Stabilization method for controlling volume and quality of road noise

Abstract

To provide a method for controlling sound quality and volume of a playback device that is compliant with environmental noise.SOLUTION: Driving noise is detected using the vibration acceleration PK(ACCin) of a vehicle structure rather than sound pressure, and a coupling path is offset by a signal R*PK(PseudoC(Sreplay)) which is the output strength of the simulated coupling path multiplied by a safety factor to address uncertain factors resulting from errors in the simulated coupling path PseudoC, which simulates the coupling path from playback to detection. The driving vibration acceleration strength RNL after offsetting is used to correct the degree of intonation EXP of the strength of the playback signal, the degree of intonation CLR of the clear voice component of the playback signal, and the degree of volume and sound quality TVR.SELECTED DRAWING: Figure 10

Description

[Technical field]

[0001] Stability of control for systems with closed loops. Adaptive Filter Ambient Sound Control [Background technology]

[0002] Volume and sound quality control for environmental noise Acoustic Signal Processing Vibration of the vehicle body during travel Car driving noise

[0003] The terms and symbols defined in the claims have the same meanings in the specification. Descriptions of running noise and running vibration acceleration are in agreement unless otherwise specified. The following considerations 1 to 12 in the development process of this proposal are related to the background technology.

[0004] Considerations in the development process of this proposal: Part 1. Current status of measures against running noise The first step in reducing noise from passenger cars while they are traveling is to use sound-absorbing materials. In other words, the most effective method is to convert as much vibration energy as possible into thermal energy. However, there is a trade-off between sound absorption performance and weight and cost, and a compromise must be made. Lightweighting tends to be a priority, especially in small cars. On the other hand, there are methods for actively suppressing running noise, but in practice, the maximum level of noise suppression is about 3 dB up to a range of 500 Hz, which is not at a level that is well received in the market. As a result, for cost-conscious cars, while some driving noise is unavoidable, at least the interior noise level is reduced. When listening, sound quality and volume control of the reproduced sound that matches the road noise is generally used.

[0005] Considerations in the development process of this proposal: Part 2. Main factors of variation in running noise As shown in Figure 1, even at the same driving speed, the noise intensity is roughly the same for small and medium-sized vehicles, with a variation of about 20 dB. This variation is due to road conditions, engine speed, and load conditions. Although we do not have a complete grasp of the market situation, many vehicle models have volume and sound quality control that depends on the driving speed instead of on road noise. From the example of actual measurements in Figure 1, we can see that the method adapted to the driving speed cannot cope with a variation of 20 dB at the same driving speed.

[0006] Considerations in the development process of this proposal. Part 3. Relationship between input regenerative signal strength and running noise strength FIG. 2 is a diagram illustrating the relationship between the playback signal strength and the running noise. If the road noise is louder than the playback signal, you will not be able to listen to whatever the signal is. If the playback signal has a large fluctuation in intensity, the playback sound may be too loud and may not be in the noisy range even if you turn up the volume. There are some weak and inaudible ranges, and in the case of announcements, it is noisy but the content cannot be heard, This causes the following inconvenience. By making the intensity constant, it is possible to adjust the playback sound intensity to a level that allows the content to be heard without increasing the maximum intensity more than necessary.

[0007] Considerations in the development process of this proposal Part 4. On the intonation of the intensity of the clear components of announcement signals Figure 3 shows an example of the inflection of the intelligible component strength extracted from a sample of a relatively low intelligibility announcement signal and a method of countering it. The figure shows an example of correction of 8ddB, Experimental results have shown that the appropriate maximum correction amount for the clear component intensity is approximately 10 dB. In this example, it can be seen that the clear component intensity fluctuates greatly. The weak intensity portion of the clear component can be stretched and made uniform. This problem seems to be solved by simply increasing the volume, but the strength of the signal itself and the strength of the clear components are not necessarily in a linear correlation relationship. Uniformly increasing the strength will overemphasize unnecessary components, causing discomfort, so it cannot be solved by simply increasing the volume.

[0008] Considerations in the development process of this proposal: Part 5. Overall required amount of intensity correction for the playback signal The average noise intensity varies by 20 dB up to 110 km / h. If the input signal strength change range is 10 dB and the clear component intonation range is 10 dB, Both are 20dB together. However, the intonation and the intensity intonation of the clear component are not completely independent. Due to common factors, 13 dB is statistically the practical range required. The variation range of road noise intensity due to road surface conditions is +-10dB from the average. Roughly speaking, a total intensity control range of 20dB+10dB+13dB=43dB is required. The essence of this proposal is that a stable and controllable intensity range of approximately 43 dB is required.

[0009] Considerations in the development process of this plan: 6.43 dB intensity control The figure of 43dB was obtained from experiments leading up to this proposal and from field testing of products that were being test marketed, and is not a universal figure. However, because it is an empirical figure that combines issues with multiple complex factors, it is a figure that is meaningful enough for product design. Even if extremely precise laboratory-level acoustic signal processing were possible, it would be difficult, according to common sense, to ensure the precision and stability of controlling the strength of a closed-loop system within a range of 43 dB. This is clear when we look at the current state of this type of functionality in regular compact cars, small hybrid cars, and small electric vehicles as of 2023.

[0010] Considerations in the development process of this proposal Part 7: How to achieve the target value of 43 dB There are three ways to deal with the 43dB noise: First, a road noise detection method that significantly reduces the closed-loop intensity gain caused by the coupling of the reproduction system and the detection system. Second, accurate and significant removal of the intensity of the reproduced sound components that are mixed into the detected signal intensity of driving noise. Third, the elimination of instability factors caused by the discrepancy between the simulated coupling path and the actual coupling path.

[0011] Considerations in the development process of this plan. Part 8. Relationship between vehicle body vibration acceleration and running noise Figure 4 shows the DIN cabinet mounted on the printed circuit board. The following shows an example of actual measurements of the relationship between the output strength of an acceleration sensor and noise intensity for each frequency band. Although there is a variation of about +-2dB in the relationship between the acceleration sensor and noise in each frequency band, it shows that there is generally a linear correlation. In other words, this shows that the vibration acceleration of the vehicle structure can be used as a substitute for the output of an air microphone.

[0012] Considerations in the development process of this proposal: Part 9. Strength of the connection between the speaker and the acceleration sensor The degree of coupling between the vibration acceleration of the vehicle body and the original playback signal is extremely important. Figure 5 shows a comparison of actual measurements of the closed-loop coupling strength between a microphone and an acceleration sensor. As a result, coupling from the accelerometer is 13dB to 14dB less than from the microphone. In other words, by substituting the vehicle acceleration for the running noise, the closed-loop coupling can be improved by 13 dB.

