JP2007256526A - Waveform synthesizing apparatus and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means for easily generating noise to be produced from a rotation apparatus having a plurality of similar portions. <P>SOLUTION: A period changing part 103 generates waveform data by extending original waveform data indicating a single sound in a time direction in accordance with rotational frequency, a frequency characteristic changing part 104 changes the frequency characteristics of the extended waveform data, a continuous waveform generation part 105 generates continuous waveform data by connecting a plurality of waveform data whose frequency characteristics are changed, and a stacked waveform generation part 106 generates stacked waveform data by stacking a plurality of continuous waveform data. The continuous waveform generation part 105 adjusts correlation between the plurality of continuous waveform data in the generation of continuous waveform data, and time fluctuation and amplitude fluctuation between single-sounds. The stacked waveform generation part 106 adjusts offset time between a plurality of continuous waveforms in the generation of stacked waveform data. An attribute value specification part 108 specifies the physical attribute values of an apparatus for generating stacked waveforms on the basis of a parameter used for the generation of the stacked waveforms. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a technique for synthesizing a sound waveform, particularly a sound waveform generated by a device having a rotational drive part.

A technique for artificially synthesizing engine sounds has been proposed for the purpose of reproduction in a car racing simulation game or the like. For example, Patent Documents 1 and 2 disclose a technique of storing a plurality of actual engine sound waveforms in accordance with an operating state such as an engine rotation speed and reading out and reproducing a suitable waveform in accordance with a user operation. Has been.
JP 2000-10576 A JP 2005-128262 A

  In addition, noise generated by the operation of a device having a rotational drive part such as an engine or a fan (hereinafter referred to as “rotary device” for the sake of convenience) may cause discomfort to the user or people around. Such noise cannot be completely removed. For example, the volume and quality of the engine sound of a private car greatly influences the driving comfort. Accordingly, there is a need to develop a device that generates noise that can be more comfortably felt by the user and the surrounding people by evaluating the volume and sound quality of these noises at the design stage.

  In order to check the noise of the rotating device at the design stage, it was necessary to repeat the work of actually manufacturing and operating a prototype and checking the noise. It takes a lot of time and money. The techniques disclosed in Patent Documents 1 and 2 are intended to artificially synthesize existing engine sounds. Therefore, these techniques can be used for evaluating noise generated by a newly developed rotating device. Can not.

On the other hand, Non-Patent Document 1 proposes a method for evaluating noise without producing a prototype by artificially synthesizing noise generated by a rotating device.
Osamu Maeda, "Virtual Evaluation Technology for Engine Sound Quality", Journal of the Acoustical Society of Japan, Acoustical Society of Japan, 2003, Vol. 59, No. 5, p. p. 288-293

  Non-Patent Document 1 proposes a technique for artificially synthesizing engine sound of a multi-cylinder engine by superimposing a plurality of continuous waveforms of existing single-cylinder engine sound (single sound for one cycle). Has been. According to this technology, noise can be confirmed at the development stage by artificially generating sounds of a non-existing multi-cylinder engine.

  In Non-Patent Document 1, when synthesizing a multi-cylinder engine sound waveform using a single sound waveform of a single cylinder engine, random noise is added and a sound volume and waveform of a single sound sound are generated in order to generate a more natural engine sound waveform. It has been proposed to give fluctuations.

  The inventor of the present application, when superimposing a plurality of continuous single sound waveforms of a single cylinder engine, the volume or waveform fluctuations in the continuous single sound waveforms, or the volume or waveform between the continuous single sound waveforms. The idea was to change the characteristics of the synthesized sound in various ways by adjusting the degree of inhomogeneity. The inventor of the present application has also conceived that various frequency characteristics of the pseudo-generated multi-cylinder engine sound waveform are changed by adjusting the frequency characteristics of the single sound waveform. These ideas are not limited to the synthesis of engine sound, and can be applied to any device having a plurality of similar parts that generate noise in association with rotational driving, such as a fan.

  Based on the above idea, the present invention provides a means for virtually generating noise generated by a rotating device having a plurality of parts of the same type under various physical characteristics and operating environment conditions without much labor and expense. The purpose is to provide.

  In order to achieve the above object, the present invention provides a parameter input means for acquiring parameters, a continuous waveform generating means for generating a continuous waveform by continuing a plurality of original waveforms that are sound waveforms to be a source of sound waveform synthesis, and A superimposed waveform generating means for generating a superimposed waveform by superimposing a plurality of continuous waveforms generated by the continuous waveform generating means, wherein the continuous waveform generating means applies fluctuations to the continuous waveform according to the parameters. A waveform synthesizer characterized by adding expansion / contraction in the amplitude direction or time direction is provided.

  According to such a waveform synthesizer, a synthesized waveform whose acoustic characteristics change variously according to the input parameters can be obtained.

  In a preferred aspect of such a waveform synthesizer, the continuous waveform generating means adds expansion or contraction in the amplitude direction or time direction having different fluctuations to a plurality of continuous waveforms used for the superposition by the overlapped waveform generating means. You may do it.

  The present invention also provides a parameter input means for acquiring parameters, a continuous waveform generating means for generating a continuous waveform by continuing a plurality of original waveforms that are sound waveforms to be a source of sound waveform synthesis, and the continuous waveform generating means. A superposition waveform generation means for generating a superposition waveform by superimposing a plurality of continuous waveforms generated by the step, wherein the superposition waveform generation means adds a plurality of continuous waveforms used for the superposition to a time corresponding to the parameter. A direction offset may be added.

  Even with such a waveform synthesizer, a synthesized waveform whose acoustic characteristics change variously according to input parameters can be obtained.

In a preferred aspect of such a waveform synthesizer, the overlapped waveform generation means includes at least one continuous waveform of the plurality of continuous waveforms used for the superposition, and the number of continuous waveforms that use the period of the original waveform for the superposition. It is also possible to add a time offset that is a non-integer multiple of the time divided by.
In this aspect, a synthesized sound that includes many non-integer overtone components of the fundamental period of the noise of the rotating device is generated.

  The present invention also provides a parameter input means for acquiring parameters, a continuous waveform generating means for generating a continuous waveform by continuing a plurality of original waveforms that are sound waveforms to be a source of sound waveform synthesis, and the continuous waveform generating means. A superposition waveform generation means for generating a superposition waveform by superimposing a plurality of continuous waveforms generated by the step, wherein the continuous waveform generation means has a correlation according to the parameter with the first continuous waveform A second continuous waveform is generated, and the superposition waveform generation means generates the superposition waveform using a plurality of continuous waveforms including the first continuous waveform and the second continuous waveform. A waveform synthesizer is provided.

  Even with such a waveform synthesizer, a synthesized waveform whose acoustic characteristics change variously according to input parameters can be obtained.

In a preferred aspect of such a waveform synthesizer, the continuous waveform generating means generates the first continuous waveform and the second continuous waveform having a correlation coefficient of less than 1 and having the same frequency characteristics. You may make it do.
In this aspect, it is easy to control the amount of the non-integer overtone component of the fundamental period of the noise generated by the rotating device.

  The present invention also provides a parameter input means for acquiring a parameter, a frequency characteristic changing means for changing a frequency characteristic according to the parameter to an original waveform that is a sound waveform that is a source of sound wave synthesis, and the frequency characteristic changing A continuous waveform generating means for generating a continuous waveform by continuing a plurality of original waveforms to which the frequency characteristics have been changed by the means, and a plurality of continuous waveforms generated by the continuous waveform generating means by superimposing the superimposed waveforms. There is provided a waveform synthesizer comprising: a superimposed waveform generation means for generating.

  Even with such a waveform synthesizer, a synthesized waveform whose acoustic characteristics change variously according to input parameters can be obtained.

In the above waveform synthesizers and their preferred embodiments, the continuous waveform generating means may generate a continuous waveform having a cycle that is changed by continuing a plurality of original waveforms having different lengths.
According to this aspect, it is possible to synthesize even the noise when the rotational speed of the rotating part of the rotating device changes.

  In the above waveform synthesizers and their preferred embodiments, operation means for outputting a parameter according to a user operation, storage means for storing correspondence data indicating a correspondence relation between the parameter and the physical attribute value, and the correspondence Attribute value specifying means for specifying a physical attribute value corresponding to the parameter acquired by the parameter input means based on relational data, wherein the parameter input means acquires the parameter output by the operating means. It may be.

  According to this aspect, the synthesized sound is generated based on the parameter input by the user's operation, and the physical attribute value corresponding to the parameter is specified. Therefore, the user can easily know the physical characteristics of the rotating device according to the generated synthesized sound.

  In the above waveform synthesizers and their preferred embodiments, an operation unit that outputs a physical attribute value according to a user operation, and a storage unit that stores correspondence data indicating a correspondence between the physical attribute value and the parameter, Parameter specifying means for measuring a parameter corresponding to the physical attribute value output by the operation means based on the correspondence data, and the parameter input means obtains the parameter specified by the parameter specifying means You may make it do.

  According to this aspect, the synthesized sound is generated according to the physical characteristics of the rotating device input by the user's operation. Therefore, the user can easily know what noise is generated in accordance with the physical identification of the rotating device.

  The present invention also provides a program for causing a computer to execute the processing performed by the waveform synthesizer. As a result, the above waveform synthesizer is realized by a computer.

