Method for generating vibration signal, acoustic device, and acoustic system

Abstract

To provide a technique of applying a vibration based on a vibration signal to a user and improving the sound envelopment for the user.SOLUTION: A method for generating a vibration signal of the present disclosure generates a vibration signal for controlling an exciter which generates vibrations, by performing vibration generation processing including delay processing of delaying a sound source signal in an expansion range obtained by expanding a reference range in which a reverberant sound determined by the rule of a first wave surface exists, into a longer delay direction; and level adjusting processing of adjusting a level.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a vibration signal generation method, an acoustic device, and an acoustic system.

Background Art

[0002] In surround sound reproduction, by controlling early reflection sounds and reverberation sounds, etc., a sense of spread of the sound source (hereinafter also referred to as ASW (Apparent Source Width)) and a sense of being surrounded by sound (hereinafter , also referred to as LEV (Listener Envelopment)) are known techniques for reproduction.

[0003] In Patent Document 1, an acoustic device has been proposed that generates a reverberation signal indicating reverberation sound from a sound source signal and performs high-quality surround reproduction.

[0004] Also, in Patent Document 2, a system has been proposed that arranges a woofer for bass inside a seating part and transmits vibrations to the skin member of the seating part to provide a comfortable personal sound field space for the seated person.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] In order to obtain sufficient LEV, a plurality of conditions such as the positional relationship between the speaker and the listener need to be satisfied. However, even if these conditions are met, in the case of an acoustic system used in a limited space such as a vehicle, for example, the range where LEV can be obtained is limited to the vicinity of the head, and it has been difficult to obtain sufficient LEV throughout the listener's surroundings. Also, there is a method of controlling the sound image to be large and close to obtain a sense of being wrapped, but in this case, there are problems such as the blurring of the sound image of the sound source and the deterioration of the sense of localization.

[0007] Therefore, as a result of intensive studies, the inventor of the present application has found that by not only reproducing the reverberant sound by a speaker but also generating a vibration signal obtained by subjecting a sound source signal to delay processing and amplification processing, and applying the vibration based on the vibration signal to the user, the user's sense of being wrapped is improved.

[0008] The present disclosure aims to provide a technology that enables the improvement of the sense of being wrapped by applying vibrations based on a vibration signal to the user.

Means for Solving the Problems

[0009] To solve the above problems, the vibration signal generation method of the present disclosure is a vibration signal generation method for generating a vibration signal for controlling an exciter that generates vibrations, including a delay process of delaying a sound source signal and a level adjustment process (amplification or attenuation process) of adjusting the level within an extended range obtained by extending a reference range where reverberant sound obtained from the first wavefront law exists in the long delay direction, and generating the vibration signal by performing a vibration generation process.

Effects of the Invention

[0010] According to the present disclosure, it is possible to provide a technology that enables the improvement of the sense of being wrapped by applying vibrations based on a vibration signal to the user.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

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Figure 10

Figure 11

Embodiments for Carrying Out the Invention

[0012] Hereinafter, with reference to the drawings, embodiments of a vibration signal generation method, an audio device, and an audio system disclosed in the present application will be described. Note that the present invention is not limited only to the embodiments shown below.

[0013] <First Embodiment> FIG. 1 is a diagram showing a schematic configuration of an audio system 100 mounted on a vehicle 1. As shown in FIG. 1, the audio system 100 includes a head unit 10, a speaker unit 20, an exciter 30, an actuator 40, and an ECU (Electronic Control Unit) 50 for AVC (Active vibration control).

[0014] The head unit 10 reads data (audio source signals) stored in a storage medium such as a CD, DVD, or semiconductor memory, reproduces an acoustic signal, outputs sound from a plurality of speaker units 20, and generates a vibration signal to output vibration from a plurality of exciters 30. In this way, the head unit 10 not only reproduces sound but also reproduces the vibration when the sound spreads, and transmits it to the body of the user (listener), thereby improving the sense of being surrounded by sound. The specific generation methods of the acoustic signal and the vibration signal will be described later.

[0015] The head unit 10 may receive radio or TV broadcasts and generate an acoustic signal and a vibration signal based on this broadcast. Further, the head unit 10 may receive content from the user's smartphone, music player, or a server on the network, etc., and generate an acoustic signal and a vibration signal based on this content. The head unit 10 of the present embodiment may be an audio-visual-navigation integrated electronic device (in-vehicle device) having, in addition to an audio function, a visual function such as video playback or TV broadcast display, and a navigation function for setting a destination and a route via point according to the operation of the occupant and performing route guidance (navigation) to the destination.

[0016] Also, the head unit 10 has an ANC (Active Noise Control) function for detecting the noise during running in the vehicle 1 and canceling the noise by outputting a sound having a phase opposite to that of this noise from the speaker unit 20.

