Active running sound effect generator

Abstract

To reduce a calculation amount in a process of generating a sound signal, and enable easy adjustment of a tone, thereby generating a highly realistic travel effective sound.SOLUTION: An active travel effective sound generator 100 is mounted on a vehicle 300, and includes: a waveform generation section 10 for generating a signal from a waveform table according to vehicle information; and a speaker 50 for outputting the signal generated by the waveform generation section 10. The waveform table is a cyclic waveform table in which an end point and a start point of the waveform table are continuous, and contains a plurality of frequency components.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an active running sound effect generating device. [Background technology]

[0002] BACKGROUND ART Conventionally, active sound effect generating devices have been considered for generating sound effects according to changes in vehicle speed caused by the driver's operation of the accelerator pedal when driving a vehicle (for example, Patent Documents 1 and 2).

[0003] As a technology related to this active sound effect generating device, the abstract of Patent Document 1 describes an active sound effect generating device that is capable of at least one of generating more natural sound effects and being applicable to electric vehicles (see Patent Document 1).

[0004] In addition, the abstract of Patent Document 2 describes an active sound effect generating device that generates sound effects in response to an increase in vehicle speed, producing highly realistic sound effects as the sound of a car traveling even at high speeds (see Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-229403 [Patent Document 2] JP 2019-128378 A Summary of the Invention [Problem to be solved by the invention]

[0006] The active sound effect generation devices described in Patent Documents 1 and 2 require a large amount of calculation, which places a heavy load on the processing, making it difficult to provide running sound effects in real time.

[0007] For example, the active sound effect generator described in Patent Document 1 is configured to include a reference signal generating means and a control signal generating means. The reference signal generating means generates a reference signal by sequentially reading waveform data from a waveform data table. The control signal generating means generates a control signal used to generate the sound effect based on the generated reference signal. The control signal generating means adjusts the amplitude of the control signal by changing the amplitude of the reference signal in accordance with the amount of frequency change and the load of the drive source.

[0008] Furthermore, the active sound effect generator described in Patent Document 1 also requires a rotational frequency change amount calculation means for calculating the rotational frequency change amount, which is the time differential value of the rotational frequency, and an engine load detection means for detecting the engine load, and therefore requires a large amount of calculation to adjust the amplitude of the control signal.

[0009] Furthermore, the active sound effect generation device described in Patent Document 2 is configured with a waveform data table and an amplitude data table. The waveform data table generates order sound signals having order sound frequencies from a sine wave of 1 [Hz]. There are, for example, three order sound frequencies. In this case, the waveform data table generates three order sound signals. Furthermore, the amplitude data table adjusts the amplitude of each of the three order sound signals. An adder generates a sound signal by synthesizing (adding) the three order sound signals whose amplitudes have been adjusted.

[0010] As described above, the active sound effect generating device described in Patent Document 2 also places a heavy load on processing due to the large amount of calculation required for the order sound signals. Furthermore, when multiple tones (sets of order sound signals) are output simultaneously or when volume and the like are controlled, the amount of calculation required for the order sound signals further increases.

[0011] Furthermore, if a user wants to individually adjust the waveform (tone) of a sound effect, it is difficult for the average user to adjust the tone because the order sound settings are difficult to understand.

[0012] The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide an active running sound effect generation device that reduces the amount of calculation in the sound signal generation process, makes it easy to adjust the tone, and generates highly realistic running sound effects. [Means for solving the problem]

[0013] That is, in order to solve the above-mentioned problems of the present invention, the active driving sound effect generating device is an active driving sound effect generating device mounted on a vehicle, and is characterized in that it comprises a waveform generating unit that generates a signal from a waveform table in accordance with vehicle information, and a speaker that outputs the signal generated by the waveform generating unit, and the waveform table is a periodic waveform table in which the end point and start point of the waveform table are consecutive, and includes a plurality of frequency components. [Effects of the Invention]

[0014] According to the present invention, the amount of calculation in the process of generating an audio signal can be reduced, and tone adjustment can be easily performed, thereby enabling the generation of highly realistic driving sound effects. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a block diagram showing a schematic configuration of an active driving sound effect generation device according to a first embodiment mounted on a vehicle. [Figure 2] FIG. 2 is a block diagram showing a schematic configuration of a waveform generating unit. [Figure 3A] FIG. 10 is an explanatory diagram (part 1) showing the concept of the generation processing unit reading out a signal (waveform data) at a position obtained by adding the acquired skip number to the previous read position. [Figure 3B] FIG. 10 is an explanatory diagram (part 2) showing the concept of the generation processing unit reading out a signal (waveform data) at a position obtained by adding the acquired skip number to the previous read position. [Figure 4] FIG. 10 is an explanatory diagram showing an example of a process for synthesizing waveform tables. [Figure 5]10 is an explanatory diagram showing the characteristics of a gain adjustment unit of a gain control unit adding gain to a signal acquired from a waveform generation unit. FIG. [Figure 6] FIG. 2 is a block diagram showing the configuration of a sound image control processing unit. [Figure 7A] 1 shows a display audio system installed in a vehicle. [Figure 7B] This shows a low-frequency waveform table that is an example of the powerful EV sports sound. [Figure 7C] This shows a high-frequency table, an example of the futuristic EV sound. [Figure 8A] FIG. 10 is an explanatory diagram showing a configuration in which a button for adding a tone (waveform table) is provided on the tone screen of the display audio. [Figure 8B] FIG. 10 is an explanatory diagram showing a waveform table added to a waveform generating unit by a user. [Figure 9A] FIG. 10 is an explanatory diagram showing a first skip table. [Figure 9B] FIG. 10 is an explanatory diagram showing a second skip table. [Figure 10] FIG. 10 is a block diagram showing a schematic configuration of an active driving sound effect generation device according to a second embodiment mounted on a vehicle. [Figure 11A] 10 shows the coefficients of a band-pass filter included in the frequency characteristic adjustment processing unit. [Figure 11B] FIG. 10 is an explanatory diagram showing frequency characteristics based on filter coefficients. [Figure 12A] 4 is an explanatory diagram showing a signal input to a frequency characteristic adjustment processing unit. FIG. [Figure 12B] 4 is an explanatory diagram showing a signal output from a frequency characteristic adjustment processing unit. FIG. [Figure 13] FIG. 10 is an explanatory diagram showing a configuration for switching filter coefficients of an active running sound effect generation device according to a second embodiment. [Figure 14] FIG. 10 is an explanatory diagram showing a comparative example in which a waveform table including a plurality of frequency components is generated. DETAILED DESCRIPTION OF THE INVENTION

[0016] The following describes in detail embodiments of the present invention. Note that the embodiments described below are examples for realizing the present invention, and should be appropriately modified or changed depending on the configuration of the device to which the present invention is applied and various conditions. The present invention is not limited to the following embodiments. In addition, in each drawing, the same components are given the same reference numerals, and their description will be omitted as appropriate.