[0013] Considerations in the development process of this proposal Part 10. Reproduction signal components mixed with running noise Removal of original regenerated signal component strength from detected signal strength Figure 6 is a quote from Table 1 of Patent Application No. 2017-077577. Let X be the original signal component and Y be the detected environmental noise. This table shows that the intensity of the original reproduced component contained in the noise can be separated from the noise intensity with an accuracy of 0.05%. This table is theoretical. The accuracy in actual operation is It is determined by the difference between the simulated coupling path characteristic that generates the cancellation signal from the original playback signal and the coupling path in the actual operating state. Since this difference can be kept within an error or drift of about 10%, the actual cancellation amount that can be achieved is about 20 dB.

[0014] Considerations in the development process of this proposal. Part 11. Countermeasures for errors in the simulated coupling path In relation to the error described in No. 10 above, the stability of the control system must be given top priority. Therefore, there is a possibility that the control system may enter an unstable region due to deviation from the actual state of the control system. Correction is applied by multiplying the output strength of the simulated coupling path by a coefficient greater than 1. Furthermore, fixed vibration intensity components are removed as necessary. By using coefficient correction, a stable control range of about 20 dB can be ensured.

[0015] Considerations in the development process of this plan Part 12. Comprehensive improvement Observations 9, 10, and 11 are: This shows that it can be used to improve the control range by 13dB + 20dB + 10dB = 43dB. Although none of these values ​​have theoretical universality, they have been experimentally verified. While abstract theory is completely useless for designing practical devices with this kind of functionality, It is guaranteed that the verification results based on actual measurements can be applied to product design. That is, by utilizing and combining known detection methods and various signal processing techniques, This enables high-performance, wide-range volume control over driving noise versus sound quality that has never been achieved before. [Prior art documents] [Non-patent literature]

[0016] There is a large amount of literature available, but most of it is purely theoretical, and does not provide any useful information to help resolve the many challenges faced when creating practical products. Considerations 1 to 12 in the development process of this proposal are reference materials in lieu of non-patent literature. [Patent documents]

[0017] Patent application 2018-70016 Acoustic system, audio reproduction device, and audio reproduction method Patent application 2015-149105 In-vehicle sound reproduction device Patent application 2011-52671 In-vehicle sound reproduction device Patent application 2007-2-1622 Automatic sound quality control device and integrated circuit Patent application 2002-149930 Audio playback device Patent application 2001-188599 Audio signal decoding device Patent application No. 10-323316 All of the above are There is no description of the vibration acceleration intensity of the vehicle structure. There is no description of a method for subtracting the combined component of the reproduced signal strength from the detected vibration acceleration strength with high accuracy to perform correction. There is no description of the overall required control range of the input reproduction signal strength, which is related to the range of inflection of the input reproduction signal strength, the range of fluctuation of the road noise strength, and the range of inflection of the clear component strength, and a method for solving the problem. is raised. This is in light of the issue of improving the current control range of 43 dB. It can be said that the content is essentially different from the present case. Patent application 2017-077577 Noise spectrum detection method and anti-noise volume and sound quality control method A method for accurately detecting noise intensity from a signal containing a mixture of noise and a reproduced sound, comprising: It does not concern improving the controllable range of the overall absolutely necessary amount of road noise. Summary of the Invention [Problem to be solved by the invention]

[0018] Challenge #1 When controlling sound quality and volume in response to driving noise inside a moving vehicle, In particular, when the signal being played back is a voice, the voice cannot be heard if its intensity is in a weak range. If there are too many interruptions, it becomes difficult to hear the whole thing. If you turn up the volume until you can hear it, the noise level will be higher in the range where the traffic noise is already strong. The volume becomes so intense that it is unbearable to listen to. As a result, the volume cannot be increased. The same applies when the playback signal is music.

[0019] Challenge #2 By reinforcing the low intensity range of the input playback signal, which has a fluctuation in intensity, the intensity becomes uniform and becomes easier to hear. However, there is a coupling path from the playback speaker to the road noise detection, and the system forms a closed loop. Increasing the amplification level creates a positive feedback effect on the strength coupling of the closed loop, Intensity control becomes unstable. Since the intensity control system does not have instantaneous signal value coupling, there is no oscillation phenomenon in a normal linear system, but even with the coupling of the intensity state, positive feedback may act depending on the conditions. For this reason, there are limitations to the control performance of volume and sound quality in response to driving noise. [Means for solving the problem]

[0020] Combines the following functions:

[0021] Method 1: Detect running noise not by sound pressure but by using the running vibration acceleration of the vehicle body structure. Fig. 2 shows the measured correlation between running noise intensity and vibration acceleration intensity of a part of the car body. A linear correlation between vibration acceleration intensity and running noise intensity is observed in all frequency bands. By converting the running noise intensity into vibration acceleration intensity, an intensity control range of approximately 13 dB is ensured.

[0022] Means 2: By subtracting the original playback signal component strength from the detected signal strength of vibration acceleration, Extract accurate vibration acceleration intensity that has a first-order correlation with running noise.

[0023] Means 3. For the error of the simulated coupling path, A correction factor R greater than 1 is applied to the output signal strength of the simulated coupling path.

[0024] Means 4. With the detected and calculated accurate and safe corrected driving vibration acceleration intensity value, Corrects and equalizes fluctuations in the intensity of the input playback signal. If necessary, the intonation of the clear components when the input playback signal is an announcement is corrected and made uniform.

[0025] Means 5 Detected and calculated accurate and safe corrected driving vibration acceleration intensity and A combination of precise signal processing ensures a stable control range of 43dB. They are, The degree of inflection of the reproduced signal strength is corrected according to the degree of the corrected running vibration acceleration strength. After the correction, the degree of the inflection of the clear component intensity of the reproduction signal is corrected in accordance with the degree of the intensity of the traveling vibration acceleration. The volume and tone quality of the reproduced signal are corrected according to the degree of intensity of the corrected traveling vibration acceleration. It is a combination of: Effect of the Invention

[0026] Effect of Method 1 By using the vibration acceleration of a part of the vehicle body that has an intensity correlation with running noise, rather than sound, Reduces the coupling between the playback system and the acceleration detection function. The reduction effect is 13dB to 14dB in actual measurements.

[0027] Effect 2 of Method 2 PK(Y)=PK(X+Y)-P(X) By the signal processing, the original reproduction signal component intensity contained in the detection signal intensity is accurately removed. Theoretically, this effect is 74 dB, but in reality, it is about 20 dB because of an estimated error of about 10% due to the difference between the simulated coupling path and the actual coupling path.