[1. Principle of sound waveform synthesis]
Hereinafter, in order to understand the present invention, the principle of a method of synthesizing sound of a multi-cylinder engine using single sound of a single-cylinder engine (hereinafter referred to as “single sound control reproduction method”) will be described. As an example, a 4-cylinder 4-stroke engine will be described below.

  In the single sounding control reproduction method, a single sounding waveform (hereinafter simply referred to as “single sounding”) of a single cylinder engine is first prepared. The cylinders of the four-stroke engine are driven by pushing the crankshaft by repeating the four steps of fuel intake, fuel compression, explosion caused by fuel ignition, and exhaust after explosion. Single sound is a sound that is emitted when one cylinder of the engine performs these four steps and one cycle of operation. A single sound waveform can be obtained, for example, by recording a sound when an actual machine is operated.

  When a single sound waveform is obtained, a sound generated when one cylinder of the engine is continuously operated (hereinafter referred to as “continuous sound”) is synthesized by continuing the single sound waveform. FIG. 1 is a diagram showing how continuous sounds are synthesized. The left diagram of FIG. 1 illustrates a single sound waveform having a maximum amplitude A0 and a time T0 (seconds). In the synthesis of continuous sounds, a single sound waveform that is the original waveform, with the expansion and contraction in the amplitude direction and the time direction, sequentially connected. In addition, in order to reduce noise generated due to discontinuity of the connecting portion, a process of multiplying a window function having zeros at both ends is performed prior to connection.

  In generating a single sound used for synthesizing continuous sounds, a predetermined fluctuation is added to the degree of expansion / contraction applied to each original waveform in order to generate a more natural sound. As a result, the amplitude and time of each single tone constituting the continuous sound are slightly different from each other. The right diagram of FIG. 1 shows a state in which continuous sounds are generated by concatenating eight single sounds, and the amplitude and time of each single sound included in the continuous sounds are sequentially changed to A1 to A8 and T1 to T1 by adding fluctuations. Each is different from T8 (seconds).

  Since the length of the single sound included in the continuous sound synthesized as described above fluctuates around the time T0 of the original waveform, the period of the continuous sound is T0 (seconds), and the fundamental tone is f0 = 1 / T0 ( Hz). In the case of a 4-stroke engine, the crankshaft rotates twice in the four steps of intake, compression, explosion, and exhaust. Therefore, if the engine speed is r (rpm), the cycle T0 = (2 × 60) / r ( Second).

  Subsequently, in order to synthesize the sound of the four-cylinder engine, four continuous sounds obtained by synthesizing as described above, that is, four sounds emitted from one cylinder are superimposed to synthesize a superposed sound. During this superposition, an offset time of T0 / 4 (seconds) is sequentially added to each continuous sound. That is, the start time of the second continuous sound is delayed from the start time of the first continuous sound by T0 / 4 seconds, and the start time of the third continuous sound is delayed from the start time of the second continuous sound by T0 / 4 seconds. The start time of the fourth continuous sound is delayed from the start time of the third continuous sound by T0 / 4 seconds. FIG. 2 is a diagram showing a state in which superposed sounds are synthesized by superposition of continuous sounds.

  In the superposed sound synthesized as described above, substantially the same waveform is repeated every time T0 / 4 (seconds). Accordingly, the cycle of the superposed sound is T = T0 / 4 (seconds), and the fundamental sound is f = f0 × 4 (Hz). The superposed sound synthesized in this way is the sound of a four-cylinder four-stroke engine generated by the single sounding control reproduction method.

  In addition, in order to simulate the sound when the engine is mounted on an automobile, a noise waveform indicating road noise, wind noise, fan noise, and the like may be further superimposed on the engine sound generated as described above. .

[2. Experiment on change of acoustic characteristics of engine sound]
Subsequently, in the process of the inventor of the present application in the process of reaching the present invention, an experiment conducted using the single sound generation control reproduction method and the result are shown below. First, the inventor of the present application finally applied expansion and contraction fluctuations in the amplitude direction and time direction (hereinafter referred to as “amplitude fluctuation” and “time fluctuation”, respectively) added to the single sound of the original waveform in the synthesis of the continuous sound. It was confirmed by experiment how it affects the resulting superposed sound. FIG. 3 is a graph showing the results of the experiment.

  3 (A-1) and 3 (A-2) are obtained in the case where amplitude fluctuation and time fluctuation are not added at all in continuous sound synthesis, that is, in the case where the original waveform is used as it is for continuous sound synthesis. The waveform and frequency characteristics of the superposed sound are shown. 3 (B-1) and 3 (B-2) show the waveform and frequency characteristics of the superimposed sound obtained when only amplitude fluctuation is added and no time fluctuation is added in the synthesis of continuous sound. Show. Further, FIG. 3 (C-1) and FIG. 3 (C-2) show the waveform and frequency characteristics of the superposed sound obtained when both amplitude fluctuation and time fluctuation are added in the synthesis of continuous sound. Yes.

  From FIG. 3, it is confirmed that the difference between the peak and valley of the amplitude in the frequency characteristic of the superposed sound is reduced by adding the amplitude fluctuation and the time fluctuation. The peak of amplitude in the low frequency region of the frequency characteristic corresponds to an integer overtone of the fundamental tone, and the greater the difference between the peak and valley of the amplitude, the higher the pure tone, the so-called clear sound. From this, it was found that the pure tone of the superimposed sound can be changed by adjusting the degree of amplitude fluctuation and time fluctuation applied to the original waveform in the synthesis of continuous sound.

  FIG. 4 is a sonagraph showing the results of another experiment conducted to confirm the effect of the addition of fluctuations on the acoustic characteristics of superposed sound. 4A and 4B, the vertical axis represents frequency, and the horizontal axis represents time. However, in the superposed sound used in the creation of FIGS. 4A and 4B, it gradually increases so as to imitate the engine sound when the rotation speed r increases at a rate of 1000 rotations / second. A continuous sound in which single sounds reduced in the time direction at a reduction rate are connected is superposed. Accordingly, a value obtained by multiplying the value on the horizontal axis in FIGS. 4A and 4B by 1000 corresponds to the engine speed r.

  In the superposed sound used for creating FIG. 4A, neither amplitude fluctuation nor time fluctuation is added during the synthesis of continuous sounds. On the other hand, in the superposed sound used for creating FIG. 4B, amplitude fluctuation is not added, but regular time fluctuation is added. Specifically, the expansion / contraction ratio in the time direction with respect to the original sound waveform constituting the continuous sound used for superposition is 0.9, 1.05, 0.95 and 1 (hereinafter, repeated) in order from the top. It has become.

  In FIG. 4A, the peaks of frequency components lined up almost linearly from the lower left to the upper right of the graph are clearly confirmed. These straight lines appearing in the sonagraph indicate the components of the rotation second order, the rotation fourth order, the rotation sixth order,... From the bottom of the graph, and these straight lines are clear in FIG. It can be seen that the peak of the frequency component of the rotation integer order is sharp. On the other hand, in FIG. 4B, it can be seen that the rotation integer order straight line is not clear compared to that in FIG. 4A, and the peak of the rotation integer order frequency component is not sharp.

  From experience, it is known that the clearer the straight line corresponding to the order obtained by dividing the number of cylinders of the engine by 2, the more impression is given to the listener that the engine is turning smoothly. The order obtained by dividing the number of cylinders by 2 is also called an explosion primary. For example, in the case of a 4-cylinder engine, the primary explosion is the secondary rotation.

  4 (A) and 4 (B), the frequency component of the rotation integer order of the synthesized sound that is finally synthesized is more conspicuous when the fluctuation is given to the single sounding than when the fluctuation is not given. In addition, it can be seen that the primary component of the explosion does not appear remarkably as compared with the other components, and that the listener feels that the sound of the engine does not turn very well.

  Next, the inventor of the present application conducted an experiment to determine what effect will occur on the final synthesized sound when different original waveforms are used for each continuous sound corresponding to each cylinder in the synthesis of continuous sounds. confirmed. FIG. 5 is a sonagraph showing the results of the experiment.

  The scales of the vertical axis and the horizontal axis in FIGS. 5A and 5B are the same as those in FIG. FIG. 5A is the same graph as FIG. 4A and is shown again for comparison with FIG. 5B. In the synthesis of the superimposed sound used in the creation of FIG. 5B, continuous sounds synthesized using original waveforms having the same frequency characteristics but uncorrelated with each other are used as continuous sounds corresponding to each cylinder. Yes.

  Although there are various methods for creating an uncorrelated original waveform having the same frequency characteristics, in the creation of FIG. 5B, a section obtained by cutting out different sections of a noise waveform having a predetermined frequency characteristic is used. It is used as an original waveform corresponding to each cylinder. Such a noise waveform itself is dissimilar to a single sounding of the engine, but after a continuous process and a superposition process, it becomes somewhat similar to the sound of a multi-cylinder engine.

  When FIG. 5B is compared with FIG. 5A, a plurality of straight lines appear between the rotation integer-order straight lines, and as a result, it is difficult to identify which straight line is the rotation integer-order. That is, as in FIG. 4B, it can be seen that the sound of FIG. 5B does not show a frequency component of the rotation integer order as compared with the sound of FIG. 5A. However, unlike FIG. 4B, each straight line in FIG. 5B is clear as in FIG. 5A. For this reason, if the original waveform used to synthesize the synthesized sound is changed for each cylinder, the frequency component of the rotating integer order does not stand out depending on the degree of the correlation, but the acoustic characteristics may differ from those due to the addition of fluctuations. I understand.