[0017] FIG. 2 is a diagram schematically showing the arrangement of the speaker units 20 provided in the vehicle. In FIG. 2, the upper side of the figure is the front of the vehicle, that is, the direction in which the vehicle advances, the lower side of the figure is the rear of the vehicle, the left side of the figure is the left of the vehicle, and the right side of the figure is the right of the vehicle.

[0018] In the example of FIG. 2, twelve speaker units 20 (CTR, FR, WFR, ROR, RR, SR, WF, FL, WFL, ROL, RL, SL) are installed in the vehicle. Among the plurality of speaker units 20, the speaker unit CTR is a so-called center speaker arranged at the front center inside the vehicle. The speaker unit FR is a speaker arranged on the right front side inside the vehicle. The speaker unit WFR is a woofer arranged on the right front side inside the vehicle and below the right front seat (driver's seat) 21. The speaker unit ROR is installed on the right side of the ceiling portion substantially in the center in the front-rear direction of the passenger compartment and is a speaker for suppressing reflected sound and ambient sound. The speaker unit RR is a speaker arranged on the right rear side inside the vehicle. The speaker unit SR is a speaker provided behind the speaker unit RR and behind the right rear seat 23. The speaker unit WF is a woofer arranged at the rear center inside the vehicle and at the lower rear of the center rear seat 24. The speaker unit FL is a speaker arranged on the left front side inside the vehicle. The speaker unit WFL is a woofer arranged on the left front side inside the vehicle and below the left front seat (passenger seat) 22. The speaker unit ROL is installed on the left side of the ceiling portion substantially in the center in the front-rear direction of the passenger compartment and is a speaker for suppressing reflected sound and ambient sound. The speaker unit RL is a speaker arranged on the left rear side inside the vehicle. The speaker unit SL is a speaker provided behind the speaker unit RL and behind the left rear seat 25. Thus, the acoustic system 100 of the present embodiment performs surround reproduction by arranging speakers so as to surround each seat of the vehicle 1 and outputting sound from around the users sitting in each seat. Note that the arrangement of the speakers is not limited to the configuration of FIG. 2, and a configuration with additional speaker units or a configuration omitting some speaker units may also be acceptable. For example, a plurality of the speaker units CTR, FR, RR, SR, FL, RL, SL may be provided with different heights in the vertical direction of the vehicle 1, respectively.

[0019] The speaker unit 20 may be configured to be connected to the head unit 10 by wire, for example, and the diaphragm is driven by an acoustic signal (electrical signal) supplied from the head unit 10 to output physical sound (vibration of air). Further, the speaker unit 20 includes a receiving unit, a driving unit, and a speaker. The receiving unit wirelessly receives an acoustic signal from the head unit 10, and the driving unit converts the acoustic signal into an electrical signal for driving the speaker and supplies it to the speaker, and the speaker outputs sound.

[0020] The exciter 30 is composed of an electro-magnetic circuit, a piezoelectric element, or other electric vibration converters, and vibrates in response to a vibration signal provided from the head unit 10. FIG. 3 is a diagram showing the arrangement of the exciters 30 provided in each seat. Among the plurality of exciters 30, the exciter EA is a vibration device that is embedded in the seat surface of the seat and vibrates the seat surface to give vibration to the user. The exciter EB is a vibration device that is embedded in the backrest (seat back) of the seat and vibrates the front surface of the backrest (the surface in contact with the user's waist and back) to give vibration to the user. A plurality of exciters EB may be provided with different positions in the vertical direction of the seat and the left-right direction of the seat (vehicle width direction). The exciter EC is a vibration device that is attached to the seat belt and vibrates the seat belt to give vibration to the user wearing the seat belt. A plurality of exciters EC may be provided with different positions in the vertical direction of the seat and the left-right direction of the seat (vehicle width direction). In the example of FIG. 3 like this, the exciters EA, EB, and EC give vibration from below, behind, and in front of the user. Not limited to this, the exciter 30 may be provided at less than three or four or more locations in each seat.

[0021] FIG. 4 is a block diagram showing a configuration example of the acoustic system 100 including the head unit 10. In FIG. 4, the components necessary for explaining the features of the present embodiment are mainly shown, and the description of general components is omitted. In other words, each configuration illustrated in FIG. 4 The elements are functionally conceptual and do not necessarily have to be physically configured as shown in the drawings. For example, the specific forms of distribution and integration of each functional block are not limited to those shown in the drawings, and all or part of them can be functionally or physically distributed and integrated in any unit according to various loads, usage situations, etc.

[0022] As illustrated in FIG. 4, the head unit 10 is an information processing device (computer) having a control unit 101, a memory 102, an input / output IF 103, and an amplifier 104 that are interconnected by a connection bus 110. In FIG. 4, the head unit 10 is configured to include the amplifier 104, but the head unit (acoustic device) and the amplifier 104 may be separate entities.

