signal according to a sound image localization instruction (for example, an instruction to localize a sound source at a position 120 degrees right backward) from a main CPU such as a game machine is input via the interface unit 33, this position control signal In accordance with the above, the CPU 31 reads out from the initial setting parameter storage unit 35 the initial parameters necessary to calculate the head-related transfer characteristics with respect to the position information, and supplies the initial parameters to the parameter calculation unit 36. The parameter calculator 36 calculates the frequency characteristic based on the given initial parameter, and supplies it to the coefficient generator 37. The coefficient generation calculation unit 37 calculates the coefficient values of the sound image localization filters 12 and 22 based on the frequency characteristic from the parameter calculation unit 36 and transfers the calculated values to the coefficient buffers 13 and 23. Specifically, the analog frequency characteristics obtained as described later are Z-transformed and designed. This method can be easily obtained by converting the analog transfer function H (s) into the transfer function Hz (Z) in the discrete domain using the S-Z conversion method (refer to the document AV · Masao Kasuga Digital Signal Processing for OA, pp. 109-113. The coefficient sequence is determined from the Z conversion equation obtained by this. The sound 10-05-2019 12 image localization filters 12 and 22 perform convolutional operation processing on the time axis according to the coefficients set in the coefficient buffers 13 and 23 for the input sound source input signals (sound source input signals of Rch and Lch). The signals calculated by the sound image localization filters 12 and 22 are sent to D / A converters 14 and 24 and reproduced from a pair of speakers. In the case of a game machine, for example, the coefficients of the sound image localization filter are switched at any time by a sound image localization command from the CPU 31 so as to correspond to the movement of the game object according to the operation of the operator. [0040] First, the method of obtaining the characteristic values of the sound image localization filters (IIR filters) 12 and 22 will be described in more detail. Also in the present invention, the design scheme of the IIR filter is basically designed in the same manner as the above-described prior art scheme, and is designed by Z conversion. That is, assuming that the sound source input signal is X (s) and the transfer functions to the left ear EL (s) and right ear ER (s) of the listener are HL (s) and HR (s), respectively, the following equation is obtained. Be [0041] [Equation 2] [0042] Note that HR (s) / HL (s) is the ratio of the characteristics between both ears. As seen in Equation 2, the s-function system on the right side is a space transfer function having these complicated frequency characteristics, and this is realized by a digital filter. As this digital filter, an IIR digital filter is adopted by providing versatility in one type, taking into consideration the number of multiplications, the filter coefficient memory, the number of registers, etc. and achieving stable filter multiplexing. The filter function is a biquad type of zeros and poles, and this is designed as a continuous function system, and this is Z-transformed to obtain a digital filter. These properties are given by the center (cutoff) frequencies Fc, Q (sharpness), L (gain), which can be changed by appropriate modifications. The transfer function H (z-1) is given by Equation 1. However, in the case of designing a complex function system as shown in FIG. 2, this design method does not establish a design method, and at present, it has to be designed by a 10-05-2019 13 heuristic method. [0043] In order to approximate an arbitrary characteristic, three design parameters Fc, Q and L will be changed. As a method of changing this, there is a method of setting a desired characteristic as a target value and approximating it while minimizing the difference between this and a design value at an appropriate frequency point. However, this method is not efficient because it needs to calculate them over many frequency points. [0044] Therefore, in the present invention, the document by Satoshi Miyauchi, Keito Mekada, Koji Hasegawa, Masao Kasuga, Harutake Yasuda "Design of an IIR filter with complex amplitude frequency characteristics and Proceedings of the Acoustical Society of Japan Conference 3-3-2-2 , As described in 571.572 (1997.3) , selecting a point near the point where the property of the function changes, that is, the point where the positive and negative of the second derivative of the function are inverted, Noting that it is appropriate as an interpolation point connected to, the inflection point of the function is adopted as a frequency point used for design calculation. In other words, by changing the three design parameters fc, Q, and L so as to minimize the difference between the design value and the desired value at a total of three points at the center frequency and the inflection points located before and after that, arbitrary characteristics are obtained. Approximate [0045] Also, the design method of the filter is as follows. That is, for example, when designing a complex function system having single-peak characteristics shown in FIG. 8, first, the filter function to be designed is second-order differentiated, and these two inflection points p and q are selected. Furthermore, the center frequency fc is selected to select these three points as sample frequency points for calculating the frequency characteristics of the approximate design of the function. Then, the difference between the design characteristic and the target characteristic at these points is obtained by calculation, and the parameter Q is controlled to approximate the frequency characteristic of the target so as to minimize the difference. 