  Next, the inventor of the present application confirmed by experiments how changes in the frequency characteristics of the original waveform used to synthesize the superimposed sound have an effect on the frequency characteristics of the finally obtained superimposed sound. FIG. 6 is a graph showing the results of the experiment. FIGS. 6A to 6D show frequency components of single sound having different waveforms and frequency components of superposed sound (engine sound) synthesized using the single sound, respectively. FIG. 6 shows that the valley of the amplitude of the superimposed sound has a strong correlation with the amplitude of the single sound used to generate the superimposed sound. That is, it can be seen that the rough acoustic characteristics of the superimposed sound are determined by the acoustic characteristics of the single sound.

[3. First Embodiment]
Subsequently, a first embodiment of the present invention will be described below. 1st Embodiment of this invention produces | generates the superposition | polymerization waveform which shows a virtual engine sound according to the parameter regarding the time fluctuation etc. which are input by the user, and the crankshaft angle of an engine which generate | occur | produces the produced | generated superposition | polymerization waveform Is a waveform synthesizer that outputs physical attribute values such as.

[3.1. Constitution]
FIG. 7 is a block diagram showing a configuration of the waveform synthesis system 1 including the waveform synthesis apparatus 10 according to the first embodiment. The waveform synthesis system 1 includes a mouse 11 that is a pointer device that outputs a signal according to a user operation to the waveform synthesis apparatus 10, a waveform synthesis apparatus 10, and an amplifier 12 that amplifies a sound waveform output from the waveform synthesis apparatus 10. A speaker 13 that converts the sound waveform output from the amplifier 12 into sound, and a display 14 that displays images and characters according to the drawing data output by the waveform synthesizer 10 to notify the user of various messages. I have.

  The waveform synthesizer 10 corresponds to an original waveform data group 1001 that is a collection of single-sound original waveforms used for waveform synthesis, and a parameter used for waveform synthesis and a physical attribute value of the engine that generates the generated engine sound. A storage unit 100 is provided for storing a correspondence DB group 1002 that is a collection of databases (hereinafter referred to as “DBs”) indicating relationships.

  The storage unit 100 further temporarily stores various data used by other components of the waveform synthesizer 10, and displays a screen for the user to input data to the waveform synthesizer 10 and a processing result for the user. Data defining a screen configuration for notification (hereinafter referred to as “screen definition data”) is stored. The screen definition data is a collection of data indicating the attributes of an object such as a text box or a command button displayed on the screen, and the user can input data to the object by an operation using the mouse 11. The processed data is also stored in the storage unit 100 as an attribute of the object.

  FIG. 8 is a diagram schematically showing the configuration of the original waveform data group 1001. The original waveform data group 1001 includes, for each of a plurality of engines, a plurality of single-tone original waveform data corresponding to the engine speed (rpm). In the example of FIG. 8, for a total of three types of engines, model 1 and model 2 of a four-stroke engine and model 3 of a two-stroke engine, a single sound corresponding to the number of revolutions at 600 rpm, 700 rpm,. When the original waveform data is included in the original waveform data group 1001 and the engine of the model 1 has a rotation speed of 600 rpm, for example, the original waveform data of a single tone is M1_600. It is stored with the file name wav.

  Note that the original waveform data included in the original waveform data group 1001 may be obtained by recording a sound generated by the operation of a single-cylinder engine (actual machine), for example, an actual engine sound with respect to random noise. It is virtually generated by applying filter processing with an equalizer or the like so that it has the same frequency characteristics as the above, or by expanding and contracting in the amplitude direction so that it has the same temporal change in amplitude as the actual engine sound. It may be. Moreover, the adjustment of the acoustic characteristic by filter processing etc. may be added to the engine sound of the actual machine.

  FIG. 9 is a diagram illustrating the configuration of the correspondence DB group 1002. The correspondence DB group 1002 includes a plurality of DBs corresponding to each physical attribute of the engine. The physical attributes of the engine are specifically the ignition timing of the spark plug, the crankshaft angle, the piston bank angle, the valve opening and closing timing, the length to the intake pipe assembly point, the exhaust pipe assembly point Length, fuel injection amount, intake air amount, etc. Each DB included in the correspondence relationship DB group 1002 has the following four types of data (hereinafter referred to as “parameter data”) related to the engine having the physical attribute value in association with the physical attribute value. Are collectively stored).

  “Correlation coefficient”: Correlation coefficient (no unit) of a single sound waveform corresponding to the first cylinder and a single sound waveform corresponding to the second cylinder.

“Degree of time fluctuation”: When the average of the lengths of a predetermined number of consecutive single _{pronunciations} is T _ave , and the maximum length of those single _{pronunciations} is T _max , the following expression 1 is obtained. e _T (%).
e _T = (T _max −T _ave ) ÷ T _ave × 100 (Equation 1)
For example, in the case of a 4-stroke engine, if the engine speed is 1000 rpm, the length of a single sound is 120 milliseconds, but the “degree of time fluctuation” 1.0% is about 118.8 for a single sound. It shows that it fluctuates in the range of milliseconds to 121.2 milliseconds.

“Degree of amplitude fluctuation”: When the average of the maximum amplitudes of each of a predetermined number of consecutive single sounds is A _ave and the maximum of the maximum amplitudes of these single sounds is A _max , Required e _A (%).
e _A = (A _max −A _ave ) ÷ A _ave × 100 (Expression 2).
For example, the maximum amplitude of each continuous single sound is 100, and the “amplitude fluctuation degree” of 1.0% indicates that the maximum amplitude of a single sound fluctuates in a range of about 99 to 101.

“Degree of offset”: In a two-cylinder engine, the start timings of a predetermined number n of continuous single sound generations of the first cylinder are i _{1 (1)} , i _{1 (2)} , i _{1 (3)} ... I _{1 ( n),} and when the subsequent start timings of the second cylinder single sounding are i _{2 (1)} , i _{2 (2)} , i _{2 (3)} ... i _{2 (n)} , respectively, S obtained in 5 (no unit).
_Istd = (i1 _(n) -i1 ₍₁₎ ) / (n-1) / 2 (Formula 3).
I _ost = {(i _{2 (1)} −i _{1 (1)} ) + (i _{2 (2)} −i _{1 (2)} ) +... + (I _{2 (n)} −i _{1 (n)} )} ÷ (n-1) (Formula 4).
s = I _ost ÷ I _std (Formula 5).

Here, I _std obtained by Equation 3 is the single sound of the first cylinder and the single sound of the second cylinder in the normal case where the single sound of the first cylinder and the single sound of the second cylinder are alternately started at equal time intervals. The time interval with the start timing of the sound is shown. On the other hand, I _ost obtained by Equation 4 represents the average value of the time interval between the actual start timing of single sound generation of the first cylinder and the subsequent start timing of single sound generation of the second cylinder. Therefore, s obtained by Expression 5 is less than 1 when the start timing of single sound generation of the second cylinder is earlier than usual as a whole, and when the start timing of single sound generation of the second cylinder is generally slower than normal. Greater than 1. For example, “degree of offset” 1.01 indicates that the start timing of single sound generation of the second cylinder is delayed by about 1% as compared with the normal case as a whole.

  FIG. 9 illustrates the contents of a DB related to ignition timing (hereinafter referred to as “ignition timing DB”) as an example of the DB included in the correspondence DB group 1002. In the ignition timing DB, an “ignition timing” column is provided as a column indicating physical attribute values. The “ignition timing” column indicates how much the ignition timing of the second cylinder is around, based on the normal case where the first cylinder and the second cylinder ignite alternately at equal time intervals in a two-cylinder engine. ing. For example, “ignition timing” 1.01 indicates that the ignition timing of the second cylinder as a whole is delayed by about 1% from the normal case. The correspondence DB group 1002 includes DBs similar to the ignition timing DBs regarding physical attributes such as crankshaft angles, piston bank angles, and valve opening / closing timings.

  Returning to FIG. 7, the description of the configuration of the waveform synthesizer 10 will be continued. The waveform synthesizer 10 specifies data input by the user (hereinafter referred to as “input data”) based on a signal output from the mouse 11 in response to a user operation, and temporarily stores the parameter in the storage unit 100. An input unit 101, an original waveform selection unit 102 that selects original waveform data according to the number of rotations closest to the desired number of rotations from the original waveform data group 1001, and the original waveform data selected by the original waveform selection unit 102 A period changing unit 103 that generates waveform data corresponding to a desired number of rotations by performing expansion and contraction in the time direction, and a frequency characteristic changing unit 104 that adjusts the frequency characteristics of the waveform data generated by the period changing unit 103 are provided. ing.

  The waveform synthesizer 10 generates a continuous waveform data by generating a series of a plurality of waveform data using the waveform data generated by the frequency characteristic changing unit 104 and connecting them, and The superposition waveform generation unit 106 that generates superposition waveform data by superimposing a plurality of continuous waveform data generated by the continuous waveform generation unit 105, and the superposition waveform data (digital data) generated by the superposition waveform generation unit 106 are analog. A D / A converter 107 that converts the data and outputs the data to the amplifier 12 is provided.