[0023] The control unit 101 controls the entire head unit and is composed of, for example, a CPU (Central Processing Unit), an MPU (Micro Processing Unit), a main memory device, etc. The control unit 101 is also referred to as a controller or a processor. The control unit 101 is not limited to a configuration having a single processor and may have a multi-processor configuration. Also, the processor constituting the control unit 101 may have a multi-core configuration. The main memory device is used as a working area of the control unit 101, a storage area for programs and data, and a buffer area for communication data. The main memory device includes, for example, a Random Access Memory (RAM), or a combination of a RAM and a Read Only Memory (ROM). The main memory device is a storage medium in which the control unit 101 caches programs and data and expands the working area.

[0024] The memory 102 is an auxiliary storage device that stores programs executed by the control unit 101, operation setting information, etc. The memory 102 is not limited to an internal storage device built into the head unit 10. For example, the memory 102 may be an HDD (Hard-disk Drive) or an SSD (Solid State Drive), EPROM (Erasable Programmable ROM), flash memory, US B memory, memory cards, etc.

[0025] The input / output IF 103 is an interface for inputting and outputting data with other devices such as a content server, a speaker unit, an amplifier 104, and an ECU 50. The input / output IF 14 inputs and outputs data to and from devices such as a disk drive that reads data from a storage medium such as a CD or DVD, an operation unit that receives operations by a user, a display device that displays a display for the user, and a communication module. Further, the input / output IF 14 inputs and outputs data to and from devices such as a tuner that receives radio or TV broadcast waves, a reader / writer that reads and writes data to and from a storage medium such as a memory card, a microphone, and a sensor. The operation unit is an input means that receives an operation by a user and inputs operation information indicating this operation to the control unit 101. The operation unit may be, for example, a button, a switch, a dial (rotary knob), a lever, or the like. Further, the operation unit may be a touch panel provided over the display surface of the display device. The display device is an output means that displays information regarding music playback and the like to the user. The communication module is an interface that communicates with other devices such as a content server and a speaker unit via a communication line. Note that a plurality of each of the above-described components may be provided, or some of the components may not be provided.

[0026] In the head unit 10, the control unit 101 functions as each processing unit such as a sound source acquisition unit 11, a sound signal generation unit 12, a vibration signal generation unit 13, an output control unit 14, an ANC unit 15, and an AVC unit 16 shown in FIG. 4 by executing an application program. However, at least some of the processing of the above-described each processing unit may be provided by a DSP (Digital Signal Processor), an ASIC (Application Specific Integrated Circuit), or the like. Also, each of the above At least a part of the processing unit may be a dedicated LS such as an FPGA (Field-Programmable Gate Array), other large scale integration (LSI), or other digital circuits. Also, a configuration in which at least a part of the above-mentioned processing unit includes an analog circuit may be adopted. I (large scale integration), or other digital circuits. Also, each of the above processing units may be configured to include an analog circuit in at least a part thereof.

[0027] The sound source acquisition unit 11 reads and acquires a sound source signal from a sound source device such as a CD, DVD, USB memory, or memory card. Also, the sound source acquisition unit 11 can acquire a sound source signal from an external sound source device such as a content server or NAS (Network Attached Storage) via a network.

[0028] The sound signal generation unit 12 generates an acoustic signal based on the sound source signal. Also, the vibration signal generation unit 13 generates a vibration signal based on the sound source signal. For example, the vibration signal generation unit 13 performs signal processing for delaying and adjusting the level of the sound source signal a plurality of times, and performs a vibration generation process of adding the outputs of each of these plurality of signal processes to generate a vibration signal. At this time, when the sound signal generation unit 12 and the vibration signal generation unit 13 receive an operation by the user regarding the on / off of the surround playback function, the degree of the sense of envelopment of the sound, etc., they generate an acoustic signal and a vibration signal that reflect this user operation.

[0029] The output control unit 14 supplies the acoustic signal to the speaker unit 20 and supplies the vibration signal to the exciter 30 via the amplifier 104. Thereby, the output control unit 14 outputs a sound corresponding to the acoustic signal and outputs a vibration corresponding to the vibration signal at the same time.

[0030] The ANC unit 15 detects the noise inside the vehicle via a microphone, generates an acoustic signal that is out of phase with this noise, supplies the acoustic signal to each speaker unit 20 via the amplifier 104, and cancels the noise by causing each speaker unit 20 to output a sound that is out of phase with the noise, thereby executing active noise control (ANC). This ANC may be continuously executed, for example, from when the accessory power supply of the vehicle 1 is turned on until it is turned off.