10-05-2019 14 [0046] Referring to FIG. 9, a flow chart of the filter design scheme according to the present invention is shown. Referring to FIG. 9, first, initialization parameters are set (step S1). Next, the parameter value Q is changed (step S2), and an error value with the target filter (target characteristic) is calculated (step S3). Next, it is determined whether the error value is smaller than a predetermined threshold value (step S4). If not smaller, the error value is set to the threshold value (step S5), and the process returns to step S2 again to change the parameter value Q. The above process is repeated, and when the error value becomes smaller than the threshold value, the optimum parameter value Q can be set (since the parameter value Q approximating the target frequency characteristic is obtained), the process ends. Do. [0047] A more specific design flow chart is performed according to the following procedure. (1) Input the target frequency characteristics. (2) Next, the number of filter stages for achieving the target characteristic and rough design parameters (fc, Q, L) are input. (3) Next, the filters are ranked in descending order of L value of the input filter, and the following processing is performed in that order. -Align the center frequency fc of the input design characteristics with the center frequency of the target characteristics. -Match the L value of the input design characteristics to the target characteristics. Find two inflection points, one for the higher frequency and one for the lower frequency. Change the Q value so as to reduce the difference between the frequency characteristics at the two inflection points. (4) If it is determined that the amount of error has converged (for example, 0.1 dB or less), the process ends. [0048] By the above procedure, characteristic parameter values required for the target sound image localization filter are determined. [0049] Next, more specific processing operation of the sound image localization control apparatus of the present invention will be described. 10-05-2019 15 The initial parameters are stored in the initial parameter storage unit 35. This initial parameter is a characteristic value of the sound image localization filter which forms a head transfer function measured in advance as shown in FIG. 2 and has parameters (fc, Q, L) in a required position unit (for example, 30 degrees unit). doing. This initial parameter is obtained by the parameter extraction unit 42 based on the frequency characteristic of the head related transfer function measured by the impulse response measurement unit 41. [0050] Thus, after the initial parameters are stored in the parameter storage unit 35, the initial parameters are sent to the parameter operation unit 36 through the CPU 31, and the parameter operation unit 36 performs parameter operation to obtain frequency characteristics. It is obtained and given to the coefficient generation operation unit 37. The coefficient generation operation unit 37 converts the analog frequency characteristic value obtained as described above into a transfer function in the discrete domain by Z conversion, and obtains a necessary coefficient set. The obtained coefficient set is sent to the coefficient buffers 13 and 23 to operate the sound image localization filters 12 and 22. [0051] Next, the interpolation calculation method of the head related transfer function between positions when changing positions will be described. In the present invention, when changing the position, for example, the parameter interpolation value calculation unit 38 performs interpolation calculation of parameter values held in units of 30 degrees. Specifically, for the above-mentioned parameters (fc, Q, L), the frequency characteristic is determined using an interpolation value obtained by dividing between two positions at certain intervals. That is, this frequency characteristic is determined by obtaining each interpolation value of the parameters (fc, Q, L) by the parameter interpolation value calculation unit 38 shown in FIG. 7, and the sound image localization filter for each frequency characteristic at a certain time interval The coefficient generation calculation unit 37 calculates the coefficients of Then, the generated coefficients are sent to the coefficient buffers 13 and 23 each time. [0052] 10-05-2019 16 As described above, using the interpolation value obtained by dividing the two positions by a certain interval in the parameter interpolation value calculation unit 38, the frequency characteristic is determined and the coefficient is calculated to change the position of the sound image. Can be moved smoothly. As for the filter problem with respect to the change of the coefficient set between the divided positions at this time, the positions can be switched more smoothly by using the fade-in / fade-out function described later. [0053] FIG. 10 is a view showing an example of the arrangement of a