  In addition, the waveform synthesizer 10 specifies a physical attribute value corresponding to the input signal based on the correspondence DB group 1002, and an attribute value specifying unit 108 that temporarily stores the specified physical attribute value in the storage unit 100. I have. Further, the waveform synthesizer 10 includes a screen generation unit 109 that generates drawing data indicating a screen based on the screen definition data stored in the storage unit 100 and outputs the drawing data to the display 14.

  The continuous waveform generation unit 105 generates noise data indicating a noise waveform, and adds to the waveform data generated by the frequency characteristic changing unit 104 the cut out sections of the generated noise data, so that each is less than 1. There is provided a correlation changing unit 1051 for generating a plurality of different waveform data indicating the correlation. Each of the plurality of waveform data generated by the correlation changing unit 1051 is single sound waveform data corresponding to each cylinder of the multi-cylinder engine. Hereinafter, for the sake of explanation, the case of four cylinders will be described as an example. In the case of four cylinders, the correlation changing unit 1051 generates four waveform data such that one set of arbitrarily selected waveform data has a predetermined correlation.

  The continuous waveform generating unit 105 includes a time fluctuation adding unit 1052 that adds time fluctuation to the waveform data generated by the correlation changing unit 1051 and an amplitude fluctuation adding unit 1053 that adds amplitude fluctuation to the waveform data generated by the time fluctuation adding unit 1052. And.

  The time fluctuation adding unit 1052 generates a series of expansion / contraction ratios having fluctuations, and sequentially converts the first waveform data of the four waveform data generated by the correlation changing unit 1051 using the generated series of expansion / contraction ratios. Stretch in the time direction. As a result, a waveform data group having a time fluctuation corresponding to the first cylinder is generated. The time fluctuation adding unit 1052 performs the same processing as the first waveform data for the second to fourth waveform data generated by the correlation changing unit 1051. As a result, a waveform data group having time fluctuation corresponding to each of the second to fourth cylinders is generated.

  The amplitude fluctuation adding unit 1053 generates a series of expansion / contraction ratios having fluctuations, and generates a series of expansion / contractions for each of the series of waveform data included in the first waveform data group generated by the time fluctuation addition unit 1052. It expands and contracts sequentially in the amplitude direction at a rate. As a result, a waveform data group having both time fluctuation and amplitude fluctuation corresponding to the first cylinder is generated. The amplitude fluctuation adding unit 1053 also performs the same processing as the first waveform data group for the second to fourth waveform data groups generated by the time fluctuation adding unit 1052. As a result, a waveform data group having time fluctuation and amplitude fluctuation corresponding to each of the second to fourth cylinders is generated.

  The continuous waveform generation unit 105 further includes a connection processing unit 1054 that connects the waveform data groups generated by the amplitude fluctuation adding unit 1053 to generate continuous waveform data. The connection processing unit 1054 multiplies each of a series of waveform data included in the first waveform data group generated by the amplitude fluctuation adding unit 1053 by a window function, and then sequentially connects them. As a result, continuous waveform data corresponding to the first cylinder is generated. Note that the process of multiplying by this window function is a process for avoiding noise caused by discontinuity in the connection portion of the waveform data. The connection processing unit 1054 performs the same processing as the first waveform data group for the second to fourth waveform data groups generated by the amplitude fluctuation adding unit 1053. As a result, continuous waveform data corresponding to each of the second to fourth cylinders is generated. The four continuous waveform data generated in this way is delivered from the continuous waveform generation unit 105 to the overlapped waveform generation unit 106.

  The overlapped waveform generation unit 106 includes an offset change unit 1061 that gives an offset in the time direction to each of the four continuous waveform data received from the continuous waveform generation unit 105, and four continuous waveform data to which an offset is given by the offset change unit 1061. And a superposition processing unit 1062 that generates superposition data by superimposing them. The superposition data generated in this way is waveform data indicating the sound of a four-cylinder engine.

[3.2. Operation]
Next, the operation of the waveform synthesis system 1 will be described. When the user performs an activation operation of the waveform synthesizer 10, the screen generator 109 of the waveform synthesizer 10 reads the screen definition data for data input from the storage unit 100, generates drawing data indicating the screen, and displays the display 14. Output to. As a result, a data input screen is displayed on the display 14.

  FIG. 10 is a diagram exemplifying a data input screen displayed on the display 14. The data input screen includes a list box 141 for selecting the number of cylinders, a list box 142 for selecting an engine model, a slider 143 for designating the number of revolutions, a fader group 144 constituting a graphic equalizer, and a correlation. A slider 145 for designating the degree of time fluctuation, a slider 146 for designating the degree of time fluctuation, a slider 147 for designating the degree of amplitude fluctuation, a slider group 148 for designating an offset, and a waveform synthesis of engine sound. A command button 149 for instructing the start, a command button 150 for instructing the end of the engine sound waveform synthesis, and a command button 151 for instructing display of the physical attribute value of the engine according to the generated engine sound It is included.

  On the data input screen, the user operates the mouse 11 to input various parameters from the number of cylinders to the offset. The mouse 11 outputs a signal corresponding to a user operation to the parameter input unit 101 of the waveform synthesizer 10. The parameter input unit 101 specifies input data input by the user based on the signal received from the mouse 11 and the screen definition data for data input stored in the storage unit 100, and includes the specified input data in the screen definition data. And stored in the storage unit 100 as attribute values of each object.

  Thereafter, the user clicks the command button 149 with the mouse 11. In response to the click operation, the original waveform selection unit 102 to the D / A converter 107 of the waveform synthesizer 10 starts engine sound synthesis processing and output processing.

  First, the original waveform selection unit 102 selects a group of original waveform data of a model corresponding to the attribute value of the list box 142 from the original waveform data group 1001 (see FIG. 8). Subsequently, the original waveform selection unit 102 selects the original waveform corresponding to the rotation speed closest to the rotation speed indicated by the input data stored as the attribute value of the slider 143 from the original waveform data group included in the selected group. Select waveform data.

  The period changing unit 103 generates waveform data corresponding to the number of rotations indicated by the attribute value of the slider 143 by expanding and contracting the original waveform data selected by the original waveform selecting unit 102 in the time direction. For example, when the number of rotations designated by the user is 620 rpm, the original waveform data corresponding to 600 rpm is selected by the original waveform selector 102, and the period changing unit 103 converts the original waveform data in the time direction at an expansion / contraction ratio of 600/620. By expanding and contracting, single sound waveform data corresponding to 620 rpm is generated.

  The frequency characteristic changing unit 104 adjusts the frequency characteristic of the waveform data generated by the period changing unit 103 based on the shape of the frequency characteristic indicated by the attribute value of the fader group 144. More specifically, the frequency characteristic changing unit 104 generates waveform data in which the frequency characteristics are adjusted, for example, by mixing the waveform data filtered by each of the plurality of bandpass filters.

  Correlation changing section 1051 of continuous waveform generating section 105 first generates random noise waveform data having the same length as the waveform data generated by frequency characteristic changing section 104. Specifically, for example, a random number sequence that changes between −1 and +1 is generated as waveform data of random noise.

  Subsequently, the correlation changing unit 1051 performs amplitude for each of the random noise waveform data and the waveform data generated by the frequency characteristic changing unit 104 with an expansion / contraction rate corresponding to the degree of correlation indicated by the attribute value of the slider 145. After applying direction stretch, mix them. More specifically, for example, when 0.8 is designated as the degree of correlation by the user, the correlation changing unit 1051 multiplies the waveform data of random noise by the maximum amplitude of the waveform data generated by the frequency characteristic changing unit 104. Further, the product obtained by further multiplying (1-0.8) = 0.2 and the product obtained by multiplying the waveform data generated by the frequency characteristic changing unit 104 by 0.8 are mixed. As a result, different waveform data having a positive correlation with the waveform data generated by the frequency characteristic changing unit 104 is generated.

  Correlation changing section 1051 repeats the above process for the number of cylinders indicated by the attribute value in list box 141. As a result, a set of waveform data in which a set of arbitrarily selected waveform data has a positive correlation with each other but is different is generated. At this time, the correlation between waveform data is higher as the degree of correlation designated by the user is higher, and lower as the correlation is lower. When the degree of correlation specified by the user is 0, the waveform data generated by the correlation changing unit 1051 is the waveform data of random noise itself, and the correlation coefficient between these waveform data is almost 0. On the other hand, when the degree of correlation specified by the user is 1, the waveform data generated by the correlation changing unit 1051 is the waveform data itself generated by the frequency characteristic changing unit 104, and the correlation coefficient between these waveform data is 1

  The time fluctuation adding unit 1052 generates a waveform data group to which time fluctuation is added for each of the same number of waveform data as the number of cylinders generated by the correlation changing unit 1051. More specifically, the time fluctuation adding unit 1052 first generates a random number sequence that changes between −1 and +1. Subsequently, the time fluctuation adding unit 1052 multiplies each generated random number by the degree of time fluctuation indicated by the attribute value of the slider 146 and then adds 1. As a result, for example, when the degree of time fluctuation specified by the user is 3%, a random number sequence that varies between 0.97 and 1.03 is generated.