[0031] The AVC unit 16 provides a vibration signal to an actuator 40 provided, for example, between the engine and the subframe of the vehicle 1, and vibrates the actuator 40 so as to cancel the vibration transmitted from the engine to the subframe, thereby executing active vibration control (AVC). In this case, vibration is detected by a sensor provided near the actuator of the subframe, and the AVC ECU 50 inputs the detection result of this vibration to the control unit 101. Based on this detection result, the AVC unit 16 generates a vibration signal so as to be a vibration out of phase with the vibration of the engine and provides it to the speaker unit 20. Note that the actuator 40 is not limited to being between the engine and the subframe, and may be near the object whose vibration is to be suppressed, such as between the suspension and the frame or between the seat and the floor surface. This AVC may be continuously executed, for example, from when the accessory power supply of the vehicle 1 is turned on until it is turned off.

[0032] [Method for Generating Acoustic Signal and Vibration Signal] FIG. 5 is an explanatory diagram for explaining acoustic characteristics. As shown in FIG. 5, it is known that a user 90 who listens to the sound from a sound source S in space can perceive a plurality of types of spatial impressions as acoustic characteristics. For example, as acoustic characteristics, there are an apparent sound source width ASW1 and an apparent sound source front-back width ASW2 defined as the "width of the apparent sound source" that is perceived by fusing the direct sound both temporally and spatially, an apparent sound source distance R defined as the "distance to the apparent sound source", and an enclosed feeling LEV defined as the "feeling that the surroundings of the listener are filled by sound sources other than the apparent sound source". Hereinafter, when the apparent sound source left-right width ASW1 and the apparent sound source front-back width ASW2 are not particularly distinguished, they are described as the apparent sound source width ASW. Note that the user 90 is an example of a listener.

[0033] FIG. 6 is a graph showing a certain sound (direct sound) and sound components including reflected sounds and reverberant sounds related to this direct sound. In the graph of FIG. 6, the horizontal axis represents time and the vertical axis represents the acoustic level. Also, in FIG. 6, the thick straight line indicates the waveform 91 of the direct sound, and the thick broken line indicates the waveforms 92 of the reflected sound and the reverberant sound.

[0034] The sound components in FIG. 6 are extracted, for example, from a sound source signal by time-frequency analysis such as Fourier transform. Also, the sound components are obtained from the sound source signal, for example, using an FIR (Finite Impulse Response) filter or , an IIR (Infinite Impulse Response) filter, etc. Then, as shown in FIG. 6, a threshold value T1 obtained from the law of the first wavefront is set. Here, the law of the first wavefront is, for example, a phenomenon in which when one of two sounds reaches the user with a sufficiently small delay with respect to the other sound, the user cannot perceive the sound that reaches with a delay. And the above-described threshold value T1 is obtained from the law of the first wavefront and is specifically the boundary of the delay that cannot be perceived. Therefore, a sound that is delayed more than the threshold value T1 will be perceived by the user as, for example, a reverberant sound. Also, when the delay with respect to the direct sound becomes larger than this reverberant sound, it will be perceived by the user as a separated sound separated from the direct sound. Thus, as shown in FIG. 6, a threshold value T2 obtained from the law of the first wavefront is set. The threshold value T2 is the boundary of the delay that becomes a separated sound among the reverberant sounds obtained by the threshold value T1. As a result, the sound components are divided into a first sound component existing in region A1 (a region with a delay less than the threshold value T1 and a low level) before the threshold value T1 and a second sound component existing in region A2 from the threshold value T1 to the threshold value T2 in the coordinate system composed of the time axis and the amplitude level axis shown in FIG. 6. Note that region A1 is also referred to as the first range. Region A2 is also referred to as the second range or the reference range. The sound signal generation unit 12 performs processes such as generating and amplifying the reverberant sound in region A2, and generates an acoustic signal so that surround sound reproduction specified by the user can be performed. For example, when the user performs an operation to specify a desired effect such as "hall", "live", "classical", etc., the sound signal generation unit 12 generates a reverberant sound or the like based on parameters corresponding to this specification, and generates an acoustic signal to be supplied to each speaker unit 20. Also, the sound signal generation unit 12 may generate an acoustic signal so as to perform sound image localization control, spread feeling control, voice emphasis, etc. Note that since known techniques can be used for the specific methods of generating these acoustic signals, detailed descriptions are omitted.

