JP4515321B2 - Engine sound synthesizer, vehicle equipped with the same, and engine sound synthesizer - Google Patents

Description

  The present invention relates to an engine sound synthesizer that synthesizes engine sound, a vehicle including the same, and an engine sound synthesis method.

The engine noise of vehicles such as automobiles and motorcycles is often just noise for roadside residents. Thus, with recent noise regulations as a trigger, improvements for reducing engine noise have been repeated, and nowadays, an engine that has been made extremely quiet has been put into practical use.
However, for the driver of the vehicle, the engine sound mounted on the vehicle has an attractive feature that is hard to throw away and is one of the pleasures of driving. Therefore, a vehicle equipped with a silenced engine cannot bring sufficient satisfaction to the driver, and may cause a decrease in the willingness to purchase the vehicle.

  Therefore, as described in Patent Document 1 below, by generating a synthetic engine sound in a vehicle interior of a four-wheeled vehicle or a helmet worn by a driver of a two-wheeled vehicle, it is quiet with respect to the surroundings. A configuration has been proposed in which the driver can feel a sufficient volume of engine sound while maintaining the above. Patent Document 1 discloses an engine sound synthesizer that reads engine sound data from storage means and synthesizes engine sound. In this apparatus, engine sound data for one combustion cycle is stored in the storage means for each of a plurality of different engine operating states, and engine sound data corresponding to the actual engine operating state is synthesized. Yes. The synthesized engine sound data for one combustion cycle is repeatedly reproduced according to the engine speed.

On the other hand, as can be seen from Patent Document 2 below, a video game apparatus that simulates the driving situation of a vehicle, such as a racing game, is highly demanded for generating realistic engine sounds. In Patent Document 2, engine sound data at the time of acceleration and deceleration of a vehicle is read according to an accelerator operation and a brake operation, and this is multiplied by a frequency correction coefficient according to the engine rotation speed to synthesize the engine sound. ing.
JP 2000-001142 A JP 2004-329290 A

  In the prior art described in Patent Document 1, since engine sound data for one combustion cycle is repeatedly reproduced, natural engine sound cannot always be reproduced. Specifically, there is a problem that it is difficult to reproduce low-frequency sound. In addition, there is a problem that it is difficult to reproduce subtle differences in explosion sound for each cylinder even when trying to reproduce the engine sound of a multi-cylinder engine.

On the other hand, in the prior art described in Patent Document 2, the reproduction frequency of the engine sound data is changed according to the engine rotation speed, so anyway in the engine rotation speed range where the engine sound data is recorded. In other engine speed ranges, it is difficult to reproduce natural engine sounds (especially high-frequency sounds).
More specifically, since the resonance frequency (natural frequency) of the engine is independent of the engine speed, there is a sound having a frequency that should be maintained regardless of the engine speed. In the technique of Patent Document 2, such sound reproducibility is poor and natural engine sound cannot be reproduced.

  According to the study of the present inventor, it has been found that the engine sound includes a resonance component having a constant frequency regardless of the engine speed and an order component whose frequency changes with the engine speed. Specifically, the resonance component is mainly composed of mechanical sound appearing in a high frequency band, and the order component is mainly composed of explosion sound and intake / exhaust sound appearing in a low frequency band. In order to reproduce a realistic engine sound, it is necessary to synthesize (reproduce) both of these resonance components and order components.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an engine sound synthesizer and an engine sound synthesis method that can synthesize engine sounds more naturally.
Another object of the present invention is to install such an engine sound synthesizer to provide an engine sound that approximates the actual sound to a vehicle occupant, thereby increasing the satisfaction of the driver or the like. It is to provide a vehicle that can.

  In order to achieve the above object, an invention according to claim 1 includes explosion interval data generation means for generating explosion interval data representing an engine explosion interval, engine sound data storage means for storing previously recorded engine sound data, and Engine sound data cutting means for cutting a plurality of engine sound data of a predetermined length from the engine sound data stored in the engine sound data storage means at different cutting positions, and the predetermined length cut by the engine sound data cutting means And a plurality of engine sound data reproducing means for sequentially reproducing the engine sound data for each time interval represented by the explosion interval data generated by the explosion interval data generating means, and the plurality of engine sound data reproducing means. Generated engine sound data by superimposing engine sound data An engine sound synthesizer which comprises a root alignment means.

  According to this configuration, a plurality of engine sound data stored in the engine sound data storage means are cut out by a predetermined length at different cut-out positions, and sequentially reproduced by the plurality of engine sound data reproduction means at every engine explosion interval. The synthesized engine sound data is generated by superimposing these. Therefore, compared with the case where the same engine sound data is repeatedly reproduced, a natural synthesized engine sound can be reproduced. More specifically, by cutting out relatively long engine sound data (for example, two explosion intervals or more) by individual engine sound data reproducing means, it is possible to satisfactorily reproduce low frequency sound. In addition, since different portions are cut out and superimposed from the recorded engine sound data, it is possible to reproduce the difference in explosion sound between the cylinders of the multi-cylinder engine.

  FIG. 15 is a waveform diagram for more specifically explaining the effect of superimposing engine sound data. When two sine waves for one cycle are slightly overlapped and added together, the overlapped parts are connected. The added waveform becomes a waveform close to a sine wave having a period T ′ shorter than the original period T by an overlap (FIG. 15A). That is, if the overlap is increased by advancing the reproduction start time of the second sine wave, the period T ′ is shortened accordingly.

Therefore, if the time interval from the reproduction of a certain engine sound data to the reproduction of the next engine sound data is made equal to the explosion interval of the engine and these are overlapped, the frequency can be changed according to the engine speed. .
Such frequency fluctuation due to the superimposition of engine sound data appears remarkably in a low frequency range. Thereby, the order component (low frequency component) whose frequency varies according to the engine speed can be reproduced.

  On the other hand, when high-frequency components including a large number of cycles are superimposed on engine sound data of a predetermined length, the amplitude may be greatly increased or canceled due to local interference, and the amplitude varies greatly (FIG. 15 (b)). . On the other hand, there is almost no frequency shift. Thereby, the resonance component (high frequency component) of the engine sound can be reproduced. Moreover, because the high-frequency components of engine sound include components of various frequencies, even if the amplitude decreases due to cancellation at any frequency, the amplitude increases due to reinforcement at another frequency. Or Therefore, local interference does not substantially affect the overall hearing.

Thus, by superimposing the engine sound data, it is possible to reproduce both the order component whose frequency varies according to the engine rotation speed and the resonance component whose frequency does not vary so much regardless of the engine rotation speed. Thereby, a sound close to the actual engine sound can be synthesized.
The explosion interval data generation means may measure the interval between engine rotation pulses and generate data representing the measurement result (pulse interval data). Measurement may be performed to generate data representing the measurement result. Further, engine explosion interval data may be generated by calculation based on engine rotation speed data.