[0017] First Embodiment [Outline of the active running sound effect generator] FIG. 1 is a block diagram showing a schematic configuration of an active driving sound effect generation device according to the first embodiment mounted on a vehicle (see FIG. 6).

[0018] As shown in FIG. 1, the active running sound effect generation device 100 according to this embodiment is configured to include a waveform generation unit 10, a gain coefficient calculation unit 20, a gain control unit 30, an audio control unit 40, and a speaker 50.

[0019] In this embodiment, the waveform generating unit 10, the gain coefficient calculating unit 20, the gain control unit 30, and the audio control unit 40 constitute an active sound control (ASC) device. Active sound control is a system that improves the quality of acceleration sounds heard inside the vehicle depending on the accelerator pedal position. That is, active sound control provides the user with acceleration sounds that correspond to the vehicle speed or the rotation speed by emitting sounds synchronized with the vehicle speed or the rotation speed from the speaker 50 inside the vehicle.

[0020] As shown in vehicle 300 in FIG. 6 described later, speaker 51 is arranged at the front of vehicle 300 (for example, in front of the driver's seat or passenger seat), speaker 52 is arranged approximately in the center of vehicle 300 (for example, to the side of the driver's seat or passenger seat), and speaker 5S is arranged at the rear of vehicle 300 (for example, behind the rear seat).

[0021] Vehicle 300 is configured as, for example, a fuel cell vehicle, an electric vehicle including a hybrid vehicle, or the like, and is configured with a motor (not shown). This motor is controlled by a motor ECU (Electronic Control Unit) (not shown).

[0022] The waveform generation unit 10 of the active driving sound effect generation device 100 generates signals from a waveform table in accordance with vehicle information. The waveform generation unit 10 is provided with a plurality of waveform tables, and generates signals from each of the plurality of waveform tables. Here, the vehicle information is the vehicle speed or the rotation speed of the power unit. Note that the power unit is not limited to a motor, and may be, for example, an engine.

[0023] The waveform generating unit 10 is configured to include a vehicle speed / rotation speed acquiring unit 11 and frequency component group generating processors 12-1, ..., 12-N. When it is not necessary to specify which of the frequency component group generating processors 12-1, ..., 12-N is used, it will be simply referred to as frequency component group generating processor 12.

[0024] The vehicle speed / rotation speed acquisition unit 11 acquires the vehicle speed or the rotation speed of the power unit as vehicle information from the vehicle 300 (see FIG. 6 ). The vehicle speed / rotation speed acquisition unit 11 is configured by, for example, a vehicle speed sensor. The vehicle speed / rotation speed acquisition unit 11 acquires the vehicle speed or the rotation speed of the power unit based on the rotation speed of the motor or the axle (not shown) using the vehicle speed sensor, and supplies it to the gain coefficient calculation unit 20.

[0025] Each of the frequency component group generation processors 12-1, ..., 12-N has a corresponding waveform table (tone). For example, the frequency component group generation processor 12-1 has a low-frequency waveform table that includes a relatively large number of low-frequency components, and the frequency component group generation processor 12-2 (when N is 2) has a high-frequency waveform table that includes a relatively large number of high-frequency components than the low-frequency waveform table. The low-frequency waveform table only needs to include more low-frequency components than high-frequency components, and may be composed of only low-frequency components. The high-frequency table only needs to include more high-frequency components than low-frequency components, and may be composed of only high-frequency components. The low-frequency waveform table and the high-frequency table are not limited to waveform tables, and may be data including low-frequency waveform signals and high-frequency signals.

[0026] Each of the frequency component group generation processors 12-1, . . . , 12-N has a different waveform table, and thus the waveform generation section 10 has a plurality of waveform tables.

[0027] Fig. 2 is a block diagram showing a schematic configuration of the waveform generation unit. As shown in Fig. 2, the waveform generation unit 10 is configured to include a skip table 123 and a generation processing unit 124. The generation processing unit 124 has a waveform table 125 that forms a tone color, and the waveform table 125 is waveform data read by the generation processing unit 124 and is configured of table values. Note that the waveform table 125 is an example of waveform data that includes multiple frequency components (1 [Hz], 2 [Hz], 4 [Hz], etc.) with 1 [s] as one period.

[0028] The skip table 123 acquires the skip number of the read position based on the vehicle information. The skip table 123 is provided in the vehicle speed / rotation number acquisition unit 11, for example.

[0029] The skip table 123 includes at least one of a vehicle speed step table 121 and a rotation speed step table 122. In the vehicle speed step table 121, a skip number (read width) ΔP is defined based on the vehicle speed [km / h] of the vehicle 300. In addition, in the rotation speed step table 122, the skip number ΔP is defined based on the rotation speed [rpm] of the power unit. Note that the skip number indicates, for example, the read width for reading waveform data when reading the waveform table 125. In other words, the skip number indicates the ratio at which the waveform table 125 is thinned out, and is the speed-up value when the waveform table 125 is played back at double speed.

[0030] The skip number ΔP is stored in table format in the skip table 123. For example, based on the vehicle speed step table 121, the vehicle speed / revolution number obtaining unit 11 reads out the skip number ΔP as 1 when the vehicle speed is 10 [km / h], and reads out the skip number ΔP as 4 when the vehicle speed is 20 [km / h]. Furthermore, the vehicle speed / revolution number obtaining unit 11 reads out the skip number ΔP as 9 when the vehicle speed is 30 [km / h], and reads out the skip number ΔP as 400 when the vehicle speed is 200 [km / h].

[0031] Furthermore, for example, the vehicle speed / rotation speed acquisition unit 11 reads out the skip number ΔP as 1 when the rotation speed of the power unit is 600 [rpm], and reads out the skip number ΔP as 2 when the rotation speed of the power unit is 700 [rpm], based on the rotation speed step table 122. Furthermore, the vehicle speed / rotation speed acquisition unit 11 reads out the skip number ΔP as 4 when the rotation speed of the power unit is 800 [rpm], and reads out the skip number ΔP as 100 when the rotation speed of the power unit is 3000 [rpm].