  Subsequently, the time fluctuation adding unit 1052 repeats the process of expanding / contracting the first waveform data generated by the correlation changing unit 1051 in the time direction at an expansion / contraction rate corresponding to each of the random numbers included in the generated random number sequence. For example, when 0.982, 1.021, 0.997,... Are generated as the random number sequence, the time fluctuation adding unit 1052 converts the first waveform data generated by the correlation changing unit 1051 to 0 in the time direction. A waveform data group obtained by expanding and contracting to .982 times, 1.021 times, 0.997 times,... Is generated. The waveform data group generated in this way indicates a single sound generation group that constitutes the engine sound emitted by the first cylinder.

  The time fluctuation adding unit 1052 uses the same magnification as that used for the first waveform data for each of the second waveform data, the third waveform data,... Generated by the correlation changing unit 1051. A second waveform data group, a third waveform data group,... Are generated by sequentially expanding and contracting in the time direction. These waveform data groups are waveform data groups corresponding to the second cylinder, the third cylinder,..., Respectively.

  The amplitude fluctuation adding unit 1053 adds amplitude fluctuation to the waveform data included in the waveform data group generated by the time fluctuation adding unit 1052. The amplitude fluctuation adding unit 1053 generates a random number sequence indicating a magnification when the waveform data is expanded and contracted in the amplitude direction by the same method as that performed by the time fluctuation adding unit 1052. However, when generating a random number sequence, the amplitude fluctuation adding unit 1053 generates a random number sequence according to the degree of amplitude fluctuation indicated by the attribute value of the slider 147 instead of the slider 146.

  The amplitude fluctuation adding unit 1053 expands / contracts the waveform data included in the first waveform data group generated by the time fluctuation adding unit 1052 in the amplitude direction at the magnification of the random number included in the random number sequence. For example, when 1.012, 0.973, 0.985,... Are generated as random number sequences, the amplitude fluctuation adding unit 1053 converts the first waveform data included in the first waveform data group into the amplitude direction. The second waveform data is expanded and contracted by 1.012 times, the amplitude of the second waveform data is 0.973 times, the third waveform data is expanded by 0.985 times in the amplitude direction, and so on. As a result, a first waveform data group to which amplitude fluctuation is added is generated.

  The amplitude fluctuation adding unit 1053 is the same as the magnification used for the first waveform data group for each of the second waveform data group, the third waveform data group,... Generated by the time fluctuation adding unit 1052. The second waveform data group, the third waveform data group, etc. to which amplitude fluctuation is added are generated by sequentially performing expansion and contraction in the amplitude direction using the magnification.

  The concatenation processing unit 1054 sequentially concatenates a series of waveform data included in the first waveform data group generated by the amplitude fluctuation adding unit 1053 and a window function. As a result, first continuous waveform data is generated. Similarly, the connection processing unit 1054 also performs processing similar to the processing performed on the first waveform data group with respect to the second waveform data group, the third waveform data group,... Generated by the amplitude fluctuation adding unit 1053. I do. As a result, second continuous waveform data, third continuous waveform data, and so on are generated.

The offset changing unit 1061 of the overlapped waveform generating unit 106 includes a time direction corresponding to the attribute value of the slider group 148 for each of the plurality of continuous waveform data generated as described above by the connection processing unit 1054 of the continuous waveform generating unit 105. Add an offset. For example, when four cylinders are selected in the list box 141, the attribute value of the slider group 148, that is, the offset value designated by the user is (I ₁ , I ₂ , I ₃ ) = (0.97, 1.. 05, 1.02).

Here, I ₁ indicates the interval between the start timings of the single sound generation of the first cylinder and the second cylinder when the interval is set to ₁ in the normal case, that is, when the start timing of the single sound generation of each cylinder is equal. ing. Similarly, I ₂ indicates the interval between the start timings of the single sound generation of the second cylinder and the third cylinder, and I ₃ indicates the interval between the start timings of the single sound generation of the third cylinder and the fourth cylinder. Note that the interval between the start timings of single sound generation of the fourth cylinder and the first cylinder is automatically determined from I _{1 to} I ₃ as 4- (0.97 + 1.05 + 1.02) = 0.96.

The interval of the start timing of single sound generation in each cylinder in a normal case is a length obtained by dividing the length of the single sound waveform data generated by the period changing unit 103 by the number of cylinders. Hereinafter, this length is set to D. The offset changing unit 1061 inserts the data of amplitude 0 having a length of D × I _{1 at} the head of the second continuous waveform data generated by the concatenation processing unit 1054. As a result, the sound generation start timing by the second continuous waveform data is delayed by a time D × I ₁ from the sound generation start timing of the first continuous waveform data.

Similarly, the offset changing unit 1061 inserts data having an amplitude of 0 having a length of D × (I ₁ + I ₂ ) at the head of the third continuous waveform data generated by the concatenation processing unit 1054. Further, the offset changing unit 1061 inserts data having an amplitude of 0 of length D × (I ₁ + I ₂ + I ₃ ) at the head of the fourth continuous waveform data generated by the concatenation processing unit 1054. Although the case where four cylinders are selected in the list box 141 has been described here, the same applies to the case where the number of cylinders is other than four.

  The superposition processing unit 1062 mixes the first continuous waveform data, the second continuous waveform data,... Whose sounding start timing has been shifted by the offset changing unit 1061, and generates superposition waveform data. The overlapping waveform data generated by the mixing processing of the overlapping processing unit 1062 is waveform data indicating the sound of the multi-cylinder engine. The superposition processing unit 1062 delivers the generated superposition waveform data to the D / A converter 107.

  When receiving the superposition waveform data from the superposition processing unit 1062 of the superposition waveform generation unit 106, the D / A converter 107 converts the superposition waveform data received into analog data and outputs it to the amplifier 12. The amplifier 12 amplifies the analog data input from the D / A converter 107 and outputs it to the speaker 13. The speaker 13 converts the analog data input from the amplifier 12 into sound and generates a sound. As a result, the user can hear the multi-cylinder engine sound synthesized by the waveform synthesizer 10.

  The user can stop outputting analog data from the waveform synthesizer 10 to the amplifier 12 by operating the mouse 11 and clicking the command button 150.

  When the user likes the engine sound generated from the speaker 13, the user can cause the display 14 to display engine physical attribute values that are likely to generate a sound close to the engine sound. Hereinafter, the operation performed by the waveform synthesizer 10 to display the physical attribute value of the engine when the two cylinders are selected in the list box 141 will be described.

  When the user operates the mouse 11 and clicks the command button 151, the attribute value specifying unit 108 of the waveform synthesizer 10 displays the input data stored as the attribute value of each object of the screen definition data for data input, more specifically, Specifically, a value indicating the degree of correlation stored as the attribute value of the slider 145, a value indicating the degree of temporal fluctuation stored as the attribute value of the slider 146, and an amplitude fluctuation stored as the attribute value of the slider 147 And a value indicating the degree of offset stored as the attribute value of the slider group 148 is read from the storage unit 100. Here, since two cylinders are selected in the list box 141, the value indicating the degree of offset stored as the attribute value of the slider group 148 is only a value related to the second cylinder. Hereinafter, the input data read in this way is referred to as “input parameter data”.

  Subsequently, the attribute value specifying unit 108 determines the engine value such as (ignition timing, crankshaft angle, piston angle,...) = (1.00, 25.0 °, 180 °,...). A combination of default values of physical attributes is read from the storage unit 100. The attribute value specifying unit 108 searches parameter data corresponding to the read default value of the physical attribute from each of the DBs included in the correspondence DB group 1002 stored in the storage unit 100.

  The attribute value specifying unit 108 thus multiplies the same type of data included in the parameter data retrieved from each DB, and relates to the ignition timing, the correlation coefficient, the degree of time fluctuation, the degree of amplitude fluctuation, and the degree of offset. One value is calculated for each. The value thus calculated is parameter data indicating a parameter that determines the characteristics of the engine sound emitted by the engine having the combination of the physical attributes. Hereinafter, the parameter data calculated in this way is referred to as “calculated parameter data”.

  The attribute value specifying unit 108 calculates the similarity between the input parameter data and the calculated parameter data. However, since the degree of correlation in the input parameter data and the correlation coefficient in the calculated parameter data are not the same type of index, the attribute value specifying unit 108 uses the correlation coefficient between the waveform data according to the degree of correlation in the input parameter data. Is used to calculate the similarity to the calculated parameter data.

There are various methods for calculating the similarity between the input parameter data and the calculated parameter data. For example, for each parameter type such as the correlation coefficient, the degree of time fluctuation,. The ratio may be calculated by calculating a ratio to the input parameter data and adding the square of the difference between the calculated ratio and 1. For example, when the calculated parameter data is (0.93, 2.7, 1.6, 1.05) and the input parameter data is (0.95, 2.2, 2.4, 0.82) These similarities are (1-0.93 / 0.95) ² + (1-2.7 / 2.2) ² + (1-1.6 / 2.4) ² + (1-1 .05 / 0.82) ² ≈ 0.242. The similarity calculated in this way is always 0 or more, and the smaller the value, the higher the similarity. The attribute value specifying unit 108 temporarily stores the similarity calculated in this way in the storage unit 100 together with the combination of physical attribute values used for the calculation.