According to a second aspect of the present invention, each of the plurality of engine sound data reproducing means does not depend on the explosion interval data generated by the explosion interval data generating means, and each of them has a constant (preferably the same as the recording time) reproduction rate . 2. The engine sound synthesizer according to claim 1, which reproduces engine sound data.
According to this configuration, even when the explosion interval fluctuates according to the engine rotation speed, the reproduction rate of each engine sound data is kept constant, so that the mechanical sound of the engine is not lost. Thereby, a more natural engine sound can be reproduced.

  According to a third aspect of the present invention, the engine sound data cut-out means includes an arbitrary pair of engine sound data reproducing means for reproducing engine sound data successively from the engine sound data stored in the engine sound data storage means. 2. A cut-out position of engine sound data in the engine sound data storage means is determined so as to reproduce the extracted engine sound data having a predetermined length that does not overlap in time. Or it is an engine sound synthesizer of 2.

According to this configuration, it is possible to suppress the same engine sound data portion from being repeatedly reproduced in a short time, so it is possible to eliminate the uncomfortable feeling caused by an unnatural sound similar to reflected sound or reverberation sound, and more natural engine sound. Can be reproduced.
The invention according to claim 4 is characterized in that each engine sound data reproduction means includes a fade means for gradually increasing the sound pressure at the start of reproduction of the engine sound data and gradually decreasing the sound pressure at the end of reproduction. The engine sound synthesizer according to any one of 1 to 3.

According to this configuration, it is possible to suppress high-frequency noise at a sound joint by fading in at the beginning of playback and fading out at the end of playback, so that more natural engine sound playback can be realized.
According to a fifth aspect of the present invention, the fade means includes a sound pressure coefficient multiplication means for multiplying engine sound data by a sound pressure coefficient, and gradually increases the sound pressure coefficient from 0 to a predetermined upper limit value over time. 5. The engine sound synthesizer according to claim 4, further comprising: a sound pressure coefficient generating means which is generated according to a window function which is held at a value and then gradually decreases from the upper limit value to 0 over time. With this configuration, fade-in and fade-out can be realized.

  FIG. 16 is a waveform diagram for explaining the effect of the fade process. Strictly speaking, the synthesized waveform shown in FIG. 15A is an original sine wave in a non-overlapping portion and a distorted waveform in an overlapping portion. When the overlap is increased to nearly one quarter of the sine wave period, the overlapped portion has a shape close to a triangular wave. (FIG. 16 (a)) For this reason, high-order component noise is generated. When the overlap is further increased, the amplitude of cancellation cancels out at the overlap portion, and the waveform also has an irregular shape (FIG. 16 (b)).

Therefore, if the overlap portion is faded as pre-processing for superposition, the waveform becomes smooth and high-frequency noise can be suppressed, and cancellation is reduced (FIGS. 16 (c) (d)).
According to a sixth aspect of the present invention, the sound pressure coefficient generating means is configured such that the period during which the sound pressure coefficient is held at the upper limit value is longer than the time represented by the explosion interval data generated by the explosion interval data generating means. 6. The engine sound synthesizer according to claim 5, wherein the sound pressure coefficient is generated so as to be long.

According to this configuration, it is possible to cut out sufficiently long engine sound data and perform a fading process thereon, so that a natural engine sound can be generated by superimposing a plurality of engine sound data. In addition, since sufficiently long engine sound data is cut out, the reproducibility of the sound in the low frequency region can be improved accordingly.
The invention according to claim 7 further includes throttle opening degree information generating means for generating throttle opening degree information indicating the throttle opening degree of the engine, wherein the engine sound data storage means includes engine sound data during acceleration and during deceleration. Engine sound data is stored, and the engine sound data cutout means obtains engine sound data during acceleration from the engine sound data storage means based on the explosion interval data generated by the explosion interval data generation means. Accelerating sound data cutting means for cutting out and decelerating sound data cutting means for cutting out engine sound data at the time of deceleration, wherein the engine sound data reproducing means outputs the engine sound data at the time of acceleration cut out by the acceleration sound data cutting out means. It is extracted by the acceleration sound data reproducing means to be reproduced and the deceleration sound data extracting means. Deceleration sound data reproducing means for reproducing engine sound data at the time of deceleration, wherein the acceleration sound data reproducing means is based on the throttle opening information generated by the throttle opening information generating means. And an acceleration sound coefficient generating means for generating an acceleration sound coefficient that defines a mixing ratio of engine sound data during deceleration, and the acceleration sound coefficient generated by the acceleration sound coefficient generating means is cut out by the acceleration sound data cutting out means Acceleration sound coefficient multiplying means for multiplying engine sound data, and the deceleration sound data reproducing means determines a deceleration sound coefficient that defines the mixture ratio based on throttle opening information generated by the throttle opening information generating means. A deceleration sound coefficient generating means to be generated, and a deceleration sound coefficient generated by the deceleration sound coefficient generating means An engine sound synthesizing device according to any one of claims 1 to 6, characterized in that it comprises a deceleration sound coefficient multiplying means for multiplying the engine sound data cut out by means.

  According to this configuration, engine sound data corresponding to an arbitrary operating state of the engine (a state represented by the throttle opening and the engine speed) can be synthesized by synthesizing the engine sound data during acceleration and deceleration. The engine sound data is synthesized by extracting engine sound data based on the explosion interval data corresponding to the engine rotation speed, and based on the throttle opening information, the mixing ratio of the engine sound data during acceleration and deceleration is calculated. This can be realized by multiplying and mixing the engine sound data at the time of acceleration and deceleration by a mixing coefficient (acceleration coefficient and deceleration coefficient) corresponding thereto. This mixing may be performed by the superimposing means or may be performed by another superimposing means.

According to an eighth aspect of the present invention, there is provided an engine sound that is reproduced by an engine that generates a driving force for rotating a wheel, the engine sound synthesizer according to any one of claims 1 to 7, and the engine sound reproducing means. And a sound output unit for outputting the sound.
With this configuration, even a vehicle equipped with a highly silent engine can provide a natural synthesized engine sound that approximates real sound to the vehicle occupant. As a result, the degree of satisfaction of the driver and other passengers can be increased.

  According to the ninth aspect of the present invention, the engine sound data having a predetermined length is cut out differently from the explosion interval data generation step for generating the explosion interval data representing the explosion interval of the engine and the engine sound data stored in the engine sound data storage means. A plurality of engine sound data cutting steps for cutting out a plurality of positions at positions, and a plurality of engine sound data pieces of the predetermined length that are cut out sequentially for each time interval represented by the explosion interval data; An engine sound synthesizing method including a superposition step of superposing the reproduced engine sound data to generate synthesized engine sound data.