[0028] Effect of Method 3 P(X+Y)-R*P(X) or P(X+Y)-R*P(X)-Bias A proportionality coefficient R greater than 1 such that By applying a fixed bias as necessary, This makes it possible to eliminate unstable factors in the control system caused by errors contained in the strength of the detection signal.

[0029] Effect of Method 4 The weak intensity parts of the input playback signal that have intensity fluctuations are stretched to correct them. The proper maximum range of extension can be improved by 10dB.

[0030] Effect of Method 5 The volume and sound quality of the playback signal, whose intensity has been equalized, is corrected in accordance with the intensity of the detected and processed driving vibration acceleration. This correction range can be secured to about 20 dB.

[0031] Combined effect of measures 1 to 5 The necessary range of 43 dB of intensity control of the input playback signal can be secured. Combining multiple methods is the essence of this invention. [Brief description of the drawings]

[0032] [Figure 1] Actual measurement examples of the relationship between driving speed and driving noise: (a) for a small vehicle with hearing weighting curve A, (b) for a medium-sized vehicle without hearing weighting [Diagram 2]An example diagram showing the relationship between the intonation of the announcement signal strength and road noise. (a) The relationship between the intonation of the announcement playback signal strength and road noise. (b) The relationship between the intonation of the playback signal and road noise when the announcement playback signal strength is increased in a road noise environment. (c) The relationship between the playback signal and road noise when the intonation of the announcement playback signal strength is kept constant in a strong road noise environment. [Diagram 3] FIG. 3(a) is a diagram for explaining the inflection of the intelligible component intensity of an announcement signal; (b) is an example of a signal in which the intelligible component intensity in FIG. 3(a) has been improved. [Figure 4] Actual measurement example of correlation between acceleration sensor output strength and noise intensity for each frequency band [Diagram 5] Actual measurement example of the coupling strength of the closed loop between an acoustic microphone and an acceleration sensor. (a) Comparative measurement results of the closed loop coupling strength depending on the type of sensor. (b) Block diagram of the measurement method for the measurement results in Figure 5(a). [Figure 6] A theoretical numerical table showing that accurate vibration acceleration can be calculated by subtracting the playback sound intensity included in the detected vibration acceleration. Excerpt from Patent Application 2017-077577 [Figure 7] Graph showing the characteristics of running noise control based on running vibration acceleration intensity [Figure 8] An explanation of sound volume and sound quality correction for vibration acceleration strength when driving [Figure 9] Graph showing closed loop gain margin of control system based on vibration acceleration strength during running [Figure 10] Block diagram for explaining the present invention [Figure 11] An example of a detailed block diagram for software design to realize the present invention BEST MODE FOR CARRYING OUT THEINVENTION

[0033] Remanufacturing equipment for small and medium-sized vehicles where weight reduction is essential [Industrial Applicability]

[0034] Acceleration sensor built into electronic circuit printed board Software for audio processors. EXAMPLES

[0035] Sound systems, like the hardware and software that are evaluated by human senses, Many of the evaluation items for industrial products are evaluated using adjectives. In such cases, if you must express a function numerically, the numerical value should be labeled with approximately The numerical values ​​used in the explanation of this case are modified by words such as "approximately" and "roughly", but these are equivalent to "statistically" and do not detract from the essence of this case. Sound quality is evaluated as a comprehensive assessment based on human senses, and if, for example, some factor changes by 1 dB negatively, it will cause a slight deterioration in some of the many different factors. In the process of arriving at the main proposal, try out one example of an improvement measure, and if it is insufficient, propose further improvements. By layering a typical cut-and-try approach, we were able to make trade-offs. There is a reason why the scope has been expanded. The essence of this proposal is The necessary control range is about 43 dB in total. The common control required for both intensity and clarity is about 13 dB. The required control amount is about 20 dB according to the average speed-dependent part of the running noise. The required control amount for driving noise according to road conditions, engine speed and load is about 10 dB. The method to satisfy the required control range of about 43 dB in total, the breakdown of which is as follows: The control range that can be improved by substituting the running noise with the running vibration acceleration is about 13 dB. The control range can be improved by about 20 dB by cutting off the closed loop coupling path of the control system. By eliminating the error factors between the actual coupling path and the simulated coupling path, the control range can be improved by about 10 dB. In both cases, the required amount is satisfied by the total improvement of multiple factors. The drawings are explained below.

[0036] Figure 1 shows an example of actual measurements of the relationship between running speed and running noise. The horizontal axis is the driving speed in [km / h]. The vertical axis is the sound level meter reading in [dB]. Running Speed ​​is the running speed. In both cases, the measurements were taken by recording the speedometer readings and sound level meter readings while driving. By increasing the number of measurements, the statistical reliability of the data is ensured. The vertical axis is dB logarithmic, and the horizontal axis is km / h, so it is proportional. Therefore, To see the correlation between the vertical and horizontal axes, for example, check the driving noise for every doubling of driving speed. Figure 1(a) shows the results for a small car. Road Noise (A-Curve) is a graph showing the relationship between driving speed and road noise. The hearing weighting is A. Since the noise level has had the low-frequency components removed, the noise level appears lower than it actually is. A Small Class Car indicates that the specimen is an example of a small car. Figure 1(b) shows the results for a medium-sized vehicle. Road Noise (Proportional) is a graph showing the relationship between driving speed and road noise. There is no hearing correction. Since this is a noise level that does not remove low-frequency components, the number shown is higher than the actual level. A Middle Class Car indicates that the specimen is an example of a medium-sized car. Figures 1(a) and 1(b) have the following three items in common, which are the essence of this proposal. First, the relationship between driving speed and driving noise is approximately linear on average. Secondly, the range of fluctuation in running noise at the same speed is roughly 20 dB, so it can be said that it fluctuates +-10 dB above or below the average trend for that speed. Thirdly, this variation depends mainly on the road condition and engine noise due to engine load.