  Subsequently, the attribute value specifying unit 108 is a combination of physical attribute values different from the default values, for example, (ignition timing, crankshaft angle, piston angle,...) = (1.01, 25.0 °, 180 The calculated parameter data is calculated for (°,...), And the similarity between the newly calculated calculated parameter data and the input parameter data is calculated.

  The attribute value specifying unit 108 compares the newly calculated similarity with the similarity stored in the storage unit 100, and when the similarity stored in the storage unit 100 is smaller, that is, stored in the storage unit 100. If the similarity is higher, the content stored in the storage unit 100 is not changed. On the other hand, when the newly calculated similarity is smaller than the similarity stored in the storage unit 100, that is, when the newly calculated similarity indicates higher similarity, the attribute value specifying unit 108 The data stored in the storage unit 100 is updated based on the combination of the similarity calculated in the above and the physical attribute value used for the calculation of the similarity.

  The attribute value specifying unit 108 repeats the above-described update processing of the combination of the similarity and the physical attribute value while sequentially changing the contents of the combination of the physical attribute values with a predetermined change width according to a predetermined rule. When the update processing by the attribute value specifying unit 108 is completed for various combinations of physical attribute values, the combination of the physical attribute values stored in the storage unit 100 at that time is the engine sound synthesized by the waveform synthesizer 10. It shows the physical attributes of the engine that produces the most similar sound. The attribute value specifying unit 108 specifies the engine physical attribute using mathematical programming such as Newton's method instead of specifying the engine physical attribute by the brute force method as described above. May be.

  By the way, when three or more cylinders are selected in the list box 141, the value indicating the degree of offset stored as the attribute value of the slider group 148 is plural because a value related to the third cylinder and later is added. Therefore, the attribute value specifying unit 108 repeats the above physical attribute specifying process for a plurality of sets of input parameter data including values indicating the degree of the plurality of offsets. As a result, physical attributes relating to the third cylinder and subsequent cylinders are also specified.

  When the attribute value specifying unit 108 completes the physical attribute specifying process, the combination of the physical attribute values stored in the storage unit 100 at that time is delivered to the screen generation unit 109. Upon receiving the combination of physical attribute values from the attribute value specifying unit 108, the screen generation unit 109 reads the screen definition data for displaying physical attribute values from the storage unit 100, and reads the received combination of physical attribute values. Using the screen definition data, drawing data indicating a physical attribute value display screen is generated and output to the display 14. As a result, the physical attribute value is displayed on the display 14.

  FIG. 11 is a diagram illustrating a display screen of physical attribute values displayed on the display 14 when four cylinders are selected on the data input screen.

  As described above, according to the waveform synthesis system 1, the user inputs various parameters such as the degree of time fluctuation characterizing the engine sound to be synthesized, thereby causing the waveform synthesis apparatus 10 to synthesize various engine sounds. It is possible to display the physical attribute value of the engine that emits a sound similar to the engine sound synthesized as described above. As a result, it is possible to know the physical attributes of an engine that emits a desired engine sound without actually making prototypes of engines having various physical attributes.

  For example, as another method of synthesizing engine sound without prototyping the engine, an engine physical model of the engine is virtually created on a computer, and air vibrations generated by operating the engine of the physical model are generated by the engine. It can also be generated as sound. However, the method using a physical model is generally computationally intensive. For example, a computer with high processing power is required to achieve the purpose of confirming the change by synthesizing engine sound while changing the rotation speed in real time. It becomes. In contrast, in the waveform synthesizer 10 according to the present invention, only parameters that greatly characterize the engine sound, such as the degree of correlation, the degree of amplitude fluctuation, the degree of time fluctuation, and the degree of offset, are used to specify physical attributes. Therefore, it is possible to quickly synthesize engine sound even when using a computer with a small calculation load and a low processing capacity.

[4. Second Embodiment]
Subsequently, a second embodiment of the present invention will be described below. In the first embodiment described above, parameters that characterize the engine sound such as the degree of correlation and the degree of amplitude fluctuation are input to the waveform synthesizer 10 by the user, and as a result, the engine sound that is synthesized is combined with the engine sound. It was a mechanism to display the physical attribute value of the engine that emits a similar sound. On the other hand, in the second embodiment, the engine physical attribute value is input to the waveform synthesizer 10 by the user, and as a result, the engine sound is synthesized.

[4.1. Constitution]
FIG. 12 is a block diagram showing a configuration of the waveform synthesis system 2 including the waveform synthesis apparatus 20 according to the second embodiment. The configuration of the waveform synthesis system 2 is common to the waveform synthesis system 1 in many respects. Therefore, in FIG. 12, the same components as those of the waveform synthesis system 1 are denoted by the same symbols (see FIG. 7) attached to the components of the waveform synthesis system 1. In order to avoid duplication of explanation, only the parts of the configuration of the waveform synthesis system 2 that are different from the waveform synthesis system 1 will be described below.

  The waveform synthesis system 2 includes a mouse 11, a waveform synthesis device 20, an amplifier 12, a speaker 13, and a display 14. That is, the overall configuration of the waveform synthesis system 2 is not different from the overall configuration of the waveform synthesis system 1 except that the waveform synthesis device 20 is provided instead of the waveform synthesis device 10.

  Compared with the waveform synthesizer 10 of the first embodiment, the waveform synthesizer 20 does not include the parameter input unit 101 and the attribute value specifying unit 108, while the attribute value input unit 201 and the parameter specifying unit 202 are provided. I have. Further, the storage unit 100 of the waveform synthesizer 20 stores a first correspondence DB group 1201 and a second correspondence DB group 1202 instead of the correspondence DB group 1002 in comparison with the storage unit 100 of the waveform synthesizer 10. Yes.

  The attribute value input unit 201 receives a signal output from the mouse 11 in response to a user operation, and receives data input by the user from the received signal (hereinafter referred to as “input data” as in the first embodiment). Identify. The input data in the waveform synthesis system 2 is data indicating a physical attribute value of the engine.

  The parameter specifying unit 202 includes a first correspondence DB group 1201 and a second correspondence DB group stored in the storage unit 100 that characterize the engine sound corresponding to the input data specified by the attribute value input unit 201. Specify based on 1202.

  The first correspondence DB group 1201 is the same as the correspondence DB group 1002 (see FIG. 9) stored in the storage unit 100 of the waveform synthesizer 10. That is, the first correspondence DB group 1201 relates to engine physical attributes such as ignition timing, and shows a correspondence relationship between physical attribute values and correlation coefficients, the degree of time fluctuation, the degree of amplitude fluctuation, and the degree of offset. It is a gathering of.

  The second correspondence DB group 1202 relates to the physical attributes of the engine such as the cylinder size, and is a DB that shows the correspondence of physical attribute values and frequency characteristics, more specifically, amplification factors corresponding to each frequency band of the graphic equalizer. It is a gathering of.

  FIG. 13 is a diagram illustrating the configuration of the second correspondence DB group 1202. The second correspondence DB group 1202 includes DBs related to various physical attributes of the engine, such as cylinder size, engine cover thickness, surge tank shape, and the like. These physical attributes are physical attributes that influence the frequency characteristics of the engine's single tone. As shown in FIG. 13, the first column of each DB shows physical attribute values, and the second and subsequent columns of DB show center frequencies (Hz) on the logarithmic scale of each frequency band of the graphic equalizer.

  The amplification factor indicated by the DB included in the second correspondence DB group 1202 is the single sound of the engine (or virtual engine) used when recording or generating the single sound source waveform data included in the original waveform data group 1001. This is a value indicating how much the frequency component of the single sound of the engine with only the target physical attribute changed is increased or decreased in each frequency band.

  According to the data illustrated in FIG. 13, the reference cylinder size is 50 mm in diameter. For example, the amplitude of the single sound frequency component of the engine having a cylinder size of 20 mm is the amplitude of the single sound frequency component of the reference engine. Is 1.00 in the frequency band of the center frequency 63 Hz, 0.93 in the frequency band of the center frequency 125 Hz,.

[4.2. Operation]
Next, the operation of the waveform synthesis system 2 will be described. When the user performs an activation operation of the waveform synthesizer 20, the screen generator 109 of the waveform synthesizer 20 reads the screen definition data for data input from the storage unit 100, generates drawing data indicating the screen, and displays the display 14. Output to. As a result, a data input screen is displayed on the display 14.

  FIG. 14 is a diagram exemplifying a data input screen displayed on the display 14 in the waveform synthesis system 2. On the data input screen in the waveform synthesis system 2, as in the waveform synthesis system 1, a list box 141 for selecting the number of cylinders, a list box 142 for selecting an engine model, and the number of revolutions are designated. And a command button 149 for instructing the start of engine sound waveform synthesis, and a command button 150 for instructing the end of engine sound waveform synthesis.

  The data input screen in the waveform synthesis system 2 includes a list box group 241 and a list box group 242 for the user to input physical attribute values of various engines. In the list box group 241, the correlation coefficient of single sound generation between cylinders in a multi-cylinder engine, the degree of time fluctuation between consecutive single sounds, the degree of amplitude fluctuation between consecutive single sounds, and the degree of offset between cylinders The physical attribute value that the user considers appropriate can be selected from the list and entered. Specific physical attributes listed in the list box group 241 are ignition timing, crankshaft angle, biston angle, and the like.