[0035] As a result of intensive research, the inventor of the present invention has found that when performing the above-described surround reproduction, a vibration signal is generated by subjecting a sound source signal to delay processing and amplification processing (level adjustment processing), and the vibration signal is supplied to the exciter 30 to cause vibration, thereby giving vibration to the user, and the sense of being wrapped perceived by the user can be improved. Here, the vibration given to the user has a lower frequency and a longer duration than sound, and has a lower resolution perceived by the user. For this reason, for example, while the acoustic signal in FIG. 6 is divided into the region A1 and the region (reference range) A2 by the threshold values T1 and T2 obtained from the law of the first wavefront, in the vibration signal, the regions A1 and A2 are divided into the region A1α and the region (expansion range) A2α expanded in the long delay direction, and the sound source signal is delayed so as to enter at least within the region A2α. The vibration signal generation unit 13 divides, for example, into a first component included in the region A1 and a second component included in the region A2 in FIG. 6, and by performing delay processing and amplification processing, extends in the time direction like the sound components in the region A1α and the region (second range) A2α in FIG. 7 to obtain a vibration signal. In FIG. 7, the first component and the second component are extended in the time direction, but the present invention is not limited to this, and only the second component may be extended in the time direction to generate a vibration signal. Since the way of feeling the reverberant sound by hearing and the way of feeling the vibration by touch are different, the vibration signal generation unit 13 of the present embodiment adjusts the difference in the way of feeling by extending the vibration signal to the long delay side as shown in FIG. 7, so that the user can appropriately associate the reverberant sound and the vibration signal generated from the same direct sound, thereby improving the sense of being wrapped.

[0036] FIG. 8 is a diagram showing an example of a configuration for generating a vibration signal in the vibration signal generation unit 13. As shown in FIG. 8, the vibration signal generation unit 13 includes a plurality of delay circuits D1 to Dn and a plurality of amplifiers AP1 to APn. In FIG. 8, a configuration for performing delay processing and amplification processing for generating a vibration signal is shown, and configurations for performing other processes are omitted. That is, the vibration signal generation unit 13 is not limited to the configuration in FIG. 8 and may include configurations other than the delay circuits D1 to Dn and the amplifiers AP1 to APn.

[0037] The sound source signal S1 is input to the delay circuit D1 and the amplifier AP1. Although the sound source signal S1 is continuously input to the delay circuit D1 and the amplifier AP1, in FIG. 8, for convenience of explanation, only a part of the waveform 91 is shown. The sound source signal S1 is amplified by the amplifier AP1 to become the signal S1A, and the waveform 91 of the sound source signal S1 is made to have the signal level H1 required by the exciter 30, like the waveform 91A of S1A. When the level of the signal required by the exciter 30 is substantially the same as that of the sound source signal S1, the amplifier AP1 may be omitted.

[0038] The sound source signal S1 input to the delay circuit D1 has its waveform 91 delayed by a predetermined delay time DT1 to become the waveform 92 and is made the signal S2. The signal S2 is input to the delay circuit D2 and the amplifier AP2. The signal S2 is amplified by the amplifier AP2 to become the signal S2A, and the waveform 92 of the signal S2 is made to have the signal level H2, like the waveform (vibration signal component) 92A of S2A. The amplifier AP2 has its amplification factor determined based on the parameters for the vibration signal such that the signal level H2 of the signal S2 is lower than the signal level H1 of the signal S1A. That is, the amplifier AP2 may have an amplification factor of less than 1 (attenuate the signal) even when the amplifier AP1 is omitted. Then, the signal S1A and the signal S2A are combined to become the signal S2B including the waveforms 91A and 92A.

[0039] The signal S2 input to the delay circuit D2 has its waveform 92 delayed by a predetermined delay time DT2 to become waveform 93, and is then made into signal S3. Signal S3 is input to the amplifier AP2 and the subsequent delay circuit. Signal S3 is amplified by the amplifier AP3 to become signal S3A, and the waveform 93 of signal S3 has its signal level set to H3, like the waveform (vibration signal component) 93A of S3A. Note that the amplifier AP3 has its amplification factor determined based on the parameters for the vibration signal such that the signal level H3 of signal S3A is lower than the signal level H2 of signal S2A. That is, the amplifiers AP1 to APn2 are set such that the amplification factor gradually decreases as going to the output side. When a plurality of vibration signal components with different delay times are generated for the same sound source signal in this way, the parameters for the vibration signal are set such that the attenuation rate of the plurality of vibration signal components over time is slower than the attenuation rate of the plurality of reverberation sounds generated from the same sound source signal over time, and the vibration signal including the plurality of vibration signal components is generated based on these parameters for the vibration signal. Then, signal S2B and signal S3A are combined to form a signal (not shown) including waveforms 91A, 92A, and 93A. Similarly, the delay process and the amplification process are repeated a plurality of times (n times) to generate the vibration signal SnB. Note that in FIG. 8, the processing of the analog signal is shown, but for the digital signal, the delay process and the amplification process may be performed in the same way. Also, in FIG. 8, an example using the delay circuits D1 to Dn and the amplifiers AP1 to APn is shown, but the control unit 101 may perform the same delay process and amplification process as in FIG. 8. The characteristics (delay characteristics and amplification factor) of each of the delay circuits D1 to Dn and the amplifiers AP1 to APn are set such that the relationship in FIG. 7 holds, that is, the parameters for the vibration signal are set such that the user can appropriately associate the reverberation sound and the vibration signal generated from the same direct sound. For example, when the control unit 101 performs the delay process and the amplification process (level adjustment process), the parameters for the vibration signal may be stored in a data table and these parameters may be used to perform each process. Also, in FIG. 8, an example using the amplifiers AP1 to APn for amplifying each signal is shown, but the amplifiers AP1 to APn may be level adjustment units that adjust each signal to the signal level required by the exciter 30.In this embodiment, further, in FIG. 8, a vibration signal was generated by performing delay processing and amplification processing on the sound source signal. However, the present invention is not limited to this. When the sound source signal or the acoustic signal is a multi-channel signal in which the direct sound and the reverberant sound are in separate channels, the signal of the reverberant sound may be extended in the time direction to generate a vibration signal. FIG. 9 is a diagram showing the process of extending the reverberant sound.