[0037] FIG. 2 is a diagram illustrating an example of the relationship between the inflection of the reproduced signal intensity and the running noise. RNL indicates the driving noise level, Weak indicates the range in which the strength of the reproduced signal is too weak compared to the noise, Strong indicates the range in which the strength of the reproduced signal is too strong compared to the noise, and Stable indicates the range in which the strength of the reproduced signal is balanced compared to the noise. Generally, playback signals have intensity fluctuations. In particular, the intensity of announcement signals varies from person to person. The intensity of a good announcer's voice in conveying information is small, but In normal conversation situations, the voice expresses emotion and other emotions, resulting in a strong intonation. Especially when the road noise is loud, the intensity of music or announcements is low. I can't hear anything at all. Therefore, if the intensity is increased to an audible level, the high intensity range will result in an extremely loud volume that can interfere with driving. It is well known that the optimal countermeasure is to make the intensity of the reproduction signal uniform. The explanation of Figure 2 shows the problem that when compensating for weak parts, the playback signal in that range must be amplified. Roughly speaking, about 10 dB of reinforcement is required, but if the playback device is Since the control system becomes unstable as the reinforcement becomes stronger due to the closed loop with acoustic coupling, the necessity of about 10 dB of correction for the intensity inflection is the essence of this proposal.

[0038] FIG. 2(a) shows the relationship between the inflection of the playback signal strength of the announcement and the running noise. If road noise becomes stronger than the playback sound, the listener will need to turn up the volume.

[0039] Figure 2(b) shows the effect of increasing the playback signal strength of the announcement in a noisy driving environment. This shows the relationship between the inflection of the playback signal and the running noise. When the noise is strong, the reproduced sound may be both too loud and too soft depending on the inflection of the intensity.

[0040] FIG. 2(c) shows the relationship between the playback signal and the road noise when the intonation of the announcement playback signal intensity is kept constant in a strong road noise environment. In low-noise conditions, the intonation-corrected signal will sound unnatural, but in high-noise conditions, this unnaturalness will be weakened and the ability to hear the entire range will actually be a positive outcome for listening. In particular, when the content of the playback signal is news or talk, a balance must be struck between maximizing the audibility of the content and minimizing the annoyance caused by the volume.

[0041] FIG. 3 is an explanatory diagram of the intonation of the clear component of an announcement signal. The strength of the clear component of the announcement depends on the strength of the original announcement signal, Regardless of the strength of the announcement signal, it also depends on other factors. The strength of the intelligible component varies regardless of the loudness of the voice, depending on various conditions such as personality, posture at the time of speaking, and emotion. When the noise level increases, the audibility drops in the range where the intelligible component intensity is weak, even with a reproduced sound with an equalized intensity. In order to improve the audibility in a loud noise environment, it is necessary to equalize not only the intensity but also the intensity of the intelligible component. This is well known, including the method. The important point in relation to this proposal is that roughly 10 dB of clear component intensity correction is required. The maximum calculation for the reinforcement of the reproduced sound and clear component intensity is 20 dB, but due to common factors, the actual amount can be estimated at about 13 dB for both. Clearness Element in UN-Clear Announcement & Improvement The figure shows the intensity of the clear components of an unclear announcement signal for about 20 seconds and explains how to improve it. Required Level is the required level of intelligibility. Signal having big dispersion in clearness shows an example where the clear component has a large inflection. Improved Clearness shows an example of improvement in the inflection of the intensity of the clear components of the test signal. Clearness is improved as 3 points to 21 points in required level by 8 dB of clearness conditioning. This shows that the number of points exceeding the required intensity of clear components has improved from 3 to 21.

[0042] FIG. 3(a) shows the change in the intelligible component intensity of an example of an announcement signal with poor intelligibility. The signal is the intelligible component extracted from the original playback signal. There are three points above the required clarity intensity.

[0043] Figure 3(b) shows an example of a signal in which the inflection of the clear component intensity in Figure 3(a) has been improved. There are 21 points above the required clarity intensity.

[0044] Figure 4 shows an example of actual measurements of the relationship between the output strength of an acceleration sensor and noise intensity for each frequency band. Both the vertical and horizontal axes are converted to detected voltage, so the figure shows that the detected acceleration and running noise are in a linear correlation relationship with an error range of +-2dB. This shows that the detected signal strength of the vibration acceleration of the mechanism connected to the car body can be substituted for the running noise strength. This is one of the essential points of this proposal. Correlation between mechanical vibration & noise SPL is The figure shows an example of actual measurements showing the correlation between vibration acceleration and driving noise. Horizontal; Acceleration on the body [mV], Vertical; Noise SPL at the driver's location [mV] is, The horizontal axis of the graph represents the vibration acceleration of a part of the car's mechanism, expressed in units of the detector's output voltage [mV].The vertical axis of the graph represents the driving noise from the driver's seat, expressed in units of the detector's output voltage [mV]. 32Hz,63Hz indicates that the frequency range is from 32Hz to 63Hz. Measurement results are shown for seven frequency bands up to 4000Hz.

[0045] Figure 5 shows an example of the measurement of the coupling strength of the closed loop in the playback system of the acoustic microphone and the acceleration sensor. It shows that the control range can be improved by about 13 [dB] by substituting the running vibration acceleration for the noise. Using the vibration acceleration to detect the running noise is the essence of this proposal. Regarding the degree of coupling of the closed loop, the reality is that noise detection using a microphone is not sufficient to stabilize the control system to accommodate the required control range. Although we have not verified the actual measurement data of each car audio, as of 2023, It can be said that there is no car, at least small or mid-sized cars, that has been evaluated as meeting the potential needs of users when it comes to features to deal with driving noise. One of the important factors is the sensor for the running noise. In the explanation of Figure 4, we showed the results of actual measurements that show a linear correlation between the running vibration acceleration and the running noise, but it is essential that the acoustic coupling from the speaker to the acceleration sensor is much weaker than that of the microphone.

[0046] Sample Car: Medium Class indicates that the sample car is a medium-sized car. Pilot Signal: 20---100Hz Random Noise is the pilot signal for measurement. Indicates random noise in the range of 20Hz to 100Hz. Sensor: The vertical columns in the table indicate the type of sensor, The vertical columns of the table indicate the location of the sensor. The vertical column of the table, Signal Output to the Howling Point, is the sensor detection voltage just before the closed loop causes howling due to the gain adjustment of the power amplifier, and is expressed in [mV]. Improved Gain Ratio [dB] is the vertical column of the table, which shows the magnification of the improvement in the coupling strength of the closed loop. The numbers in parentheses indicate the dB conversion of the magnification. Microphone Non-Porlar is a microphone with a non-directional sensor. Acceleration Vertical-Polar: The sensor detects acceleration in the vertical direction. Driver's Head Rest: The measurement point is the driver's head restraint. Din-Box Frame: The measurement point is the frame of a DIN box. PCB installed in the DIN Box Cabinet indicates that the measurement point is housed in a DIN box. Print board in the cabinet, Microphone is a microphone. Acceleration is an acceleration sensor, Switch is the sensor changeover switch. M, N, and A indicate whether the switch is on the microphone side, neutral, or acceleration sensor side, respectively. Sensor Amp is an amplifier circuit for the sensor output signal. OSC 20-100Hz Random Noise: The measurement signal is random noise in the range of 20Hz to 100Hz. MIX is addition, Power Amp is a power amplifier with adjustable gain. Speaker L and Speaker R are the left and right playback speakers, V is a voltmeter for measuring the output level of the measurement signal. It is. A fixed bias signal is added to the acceleration signal and the degree of coupling is obtained by the voltmeter reading of the bias signal level at the feedback point. The standard is 200mV for a microphone, and 850mV and 1100mV indicate that the coupling is 4.25 times (12.6dB) and 5.5 times (14.8dB), respectively. Figure 5(a) shows the comparative measurement results of the degree of closed-loop coupling depending on the type of sensor. FIG. 5(b) is a block diagram of a method for measuring the measurement results of FIG. 5(a).