  By this method, a natural synthesized engine sound can be generated. Specifically, relatively long engine sound data (for example, two explosion intervals or more) is cut out and sequentially played, so that low-frequency sound (especially fundamental frequency components based on engine explosion and high-order component sounds). ) Can be reproduced well. In addition, the difference in explosion sound between the cylinders of the multi-cylinder engine can be reproduced well.

Furthermore, by sequentially reproducing and superimposing engine sound data at time intervals corresponding to the explosion interval data, both engine resonance components and order components can be reproduced well. Thereby, a natural engine sound close to a real sound can be synthesized.
The invention according to claim 10 is characterized in that reproduction of each of the plurality of cut out engine sound data is performed at a constant reproduction rate irrespective of the explosion interval data generated by the explosion interval data generation step. The engine sound synthesis method according to claim 9.

  According to this method, since the reproduction rate of the engine sound data is kept constant, mechanical sound or the like due to engine resonance is not lost. Thereby, a natural engine sound can be reproduced.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a conceptual diagram for explaining the configuration of a four-wheeled vehicle that is a vehicle equipped with an engine sound synthesizer according to an embodiment of the present invention. The automobile 1 travels by using, for example, an engine 2 (a four-cylinder engine in this embodiment) composed of an electronically controlled four-cycle engine as a power source and transmitting driving force from the engine 2 to wheels 3. A car audio device main body 7 is arranged on the operation panel 6 in front of the driver seat 5 in the passenger compartment 4. The speakers 8 connected to the car audio device main body 7 are disposed, for example, at a position near the driver's seat 5 and at a rear position of the passenger compartment 4.

The car audio device body 7 is equipped with an external audio input terminal, and can amplify an audio signal input from the external audio input terminal and transmit it to the speaker 8. As a result, an audio signal input from the outside can be acousticized and output into the passenger compartment 4, and the car audio device body 7 and the speaker 8 constitute a sound output unit.
The engine sound synthesizer 10 generates, for example, an engine sound signal of a four-cylinder engine. Has been. That is, the synthesized engine sound signal generated by the engine sound synthesizer 10 is amplified by the car audio device main body 7, is sonicated from the speaker 8 into the vehicle interior 4, and is output.

The engine 2 is equipped with a throttle opening sensor 11 for detecting the throttle opening, and a rotation pulse generator 13 as a rotation pulse generating means for generating a rotation pulse of the engine 2, and these output signals are: Input to the engine sound synthesizer 10. The rotation pulse generator 13 outputs, for example, two pulses for each rotation of the crankshaft.
Since the throttle opening of the engine 2 corresponds to the operation amount of the accelerator pedal 9 provided near the floor of the driver's seat, the accelerator operation amount for detecting the operation amount of the accelerator pedal 9 instead of the throttle opening sensor 11. The output signal of the sensor 14 can also be input to the engine sound synthesizer 10.

  FIG. 2 is a block diagram for explaining the electrical configuration of the engine sound synthesizer 10. The engine sound synthesizer 10 includes a throttle opening detector 21 (throttle opening information generating means) that generates throttle opening data A based on an output signal of the throttle opening sensor 11 or the accelerator operation amount sensor 14, and a rotation pulse. A pulse interval detector 22 (explosion interval data generating means) that detects a pulse interval (corresponding to an engine explosion interval) that is a time interval of the rotation pulse B generated by the generator 13 and generates pulse interval data C; The synthesis engine sound data generation unit 24 and an output processing unit 25 having a digital / analog conversion function for converting the synthesis engine sound data generated by the synthesis engine sound data generation unit 24 into an analog voice signal are provided. The synthesized engine sound data generation unit 24 is input with throttle opening data A, rotation pulse B, and pulse interval data C, and the synthesized engine sound data generation unit 24 generates synthesized engine sound data based on these. . The throttle opening degree detection unit 21 and the pulse interval detection unit 22 constitute an operation state detection unit 20 that detects the operation state of the engine. Since the pulse interval data C is data corresponding to the engine rotation speed on a one-to-one basis, it can be said that the pulse interval data C is data representing the engine rotation speed.

The pulse interval detection unit 22 can be configured by a counter that counts a reference clock (for example, a frequency of 44.1 kHz) and that is reset by outputting a count value every time the rotation pulse B is given. That is, the reference clock number between the input intervals of the rotation pulse B becomes the pulse interval data C.
FIG. 3 is a block diagram for explaining a configuration example of the synthesis engine sound data generation unit 24. The synthesized engine sound data generation unit 24 stores an engine sound data storage unit 30 that stores engine sound data obtained by pre-recording engine sounds (the engine sound of the engine 2 is not necessary), and this engine sound data storage. An acceleration sound data extraction control unit 31 (acceleration sound data extraction unit) that extracts an acceleration sound section from the engine sound data stored in the unit 30 (engine sound data storage unit); and an engine stored in the engine sound data storage unit 30 A deceleration sound data extraction control unit 32 (deceleration sound data extraction means) that extracts a deceleration sound section from the sound data is provided. Further, the synthesized engine sound data generation unit 24 reproduces the acceleration sound data extracted by the acceleration sound data extraction control unit 31, respectively, first, second, third and fourth acceleration sound data reproduction units 41, 42, 43, 44 (acceleration sound data reproduction means) and first, second, third and fourth deceleration sound data reproduction units 46, 47, 48, 49 for reproducing the deceleration sound data cut out by the deceleration sound data cutout control unit 32, respectively. (Deceleration sound data reproduction means), acceleration sound data reproduced by the first to fourth acceleration sound data reproduction units 41, 42, 43, 44 and first to fourth deceleration sound data reproduction units 46, 47, 48, And a superimposing unit 50 (superimposing means) for superimposing the deceleration sound data reproduced by 49.

  The acceleration sound data cutout control unit 31 generates an acceleration sound start address table 33 for generating a cutout position (reproduction start address) of the engine sound data recorded in the engine sound data storage unit 30, and reproduces the first to fourth acceleration sound data. First, second, third and fourth acceleration sound address controllers 51, 52, 53 and 54 corresponding to the units 41, 42, 43 and 44, respectively. Based on the pulse interval data C, the acceleration sound start address table 33 generates reproduction start addresses of engine sound data to be reproduced by the first to fourth acceleration sound data reproduction units 41, 42, 43, 44 to generate first to first acceleration sound data. The fourth acceleration sound address controllers 51 to 54 are set. More specifically, the acceleration sound start address table 33 sequentially sets different reproduction start addresses for the first to fourth acceleration sound address controllers 51 to 54.

  The first to fourth acceleration sound address controllers 51 to 54 sequentially generate address values that are incremented every time a reference clock is input, starting from the set reproduction start address, and give the generated address values to the engine sound data storage unit 30. As a result, engine sound data at addresses specified by the first to fourth acceleration sound address controllers 51 to 54 is provided to the first to fourth acceleration sound data reproducing units 41 to 44, respectively.