[0032] In this way, when the vehicle speed or the rotation speed of the power unit is acquired by the vehicle speed / rotation speed acquisition unit 11, the waveform generation unit 10 acquires the skip number ΔP of the read position based on the vehicle speed or the rotation speed. Note that the skip number ΔP of the vehicle speed step table 121 or the rotation speed step table 122 is defined as the skip number desired by the user.

[0033] On the other hand, a generation processing unit 124 is provided for each of frequency component group generation processing units 12-1, ..., 12-N. That is, a generation processing unit 124 corresponds to each of frequency component group generation processing units 12-1, ..., 12-N. Based on the skip number ΔP acquired by vehicle speed / rotation speed acquisition unit 11, generation processing unit 124 reads out a signal at a position obtained by adding the acquired skip number ΔP to the previously read position of waveform table 125, thereby generating a signal to be input to speaker 50 (i.e., a waveform table of skip number ΔP).

[0034] Here, the signal generated by the generation processing unit 124 is defined by the following equation (1).

[0035]

number

[0036] As shown in equation (1), the signal input to speaker 50 is generated by vehicle speed / rotation speed acquisition unit 11 reading waveform table 125 for skip number ΔP at the previous value of pointer P(t) based on skip number ΔP read from skip table 123 and the previous value of pointer P(t). In this case, the waveform data in waveform table 125 for skip number ΔP becomes the signal (tone).

[0037] 3A and 3B are explanatory diagrams showing the concept of the generation processing unit reading out a signal (waveform data) at a position obtained by adding the acquired skip number to the previous read position.

[0038] 3A shows the concept of the generation processing unit 124 reading out signals (waveform data) from the waveform table 126 when, for example, the skip number ΔP is 2. As shown in FIG. 3A, the generation processing unit 124 reads out waveform data (waveform table 127) from the previous read position at twice the cycle (two round trips) of the waveform data (waveform table 126) for one cycle per second.

[0039] 3B shows the concept of generation processing unit 124 reading out signals from waveform table 128 when, for example, skip count ΔP is 3. As shown in FIG. 3B, generation processing unit 124 reads out waveform data (waveform table 129) from the previous read position at a cycle three times longer (three round trips) than the one cycle of waveform data (waveform table 128) per second.

[0040] Here, the waveform tables 126 and 128 hold the value of the signal (waveform data) for one period in a table format. In this embodiment, the waveform tables 126 and 128 from which the waveform generating section 10 reads waveform data are characterized.

[0041] Fig. 4 is an explanatory diagram showing an example of a process for synthesizing waveform tables. Fig. 4 shows a process for synthesizing waveform table 134 of waveform data having three frequency components from waveform table 131 with a frequency of 1 [Hz], waveform table 132 with a frequency of 1.25 [Hz], and waveform table 133 with a frequency of 1.5 [Hz].

[0042] The three waveform tables 131, 132, and 133 have different periods, and therefore cannot be synchronized in units of one second. Therefore, in this embodiment, to generate a waveform table 134 having three frequency components, the frequencies of the waveform tables 131, 132, and 133 are multiplied by an integer while maintaining their ratio, and the minimum time [s] (multiplier) at which synchronization can be achieved is determined from the integer value. By making the frequency ratio an integer, the waveform data of the waveform tables 131, 132, and 133 have the same value at their start and end points, allowing synchronization at each timing. Therefore, in this embodiment, the minimum time [s] at which synchronization can be achieved among the waveform tables 131, 132, and 133 is defined as one period, and the waveform data of each waveform table 131, 132, and 133 is synthesized to generate the waveform table 134 having three frequency components.

[0043] In this manner, in this embodiment, after the ratio of the frequencies in the waveform tables 131, 132, and 133 is made into an integer, the minimum required time (minimum time) of the data string of waveform data is determined.

[0044] In the example of Figure 4, the frequency ratio between waveform table 131 (1 Hz), waveform table 132 (1.25 Hz), and waveform table 133 (1.5 Hz) is 1:1.25:1.5. Integer multiplication of this frequency ratio results in 4:5:6 or 100:125:150. In this case, the minimum time (s) at which waveform tables 131, 132, and 133 can be synchronized is determined to be 4 s, since (1:1.25:1.5) x 4 is 4:5:6. Once the minimum time (4 s) is determined, the waveform data in waveform table 131 will be waveform data for four periods, the waveform data in waveform table 132 will be waveform data for five periods, and the waveform data in waveform table 133 will be waveform data for six periods.

[0045] Then, waveform table 134 generates waveform data with the minimum time [s] as one period by adding period data (4 periods, 5 periods, 6 periods) that is an integer multiple of each of waveform tables 131, 132, and 133 over the minimum time (4 [s]) that allows synchronization between waveform tables 131, 132, and 133. As a result, the generated waveform table 134 is a periodic waveform table in which the end and start points of the waveform data are consecutive, and is a table containing a plurality of frequency components.

[0046] In other words, in this embodiment, the waveform table 134 is formed from waveform data in which the period of the waveform table is the smallest multiplier (i.e., the smallest time) that makes all of the frequency ratios integers while maintaining the ratios of multiple frequencies.

[0047] In this way, the waveform table 134 containing a plurality of frequency components is generated from the waveform data of the waveform tables 131, 132, and 133 containing the frequency components desired by the user.

[0048] Returning to FIG. 1, the gain coefficient calculation unit 20 of the active driving sound effect generation device 100 is configured to include an accelerator opening sensor 21, an acceleration calculation unit 22, a rotation speed change amount calculation unit 23, a vehicle speed / rotation speed gain table 24, an accelerator gain table 25, an acceleration gain table 26, and a rotation speed change gain table 27.

[0049] The accelerator opening sensor 21 detects the opening of the accelerator pedal when the user depresses the accelerator pedal of the vehicle 300 (this is referred to as accelerator opening θ).

[0050] The acceleration calculation unit 22 acquires the vehicle speed or the rotation speed of the power unit from the vehicle speed / rotation speed acquisition unit 11, and calculates the acceleration Δa.