[0047] Figure 6 is a theoretical numerical table showing that accurate vibration acceleration can be calculated by subtracting the reproduced sound intensity included in the vibration acceleration. The essence of this proposal is that the control range can be improved by about 10 dB by using a theoretically accurate and reliable noise calculation method and then correcting the error caused by the deviation between the simulated coupling path and the coupling path of the actual device. This table is an excerpt from Patent Application No. 2017-077577 and shows that noise intensity can be accurately calculated from a signal that contains a mixture of noise and reproduced sound. However, this is the case when the noise and the reproduced sound are uncorrelated with each other. The driving noise and the reproduced sound are generally completely independent and uncorrelated. The parts of this table that are related to this proposal are max(Noise), max(Sig), max(Noise+Sig), max(noise+Sig)-max(sig) Each vertical column represents the time around that time. Noise intensity, playback input signal intensity, noise and playback signal mixed signal intensity, The intensity of the signal that contains the noise and the playback signal minus the intensity of the noise, This indicates that. Let Y be the pure running vibration acceleration, and X be the signal that is mixed into the sensor detection signal through the coupling path from the playback signal to the vibration acceleration sensor, Show that PK(Y)=PK(X+Y)-PK(X) holds with high accuracy. That is, it is possible to calculate an accurate running vibration acceleration intensity. For example, when PK(Y) is 30 and PK(x) is 1.0, the value of Pk(X+Y)-PK(X) is 29.986, and the accuracy is 0.05%. In theory, this shows that it is possible to detect pure running noise with amazing accuracy. In reality, an error of about 10% occurs due to the deviation between the simulated coupling path and the actual coupling path. This corresponds to about 20 dB in control amount, and is still an extremely effective method.

[0048] FIG. 7 is an explanatory diagram of the correction factor based on the running vibration acceleration intensity. The horizontal axis represents the running vibration acceleration intensity, and the vertical axis represents the correction factor. Expansion Curve indicates that the figure is an example of expansion characteristics. RNL is the running vibration acceleration intensity, EXPgain is the compensation control signal. RNLstart is the minimum point of the input playback signal strength intonation correction. RNLmax is the maximum point of intonation correction of the input playback signal strength. EXPmax is the maximum correction factor. The slope range of the correction starts at RNLstart and goes up to RNLmax. The correction characteristic EXPgain is used to correct the inflection of the input playback signal strength, the inflection of the clear components, This is the intermediate signal that is the basis for volume and sound quality correction. The specific control characteristics represented by the numerical values ​​are determined by design.

[0049] FIG. 8 is an explanatory diagram of sound quality and volume correction based on the intensity of vibration acceleration while traveling. The essence of this invention is to correct the sound quality and volume according to the vibration acceleration intensity after correction. The vibration acceleration during driving increases with the driving speed. The low frequency components tend to rise when the vehicle speed is low, and the high frequency components tend to become stronger as the vehicle speed increases. Therefore, the optimal control for the listener of the intensity of the vehicle noise is Depends on the playback frequency band. This diagram shows an example of control for three types of volume: bass, treble, and overall volume. The horizontal axis represents the running vibration, and the vertical axis represents the intensity correction factor. Compensation Curve indicates that the figure is an example of the characteristics of intensity compensation. Explanation of the same symbols as in FIG. 7 will be omitted. Gain Compensation is the amount of strength compensation. 0dB is no correction, Sample1, Sample2, and Sample3 are examples of correction of overall intensity, bass intensity, and treble intensity, respectively. S1max, S2max, and S3max are the maximum correction amounts for Sample1, Sample2, and Sample3, respectively. It is. The specific control characteristics represented by the numerical values ​​are determined by design.

[0050] 9 is an explanatory diagram of the closed loop gain margin of the control system for the reproduction signal strength based on the traveling vibration acceleration strength before and after improvement. The horizontal axis is the strength correction amount, and the vertical axis is the gain margin. The closed-loop gain margin of the signal strength control system is not as difficult as that of a linear system, and The system can be stabilized by simply correcting the error in strength. However, if the error is corrected too much in the direction of stability, the accuracy will deteriorate, so the degree of error correction is determined by a trade-off between performance and stability. This shows that the total control range after the improvement by this proposal is significantly expanded whether the closed loop gain margin is 3dB or 6dB. 43dB is the target value and is a achievable value. Gain Margin by Compensation is the gain margin by intensity compensation. Total Gain Compensation: Variation by RNL & Signal The horizontal axis is the total gain correction, i.e. the intensity correction amount, which depends on the RNL and the signal condition. Loop Gain Margin is the gain margin of the control system. 0dB, ​​3dB, 6dB are the closed loop gain margins. Before Improved is the characteristic before improvement, After Improved: characteristics after improvement, It is. The essence of the present invention is to significantly improve the overall control range by combining multiple elements.

[0051] FIG. 10 is a block diagram illustrating a basic design for realizing the present invention. It consists of a detection unit, a control signal generation unit, and a control unit. EXPC is the intensity correction function consisting of EXP. CLRC is a clear component strength intonation correction function consisting of CLR and CLRctrl. TVRC is an overall volume and sound quality correction function consisting of TVR and TVctrl. It is. Expctrl, CLRctrl and TVRctrl are intermediate signals corresponding to RNL. and generate the control signals Kexp, Kclr, and Ktvr, respectively. EXP, CLR, and TVR are control functions that receive their respective control signals. Coupling Detection calculates the strength of the original playback signal component contained in the detected vibration acceleration. To govern. Sreplay is the original playback signal, PseudoC() simulated connection path, Intensity in Pk() (), R is the error correction coefficient for the output strength of the simulated coupling path, R*PK(PseudoC(Sreplay)) is the output.