  Similarly, the deceleration sound data extraction control unit 32 generates a deceleration sound start address table 34 for generating the extraction position (reproduction start address) of the engine sound data recorded in the engine sound data storage unit 30, and the first to fourth decelerations. First, second, third, and fourth deceleration sound address controllers 56, 57, 58, and 59 corresponding to the sound data reproducing units 46, 47, 48, and 49, respectively. Based on the pulse interval data C, the deceleration sound start address table 34 generates reproduction start addresses of engine sound data to be reproduced by the first to fourth deceleration sound data reproduction units 46, 47, 48, and 49, and generates first to first reproduction sound addresses. The fourth deceleration sound address controllers 56 to 59 are set. More specifically, the deceleration sound start address table 34 sequentially sets different reproduction start addresses for the first to fourth deceleration sound address controllers 56 to 59.

  The first to fourth deceleration sound address controllers 56 to 59 sequentially generate address values that are incremented for each input of the reference clock, starting from the set reproduction start address, and give the generated address values to the engine sound data storage unit 30. As a result, engine sound data at addresses specified by the first to fourth deceleration sound address controllers 56 to 59 are provided to the first to fourth deceleration sound data reproducing units 46 to 49, respectively.

  The engine sound data storage unit 30 stores, for example, engine sound data as shown in FIG. That is, acceleration is performed with the throttle fully opened, and then the throttle is fully closed to decelerate, and the engine sound at that time is recorded to obtain engine sound data. FIG. 4 (a) shows the change over time in engine speed during recording of engine sound, FIG. 4 (b) shows the corresponding engine sound waveform (sound pressure waveform), and FIG. 4 (c) shows the engine speed of 4000 rpm. The engine sound waveform (sound pressure waveform) in the case of is shown in an enlarged manner.

  The operating state of the engine 2 can be represented by, for example, a throttle opening and an engine speed as shown in FIG. In this case, in the engine sound data shown in FIG. 4, the acceleration range where the engine rotation speed increases corresponds to the operating state area A1 corresponding to the throttle fully opened, and the deceleration area where the engine rotation speed decreases corresponds to the throttle fully closed. This corresponds to the operating state area A2. Engine sound data in an operating state other than these operating state regions A1 and A2 can be obtained by so-called interpolation processing. That is, the engine sound data of the operation state a (x, y) corresponding to the throttle opening x and the engine rotation speed y is the engine sound data of the operation states a1 and a2 corresponding to the engine rotation speed y in the operation state regions A1 and A2. Data can be synthesized by superimposing at a mixing ratio corresponding to the throttle opening x. In this way, engine sound data corresponding to an arbitrary operation state can be synthesized. Or you may make it produce the engine sound data corresponding to arbitrary driving | running states by each acquiring the engine sound data of each some area | region in driving | running state area | region A1, A2, and combining these.

  Referring to FIG. 3 again, the acceleration sound start address table 33 and the deceleration sound start address table 34 generate a reproduction start address corresponding to the pulse interval data C. Thus, the first to fourth acceleration sound data reproducing units 41 to 44 and the first to fourth deceleration sound data reproducing units 46 to 49 reproduce engine sound data corresponding to the engine rotation speed of the engine 2. . However, as will be described in detail later, the first to fourth acceleration sound data reproducing units 41 to 44 reproduce engine sound data (acceleration sound data) having a predetermined length from different reproduction start positions, and similarly, The fourth deceleration sound data reproducing units 46 to 49 reproduce engine sound data (deceleration sound data) having a predetermined length from different reproduction start positions.

  Engine sound data from the engine sound data storage unit 30 is given to the first to fourth acceleration sound data reproduction units 41 to 44 and the first to fourth deceleration sound data reproduction units 46 to 49 based on the reference clock. become. This reference clock has the same frequency as the sampling frequency of the engine sound data stored in the engine sound data storage unit 30. Accordingly, the first to fourth acceleration sound data reproducing units 41 to 44 and the first to fourth deceleration sound data reproducing units 46 to 49 reproduce the engine sound data at a constant reproduction rate defined by the frequency of the reference clock. It will be.

  The first to fourth acceleration sound data reproducing units 41 to 44 each have a fluctuation processing unit P1 for giving a fluctuation of sound pressure to the engine sound data read from the engine sound data storage unit 30, and the engine A sound pressure correction processing unit P2 for performing sound pressure correction corresponding to the throttle opening degree on the sound data and performing the above-described interpolation processing, and a fade processing unit P3 (fade processing) for performing fade processing on the engine sound data Means).

The fluctuation processing unit P1 generates a random number every time the rotation pulse B is given, and generates a fluctuation coefficient of sound pressure, and the fluctuation coefficient generated by the fluctuation coefficient generation unit 61 is stored in engine sound data. A multiplication unit 62 that multiplies the engine sound data read from the unit 30.
The sound pressure correction processing unit P2 includes an acceleration sound coefficient generation unit 63 (acceleration sound coefficient generation means) that generates an acceleration sound coefficient that is an interpolation coefficient corresponding to the throttle opening data A when the rotation pulse is given, A multiplication unit 64 (acceleration sound coefficient multiplication means) for multiplying the engine sound data (engine sound data after the fluctuation process) by the acceleration sound coefficient generated by the acceleration sound coefficient generation unit 63 is provided.

  The fade processing unit P3 includes a time window coefficient generation unit 65 (sound pressure coefficient generation means) that generates a time window coefficient for fade processing based on the rotation pulse B, the pulse interval data C, and the reference clock, and the time window. A multiplier 66 (sound pressure coefficient multiplier) that multiplies engine sound data (engine sound data after sound pressure correction processing) by a time window coefficient generated by the coefficient generator 65; The time window coefficient generation unit 65 starts generation of a time window coefficient in response to the rotation pulse B, and based on the increment data and the reference clock from the increment generation unit 37 that generates a value corresponding to the pulse interval data C. Vary the time window factor.

  Similarly, the first to fourth deceleration sound data reproducing units 46 to 49 are a fluctuation processing unit P4 for giving fluctuations in sound pressure to the engine sound data read from the engine sound data storage unit 30, respectively. A sound pressure correction processing unit P5 for performing sound pressure correction corresponding to the throttle opening on the engine sound data and performing the above-described interpolation processing, and a fade processing unit for performing fade processing on the engine sound data P6 (fade means).