[0051] The rotation speed change amount calculation unit 23 acquires the vehicle speed or the rotation speed of the power unit from the vehicle speed / rotation speed acquisition unit 11, and calculates the rotation speed change amount Δb.

[0052] The vehicle speed / rpm gain table 24 has a characteristic of adding a gain to the supplied vehicle speed or power unit rpm. The accelerator gain table 25 has a characteristic of adding a gain to the detected accelerator opening θ. The acceleration gain table 26 has a characteristic of adding a gain to the calculated acceleration Δa. The rpm change gain table 27 has a characteristic of adding a gain to the calculated rpm change amount Δb.

[0053] The vehicle speed / revolution gain table 24, accelerator gain table 25, acceleration gain table 26, and revolution speed change gain table 27 are set in table format as appropriate to the predetermined characteristics desired by the user.

[0054] The gain control unit 30 of the active running sound effect generation device 100 is configured to include a plurality of gain adjustment units 31, ... 3N. The gain control unit 30 obtains from the waveform generation unit 10 the signals u1, ... uN generated by each frequency component group generation processing unit 12-1, ... 12-N, and obtains from the gain coefficient calculation unit 20 a coefficient for adjusting the gain of each signal u1, ... uN.

[0055] Each of the multiple gain adjustment units 31,...3N corresponds to a respective signal u1,...uN generated from the waveform table of the frequency component group generation processing units 12-1,...12-N. Thus, each gain adjustment unit 31,...3N adjusts the gain of each corresponding signal u1,...uN generated by the frequency component group generation processing units 12-1,...12-N using the gain coefficient obtained from the gain coefficient calculation unit 20.

[0056] FIG. 5 is an explanatory diagram showing the characteristics of the gain adjustment unit of the gain control unit adding gain to the signal acquired from the waveform generation unit.

[0057] 5, when the vehicle speed or rotation speed is relatively low, the gain control unit 30 increases (raises) the gain of the low-frequency waveform table by a gain G1 indicating a low-frequency component. On the other hand, when the vehicle speed or rotation speed is relatively high, the gain control unit 30 increases (raises) the gain of the high-frequency waveform table by a gain G2 indicating a high-frequency component.

[0058] In FIG. 5, gain G1 indicates the gain characteristics of low frequency components (low frequency waveform signals), and gain G2 indicates the gain characteristics of high frequency components (high frequency waveform signals).

[0059] For example, if the frequency component group generation processing unit 12-1 has a low-frequency waveform table and the frequency component group generation processing unit 12-2 (when N is 2) has a high-frequency waveform table, the gain adjustment unit 31 uses gain G1 to emphasize and output the low-frequency components of the low-frequency waveform table of the frequency component group generation processing unit 12-1 when the vehicle speed or rotation speed is relatively low.

[0060] On the other hand, when the vehicle speed or rotation speed is relatively high, the gain adjuster 32 (when N is 2) emphasizes and outputs the high frequency components of the high frequency table of the frequency component group generator 12-2 using the gain G2.

[0061] The acoustic control unit 40 (see FIG. 1) of the active running sound effect generation device 100 is configured to include a sound image control processing unit 41. The sound image control processing unit 41 changes (adjusts) the magnitude of the output of each of the plurality of speakers 50 (51, 52, ... 5S) for each of the plurality of signal components y1, ... yN.

[0062] The sound image control processing unit 41 inputs a signal to each speaker 50, and the output sound output from each speaker 50 is expressed by the following equation (2).

[0063]

number

[0064] As shown in equation (2), the sound image control processing unit 41 adjusts the magnitude and delay time of the signals u1, ... uN generated by each frequency component group generation processing unit 12-1, ... 12-N by multiplying them by the gain coefficient set for each speaker 50. As a result, the output sound of each speaker 51, 52, ... 5S becomes the sum (result) of the frequency components whose magnitudes have been adjusted.

[0065] As a result, the sound image control processing unit 41 outputs a low-frequency waveform signal (low-frequency waveform component) at a relatively low level and a high-frequency component at a relatively high level from the speaker 51 located at the front of the vehicle 300, and outputs a low-frequency waveform signal (low-frequency waveform component) at a relatively high level and a high-frequency component at a relatively low level from the speaker 5S located at the rear of the vehicle 300 compared to the speakers 51, 52 located at the front.

[0066] Furthermore, the sound image control processing unit 41 can adjust the phase of the signal for each of the plurality of signal components y1,...,yN for each speaker 50. Therefore, the speaker 51 arranged at the front of the vehicle 300 can output a high-frequency waveform signal earlier and a low-frequency waveform signal later than the speaker 5S arranged at the rear of the vehicle 300.

[0067] Fig. 6 is a block diagram showing the configuration of a sound image control processing unit. As shown in Fig. 6, sound image control processing unit 41 includes amplifiers 421, 422,... 42S, 441, 442,... 44S that multiply each of a plurality of signal components y1,... yN by a constant for each speaker 51, 52,... 5S.

[0068] 6, when speakers 51, 52, ..., 5S are arranged, the sound image control processing unit 41 sets, for example, a coefficient of 1.0 for amplifier 421, a coefficient of 0.5 for amplifier 422, and a coefficient of 0.0 for amplifier 42S for signal component y1 of frequency component group generation processing unit 12-1, which assumes intake sound. As a result, the sound image control processing unit 41 localizes the sound image of signal component y1 in the front of the vehicle cabin.

[0069] On the other hand, for the signal component yN of the frequency component group generation processing unit 12-N that assumes the exhaust noise, the sound image control processing unit 41 sets, for example, a coefficient of 0.0 for the amplifier 441, a coefficient of 0.5 for the amplifier 442, and a coefficient of 1.0 for the amplifier 44S. As a result, the sound image control processing unit 41 localizes the sound image of the signal component yN at the rear of the vehicle interior.

[0070] In this way, speaker 51 outputs high frequency components relatively louder than speakers 52 and 5S, and speaker 52 outputs high frequency components relatively louder than speaker 5S. On the other hand, speaker 5S outputs low frequency components relatively louder than speakers 51 and 52, and speaker 52 outputs low frequency components relatively louder than speaker 51. Note that sound image control processing unit 41 may divide multiple speakers 50 (51, 52, ... 5S) into those for the front and rear of the vehicle cabin and control them collectively.

[0071] The sound image control processing unit 41 also includes delay adjustment elements 431, 432, ··· 43S, 451, 452, ··· 45S that adjust the phase of the signal for each of the speakers 51, 52, ··· 5S for each of the plurality of signal components y1, ··· yN.