[0052] ACC Detection is a function that detects vibration acceleration caused by driving. The sensor element is usually mounted on a printed circuit board for easy assembly. The location of the sensor is determined by design. Accin is the detection signal of the vibration acceleration during driving. PK() is the strength in (), PK(ACCin) is the driving vibration acceleration intensity, Bias is a fixed portion of background or miscellaneous noise. If the bias does not affect performance, there is no need to provide it. Since PK(ACCin) includes the intensity of the vibration component generated by the speaker, The running vibration acceleration strength RNL used to control the entire system is It is calculated by subtracting R*(PK(PSEUDOC(Sreplay)) and Bias from PK(ACCin). RNL = PK(ACCin)-R*(PK(PSEUDOC(Sreplay))-Bias. RNL is the corrected running vibration acceleration intensity.

[0053] FIG. 11 is an example of a detailed block diagram for designing software and hardware to realize the present invention. The following is an explanation based on the block diagram of FIG. 10, in comparison with each block in FIG. The same symbols in Figure 11 as those in Figure 10 have the same functions. The double circle "adjusted for the best" indicates the factor that is adjusted to the best state. Below is a brief explanation

[0054] In the figure, (a) The Compensation Curve is a graph showing the change in the control signal over the range of RNL variation. The relationship between the corrected control signal EXPgain and the corrected running vibration acceleration intensity RNL is shown. As a result of actual measurements, depending on the vehicle model and road conditions, If some kind of correction is applied to the playback signal when the vehicle is moving from a stopped state to a speed of, say, 20km / h or less, it will sound strange to the ear. This also depends on the characteristics of hearing. Even when driving at low speeds, there is strong ultra-low frequency noise, but it is not noticeable to the ear. However, if the music being played contains ultra-low frequencies, the reproduced ultra-low frequency sound will be The ultra-low frequency of the noise masks it, making it difficult to feel. However, if you reinforce the ultra-low frequency, There are cases where you may feel uncomfortable. For example, 20km / h corresponds to this boundary RNLstart. When driving at high speeds and on poor road conditions, the road noise can be extremely loud. Noise control has limitations on the control range, and a maximum point is necessary. This value corresponds to RNLmax. The values ​​of RNLstart and RNLmax are determined by design.

[0055] In the figure, (b) (b1) to (b6) For a constant running vibration acceleration intensity RNL shown in (b1), The signal changes at each part corresponding to the input reproduction signal having intensity fluctuations shown in (b2) are shown. The horizontal axis indicates the passage of time, and the vertical axis indicates the respective signal intensities. t0, t1, t2, t3, t4, t5, and t6 are the timings of signal changes. (b1) is the state where the corrected running vibration acceleration RNL noise is constant, (b2) is the change in the intensity of the signal Sin within a short period of time, e.g., within 1 second. (b3) is the output QhS(PK(Sin)) of the time constant function Qh / S, (b4) is the output QQ(PK(Sin)) of the time constant function Q / Q, (b5) is the expansion control signal Kexp, (b6) is the intensity of the intonation-corrected signal Sexp when the road noise is loud. Shows the change in. On the condition that RNL is strong, In the time periods when Sin is weak, the expansion is applied, and the intonation of the input playback signal is corrected.

[0056] Regarding (b7) in the figure, (b7) shows the state where the input playback signal Sin continues to have a constant intensity. This shows how the signals of each part change when the corrected running vibration acceleration RNL changes suddenly. The sudden change in RNL is mainly due to discontinuous changes in road conditions while driving at high speeds. t7 to t16 are the timing of signal changes. Between t8 and t9, a short-lived strong RNL; Between t10 and t11, a short-time weak RNL; Between t12 and t14, a long and strong RNL; From t16 onwards, medium RNL; In the direction where the noise becomes stronger, the tracking is slowed down and the strength of Sout is slowly increased. The attack time is relatively long, about 8 seconds in one example. If the driving noise suddenly increases, This is a technique that was developed experimentally because making the response speed faster creates an unpleasant sensation when heard. In the direction in which the noise weakens, the tracking is accelerated and the intensity of Sout is rapidly lowered. The release time is relatively short, about one second in one example. When road noise suddenly changes from a loud state to a quiet state, if the response speed is slow, it will sound strange, so the release must be made quick. The specific values ​​of slow, fast, slow, and rapid are selected and determined by design.

[0057] ACC Detection: Driving vibration acceleration detection function ACCin, Detected Road Noise is the detected road vibration acceleration signal input, PK(ACCin) is the intensity of ACCin The driving vibration acceleration signal includes The original playback signal component from the speaker to the acceleration sensor. It contains some fixed vibrational components. About Bias The bias is a value for canceling the constant vibration noise of the system in actual operation and the noise generated by the detection system. RNL=PK(ACCin)- R*(PK(PSEUDOC(Sreply))-Bias is the corrected running vibration acceleration intensity.

[0058] Coupling Detection Coupling path correction intensity signal generation function PseudoC() is a simulated coupling path from the speaker to the accelerometer. Its characteristics are determined by design according to the actual conditions of the vehicle in which it is to be installed. Pseudo Coupled Signal is the output of PK() outputs the strength of the signal in (), R is a coefficient greater than 1, R*(PK(PseudoC(Sreply)) is the output, R is a coefficient that corrects the error between the simulated coupling path and the actual state. In order to avoid instability in the control system caused by this error, a coefficient R is inserted. Its value is To ensure the accuracy of the control system, To the maximum extent possible, the control system should not enter an unstable region. The trade-off relationship between these two is determined by design to optimize all functions.

[0059] About the EXPC Intensity and Inflection Correction Function EXP is the expansion factor. Expansion control signal generation function EXPctrl takes the compensation control signal Expgain and the playback input signal Sin as inputs, Decompression Control Signal Generates Kexp and controls the expansion factor EXP. The strength of the input playback signal PK(Sin) is the fast attack and hold The peak value is held for a certain period of time by the slow release time constant function Qh / S, and QhS(PK(Sin)) is output. On the other hand, PK(Sin) is a function of the time constant Q / Q, which has a fast attack and release. Construct QQ(PK(Sin)). Then, QhS(PK(Sin))-QQ(PK(Sin)) is generated, The decompression control signal generation function Expctrl is QhS(PK(Sin))-QQ(PK(Sin)) is multiplied by a coefficient that depends on EXPgain to generate an expansion control signal Kexp of a range appropriate for control. The input playback signal with intensity variation is For weak noise, no action is taken, but for strong noise, depending on the intensity of the running vibration acceleration, Kexp controls the expansion coefficient EXP, The weak range of the input playback signal strength is expanded and the intonation is suppressed.