  On the other hand, in the list box group 242, regarding a physical attribute that affects the frequency characteristics of a single tone, a physical attribute value that the user considers appropriate can be selected from the list and input. The physical attributes listed in the list box group 242 are specifically cylinder size, engine cover thickness, surge tank shape, cylinder material, exhaust pipe length, intake pipe length, silencer type, etc. It is.

  On the data input screen, the user operates the mouse 11 to input the physical attribute value of the engine for which engine sound synthesis is desired. The mouse 11 outputs a signal corresponding to a user operation to the attribute value input unit 201 of the waveform synthesizer 20. The attribute value input unit 201 specifies input data input by the user based on the signal received from the mouse 11 and the screen definition data for data input stored in the storage unit 100, and the specified input data is used as screen definition data. The attribute value of each included object is stored in the storage unit 100.

  Thereafter, the user clicks the command button 149 with the mouse 11. In response to this click operation, the parameter specifying unit 202 and the original waveform selection unit 102 to the D / A converter 107 of the waveform synthesizer 20 start an engine sound synthesis process and an output process thereof.

  First, the parameter specifying unit 202 uses each of the input data stored as attribute values of the list box group 241 as a search key, from among the corresponding physical attribute DBs included in the first correspondence DB group 1201. Identify the corresponding parameters such as correlation coefficients.

  For example, when the user selects four cylinders in the list box 141, the list box group 241 includes "first cylinder-second cylinder", "second cylinder-third cylinder", "third cylinder" as attribute values related to ignition timing. -"Fourth cylinder" column is displayed, and the user can input the ignition timing between the cylinders as a numerical value with respect to the normal ignition timing interval.

  Here, for example, when the user inputs 1.01 in the column of “first cylinder-second cylinder” of the ignition timing, the parameter specifying unit 202 first has that attribute value is an attribute value related to the ignition timing. The ignition timing DB is selected from the first correspondence DB group 1201 (see FIG. 9). Subsequently, the parameter specifying unit 202 searches the selected DB for the corresponding record by setting the search field to “ignition timing” and the search key to “1.01”. As a result, for example, correlation coefficient: 0.94, degree of time fluctuation: 2.9, degree of amplitude fluctuation: 1.6, and degree of offset: 1.01 are specified as parameters relating to the first cylinder and the second cylinder. To do. The parameter specifying unit 202 performs the same parameter specifying process for all items included in the list box group 241.

  The parameter specifying unit 202 calculates a parameter for synthesizing the engine sound by multiplying the same type of parameters among the plurality of parameters specified as described above. For example, with respect to each of the ignition timing, the crankshaft angle, the piston angle,..., The correlation coefficients corresponding to the attribute values input in the column “first cylinder-second cylinder” are 0.94, 0, respectively. .87, 0.96,..., The parameter specifying unit 202 calculates 0.94 × 0.87 × 0.96. The correlation coefficient calculated in this way is a correlation coefficient used for engine sound synthesis. The parameter specifying unit 202 stores the parameter thus calculated in the storage unit 100 as specific parameter data.

  In addition, the parameter specifying unit 202 uses the input data stored as the attribute values of the list box group 242 as search keys, from among the corresponding physical attribute DBs included in the second correspondence DB group 1202. The corresponding parameter, that is, the amplification factor group of each frequency band is specified.

  For example, when the user inputs 30 (mm) in the cylinder size column in the list box group 242, the parameter specifying unit 202 first has an attribute value related to the cylinder size. A cylinder size DB is selected from 1202 (see FIG. 13). Subsequently, the parameter specifying unit 202 searches the selected DB for the corresponding record by setting the search field to “cylinder size” and the search key to “30”. As a result, for example, the amplitude ratio of the frequency band of the center frequency 63 Hz: 0.92, the amplitude ratio of the frequency band of the center frequency 125 Hz: 0.99,. The parameter specifying unit 202 performs the same parameter specifying process for all items included in the list box group 242.

  The parameter specifying unit 202 calculates a parameter for synthesizing the engine sound by multiplying the same type of parameters among the plurality of parameters specified as described above. For example, regarding the cylinder size, engine cover thickness, surge tank shape, etc., if the amplitude ratio of the frequency band of the center frequency of 63 Hz is 0.92, 1.15, 0.84,. The parameter specifying unit 202 calculates 0.92 × 1.15 × 0.84. The amplitude rate calculated as such is the amplitude rate used for engine sound synthesis. The parameter specifying unit 202 stores the parameter thus calculated in the storage unit 100 as specific parameter data, similarly to the parameter specified using the first correspondence DB group 1201.

  As described above, when the storage of the specific parameter data by the parameter specifying unit 202 is completed, the original waveform selecting unit 102 to the D / A converter 107 perform the engine sound synthesis process. In the waveform synthesizer 10, input data input by the user on the data input screen (see FIG. 10) is used as a parameter for engine sound synthesis. In the waveform synthesizer 20, the parameter is specified by the parameter specifying unit 202. Specific parameter data indicating the selected parameters is used. In the processing of the original waveform selection unit 102 to the D / A converter 107, all other points are the same as those in the waveform synthesizer 10, and a description thereof will be omitted.

  When engine sound is synthesized according to the specific parameter data by the waveform synthesizer 20, the waveform data of the engine sound synthesized from the waveform synthesizer 20 to the amplifier 12 is output, and the waveform data amplified by the amplifier 12 is output from the speaker. 13 is converted into sound. As a result, the user can hear the synthesized engine sound. The engine sound synthesized in this way is similar to the sound emitted by the engine having the physical attribute value input by the user on the data input screen (see FIG. 14).

  As described above, according to the waveform synthesis system 2, when the user inputs various physical attribute values of the engine, the waveform synthesis device 20 generates a sound similar to the sound emitted by the engine having the desired physical attribute value. Can be synthesized and heard. As a result, it is possible to know the engine sound of an engine having a desired physical attribute without actually making prototypes of engines having various physical attributes.

[5. Modified example]
The first and second embodiments described above can be variously modified within the scope of the technical idea of the present invention. Such a modification is shown below.

[5.1. First Modification]
The embodiment described above relates to the synthesis of engine sound. However, the present invention can be applied to the synthesis of sound of any other device having a plurality of the same type of sound generation parts. For example, the acoustic characteristics of wind noise of a fan (electric fan) are affected by the number of blades, the shape of the blades, the angle between adjacent blades, and the like. These physical attributes include the sound generated when one blade of a fan makes one revolution, that is, the frequency characteristics of single sound, the degree of time fluctuation and amplitude fluctuation when multiple single sounds are continued, and the distance between the blades. Determine the correlation of single pronunciation. Further, when parameters for determining these acoustic characteristics are given, it is possible to specify the physical attribute value of the fan that gives such parameters by mathematical programming or the like.

  Therefore, the sound generated when one blade of the fan makes one rotation is set as a single sound, and the user can actually perform the fan synthesis by performing the same processing as that of the above-described embodiment regarding the synthesis of the sound of the fan. It is possible to synthesize the wind noise of the fan without making a prototype, and to confirm the physical attribute value of the fan that emits such wind noise.

[5.2. Second Modification]
Further, in the above-described embodiment, a single sound is generated in the process in which one cylinder of the engine performs a series of operations such as intake, compression, explosion, and exhaust (in the case of a four-stroke engine), and the single sound is converted into the original waveform data. Although explained as what is handled as one unit, it is not restricted to it.

  For example, as the original waveform data, an intake sound, a compressed sound, an explosion sound, and an exhaust sound may be treated as different single sounds. In that case, for example, it is possible to add different time fluctuations or the like between the intake air and the explosion. As a result, more flexible engine sound synthesis and physical attribute value specification are possible.

  Further, for example, as for the ignition timing, as a result of the ignition timing interval being shortened according to the engine speed, the influence of the ignition timing bias on the explosion timing becomes smaller as the engine speed increases. On the other hand, the length of the intake pipe always brings a constant bias to the intake timing regardless of changes in the engine speed. Therefore, if each process of intake, compression, explosion, and exhaust is handled individually, an offset time that does not change regardless of the rotational speed is given to the intake air, whereas an offset that changes according to the rotational speed is provided for the explosion. Processing such as giving time is possible.

[5.3. Third Modification]
Further, in the above-described embodiment, it has been described that when a time fluctuation and an amplitude fluctuation are given, a single sound is set as one unit, and expansion or contraction in the time direction or the amplitude direction is performed for each single sound. However, the present invention is not limited thereto. For example, the expansion / contraction rate may vary with fluctuation every predetermined time regardless of the length of a single tone.

[5.4. Fourth Modification]
In the above-described embodiment, the engine sound synthesis process has been described on the assumption that the amplitude fluctuation is added after the time fluctuation is added, but the present invention is not limited to this. For example, the time fluctuation may be added after the amplitude fluctuation is added, or after the time fluctuation is added to the single sound generation for each of the multi-cylinder cylinders, the superposition is performed before the connection and the superposition waveform is connected. Thus, the engine sound may be synthesized. In any case, as long as the same composite waveform is generated as a result, it is included in the technical scope of the present invention.