[0072] Delay adjustment elements 431, 432,... 43S, 451, 452,... 45S set delay times by digital values ​​for each of signal components y1,... yN. This enables speaker 51 located at the front of vehicle 300 to output high-frequency components earlier and low-frequency waveform signals (low-frequency waveform components) later than speakers 52,... 5S located at the rear of vehicle 300.

[0073] As a result, speaker 51 adds, in adder 461, a signal amplified by amplifier 421 and delayed by delay adjustment element 431 and a signal amplified by amplifier 441 and delayed by delay adjustment element 451, and outputs the resulting sum signal s1 into the vehicle cabin. Speaker 52 adds, in adder 462, a signal amplified by amplifier 422 and delayed by delay adjustment element 432 and a signal amplified by amplifier 442 and delayed by delay adjustment element 452, and outputs the resulting sum signal s2 into the vehicle cabin. Speaker 5S can add, in adder 46S, a signal amplified by amplifier 42S and delayed by delay adjustment element 43S and a signal amplified by amplifier 44S and delayed by delay adjustment element 45S, and output the resulting sum signal sS into the vehicle cabin.

[0074] [Active running sound effect generator in operation] <Operation 1> Next, the operation of the active running sound effect generation device 100 according to the first embodiment will be described with reference to FIG. 1 and FIGS. 7A to 9B.

[0075] The active running sound effect generation device 100 acquires the vehicle speed or the rotation speed of the power unit as vehicle information of the vehicle 300 by the vehicle speed / rotation speed acquisition unit 11. The vehicle speed / rotation speed acquisition unit 11 acquires the skip number ΔP based on the acquired vehicle speed or the rotation speed of the power unit.

[0076] The frequency component group generators 12-1, . . . , 12-N (generator 124) read out the signal at the position obtained by adding a skip number ΔP to the read position P(t) of each waveform table, and input the signal to the gain controller 30.

[0077] The gain coefficient calculation unit 20 calculates a gain coefficient for each of the signals u1, . . . uN from a vehicle speed / rotation speed gain table 24, an accelerator gain table 25, an acceleration gain table 26, and an acceleration gain table 26 based on the accelerator opening θ of the accelerator opening sensor 21 and the vehicle speed or the rotation speed of the power unit acquired by the vehicle speed / rotation speed acquisition unit 11.

[0078] The gain control unit 30 controls (adjusts) the gains corresponding to the signals u1, ..., uN generated from the plurality of waveform tables of the frequency component group generation processing units 12-1, ..., 12-N, using the gain coefficients calculated by the gain coefficient calculation unit 20.

[0079] The acoustic control unit 40 changes the magnitude of the output for each of the multiple speakers 50 for each signal component y1, ..., yN and inputs it to each speaker 50. This allows each speaker 50 to output the signals u1, ..., uN generated by the waveform generation unit 10.

[0080] <Operation 2> In this embodiment, the active running sound effect generator 100 has a waveform table for each of the frequency component group generation processing units 12-1, ..., 12-N in the waveform generation unit 10, and is therefore provided with a plurality of waveform tables. Therefore, the waveform generation unit 10 can accept a user operation and switch the waveform table from among the plurality of waveform tables in response to the user's operation.

[0081] 7A to 7C are explanatory diagrams showing that a desired waveform table can be selected from a plurality of waveform tables provided in the frequency component group generation processing unit of the waveform generating unit.

[0082] 7A shows a display audio provided in a vehicle 300. As shown in FIG. 7A, the display audio 200 is provided with a volume screen 201 and a tone screen 202.

[0083] The volume screen 201 allows the user to turn volume customization ON / OFF, and when it is ON, the volume can be adjusted.

[0084] The tone screen 202 allows the user to switch between tones using a button in response to a selection operation. For example, the tone screen 202 allows the user to select between a powerful EV (Electric Vehicle) sports tone and a futuristic EV tone. In this case, when the user selects the powerful EV sports tone, the waveform table 1201 shown in FIG. 7B is selected from the frequency component group generation processing units 12-1, ..., 12-N of the waveform generation unit 10. On the other hand, when the user selects the futuristic EV tone, the waveform table 1202 shown in FIG. 7C is selected from the frequency component group generation processing units 12-1, ..., 12-N of the waveform generation unit 10.

[0085] Waveform table 1201 in FIG. 7B shows a low-frequency waveform table that is an example of a powerful EV sports tone, and waveform table 1202 in FIG. 7C shows a high-frequency waveform table that is an example of a futuristic EV tone.

[0086] For example, waveform table 1201 corresponds to frequency component group generation processing unit 12-1, and waveform table 1202 corresponds to frequency component group generation processing unit 12-2, allowing the user to select a waveform table that outputs a preferred tone.

[0087] Furthermore, a waveform table that outputs a desired tone color may be added separately by the user. For example, the tone color screen 202 may be configured to include a button 203 that allows the user to add a tone color.

[0088] <Operation 3> Fig. 8A is an explanatory diagram showing a configuration in which a button for adding a tone (waveform table) is provided on the tone screen of the display audio. Fig. 8B is an explanatory diagram showing a waveform table added by a user to the waveform generation unit. Waveform table 1203 is waveform data downloaded from the Internet by the user as tone data. Like waveform table 134, waveform table 1203 is a periodic waveform table in which the end point and start point of the waveform table are consecutive, and includes multiple frequency components.

[0089] 8A, the user can add a desired waveform table to the waveform generating section 10 by pressing button 203. This allows the waveform generating section 10 to add waveform table 1203 to multiple waveform tables (frequency component group generation processing sections 12-1, ..., 12-N).

[0090] The waveform generating section 10 can be configured to be able to switch the waveform table that generates the signal to be input to the speaker 50 from among the multiple waveform tables to the added waveform table 1203. In this case, the user can add the waveform table 1203 from the Internet or an external memory, for example, and can select to output the signal of the added waveform table 1203.

[0091] In this way, the waveform generating section 10 can accept addition of the waveform table 1203 and can also accept selection of waveform data (tone) of the waveform table 1203 to be output by the speaker 50.

[0092] <Operation 4> The waveform generating unit 10 also includes a vehicle speed / rotation speed acquiring unit 11, which includes a skip table 123.