  The fluctuation processing unit P4 generates a random number every time the rotation pulse B is given, and generates a fluctuation coefficient of the sound pressure, and the fluctuation coefficient generated by the fluctuation coefficient generation unit 71 is stored as engine sound data. A multiplication unit 72 that multiplies the engine sound data read from the unit 30. The sound pressure correction processing unit P5 includes a deceleration sound coefficient generation unit 73 (deceleration sound coefficient generation means) that generates a deceleration sound coefficient that is an interpolation coefficient corresponding to the throttle opening data A when the rotation pulse B is given. A multiplication unit 74 (deceleration sound coefficient multiplication means) for multiplying engine sound data (engine sound data after fluctuation processing) by the deceleration sound coefficient generated by the deceleration sound coefficient generation unit 73 is provided. The fade processing unit P6 includes a time window coefficient generation unit 75 (sound pressure coefficient generation means) that generates a time window coefficient for fade processing based on the rotation pulse B, the pulse interval data C, and the reference clock, and the time window. A multiplier 76 (sound pressure coefficient multiplier) for multiplying engine sound data (engine sound data after sound pressure correction processing) by a time window coefficient generated by the coefficient generator 75; The time window coefficient generation unit 75 starts generation of the time window coefficient in response to the rotation pulse B, and based on the increment data and the reference clock from the increment generation unit 37 that generates a value corresponding to the pulse interval data C. Vary the time window factor.

  FIG. 6 is a diagram for explaining the extraction of the engine sound data stored in the engine sound data storage unit 30 and shows the sound pressure waveform of the engine sound corresponding to the engine sound data. Cylinder numbers # 1, # 2, # 3, and # 4 indicate the explosion timings of the first to fourth cylinders, respectively. The cylinder numbers # 1, # 2, # 3, and # 4 do not need to coincide with the actual order of cylinders in the engine, and are used to distinguish the explosion sound of each cylinder based on the engine sound waveform. It is a convenient number determined in the order of explosion.

  The first acceleration sound data reproduction unit 41 and the first deceleration sound data reproduction unit 46 reproduce the acceleration sound data and the deceleration sound data D1 of the four explosion sections starting from the explosion sound of the first cylinder, respectively. Similarly, the second acceleration sound data reproducing unit 42 and the second deceleration sound data reproducing unit 47 reproduce the acceleration sound data and the deceleration sound data D2 of the four explosion sections starting from the explosion sound of the second cylinder, respectively. The three acceleration sound data reproducing unit 43 and the third deceleration sound data reproducing unit 48 reproduce the acceleration sound data and the deceleration sound data D3 of the four explosion sections starting from the explosion sound of the third cylinder, respectively, and the fourth acceleration sound data The reproduction unit 44 and the fourth deceleration sound data reproduction unit 49 reproduce the acceleration sound data and the deceleration sound data D4 of the four explosion sections starting from the explosion sound of the fourth cylinder, respectively. In other words, the acceleration sound start address table 33 and the deceleration sound start address table 34 set the first cylinder explosion sound start addresses for the first acceleration sound address controller 51 and the first deceleration sound address controller 56, respectively. Then, the start address of the second cylinder explosion sound is set to the second acceleration sound address controller 52 and the second deceleration sound address controller 57, and the third acceleration sound address controller 53 and the third deceleration sound address controller 58 are set. Then, the start address of explosion sound of the third cylinder is set, and the start address of explosion sound of the fourth cylinder is set to the fourth acceleration sound address controller 54 and the fourth deceleration sound address controller 59. Since the start address is set every time the pulse interval data C is given (that is, every rotation pulse B), the first to fourth acceleration sound data reproducing unit 41 and the first to fourth deceleration sound data are reproduced. The units 46 to 49 reproduce the acceleration sound data and the deceleration sound data of the four explosion sections, respectively, at the timing sequentially shifted by the interval of the rotation pulse B.

  As seen in FIG. 6, the explosion sound waveforms of the individual cylinders are similar. Therefore, the first to fourth acceleration sound data reproducing units 41 to 44 and the first to fourth deceleration sound data reproducing units 46 to 49 all reproduce the engine sound data of the four explosion sections starting from the explosion sound of the first cylinder. If this is done, the variation in explosion sound between the cylinders cannot be reproduced, and it may be perceived as an engine sound having a fourfold rotational speed. Therefore, in this embodiment, as described above, engine sound data starting from explosion sounds of different cylinders is sequentially reproduced at every pulse interval.

  Further, as shown in FIG. 7, engine sound data d1 to d4 in sections that overlap in time are cut out to obtain first to fourth acceleration sound data reproduction units 41 to 44 and first to fourth deceleration sound data reproduction unit 46. It is also possible to reproduce the sound sequentially at -49, but in this case, the same explosion sound is reproduced at short time intervals, and a synthetic engine sound that feels like a reverberant sound may be generated. .

  Therefore, in this embodiment, as shown in FIG. 6, engine sound data in sections that do not overlap each other is cut out, and the first to fourth acceleration sound data reproduction units 41 to 44 and the first to fourth deceleration sound data reproduction are performed. The start address of the engine sound data is generated so as to be reproduced by the units 46-49. More specifically, the cut-out positions of the engine sound data reproduced by the first to fourth acceleration sound data reproducing units 41 to 44 and the first to fourth deceleration sound data reproducing units 46 to 49 are reproduced one after another. The engine sound data extraction start position is opened by 5 times the pulse interval ΔT (here, the pulse interval ΔT12 between the first cylinder and the second cylinder), and is shifted in time by + 5ΔT. .

  However, the same effect can be obtained by the cutting method as shown in FIG. In this example, the cut-out positions of the engine sound data D1, D2, D3, and D4 reproduced one after another are shifted by -3ΔT in terms of time, and the entire necessary data length is shortened. In this example, for example, after the engine sound data D1 is reproduced by the first acceleration sound data reproducing unit 41, the engine sound data D2 is reproduced by the second acceleration sound data reproducing unit 42. There is a time interval of 4ΔT from when the sound data reproduction unit 41 reproduces the explosion sound data of the first cylinder until the second acceleration sound data reproduction unit 42 reproduces the explosion sound data of the first cylinder, After all, there is no time overlap in the engine sound data to be reproduced. In addition, since engine sound data that are discontinuous in time are reproduced one after another, there is little possibility that a synthesized sound that is perceived as an echo sound is reproduced. In addition, since the sound pressure in the initial and final parts of the engine sound data D1 to D4 is suppressed by the fade process described later, the overlap of the engine sound in the part where the fade process is performed is a big problem. Don't be.

In general, when the cut-out section is so close that the end of the cut-out section of the engine sound data overlaps with the initial part of the cut-out section of the engine sound data to be reproduced subsequently, it is perceived as an echo sound. Synthetic engine sound is likely to occur.
FIG. 9 is a diagram illustrating an example of the acceleration sound start address table 33. The acceleration sound start address table 33 generates the start address of the acceleration sound, and the deceleration sound start address table 34 generates the start address of the deceleration sound. Only the configuration of the address table 33 will be described.