sound image localization control apparatus having a fade in / fade out function. The sound image localization control apparatus of FIG. 10 uses a single sound image filter for each of Rch and Lch. It has a function to realize cross fade when switching coefficients. Referring to FIG. 10, this sound image localization control device includes a CPU 51 that controls the whole, a coefficient ROM 52 storing coefficient sets of sound image localization filters, an interface unit 53 to which a position control signal is input, and Rch (R- And a sound image localization filter unit 55 for Lch (L-channel). [0054] Here, the sound image localization filter unit 54 for Rch comprises an A / D converter 61 for converting a sound source input signal (analog signal) of Rch into a digital signal, and one sound image localization filter (FIR filter) 12 A coefficient buffer 64 in which coefficients of the sound image localization filter 12 are loaded from the coefficient ROM 52 and stored respectively, a selector SEL, an input buffer 62 storing sound source signals to be input signals of the sound source localization filter 12, sound image localization Output buffers 65 and 66 for storing the output signal of the filter 12 for a fixed time, a buffer control unit 63 for controlling the input buffer 62, the output buffers 65 and 66, and the selector SEL, an output signal from the fader 67 and the sound image localization filter 12 And D / A converter 68 for converting (digital signal) into an analog signal. [0055] Further, the sound image localization filter unit 55 for Lch comprises an A / D converter 71 for converting a sound source input signal (analog signal) of Rch into a digital signal, a sound image localization filter (FIR filter) 22 and A coefficient buffer 74 in which each coefficient of the sound image localization filter 22 is loaded from the coefficient ROM 52 and stored, a selector SEL, an input buffer 72 for storing a sound source signal to be an input signal of the sound source localization filter 22; 22. Output signals from the sound image localization filter 22 (the output buffers 75 and 76 for storing the output signals of 22 for a predetermined time, the buffer 10-05-2019 17 control unit 73 for controlling the input buffer 72, the output buffers 75 and 76, and the selector SEL) And D / A converter 78 for converting a digital signal into an analog signal. [0056] Each of the faders 67 and 77 is configured as a cross fade means by two variable attenuators and an addition means. [0057] In such a configuration, in the normal case, the selector SEL is set to the sound image localization filters 12 and 22 side and the output buffers 65 and 75 side, and the A / D converters 61 and 71 according to the sample period. The digital signal sequence output from the signal processing unit is processed by the sound image localization filters 12 and 22 described above, and is sent to the output buffers 65 and 75. The output buffers 65 and 75 are FIFO type registers, and the signals from the sound image localization filters 12 and 22 are output with a delay according to a sample period for a certain fixed time (fade out time). Also at this time, the digital buffers from the A / D converters 61 and 71 are stored in the input buffers 62 and 72. [0058] Next, when the sound image localization position change signal (position control signal) is input to the interface unit 53, the coefficients of the coefficient buffers 64 and 74 are first replaced. After that, the selector SEL is switched, and the output of the sound image localization is calculated by the sound image localization filters 12 and 22 at high speed using the digital signal string of the input buffers 62 and 72 stored up to then. It is stored in the buffers 66 and 76. The calculation of the sound image localization filter does not depend on the sample period, and since the known data of the input buffers 62 and 72 can be used as it is, high-speed calculation is possible. 10-05-2019 18 [0059] The contents of the output buffers 65 and 75 and the contents of the output buffers 66 and 76 thus obtained become the output data for the old coefficient and the output data for the new coefficient, and in the faders 67 and 77, If fade-in / fade-out processing is performed using these two data as shown in FIG. 11, it is possible to smoothly move the sound image without causing a problem at the time of coefficient switching. [0060] As described above, according to the first aspect of the present invention, A / D conversion means for converting input sound source signals into digital signals, and each sound image localization position The characteristics of the sound image localization filter are manipulated by changing the coefficients stored in the sound image localization filter that simulates the measured head-related transfer function, the coefficient storage unit that stores the coefficients of the sound image localization filter, and the coefficient storage unit Control means for controlling the position of the sound source signal in the auditory sense, and D / A conversion means for converting the digital output signal of the sound image localization filter into an analog signal, wherein the sound image localization filter comprises a single IIR filter Is used for the sound image localization filter simulating the head related transfer function, and the control means uses sound parameter determination to approximate the frequency characteristics of the given target