[0040] In the example of FIG. 9, the vibration signal generation unit 13 includes a plurality of extension circuits E1, E2 and a plurality of amplifiers AP1 to AP3. In the vibration signal generation unit 13 of FIG. 9, an acoustic signal M1 including a reverberant sound is input to the extension circuit E1 and the amplifier AP1 as an input signal. The acoustic signal M1 is continuously input to the extension circuit E1 and the amplifier AP1. However, in FIG. 9, for convenience of explanation, some waveforms are shown. The acoustic signal M1 is amplified by the amplifier AP1 to the signal level required by the exciter 30 and becomes the signal M1A. When the level of the signal required by the exciter 30 is substantially the same as that of the acoustic signal M1, the amplifier AP1 may be omitted.

[0041] The acoustic signal M1 input to the stretching circuit E1 is stretched in the time direction as shown in FIG. 7 to obtain a signal M2. The signal M2 is amplified by the amplifier AP2 to obtain a signal M2A, and this signal M2A and the signal M1A are combined to obtain a signal M2B. Similarly, the signal M2 is stretched by the stretching circuit E2, amplified by the amplifier AP3 to obtain a signal M3A, and this signal M3A and the signal M2B are combined to generate a vibration signal. Note that the number of the stretching circuits E1 and E2 and the amplifiers AP1 to AP3 is not particularly limited. However, since the input signal contains a plurality of sound components generated from the same sound source signal as reverberation sounds, the number may be smaller than that of the delay circuits D1 to Dn and the amplifiers AP1 to APn in FIG. 8. For example, a configuration including the stretching circuit E1 and the amplifiers AP1 and AP2 may be used. Note that, in FIG. 9, the processing of an analog signal is shown, but stretching processing and amplification processing (level adjustment processing) may be similarly performed on a digital signal. Also, in FIG. 9, an example using the stretching circuits E1 and E2 and the amplifiers AP1 to AP3 is shown, but the control unit 101 may perform delay processing and amplification processing similar to those in FIG. 9. The characteristics (delay characteristics and amplification factors) of each of the stretching circuits E1 and E2 and the amplifiers AP1 to AP3 are set with parameters for the vibration signal so that the relationship in FIG. 7 holds. For example, when the control unit 101 performs stretching processing and amplification processing, the parameters for the vibration signal may be stored in a data table, and each processing may be performed using the parameters.

[0042] FIG. 10 is a flowchart of a process for generating a vibration signal. For example, when reproduction of content is instructed by a user operation, the control unit 101 starts the process in FIG. 10.

[0043] In step S10, the control unit 101 determines whether the user's specification is a mode for performing surround playback. If the determination in step S10 is negative, the control unit 101 ends the processing of FIG. 10. If the determination in step S10 is positive, the control unit 101 proceeds to step S20 and turns off at least one of ANC and AVC. Thereby, the control unit 101 prevents the sound output for ANC and the vibration for AVC from affecting the sound output and vibration during surround playback. Note that when surround playback is not performed, ANC and AVC are not turned off, so a process of separately playing back (outputting sound) other content with ANC and AVC turned on may be executed. Also, step S20 is not an essential step. For example, when the influence of ANC and AVC can be ignored, the subsequent steps (surround playback) may be executed with ANC and AVC turned on.

[0044] In step S30, the control unit 101 acquires the first sound component in region A1 and the second sound component in region A2 from the sound source signal.

[0045] In step S40, the control unit 101 analyzes the sound source signal to obtain the degree of the sense of spread of the sound source. For example, when music is played in a large hall, the time from when the reverberant sound is reflected off a wall or the like until it reaches the user becomes longer, so the degree of the sense of spread is numerically obtained based on the time interval of the reverberant sound. For example, the value of the sense of spread is determined such that the longer the time interval of the reverberant sound, the larger the value of the sense of spread, and the shorter the time interval of the reverberant sound, the smaller the value of the sense of spread.