[0093] The skip table 123 may include, for example, a vehicle speed step table 121 and a rotation speed step table 122. Therefore, the skip table 123 can be switched by selecting either the vehicle speed step table 121 or the rotation speed step table 122 through a user selection operation.

[0094] 9A is an explanatory diagram showing the first skip table 1231. As shown in FIG. 9A, the first skip table 1231 exponentially increases the skip number from a lower limit value to an upper limit value based on an increase in vehicle speed or power unit rotation speed, and returns to the lower limit value when the upper limit value is reached. In the first skip table 1231, the skip number is returned to the lower limit value, and then exponentially increased again. This allows the first skip table 1231 to generate an infinite scale signal.

[0095] 9B is an explanatory diagram showing the second skip table 1232. As shown in FIG. 9B, the second skip table 1232 increases the frequency in proportion to an increase in vehicle speed or power unit rotation speed, and decreases the frequency by a predetermined amount when the vehicle speed or power unit rotation speed reaches a predetermined value. After decreasing the frequency, the second skip table 1232 increases the frequency again in proportion to an increase in vehicle speed or power unit rotation speed, increasing it in a stepped manner. This allows the second skip table 1232 to generate an engine wind signal.

[0096] For example, when a futuristic EV tone is selected by a user's selection operation on tone screen 202 of Fig. 7A or 8A, first skip table 1231 of Fig. 9A is selected. On the other hand, when an engine-like tone is selected by a user's selection operation on tone screen 202, second skip table 1232 of Fig. 9B is selected.

[0097] As a result, when the first skip table 1231 is selected, the waveform generation unit 10 is able to generate a futuristic EV signal (infinite scale signal) in the vehicle speed / rotation speed acquisition unit 11. On the other hand, when the second skip table 1232 is selected, the waveform generation unit 10 is able to generate an engine wind signal in the vehicle speed / rotation speed acquisition unit 11.

[0098] In particular, when the first skip table 1231 (infinite scale signal) is selected, the waveform generating unit 10 can output an engine-like tone, but can output an infinite scale signal by outputting the low-frequency waveform signal and the high-frequency waveform signal directly from the speakers 51, 52, ... 5S without deliberately controlling them according to the position of the speaker 50.

[0099] As described above, the active running sound effect generation device 100 according to the first embodiment is configured to include the waveform generation unit 10 and the speaker 50. The waveform generation unit 10 generates signals u1...uN from the waveform tables 125, 134... in accordance with vehicle information. The speaker 50 outputs the signals u1,...uN generated by the waveform generation unit 10. The waveform tables 125, 134... are periodic waveform tables in which the end point and start point of the waveform table are consecutive, and contain a plurality of frequency components.

[0100] According to this configuration, the waveform tables 125, 134, etc. included in the waveform generating unit 10 include multiple frequency components. Therefore, the amount of calculation can be reduced compared to the prior art (e.g., Japanese Patent Application Laid-Open No. 2015-229403, Japanese Patent Application Laid-Open No. 2019-128378, etc.) in which multiple frequency components are generated from a waveform table of a single frequency component (e.g., a sine wave) and order acoustic signals are synthesized (superimposed).

[0101] That is, the active running sound effect generation device 100 according to the first embodiment can generate the signals u1...uN to be output from the speaker 50 simply by reading out the waveform data from the waveform tables 125, 134... which are periodic waveform tables. This allows the active running sound effect generation device 100 to generate sound signals without performing calculations that impose a processing load.

[0102] In particular, as described with reference to Fig. 4, the waveform generating section 10 includes a waveform table 134 of waveform data having three (multiple) frequency components. This waveform table 134 is a periodic waveform table in which the end point and start point of the waveform data are consecutive, and is a table including three (multiple) frequency components.

[0103] Waveform table 134 is waveform data that does not cause discontinuities by adding periodic data that is an integer multiple of each waveform table 131, 132, and 133 in the shortest time (4 seconds) that allows synchronization between waveform tables 131, 132, and 133.

[0104] <Comparative Example> Here, a comparative example will be described. Fig. 14 is an explanatory diagram showing a comparative example of synthesizing a waveform table containing multiple frequency components. Fig. 14 shows the process of synthesizing waveform table 164 of waveform data having three frequency components from waveform table 161 with a frequency of 1 [Hz], waveform table 162 with a frequency of 1.25 [Hz], and waveform table 163 with a frequency of 1.5 [Hz].

[0105] Since the three waveform tables 161, 162, and 163 each have a different period, if waveform data for 1 [s] is added as is by adder 135, a waveform table 164 without periodicity will be synthesized.

[0106] In particular, since the waveform table 164 sums up waveform data for one second each in the waveform tables 161, 162, and 163, values ​​are added up midway through each cycle, and the waveform data for one cycle is not aligned. That is, in the waveform table 164, even if the start point of one second of waveform data is 0, the end point is 1, and the start and end points are not aligned. In this case, when the waveform data of the waveform table 164 is repeatedly read out, discontinuity occurs due to the misalignment of the start and end points. As a result, when the waveform table 164 is applied to a repetitively continuous periodic waveform table, the active running sound effect generator 100 will experience a sound misalignment between the start and end points.

[0107] Therefore, in the prior art, in order to avoid audio misalignment due to discontinuities in the waveform tables, multiple waveform tables for a single frequency component were prepared, and various predetermined calculations were performed using each waveform table, and then the results were combined using an adder.

[0108] In contrast, the waveform table 134 of the first embodiment determines the minimum required time (minimum time) for the data string of waveform data as one period after the frequency ratio of each waveform table 131, 132, and 133 is set to an integer. In other words, the waveform table 134 defines the minimum time [s] that allows synchronization of each waveform table 131, 132, and 133 as one period, and adds up period data (waveform data) of integer multiples of each waveform table 131, 132, and 133 to generate the desired waveform data. Therefore, sound lag does not occur midway through any period, and sound continuity can be ensured even when repeatedly read. In particular, since the waveform table 134 can be generated by synthesizing waveform tables containing desired frequency components, the user can easily adjust the tone color as desired.

[0109] In this way, the active running sound effect generation device 100 according to the first embodiment can easily adjust the tone, and can therefore generate highly realistic running sound effects.

[0110] The waveform generating unit 10 is provided with a plurality of waveform tables and generates signals u1, ..., uN from the plurality of waveform tables, respectively. The active running sound effect generating device 100 is configured to include a plurality of gain adjusting units 31, ..., 3N corresponding to the signals u1, ..., uN generated by the waveform generating unit 10 from the plurality of waveform tables, respectively.