[0060] About clear component intensity correction The method of correcting the intensity of the clear component is well known and is not essential to the present invention. The essence of this proposal is to make the intensity of the clear component correspond to the corrected vibration acceleration intensity corresponding to the running noise. It's in the control. The intelligibility component strength correction is used in situations where the playback signal is mainly news or commentary programs, etc., in a high-noise environment. This is an effective function for announcement signals that need to convey content accurately. In general, the intelligible components are the components necessary for the reproduction of the first, second, and third formants and consonants of speech. This is a high-frequency component, experimentally ranging from 1000Hz to 7000Hz. In the case of speech, the strength of the pitch component has an adverse effect on intelligibility, so although pitch is present, removing the energy of the pitch component significantly improves intelligibility. The method of correcting the intensity of the clear component is well known and is not the essence of the present invention. The essence of the present invention is to correct the intensity of the clear component in accordance with the intensity of the running vibration acceleration. The clear component expansion control signal Kclr, which is output by the clear component expansion control function CLRctrl, which receives the correction control signal EXPgain as input, controls the intensity of the clear component. CLR is the clarity control function. In one example, the frequency band from 1000Hz to 7000Hz is extracted and its intensity is controlled by Kctrl. Since this is specifically a control of the intonation of the intensity, it can be substituted with the same configuration as EXPctrl. Since this is a known function, a detailed description will be omitted.

[0061] About volume and sound intensity correction The method of correcting the intensity of the sound volume and sound quality is well known and is not essential to the present invention. The essence of this proposal is to make the strength of the regenerative signal correspond to the vibration acceleration strength after correction corresponding to the running noise. It's in the control. The compensation control signal EXPgain is received, and the sound quality volume control signal generation function TVRctrl The generated tone volume control signal Ktvr controls the tone volume intensity. An example of volume and sound quality control divided into volume, bass, and treble is shown in Fig. 5. The time-dependent characteristics of the control are adjusted to maximize the effect and minimize discomfort to the ear. The trade-offs are adjusted, especially the slow attack and fast release. The situation is as explained in FIG. 11(b7). [Explanation of symbols]

[0062] Road Noise (A-Curve) Actual measurement example of A-correction of the relationship between road speed and road noise A Small Class Car The sample is a small car. Road Noise (Proportional) Example of actual measurement of the relationship between road speed and road noise without correction A Middle Class Car The sample is a medium-sized car. Running Speed ​​[km / h] Car running speed [km / h] dB Noise Level

[0063] RNL Running Noise Level Weak The range where the playback sound intensity is too weak compared to noise. Strong: The range where the playback sound intensity is too strong compared to noise. Stable: The range in which the playback signal strength is balanced against noise.

[0064] Clearness Element in UN-Clear Announcement & Improvement The strength of clear components of unclear announcement signals and methods for improving them Required Level: Required level of clarity Signal Having Big Dispersion in Clearness Example of large fluctuation in clear component intensity Improved Clearness Example of improvement in the intonation of clear component strength Clearness is improved as 3 points to 21 points in the required level by 8dB of clarity conditioning. Improved the number of points required to meet the required standard from 3 to 21

[0065] Correlation between mechanical vibration & noise SPL Measurement example of correlation between running vibration acceleration intensity and running noise Horizontal; Acceleration on the body [mV] The horizontal axis is the vibration acceleration of the body in [mv]. Vertical; Noise SPL at the driver's location [mV] The vertical axis is the noise level from the driver's seat in [mv]. AAHz,BBHz band is from AAHz to BBHz

[0066] Sample Car: Medium Class The sample car is a medium-sized car. Pilot Signal: 20---100Hz Random Noise The pilot signal for the measurement Random noise in the range of 20Hz to 100Hz Sensor The vertical columns in the table indicate the type of sensor. Location The vertical columns in the table indicate where the sensor is installed. Signal Output to the Howling Point The vertical columns of the table show the sensor detection voltage just before the closed loop starts to howl. Improved Gain Ratio [dB] The vertical columns of the table show the ratio of improvement in the closed loop coupling strength. Microphone Non-Porlar The sensor is a non-directional microphone. Acceleration Vertical-Polar Sensor detects vertical acceleration Driver's Head Rest Measurement point is the driver's head rest Din-Box Frame Measurement point is the frame of a DIN box PCB installed in the DIN Box Cabinet The measurement point is a printed circuit board in a cabinet housed in a DIN box. Microphone Microphone sensor Acceleration Switch Sensor changeover switch, The M, N, and A switches are for the microphone, neutral, and acceleration sensor, respectively. Sensor Amp Amplification circuit for the sensor output signal OSC 20-100Hz Random Noise The measurement signal is random noise between 20Hz and 100Hz. MIX addition, Power Amp Gain adjustable power amplifier, Speaker L, Speaker R Left and right playback speakers V Voltmeter for measuring the output level of the measurement signal

[0067] A way to detect Noise from (Noise+Signal) A method for extracting noise from a noise-signal mixture. max(Noise) Noise intensity max(Sig) The strength of the playback input signal max(Noise+Sig) The strength of the signal that contains both noise and the original signal. max(noise+Sig)-max(sig) From the signal strength of the mixture of noise and the original playback signal Noise intensity subtracted Y Noise X: The original regenerated signal component mixed into the sensor detection signal by the coupling path PK(Y) Noise intensity PK(X) is the strength of the regenerative signal component mixed into the sensor detection signal PK(X+Y) The intensity of the composite signal of noise and playback signal components PK(X+Y)-P(x) is the theoretically calculated noise intensity that does not include the error of the actual equipment.