[0046] In step S50, the control unit 101 acquires information indicating the driving environment of the vehicle 1. Here, the driving environment of the vehicle 1 is, for example, the vehicle speed (driving speed), the degree of vibration, the magnitude of noise (noise level), the direction from which the noise can be heard, and the like.

[0047] In step S60, the control unit 101 acquires the parameters related to the surround playback specified by the user. For example, when the user operates the operation unit, "surround level" When parameters related to surround playback, such as "degree of sense of spaciousness" and "degree of sense of being wrapped", are input and stored in the memory 102, the control unit 101 reads and acquires these parameters from the memory 102.

[0048] In step S70, the control unit 101 adjusts the first sound component and the second sound component acquired in step S30 based on the driving state of the vehicle 1 acquired in step S50 and the parameters acquired in step S60, and generates an acoustic signal to each speaker unit 20. For example, when the user designates surround playback that reverberates in a relatively large space such as a hall, the control unit 101 performs processing such as delaying and amplifying the second sound component, or adding a pseudo-reverberation sound obtained by delaying the second sound component, and adjusts the acoustic signal of the reverberation sound output to each speaker unit 20. Further, based on the driving state, in a situation where the noise from the ceiling direction due to rain is greater than a predetermined value, the control unit 101 generates an acoustic signal output to each speaker unit 20 so that the sound image localization position is formed below the normal (reference position). Note that since a known technique can be used as a specific method for generating an acoustic signal output to each speaker unit 20 based on the driving state and parameters related to surround playback, detailed description thereof is omitted.

[0049] In step S80, the control unit 101 generates a vibration signal by performing delay processing and amplification processing on the first sound component and the second sound component acquired in step S30. Here, the control unit 101 adjusts based on the degree of sense of spread acquired in step S40, the driving state of the vehicle 1 acquired in step S50, and the parameters acquired in step S60, and generates a vibration signal to be provided to each exciter 30. For example, the control unit 101 mainly performs delay processing and amplification processing on the first sound component to generate a vibration signal for the exciter EC arranged on the front side of the user. Also, the control unit 101 mainly performs delay processing and amplification processing on the second sound component to generate vibration signals for the exciter EA arranged on the lower side of the user and the exciter EB arranged on the rear side of the user. Here, when the control unit 101 generates a vibration signal for the exciter EB, it may set a larger delay time when performing delay processing than when generating a vibration signal for the exciter EA. Also, when the degree of sense of spread acquired in step S40 or the degree of sense of spread specified by the user in step S60 is large, the control unit 101 sets a relatively large value for the delay time when performing delay processing. That is, the delay time when performing delay processing is set to a value corresponding to the degree of sense of spread.

[0050] Also, based on the driving state acquired in step S50, when the noise is large or the vibration due to driving (driving vibration) is large, the control unit 101 generates a vibration signal with a high vibration level according to the magnitude of the noise or driving vibration. Thereby, for example, even when the noise and vibration during driving are large and the surround effect is masked, the level of vibration given to the user from the exciter 30 is increased, and a sense of being surrounded by sound is ensured.

[0051] In step S90, the control unit 101 outputs the acoustic signal generated in step S70 to each speaker unit 20 and outputs the vibration signal generated in step S80 to each exciter 30. As a result, respective sounds are output from each speaker unit 20, surround reproduction is performed, and by applying vibration to the user from each exciter 30, the sense of being wrapped that the user perceives is improved. For example, compared with the case where the range of the sense of being wrapped obtained only by the sound of the acoustic signal is only near the head, when vibration by the exciter 30 is added, a sense of being wrapped that wraps the entire body is obtained as the body feels the vibration. Note that the control unit 101 performs each step, for example, in a predetermined time unit, for the generation of the acoustic signal (step S70), the generation of the vibration signal (step S80), and the output of the acoustic signal and the vibration signal (step S90), and repeats the flow of FIG. 10 periodically, so that the content can be continuously reproduced. That is, the acoustic signal and the vibration signal generated in steps S70 and S80 are output to the amplifier 104 in step S90, and while the amplifier 104 outputs sound based on this acoustic signal and vibration based on the vibration signal, the control unit 101 performs the next In the cycle, the acoustic signal and the vibration signal are generated in steps S70 and S80, and the next acoustic signal and vibration signal are output to the amplifier 104, so that continuous reproduction is performed. Not limited to this, the control unit 101 may perform parallel processing of the generation and output of the acoustic signal and the generation and output of the vibration signal by a multiprocessor or a multi-core.