[0111] According to this configuration, each frequency component group generation processing unit 12-1, ..., 12-N has a waveform table, and the active running sound effect generation device 100 is provided with gain adjustment units 31, ..., 3N corresponding to each frequency component group generation processing unit 12-1, ..., 12-N.

[0112] As a result, the active running sound effect generating device 100 can adjust the gain of each of the generated signals u1, ... uN, and can also superimpose signals u1, ... uN whose gains have been adjusted, thereby making it possible to combine chords and generate desired complex tones.

[0113] Moreover, the waveform generating unit 10 is configured to include a waveform table 1201 (low-frequency waveform table) that contains a relatively large number of low-frequency components, and a waveform table 1202 (high-frequency table) that contains a relatively large number of high-frequency components than the waveform table 1201. The vehicle information is the vehicle speed or the number of revolutions of the power unit, and when the vehicle speed or the number of revolutions is relatively low, the gain of the waveform table 1201 is increased, whereas when the vehicle speed or the number of revolutions is relatively high, the gain of the waveform table 1202 is increased.

[0114] With this configuration, the waveform generating unit 10 can generate a powerful and impressive signal like an engine sound by increasing the gain of the low frequency components in the waveform table 1201 using gain G1 and lowering the gain of the high frequency components in the waveform table 1202 using gain G2 in the low vehicle speed range, as shown in Fig. 5. This allows the waveform generating unit 10 to generate a tone that gives a sense of acceleration.

[0115] Furthermore, as the vehicle 300 accelerates, the waveform generating unit 10 increases the gain of the high frequency components in the waveform table 1202 by using the gain G2 in the high vehicle speed range, and also sets the gain of the low frequency components in the waveform table 1201 low by using the gain G1, thereby generating a light exhaust sound signal. This allows the waveform generating unit 10 to generate an exhilarating tone.

[0116] As explained in operation 2 using FIGS. 7A to 7C, the waveform generating section 10 includes a plurality of waveform tables 1201, 1202, which can be switched by user operation.

[0117] According to this configuration, the waveform generating unit 10 can switch between a powerful EV sports tone and a futuristic EV tone at the user's choice on the tone screen 202 of the display audio 200, thereby providing the occupants of the vehicle 300 with a more preferred sound.

[0118] Furthermore, the multiple waveform tables may include a waveform table 1203 added by user operation, as described in operation 3 using Figures 8A and 8B, and the waveform generation unit 10 may be able to switch the waveform table that generates signals u1, ... uN from the multiple waveform tables to the added waveform table 1203.

[0119] According to this configuration, the waveform generation unit 10 can add waveform data of a tone desired by the user later, in addition to the waveform data incorporated as standard equipment in the active running sound effect generating device 100, thereby making the active running sound effect generating device 100 even more user-friendly.

[0120] 2, the waveform generating unit 10 may also include a skip table 123 and a generation processing unit 124. The skip table 123 acquires a skip number ΔP for the readout position based on vehicle information. The generation processing unit 124 reads out a signal at a position obtained by adding the acquired skip number ΔP to the previously readout position of the waveform table, and generates signals u1, ..., uN to be input to the speaker 50.

[0121] With this configuration, the waveform generating unit 10 simply reads the skip number ΔP from the skip table 123 according to the driving state of the vehicle 300 and adds the skip number ΔP to the previously read position, thereby further reducing the amount of calculation.

[0122] As shown in FIGS. 9A and 9B, a plurality of skip tables 123 may be provided, such as a first skip table 1231 and a second skip table 1232, and may be switched by a user's selection operation.

[0123] With this configuration, waveform generating unit 10 can switch frequencies based on the vehicle speed or the number of revolutions of the power unit and the skip number ΔP according to the driving state of vehicle 300, thereby further enhancing user preference. In particular, a desired tone can be implemented simply by switching waveform data (table-format data values) such as first skip table 1231 and second skip table 1232, so there is no need to change the software calculation formula and it is possible to easily switch to the desired skip table 123.

[0124] In addition, the vehicle information is vehicle speed or power unit rotation speed, and the first skip table 1231 in Figure 9A may be set to exponentially increase from a lower limit value to an upper limit value based on an increase in vehicle speed or rotation speed, and to return to the lower limit value when the upper limit value is reached.

[0125] With this configuration, first skip table 1231 in Fig. 9A can generate an infinite scale signal, which allows waveform generation section 10 to easily generate an infinite scale using first skip table 1231 in Fig. 9A.

[0126] Second Embodiment [Outline of the active running sound effect generator] FIG. 10 is a block diagram showing a schematic configuration of an active driving sound effect generation device according to the second embodiment mounted on a vehicle.

[0127] 10, the active running sound effect generation device 101 according to the second embodiment is configured by further including frequency characteristic adjustment processing units 13-1, ..., 13-N in addition to the waveform generation unit 10 of the active running sound effect generation device 100 according to the first embodiment. Note that when it is not necessary to limit any one of the frequency characteristic adjustment processing units 13-1, ..., 13-N, they are also simply referred to as frequency characteristic adjustment processing unit 13.

[0128] Each frequency characteristic adjustment processing unit 13-1, ..., 13-N has a band-pass filter that is applied to signals u1, ..., uN generated by the corresponding frequency component group generation processing unit 12, ..., 12-N (generation processing unit 124). The band-pass filter has a pass band between the frequency of a signal generated at the upper limit value of skip number ΔP in the skip table and the frequency of a signal generated at the lower limit value.

[0129] Fig. 11A is an explanatory diagram showing coefficients of a band-pass filter included in a frequency characteristic adjustment processing unit, and Fig. 11B is an explanatory diagram showing frequency characteristics based on the filter coefficients.

[0130] Each of the frequency characteristic adjustment processing units 13-1, ..., 13-N constitutes a band-pass filter that passes a predetermined frequency band based on a predetermined filter coefficient. Also, the frequency characteristic shown in Fig. 11B provides a predetermined pass frequency band by combining a low-pass filter that attenuates frequency components higher than a predetermined cutoff frequency without attenuating low-frequency components, and a high-pass filter that attenuates frequency components lower than the predetermined cutoff frequency without attenuating high-frequency components.