  The acceleration sound start address table 33 generates a start address table corresponding to the pulse interval data C and the cylinder number corresponding to the explosion sound. More specifically, the start address Ank corresponding to the pulse interval data Cn (n = 1, 2, 3,..., N) and the cylinder number k (k = 1, 2, 3, 4) to be reproduced is set. appear. More specifically, start addresses An1, An2, An3, An4 are determined for each of cylinder numbers # 1, # 2, # 3 and # 4 corresponding to the value Cn of each pulse interval data. These start addresses An1, An2, An3, and An4 are used to shift the cut-out section of engine sound data to be reproduced successively by + 5ΔT or −Δ3T as described with reference to FIG. 6 or FIG. Is set.

For the pulse interval data C1, C2,..., CN, for example, the minimum pulse interval data C1 corresponds to the maximum engine speed, and the maximum pulse interval data CN corresponds to the minimum engine speed (idle speed). The value may be set to increase monotonically from C1 to CN.
The acceleration sound start address table 33 gives a start address An1 corresponding to the cylinder number # 1 to the first acceleration sound address controller 51, and sets a cylinder number # 2 to the second acceleration sound address controller 52. A corresponding start address An2 is given, a start address An3 corresponding to the cylinder number # 3 is given to the third acceleration sound address controller 53, and a cylinder number # 4 is given to the fourth acceleration sound address controller 54. It operates to give the corresponding start address An4. As a result, the first acceleration sound data reproducing unit 41 starts reproduction from the start address An1 corresponding to the cylinder number # 1 and reproduces engine sound data in the section of 4ΔT, and the second acceleration sound data reproducing unit 42 The reproduction is started from the start address An2 corresponding to the number # 2, and the engine sound data in the section of 4ΔT is reproduced. The third acceleration sound data reproducing unit 43 starts the reproduction from the start address An3 corresponding to the cylinder number # 3. The engine sound data in the 4ΔT section is reproduced, and the fourth acceleration sound data reproducing unit 44 starts reproduction from the start address An4 corresponding to the cylinder number # 4 and reproduces the engine sound data in the 4ΔT section.

  Each time the pulse interval data C is input, the acceleration sound start address table 33 cyclically gives start addresses (start addresses of corresponding cylinder numbers) to the first to fourth acceleration sound address controllers 51 to 54. . Further, different parts of the engine sound data are reproduced according to the pulse interval data C (that is, according to the engine speed), and engine sound data reproduction is started by the first to fourth acceleration sound data reproduction units 41 to 44. Timing also varies. Specifically, during engine acceleration (when the engine speed is increasing) and engine deceleration (when the engine speed is decreasing), the first to fourth acceleration sound data reproducing units are changed while changing the cutout position of the engine sound data. The engine sound data reproduction start timing by 41 to 44 also changes.

In this way, when the engine sound data generated by the first to fourth acceleration sound data reproducing units 41 to 44 is finally superimposed by the overlapping unit 50, natural synthesis reflecting the variation in explosion sound of the four cylinders is performed. Synthetic engine sound data capable of generating engine sound is obtained.
As described above, the deceleration sound start address table 34 has the same configuration as the acceleration sound start address table 33 and operates in the same manner with respect to the first to fourth deceleration sound address controllers 56 to 59. The engine sound data generated by the first to fourth acceleration sound data reproducing units 41 to 44 and the engine sound data reproduced by the first to fourth deceleration sound data reproducing units 46 to 49 depend on the throttle opening. According to the acceleration sound coefficient and the deceleration sound coefficient set in the above manner, mixing is performed at an appropriate ratio in the superimposing unit 50, thereby generating a natural synthesized engine sound according to the operating state of the engine 2.

  FIG. 10 is a diagram for explaining the operation of the fade processing units P3 and P6. The time window coefficient generation units 65 and 75 provided in the fade processing units P3 and P6 generate time window coefficients according to the window function shown in FIG. That is, the generation of the time window coefficient is started at the timing when the rotation pulse B is input (that is, the timing at which the acceleration sound data reproduction units 41 to 44 and the deceleration sound data reproduction units 46 to 49 start reproducing the engine sound data) The time window coefficient is sequentially updated according to the input of the reference clock.

The time window coefficient is set as a value corresponding to the index i (i = 0, 1, 2, 3,...). That is, as the index i increases, the time window coefficient gradually increases from “0”, which is the lower limit value, to “1”, which is the predetermined upper limit value. After being held, it is determined to gradually decrease to the lower limit value “0”.
The time window coefficient generators 65 and 75 set the index i to the initial value “0” by the input of the rotation pulse B, and thereafter, the increment data generated by the increment generator 37 every time the reference clock is input. The index i is increased by Δi (Δi = 1, 2, 3,...). Then, a time window coefficient corresponding to the index i set by sequentially updating the increment data Δi is generated.

  The increment generator 37 generates the increment data Δi corresponding to the pulse interval data C, that is, the increment data Δi corresponding to the engine speed. More specifically, the smaller the pulse interval data C (that is, the higher the engine rotation speed), the larger incremental data is generated. As a result, the time window coefficient quickly rises to the upper limit value “1” and quickly decreases to the lower limit value “0” as the high-speed operation is performed.

  The section length (time length) in which the time window coefficient is held at the upper limit “1” is set to be at least one pulse interval ΔT or more. In this embodiment, the time window function is determined such that the time window coefficient is held at the upper limit value “1” over a section length of about 2ΔT to 3ΔT, and the increment generator 37 stores the increment data Δi. Generate. As a result, the low-frequency component of the engine sound can be satisfactorily reproduced, and the fundamental frequency component and its higher-order component based on the engine explosion are not lost.

  When the sound pressure waveform corresponding to the engine sound data before the fading process is as shown in FIG. 10 (b), the fading process using the window function of FIG. Engine sound data corresponding to the sound pressure waveform is obtained. Thereby, the engine sound data reproduced by the acceleration sound data reproducing units 41 to 44 and the deceleration sound data reproducing units 46 to 49 can be faded in and faded out. As a result, high-frequency noise (sound distortion) caused by sudden start and end of reproduction is reduced, and natural synthesized engine sound can be reproduced even in a high engine speed state (FIG. 16 (c)). reference). In addition, cancellation of the overlapping portions of the front and rear engine sound data can be reduced, and the decrease in amplitude can be suppressed (see FIG. 16D).

The window function that defines the time window coefficient is not necessarily a linear trapezoidal function as shown in FIG. 10A, and a curved window function as shown in FIG. 11 may be applied.
FIG. 12 is a diagram for explaining the superimposition of engine sound data. 12A shows a sound pressure waveform corresponding to the acceleration sound data generated by the first acceleration sound data reproducing unit 41, and FIG. 12B shows the acceleration sound data generated by the second acceleration sound data reproducing unit 42. The corresponding sound pressure waveform is shown, FIG. 12 (c) shows the sound pressure waveform corresponding to the acceleration sound data generated by the third acceleration sound data reproducing unit 43, and FIG. 12 (d) is the fourth acceleration sound data reproducing unit. The sound pressure waveform corresponding to the acceleration sound data which 44 produces | generates is shown. FIG. 12E shows an enlarged sound pressure waveform of the synthesized engine sound data obtained by superimposing these acceleration sound data.