head related transfer function. It has coefficient calculation means for calculating the coefficient value of the filter, and the sound image localization filter is simplified by using a single IIR filter instead of the FIR filter which conventionally required large-scale hardware. Sound image localization control can be performed by hardware. In particular, according to the present invention, it is possible to provide a sound image localization apparatus which is small in circuit scale and can be mounted on game machines, personal computers and the like, and is excellent in the sound image localization feeling. [0061] According to the second aspect of the present invention, in the sound image localization control device according to the first aspect, the coefficient calculating means changes the characteristic value of the sound image localization filter by changing the characteristic parameter value. Conventionally, the characteristic value of the sound image localization filter, which could not be easily changed since the coefficient set for the impulse response measured in advance was held, 10-05-2019 19 is the characteristic parameter (center frequency, cut-off frequency, sharpness, gain) representing the frequency characteristic. It can be easily changed by changing it. [0062] According to the invention of claim 3, in the sound image localization control apparatus according to claim 1 or 2, when the control means further changes the auditory position of the sound source signal, Parameter interpolation value calculation for calculating an interpolation value between the characteristic parameter value at the position before change and the characteristic parameter value at the position after change for the characteristic parameter value approximating the frequency characteristic of the head related transfer function By including the means, it is possible to easily calculate the interpolation value of the parameter between the two positions of the sound image localization filter, and to move the sound image smoothly. [0063] Further, according to the invention of claim 4, a single sound image localization filter, coefficient switching means for switching the coefficients of the sound image localization filter to change the characteristics of the single sound image localization filter, and the coefficient switching Coefficient holding means for storing the coefficients switched by means, input buffer means for storing the sound source signal as an input signal of the sound source localization filter, output buffer means for storing the output signal of the sound image localization filter for a fixed time, fade in of the output buffer means · A fade-in / fade-out control means for controlling a fade-out function, and when switching the coefficients of a single sound image localization filter, after switching the output signal and coefficients before switching the coefficients in a single sound image localization filter Control to cross-fade the output signal of the Using a plurality of largescale FIR filter when switching of the functions of the fade-out, it is possible to perform a single sound image localization filter. Also for the IIR filter, although the time until the filter characteristics stabilize is short, similar effects can be obtained. [0064] Brief description of the drawings [0065] 10-05-2019 20 1 is a diagram for explaining the basic principle of the sound image localization control system. [0066] 2 is a diagram showing an example of a head related transfer function. [0067] 3 is a diagram showing an example of the configuration of a conventional sound image localization control device. [0068] 4 is a diagram showing an example of the configuration of a conventional sound image localization control device having a function of performing cross fade. [0069] 5 is a diagram for explaining the timing of the cross fading process. [0070] <Figure 6> It is the figure which shows the constitution example of the sound image localization control device which relates to this invention. [0071] 7 is a diagram showing a specific example of the control means of FIG. [0072] <Figure 8> It is the figure which shows the complex function system which consists of the unimodal characteristic. [0073] <Figure 9> It is the flowchart in order to explain the filter design system of this invention. [0074] <Figure 10> It is the figure which shows the constitution example of the sound image localization 10-05-2019 21 control device which relates to this invention. [0075] 11 is a diagram for explaining the fade in · fade out process in the sound image localization control device of FIG. [0076] Explanation of sign [0077] 1 control means 4 sound image localization filter unit 5 for Rch (R-channel) sound image localization filter unit 11 for Lch (L-channel) 11, 21 A / D converter 12, 22 sound image localization filter 13, 23 coefficient buffer 14, 24 D / A converter 31 CPU 33 interface unit 34 parameter generation unit 35 initial setting parameter storage unit 36 parameter operation unit 37 coefficient generation operation unit 38 parameter interpolation value operation unit 41 impulse response measurement unit 42 parameter extraction unit 51 CPU 52 coefficient ROM 53 interface unit 61, 71 A / D converter 62, 72 Input buffer 63, 73 Buffer control unit 64, 74 Coefficient buffer 65, 75 Output buffer 66, 76 Output buffer 67, 77 Fader 68 D / A converter 10-05-2019 22
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