[0068] Expansion Curve Example of expansion characteristics RNL Running vibration acceleration intensity Expansion rate EXPgain Correction Control Signal RNLstart The minimum driving vibration acceleration intensity at which correction is applied. RNLmax Maximum running vibration acceleration intensity that applies correction EXPmax Maximum expansion rate

[0069] Compensation Curve Example of intensity compensation characteristics RNL Running vibration acceleration intensity Gain Compensation Intensity compensation amount RNLstart Minimum point of volume sound quality correction RNLmax Maximum volume and sound quality correction point 0dB No correction Sample1, Sample2, Sample3: Examples of correction of overall intensity, bass intensity, and treble intensity S1max, S2max, S3max Maximum correction amount for overall intensity, bass intensity, and treble intensity, respectively

[0070] Gain Margin by Compensation Gain Margin by Intensity Compensation Total Gain Compensation: Variation by RNL & Signal The horizontal axis represents the total gain correction amount that depends on the RNL and the signal state. Loop Gain Margin Closed loop gain margin of the control system 0dB, ​​3dB, 6dB closed loop gain margin Before Improved, After Improved: Examples of characteristics before and after improvement 43dB The improvement in control range by this proposal is 43dB

[0071] Sin, Sout, Sreplay are the input playback signal, the output playback signal, and the original playback signal, respectively. EXPC, CLRC, TVRC respectively, Intensity and intonation correction function, clear component intensity and intonation correction function, overall volume and sound quality correction function EXP, CLR, TVR: Signal strength inflection, clarity component strength, and sound quality volume strength adjustment functions Expctrl , CLRctrl, TVRctrl generate the control signals Kexp, Kclr, and Ktvr, respectively. Coupling Detection Calculation of the strength of the original playback signal component contained in the vibration acceleration PseudoC() simulated connection path Signal strength in Pk() R Error correction coefficient for strength simulated coupling path ACCdetection: Detects vibration acceleration while driving Accin: Driving vibration acceleration detection signal, PK(ACCin) Driving vibration acceleration intensity Bias Fixed amount of background noise or miscellaneous noise RNL corrected running vibration acceleration intensity Generate EXPgain from Compensation Curve RNL Control signals for correction of intonation, clarity and loudness Ability to generate EXPgain from CMP RNL EXPgain correction control signal

[0072] ACCin, Detected Road Noise Detected vibration acceleration signal input PK(ACCin) ACCin strength RNL=PK(ACCin)- R*(PK(PSEUDOC(Sreply))-Bias Corrected driving vibration acceleration intensity Expansion Curve Change in compensation control signal relative to the RNL fluctuation range EXPgain correction control signal Qh / S Time constant function with peak value hold function for a certain period of time Q / Q, S / Q time constant function t Time lapse t0, t1,,,t6 are the timings of signal changes (b1) Fixed RNL (b2) Sin with inflection (b3) Intermediate signal for generating control signal for expansion (b4) Intermediate signal for generating control signal for expansion (b5) Decompression control signal (b6) Signal intensity after stretching t7, t8,,,t16 Signal change timing (b7) Signals of each part when the intensity of Sin is constant and the running noise changes greatly

Claims

1. The input reproduction signal is the input reproduction signal for the signal processing of the present invention. The output reproduction signal is the input of the reproduction signal for the signal processing of the present invention. The original playback signal is a signal that is combined with the speaker drive signal at a fixed constant. The optimum original playback signal in the actual device is the input of the power amplifier, Intensity is the maximum value of the signal within a certain period of time. A function is a set of electronic elements, circuits, algorithms, and programs that perform a specific function. Either of these means: The driving vibration acceleration signal is a signal obtained by amplifying the output of an acceleration sensor attached to a structure connected to the vehicle body structure. The intensity of the running vibration acceleration signal is defined as the running vibration acceleration intensity. The intensity of the noise from a vehicle running is defined as the running noise intensity. First, we take advantage of the fact that the actual measurement results show that the running vibration acceleration intensity has a linear correlation with the running noise intensity. The playback device is a car audio playback device. The coupling path of vibration from the original playback signal of the playback device, through the vibration generated by the speaker, and then through the structure and air to the acceleration sensor is defined as the coupling path. Secondly, we take advantage of the fact that the strength of the coupling path using the acceleration sensor is significantly smaller than that when using a microphone for detecting sound waves. This "significantly small" means that a difference of 13 dB in actual measurements can be judged to be effective. A function for simulating a coupling path is defined as a simulated coupling path, The strength of the output signal of the simulated coupling path is set as the simulated coupling signal strength. The coefficient multiplied by the simulated combined signal strength is set as an error correction coefficient, The error correction coefficient is greater than 1. The simulated coupling signal strength is multiplied by the error correction coefficient to obtain a corrected simulated coupling strength. The simulated coupling strength after correction is affected by errors due to differences in the characteristics of the simulated coupling path and the actual coupling path. The property that the probability that the operation of the control system enters the unstable range is influenced is utilized. This can be achieved by adjusting the error correction coefficients: By weighing the sacrifice of control system accuracy against the stability of the control system, it is possible to achieve both the required accuracy and the required stability to a satisfactory state in light of practicality. Third, using an error correction factor; This "satisfactory state" means that it is possible to improve the theoretical and measured values ​​by 30 dB. The value obtained by subtracting the corrected simulated combined signal strength from the running vibration acceleration strength is The corrected running vibration acceleration intensity is The fourth feature is to have a function of controlling the degree of inflection of the intensity of the input reproduction signal to the reproduction device depending on the degree of the corrected running vibration acceleration intensity. The fifth feature is to have a function of controlling the volume and sound quality of the input playback signal of the playback device depending on the degree of the corrected running vibration acceleration intensity. having first, second, third, fourth and fifth channels to obtain an output reproduction signal; A method for controlling the sound quality and volume of a car playback device.

2. The clarity of the input playback signal of the playback device is determined depending on the degree of the corrected running vibration acceleration intensity. The sixth is to have a function of controlling the degree of intonation; 6. A method for controlling sound quality and volume of a playback device in a vehicle, comprising the steps of claim 1, claim 2, claim 3, claim 4 and claim 5.

3. PK() is the strength of the signal in (), Q / Q is the time constant for fast attack and fast release. Qh / S is the time constant for fast attack, maximum hold, and slow release. The fast and slow time constants are the relative relationship between attack and release. The speed and hold time of each are determined individually by design. The corrected running vibration acceleration intensity of claim 1 is provided with a range from a minimum point RLNstart to a maximum point RNLmax, EXPctrl is the expansion control signal generation function, A correction control characteristic EXPgain with a slope is set corresponding to RNLstart to RNLmax, Let's say EXPgain is used to correct the intensity of the input playback signal, The strength of the input playback signal to the playback device is the input playback signal strength PK(Sin), PK(Sin) is the common input for two time constant functions Q / Q and Qh / S, which have different time constants. The difference between the outputs of Q / Q and Qh / S, which occurs due to the time difference between their releases, is used. The signal obtained by subtracting the output of the Q / Q side from the output of the Qh / S side is Generate the signal QhS(PK(Sin))-QQPK(Sin)) that is the basis of the expansion control signal, This signal is input to EXPctrl, In addition, the expansion control signal Kexp is generated by applying EXPgain to EXPctrl. The seventh step is to correct the degree of inflection of the input reproduction signal corresponding to the corrected running vibration acceleration by using Kexp. A sound quality and volume control method according to claim 1, wherein the fourth or seventh aspect is a sound quality and volume control method.

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