  Each of the acceleration sound data reproducing units 41 to 44 cuts out and reproduces engine sound data having a length of 4ΔT, so that it has a lower frequency range than a case where only one explosion sounding part is reproduced. Sound reproducibility is good, and since the fade process is performed, high-frequency noise caused by switching of the reproduced sound does not occur and the amplitude does not significantly decrease (see FIG. 16). Furthermore, since the engine sound data playback rate is constant at the playback rate at which the engine sound at the time of recording is reproduced (for example, 44.1 kHz, which is equal to the sampling rate of engine sound data), mechanical sound due to resonance, etc. Can be reproduced well. Then, engine sound data having different reproduction positions for each pulse interval is superimposed and reproduced. Therefore, both the resonant component (frequency mechanical sound) with a constant frequency regardless of the engine speed and the order component (intake and exhaust sound in the low frequency band) whose frequency changes with the engine speed can be reproduced well. . In addition, the variation between the cylinders can be reproduced well.

FIG. 13 is an illustrative view showing a configuration example of a two-wheeled vehicle (motorcycle) as a vehicle according to another embodiment of the present invention. In FIG. 13, portions corresponding to the respective portions shown in FIG. 1 are denoted by the same reference numerals as in FIG.
The two-wheeled vehicle 80 travels with the engine 2 as a drive source and the driving force from the engine 2 is transmitted to the wheels 81. The engine sound synthesizer 10 is disposed, for example, below the seat 82 on which the driver 95 is seated. On the other hand, the helmet 96 worn by the driver 95 includes an amplifier 97, a speaker 98, and an infrared receiver 86. The amplifier 97 and the infrared receiver 86 are disposed, for example, on the jaw portion of the helmet 96 (portion facing the driver's 95 jaw), and the speaker 98 is the ear portion of the helmet 96 (portion facing the driver's 95 ear). ). The infrared receiver 86 is attached so that the reception direction faces the front of the driver in a state where the driver 95 wears the helmet 96.

An infrared transmitter 85 is disposed in front of the driver 95 in front of the vehicle body, for example, at the top of the fuel tank 83. The infrared signal generated by the infrared transmitter 85 is received by the infrared receiver 86 provided in the helmet 96 worn by the driver 95.
A sound signal corresponding to the synthesized engine sound data is given to the infrared transmitter 85 from the engine sound synthesizer 10.

  With such a configuration, an audio signal corresponding to the synthesized engine sound data generated by the engine sound synthesizer 10 is sent from the infrared transmitter 85 to the infrared receiver 86, amplified by the amplifier 97, and then output by the speaker 98. Sounded and output. As a result, even when the engine 2 is highly quiet, the driver 95 enjoys driving the two-wheeled vehicle 80 while sufficiently feeling the synthesized engine sound having substantially the same characteristics as the actual characteristics of the engine 2. Can do.

  As mentioned above, although two embodiment of this invention was described, this invention can also be implemented with another form. For example, in the above-described embodiment, so-called interpolation processing is performed by multiplying the acceleration sound data and the deceleration sound data by the acceleration sound coefficient and the deceleration sound coefficient corresponding to the throttle opening, and thereby, the synthesis engine in various operating states. Sound data is generated, but, of course, not only during acceleration and deceleration, but also during normal operation, engine sound data is recorded in advance, and such engine sound data is played back according to the operating state of the engine. You may make it do. More specifically, as shown in FIG. 14, based on the engine rotation speed (corresponding to the pulse interval) and the throttle opening, the entire operation area of the engine 2 is divided into a plurality of (25 in the example of FIG. 4) operation areas. The engine sound data (preferably each data of acceleration sound and deceleration sound) of a predetermined time length (for example, 0.6 seconds) is recorded in advance for each operation region, and the pulse interval and What is necessary is just to read and use the engine sound data of the operation region specified by the throttle opening.

  In the above-described embodiment, an example of synthesizing engine sound of a 4-cylinder engine has been described. However, the number of cylinders is not limited to this, and reproduction of synthesized engine sound data of a 6-cylinder engine or an 8-cylinder engine is possible. The present invention can be applied in the same manner. In this case, it is preferable that the number of acceleration sound data reproduction units and deceleration sound data reproduction units is the same as the number of cylinders of the engine.

  Furthermore, in the above-described embodiment, the configuration for generating the synthesized engine sound in the vehicle on which the engine 2 is mounted has been described. However, the present invention is also applied to the synthesis of the engine sound of the engine virtually mounted on the vehicle. can do. For example, in an electric vehicle that drives wheels using an electric motor as a drive source, a virtual engine throttle opening is calculated based on an operation of a driving operation unit such as an accelerator pedal, or the vehicle traveling speed is calculated. A virtual engine operating state can be detected by calculating the engine speed based on the throttle opening. The configuration shown in FIG. 3 can be used by generating rotation pulses at time intervals corresponding to the engine rotation speed. In this case, the fluctuation of the explosion interval occurring in the actual engine can be reproduced in a pseudo manner by giving fluctuation to the generation interval of the rotation pulse.

Similarly, the present invention can be applied to synthesis of engine sounds of virtual engines in a racing game or the like.
In addition, various design changes can be made within the scope of matters described in the claims.