[0131] 12A is an explanatory diagram showing signals input to a frequency characteristic adjustment processing unit. As shown in FIG. 12A, when signals u1, uN input to frequency characteristic adjustment processing units 13-1, 13-N switch from a high frequency to a low frequency in response to a change in vehicle speed, the frequency switch is clearly (distinctly) output, as indicated by arrow 150.

[0132] In contrast, Fig. 12B is an explanatory diagram showing signals output from a frequency characteristic adjustment processing unit. As shown in Fig. 12B, signals f1,...fN output from frequency characteristic adjustment processing units 13-1,...13-N are obtained by applying band-pass filters having frequency characteristics as shown in Fig. 11B to signals u1,...uN input to frequency characteristic adjustment processing units 13-1,...13-N, respectively, to attenuate high and low frequency components. As a result, signals f1,...fN output from frequency characteristic adjustment processing units 13-1,...13-N can fade in and fade out each frequency component when switching from high to low frequency components.

[0133] [Active running sound effect generator in operation] The operation of the active running sound effect generation device according to the second embodiment will be described with reference to FIG.

[0134] FIG. 13 is an explanatory diagram showing a configuration for switching the filter coefficient of the active running sound effect generation device according to the second embodiment.

[0135] 13, the frequency characteristic adjustment processing unit 13 has a filter coefficient setting table 143. The filter coefficient setting table 143 has filter coefficients to be set in the band-pass filter according to the vehicle speed range.

[0136] For example, when the vehicle speed of the vehicle 300 is up to 60 [kph], the data set 144 is applied, and predetermined filter coefficients (0.0, 0.32, 0.01) are applied to the band-pass filter. When the vehicle speed of the vehicle 300 is from 100 [kph] to 160 [kph], the data set 145 is applied, and predetermined filter coefficients (0.0, 0.35, 0.00) are applied to the band-pass filter.

[0137] As a result, the frequency characteristic adjustment processing unit 13 switches the filter coefficient depending on the vehicle speed range, and applies a band pass filter to the signals u1, . . . uN input to the frequency characteristic adjustment processing units 13-1, . . . 13-N.

[0138] As described above, the active running sound effect generation device 101 according to the second embodiment has a band-pass filter in the waveform generation unit 10. The band-pass filter is applied to the signals u1, ... uN generated by the waveform generation unit 10. The band-pass filter has a pass frequency band between the frequency of the signal generated at the upper limit value of the skip table 123 and the frequency of the signal generated at the lower limit value.

[0139] According to this configuration, the active running sound effect generation device 101 of the second embodiment can apply a band-pass filter to the signals u1, ... uN input to the frequency characteristic adjustment processing units 13-1, ... 13-N, thereby eliminating the feeling of frequency switching that accompanies changes in vehicle speed and generating natural sound effects. [Explanation of symbols]

[0140] 10 Waveform generator 11 Vehicle speed / rotation speed acquisition unit 12, 12-1, 12-2, 12-N Frequency component group generation processing unit 13, 13-1, 13-N Frequency characteristic adjustment processing section 20 Gain coefficient calculation section 21 Accelerator opening sensor 22 Acceleration calculation unit 23 Rotation speed change calculation unit 24 Vehicle speed / rpm gain table 25 Acceleration Gain Table 26 Acceleration Gain Table 27 RPM Change Gain Table 30 Gain control section 31 Gain adjustment section 40 Sound control section 41 Sound image control processing section 121 Vehicle speed step table 122 Rotational Speed ​​Step Table 123 Skip Table 124 Generation processing unit 125,127,129,134 Wavetable 1201,1202,1203 Waveform Table 1231 First Skip Table 1232 Second Skip Table 131,132,133 Wavetable 161,162,163 Wavetable 300 vehicles

Claims

1. An active driving sound effect generating device mounted on a vehicle, a waveform generating unit that generates a signal from a waveform table in accordance with vehicle information; a speaker that outputs the signal generated by the waveform generating unit, The waveform table includes: A periodic waveform table is generated by adding up periodic data of an integer multiple of a plurality of waveform data with different periods, where the minimum time [s] that can be synchronized with the plurality of waveform data is defined as one period, and the end point and start point of the waveform table are consecutive, and the periodic waveform table includes a plurality of frequency components due to the plurality of waveform data. An active running sound effect generating device characterized by:

2. The waveform generating unit A plurality of the waveform tables is provided, and signals are generated from the plurality of waveform tables, respectively; The device itself is further comprising a plurality of gain adjustment units respectively corresponding to the signals generated from the plurality of waveform tables; 2. The active running sound effect generating device according to claim 1.

3. The waveform generating unit a low-frequency waveform table containing a relatively large number of low-frequency components, and a high-frequency waveform table containing a relatively large number of high-frequency components compared to the low-frequency waveform table; the vehicle information is a vehicle speed or a power unit rotation speed; When the vehicle speed or the rotational speed is relatively low, the gain of the low-frequency waveform table is increased, and when the vehicle speed or the rotational speed is relatively high, the gain of the high-frequency waveform table is increased.

3. The active running sound effect generating device according to claim 2.

4. the waveform generating unit includes a plurality of the waveform tables, The plurality of waveform tables include: It can be switched by user operation.

2. The active running sound effect generating device according to claim 1.

5. the plurality of waveform tables includes a waveform table added by a user operation; The waveform generating unit Among the plurality of waveform tables, the waveform table for generating the signal can be switched to the added waveform table.

5. The active running sound effect generating device according to claim 4.

6. The waveform generating unit a skip table that acquires the skip number of the read position based on the vehicle information; a generation processing unit that reads a signal at a position obtained by adding the acquired skip number to the previously read position of the waveform table, and generates a signal to be input to the speaker; 2. The active running sound effect generating device according to claim 1.

7. A plurality of the skip tables are provided, It can be switched by user selection.

7. The active running sound effect generating device according to claim 6.

8. The vehicle information includes: Vehicle speed or power unit rotation speed, The skip table is exponentially increasing the value from a lower limit value to an upper limit value based on an increase in the vehicle speed or the rotation speed, and returning to the lower limit value when the upper limit value is reached; 7. The active running sound effect generating device according to claim 6.

9. The waveform generating unit a band-pass filter applied to the signal generated by the generation processing unit; The bandpass filter is a pass frequency band is provided between the frequency of a signal generated at the upper limit value of the skip table and the frequency of a signal generated at the lower limit value; 9. The active running sound effect generating device according to claim 8.

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