[5.5. Fifth Modification]
Further, in the above-described embodiment, the relationship between the physical characteristic value and the parameter has been described as being fixed regardless of the rotation speed, but is not limited thereto. For example, even if the ignition timing is the same according to the rotational speed, different data for each rotational speed is stored in the correspondence DB so that parameters such as the correlation coefficient and the degree of time fluctuation change, and the rotational speed is stored. Different data may be retrieved and used in accordance with the change in.

[5.6. Sixth Modification]

  In the above-described embodiment, the original waveform data group 1001 has been described as including different original waveform data depending on the number of rotations, but is not limited thereto. For example, the original waveform data group 1001 includes different original waveform data according to the combination of the rotational speed and the engine load, and selects and uses different original waveform data even at the same rotational speed according to a change in the engine load. You may do it.

[5.7. Seventh Modification]
In the above-described embodiment, the time fluctuation adding unit 1052 and the amplitude fluctuation adding unit 1053 generate the waveform data group having the fluctuation corresponding to each cylinder of the multi-cylinder engine, and the same random number sequence between the cylinders. However, the present invention is not limited to this, and a different random number sequence may be used for each cylinder. In that case, the user can input different degrees of time fluctuation and amplitude fluctuation for each cylinder, and a random number sequence with different variation widths for each cylinder may be generated and used for addition of time fluctuation and amplitude fluctuation. .

[5.8. Eighth Modification]
In the embodiment described above, the waveform synthesizer 10 and the waveform synthesizer 20 may be realized by a combination of dedicated hardware circuits corresponding to each component, but are not limited thereto. That is, the waveform synthesizer 10 and the waveform synthesizer 20 may be realized by causing a general-purpose computer to execute processing according to an application program.

[6. Remarks]
The correlation coefficient, the correlation value, the time fluctuation degree, the amplitude fluctuation degree, the offset degree, and other numerical values, and the calculation method of those numerical values, described in the above-described embodiment and its modifications, explain the present invention. The technical scope of the present invention is not limited to these numerical values and calculation methods.

It is the figure which showed a mode that the continuous sound concerning this invention was synthesize | combined. It is the figure which showed a mode that the superposition | polymerization sound concerning this invention was synthesize | combined. It is the graph which showed the influence which addition of the fluctuation concerning the present invention gives to superposition sound. It is the sonograph which showed the influence which the addition of the fluctuation concerning the present invention gives to superposition sound. It is the graph which showed the influence which the change of the original waveform concerning this invention has on superposition | polymerization sound. It is the graph which showed the influence which the change of the frequency characteristic of the original waveform concerning this invention has on superposed sound. It is the block diagram which showed the structure of the waveform synthesis system concerning 1st Embodiment of this invention. It is the figure which showed the structure of the original waveform data group concerning 1st Embodiment of this invention. It is the figure which showed the structure of the correspondence DB group concerning 1st Embodiment of this invention. It is the figure which showed the screen for data input concerning 1st Embodiment of this invention. It is the figure which showed the display screen of the physical attribute value concerning 1st Embodiment of this invention. It is the block diagram which showed the structure of the waveform synthesis system concerning 2nd Embodiment of this invention. It is the figure which showed the structure of the 2nd correspondence DB group concerning 2nd Embodiment of this invention. It is the figure which showed the screen for data input concerning 2nd Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 * 2 ... Waveform synthesis system, 10 * 20 ... Waveform synthesis apparatus, 11 ... Mouse, 12 ... Amplifier, 13 ... Speaker, 14 ... Display, 100 ... Memory | storage part, 101 ... Parameter input part, 102 ... Original waveform selection part, DESCRIPTION OF SYMBOLS 103 ... Period change part, 104 ... Frequency characteristic change part, 105 ... Continuous waveform generation part, 106 ... Overlapping waveform generation part, 107 ... D / A converter, 108 ... Attribute value specific | specification part, 109 ... Screen generation part, 201 ... Attribute Value input unit 202 202 Parameter specifying unit 1001 Original waveform data group 1002 Correspondence DB group 1051 Correlation changing unit 1052 Time fluctuation adding unit 1053 Amplitude fluctuation adding unit 1054 Connection processing unit 1061 ... Offset changing unit, 1062 ... Superposition processing unit, 1201 ... First correspondence DB group, 1202 ... Second correspondence DB group.

Claims (14)

Parameter input means for acquiring parameters;
A continuous waveform generating means for generating a continuous waveform by continuing a plurality of original waveforms that are sound waveforms to be a source of sound waveform synthesis;
A superimposed waveform generating means for generating a superimposed waveform by superimposing a plurality of continuous waveforms generated by the continuous waveform generating means,
The waveform synthesizer, wherein the continuous waveform generating means adds an expansion or contraction in an amplitude direction or a time direction having a fluctuation according to the parameter to the continuous waveform. The said continuous waveform production | generation means adds the expansion-contraction of the amplitude direction which has a different fluctuation | variation, or a time direction to the several continuous waveform used for the said superimposition by the said superposition | polymerization waveform production | generation means. Waveform synthesizer. Parameter input means for acquiring parameters;
A continuous waveform generating means for generating a continuous waveform by continuing a plurality of original waveforms that are sound waveforms to be a source of sound waveform synthesis;
A superimposed waveform generating means for generating a superimposed waveform by superimposing a plurality of continuous waveforms generated by the continuous waveform generating means,
The waveform synthesizer characterized in that the superimposed waveform generation means adds an offset in a time direction according to the parameter to a plurality of continuous waveforms used for the superposition. The overlapping waveform generation means has a time that is a non-integer multiple of a time obtained by dividing the period of the original waveform by the number of continuous waveforms used for the superposition, to at least one continuous waveform of the plurality of continuous waveforms used for the superposition. The waveform synthesizer according to claim 3, wherein an offset is added. Parameter input means for acquiring parameters;
A continuous waveform generating means for generating a continuous waveform by continuing a plurality of original waveforms that are sound waveforms to be a source of sound waveform synthesis;
A superimposed waveform generating means for generating a superimposed waveform by superimposing a plurality of continuous waveforms generated by the continuous waveform generating means,
The continuous waveform generating means generates a second continuous waveform having a correlation according to the parameter with the first continuous waveform,
The waveform synthesizer characterized in that the overlapping waveform generation means generates the overlapping waveform using a plurality of continuous waveforms including the first continuous waveform and the second continuous waveform. The said continuous waveform production | generation means produces | generates the said 1st continuous waveform and the said 2nd continuous waveform whose mutual correlation coefficient is less than 1, and has the same frequency characteristic. Waveform synthesizer. Parameter input means for acquiring parameters;
A frequency characteristic changing means for adding a frequency characteristic change corresponding to the parameter to the original waveform which is a sound waveform that is a source of sound waveform synthesis;
Continuous waveform generating means for generating a continuous waveform by continuing a plurality of original waveforms to which a change in frequency characteristics has been made by the frequency characteristic changing means;
A waveform synthesizer comprising: a superimposed waveform generating unit that generates a superimposed waveform by superimposing a plurality of continuous waveforms generated by the continuous waveform generating unit. The waveform synthesizer according to any one of claims 1 to 7, wherein the continuous waveform generating means generates a continuous waveform having a cycle that is changed by continuing a plurality of original waveforms having different lengths. An operation means for outputting a parameter according to a user operation;
Storage means for storing correspondence data indicating correspondence between parameters and physical attribute values;
An attribute value specifying means for specifying a physical attribute value corresponding to the parameter acquired by the parameter input means based on the correspondence data;
The waveform synthesizer according to any one of claims 1 to 8, wherein the parameter input unit acquires a parameter output by the operation unit. An operation means for outputting a physical attribute value corresponding to a user operation;
Storage means for storing correspondence data indicating correspondence between physical attribute values and parameters;
Parameter specifying means for measuring a parameter corresponding to the physical attribute value output by the operating means based on the correspondence data; and
The waveform synthesizing apparatus according to claim 1, wherein the parameter input unit acquires the parameter specified by the parameter specifying unit. On the computer,
Processing to get parameters,
A process of generating a continuous waveform by continuing a plurality of original waveforms that are sound waveforms that are the source of sound waveform synthesis and adding expansion or contraction in the amplitude direction or time direction having fluctuations according to the parameters to the continuous waveform;
A program that executes a process of generating a superimposed waveform by superimposing a plurality of generated continuous waveforms. On the computer,
Processing to get parameters,
A process of generating a continuous waveform by continuing a plurality of original waveforms that are sound waveforms that are the basis of sound waveform synthesis;
A program for executing a process of generating a superimposed waveform by adding an offset in a time direction according to the parameter to a plurality of continuous waveforms generated by the continuous waveform generating means and superimposing them. On the computer,
Processing to get parameters,
A second continuous waveform having a correlation according to the parameter between the first continuous waveform and the first continuous waveform by continuing a plurality of original waveforms that are the sound waveforms that are the source of the sound waveform synthesis. Processing to generate and
A program for executing a process of generating a superimposed waveform by superimposing a plurality of continuous waveforms including the first continuous waveform and the second continuous waveform. On the computer,
Processing to get parameters,
Processing for changing the frequency characteristics according to the parameters to the original waveform which is the sound waveform that is the source of sound waveform synthesis;
A process of generating a continuous waveform by continuing a plurality of original waveforms to which the change of the frequency characteristic is added; and
A program that executes a process of generating a superimposed waveform by superimposing a plurality of generated continuous waveforms.