It is a conceptual diagram for demonstrating the structure of the four-wheeled vehicle which is a vehicle equipped with the engine sound synthesizer which concerns on one Embodiment of this invention. It is a block diagram for demonstrating the electrical structure of an engine sound synthesizer. It is a block diagram for demonstrating the structural example of a synthetic | combination engine sound data generation part. It is a figure which shows the example of the engine sound data memorize | stored in the engine sound data storage part. It is a figure for demonstrating the driving | running state of an engine. It is a figure for demonstrating extraction of the engine sound data memorize | stored in the engine sound data storage part. It is a figure which shows the other example of the cut-out aspect of engine sound data. It is a figure which shows the other cut-out aspect of engine sound data. It is a figure which shows an example of an acceleration sound start address table. It is a figure for demonstrating the function of a fade process part. It is a figure which shows an example of a window function. It is a figure for demonstrating the superimposition of engine sound data. It is an illustration figure which shows the structural example of the two-wheeled vehicle (motorcycle) as a vehicle which concerns on other embodiment of this invention. It is a figure for demonstrating the example which memorize | stores engine sound data for every some driving | operation area | region. It is a wave form diagram for demonstrating more specifically the effect by superimposition of engine sound data. It is a wave form diagram for demonstrating the effect of a fade process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Car 2 Engine 3 Wheel 4 Car compartment 5 Driver's seat 6 Operation panel 7 Car audio apparatus main body 8 Speaker 9 Accelerator pedal 10 Engine sound synthesizer 11 Throttle opening sensor 13 Rotation pulse generator 14 Accelerator operation amount sensor 20 Operation state detection part DESCRIPTION OF SYMBOLS 21 Throttle opening detection part 22 Pulse interval detection part 24 Synthetic engine sound data generation part 25 Output processing part 30 Engine sound data storage part 31 Acceleration sound data extraction control part 32 Deceleration sound data extraction control part 33 Acceleration sound start address table 34 Deceleration Sound start address table 37 Increment generation unit 41 First acceleration sound data reproduction unit 42 Second acceleration sound data reproduction unit 43 Third acceleration sound data reproduction unit 44 Fourth acceleration sound data reproduction unit 46 First deceleration sound data reproduction unit 47 2 Deceleration sound data reproduction part 48 3rd deceleration sound data Data reproduction unit 49 fourth deceleration sound data reproduction unit 50 superposition unit 51 first acceleration sound address controller 52 second acceleration sound address controller 53 third acceleration sound address controller 54 fourth acceleration sound address controller 56 first deceleration sound address controller 57 second deceleration sound address controller 58 third deceleration sound address controller 59 fourth deceleration sound address controller 61 fluctuation coefficient generation unit 62 multiplication unit 63 acceleration sound coefficient generation unit 64 multiplication unit 65 time window coefficient generation unit 66 multiplication unit 71 fluctuation coefficient Generation unit 72 Multiplication unit 73 Deceleration sound coefficient generation unit 74 Multiplication unit 75 Time window coefficient generation unit 76 Multiplication unit 80 Two-wheeled vehicle 81 Wheel 82 Seat 83 Fuel tank 85 Infrared transmitter 86 Infrared receiver 95 Driver 96 Helmet 97 Amplifier 98 Speaker A Throttle opening data B Rotation pulse C Pulse interval data D1 to D4 Engine sound data d1 to d4 Engine sound data P1 Fluctuation processing unit P2 Sound pressure correction processing unit P3 Fade processing unit P4 Fluctuation processing unit P5 Sound pressure correction processing unit P6 Fade Processing part

Claims (10)

Explosion interval data generating means for generating explosion interval data representing the explosion interval of the engine;
Engine sound data storage means for storing pre-recorded engine sound data;
Engine sound data cutout means for cutting out a plurality of engine sound data of a predetermined length from engine sound data stored in the engine sound data storage means at different cutout positions;
A plurality of engine sound data reproduction for sequentially reproducing the plurality of engine sound data of the predetermined length cut out by the engine sound data cutting out means at every time interval represented by the explosion interval data generated by the explosion interval data generating means Means,
An engine sound synthesizer comprising: superimposing means for superimposing engine sound data reproduced by the plurality of engine sound data reproducing means to generate synthesized engine sound data. The plurality of engine sound data reproducing means reproduces each engine sound data at a constant reproduction rate irrespective of the explosion interval data generated by the explosion interval data generating means. The engine sound synthesizer according to 1.   The engine sound data cut-out means includes a pair of engine sound data reproducing means for reproducing engine sound data one after the other in time overlapping portions extracted from the engine sound data stored in the engine sound data storage means. 3. The engine sound synthesizer according to claim 1, wherein the engine sound data cut-out position in the engine sound data storage means is determined so as to reproduce the engine sound data of the predetermined length without any noise. .   4. Each of the engine sound data reproducing means includes fade means for gradually increasing the sound pressure at the start of reproduction of engine sound data and gradually decreasing the sound pressure at the end of reproduction. Engine sound synthesizer.   The fade means includes a sound pressure coefficient multiplying means for multiplying engine sound data by a sound pressure coefficient, and gradually increases the sound pressure coefficient from 0 to a predetermined upper limit value as time elapses, and then maintains the upper limit value. 5. The engine sound synthesizer according to claim 4, further comprising: a sound pressure coefficient generating means that is generated according to a window function that gradually decreases from the upper limit value to 0 as time passes.   The sound pressure coefficient generating means is configured to cause the sound pressure coefficient to be longer than the time represented by the explosion interval data generated by the explosion interval data generating means. 6. The engine sound synthesizer according to claim 5, which generates a coefficient. Further comprising throttle opening information generating means for generating throttle opening information representing the throttle opening of the engine,
The engine sound data storage means stores engine sound data during acceleration and engine sound data during deceleration,
The engine sound data extraction means includes acceleration sound data extraction means for extracting engine sound data during acceleration from the engine sound data storage means based on the explosion interval data generated by the explosion interval data generation means, and deceleration time data Decelerating sound data extracting means for extracting engine sound data of
The engine sound data reproducing means includes acceleration sound data reproducing means for reproducing the engine sound data during acceleration extracted by the acceleration sound data extracting means, and engine sound data during deceleration extracted by the deceleration sound data extracting means. A deceleration sound data reproducing means for reproducing
The acceleration sound data reproducing means generates an acceleration sound coefficient that defines a mixing ratio of the engine sound data during acceleration and the engine sound data during deceleration based on the throttle opening information generated by the throttle opening information generation means Accelerating sound coefficient generating means, and acceleration sound coefficient multiplying means for multiplying the engine sound data cut out by the acceleration sound data cutting out means by the acceleration sound coefficient generated by the acceleration sound coefficient generating means,
The deceleration sound data reproduction means includes a deceleration sound coefficient generation means for generating a deceleration sound coefficient that defines the mixing ratio based on the throttle opening information generated by the throttle opening information generation means, and the deceleration sound coefficient generation The engine sound according to any one of claims 1 to 6, further comprising a deceleration sound coefficient multiplication means for multiplying the engine sound data cut out by the deceleration sound data cutting means by the deceleration sound coefficient generated by the means. Synthesizer. An engine that generates a driving force to rotate the wheels;
The engine sound synthesizer according to any one of claims 1 to 7,
And a sound output unit that outputs engine sound reproduced by the engine sound reproducing means. Explosion interval data generation step for generating explosion interval data representing the explosion interval of the engine;
An engine sound data cutting step of cutting out a plurality of engine sound data of a predetermined length at different cutting positions from the engine sound data stored in the engine sound data storage means;
Engine sound data reproduction step of sequentially reproducing the cut-out plurality of engine sound data of the predetermined length for each time interval represented by the explosion interval data;
An engine sound synthesizing method comprising: an overlaying step of superimposing the reproduced engine sound data to generate synthesized engine sound data. The engine sound according to claim 9, wherein the reproduction of each of the plurality of engine sound data cut out is performed at a constant reproduction rate irrespective of the explosion interval data generated by the explosion interval data generation step. Synthesis method.

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