[0052] [Effects of the Embodiment] (1) According to the present embodiment, by performing delay processing and amplification processing on the sound source signal, a vibration signal for controlling the exciter 30 is generated, and vibration is generated for the user. As a result, in addition to the surround effect by the sound of the speaker unit 20 arranged so as to surround the user, when the user perceives the vibration of the exciter 30 as if it were the vibration when the sound spreads, a sense of being wrapped in which the entire body is wrapped in sound is obtained, and the LEV is improved.

[0053] (2) In the acoustic system 100 of this embodiment, a reverberation sound generated from a sound source signal is extended in the time direction to generate a vibration signal. As a result, vibrations that are perceived later than the direct sound, such as reverberation sound, are accurately reproduced, and an appropriate sense of being wrapped is obtained.

[0054] (3) In the acoustic system 100 of this embodiment, the vibration generation process is a process of performing signal processing for delaying and adjusting the level of the sound source signal a plurality of times, and adding the outputs of the plurality of signal processes to generate the vibration signal. As a result, a reverberation sound can be obtained with high accuracy, and a vibration signal based on the reverberation sound can be obtained more appropriately.

[0055] (4) In the acoustic system 100 of this embodiment, when a plurality of vibration signal components having different delay times are generated for the same sound source signal, the attenuation rate of the plurality of vibration signal components over time is slower than the attenuation rate of a plurality of reverberation sounds generated from the same sound source signal. Thus, a vibration signal including the plurality of vibration signal components is generated. By setting the attenuation rate of the vibration indicated by the vibration signal to be slow in this way, the difference between the way the user feels the sound and the way the user feels the vibration is reduced, and a more appropriate sense of being wrapped is obtained.

[0056] (5) In the acoustic system 100 of this embodiment, the control unit 101 analyzes the sound source signal to obtain a sense of spread of the sound source, and generates a reverberation vibration signal so that the level of the vibration increases as the sense of spread of the sound source becomes stronger. When the sound spreads widely, the user has an empirical rule that the vibration caused by this sound also becomes larger. Therefore, when the sense of spread of the sound source is strong, the acoustic system 100 of this embodiment can improve the sense of presence by making the user perceive a large vibration corresponding thereto.

[0057] (6) In the acoustic system 100 of this embodiment, the driving environment of the vehicle in which the user is riding is acquired, and the vibration level of the vibration signal is set according to the driving environment. For example, when the noise during driving is large and the sound output from each speaker unit 20 is blocked and the sense of being wrapped is reduced, the level of vibration applied to the user by the exciter 30 can be increased to compensate for the sense of being wrapped.

[0058] (7) In the acoustic system 100 of this embodiment, during content playback, active noise vibration control is performed when the surround function is not used, and active noise vibration control is not performed when the surround function is used. Thereby, the acoustic system 100 prevents the sound output for ANC and the vibration for AVC from affecting the sound output and vibration during surround playback, and enables an appropriate sense of being wrapped to be obtained.

[0059] <Second Embodiment> FIG. 11 is a diagram showing the configuration of the acoustic system 200 according to the second embodiment. In this embodiment differs from the above-described first embodiment in that it includes a head-up display (HUD) 80, and the other configurations are the same. Therefore, in this embodiment, the same reference numerals are given to the same elements as those in the first embodiment described above, and the repeated description is omitted.

[0060] In addition to the display unit 60 provided on the front of the main body, the head unit 10A of the present embodiment includes a HUD 80. The HUD 80 includes a projection unit 81 provided on the upper part of the instrument panel of the vehicle 1 and a half mirror 82 provided along the front window. When the HUD 80 receives a video signal from the control unit 101, the projection unit 81 projects an image based on this video signal toward the half mirror 82. As a result, each user views the image through the half mirror 82, and thus perceives that the image is displayed in front of the front window where the half mirror 82 is provided. Further, in the audio system 200 of the present embodiment, the sound image formed by the sound output from each speaker unit 20 is localized in front of each user and on the center side of the vehicle. When each seat of the vehicle 1 is used as the listening position of the user and this listening position is used as a reference, the HUD 80 displays the video at a position in the same direction as the position where the sound image is formed. Note that the direction of the sound image and the direction of the image do not necessarily need to exactly match. For example, it is sufficient that for each user's listening position, it is the same whether it is in front or behind in the front-rear direction and whether it is on the right or left in the left-right direction.

[0061] When the content to be played includes a video signal, the head unit 10 provides the acoustic signal generated as described above to each speaker unit 20, provides the vibration signal to each exciter 30, and provides the video signal to the HUD 80 to display an image. Note that when there is a rich reverberant sound like classical music, the sound image may give an impression of being blurred. For this reason, the control unit 101 may process the video signal so as to blur the image to be displayed on the HUD 80 according to the sound image. For example, the control unit 101 smooths the image included in the video signal using a Gaussian filter or the like. Note that when the sense of spread of the sound is strong and the vibration level is increased, the control unit 101 may increase the smoothness when smoothing, and when the vibration level is decreased, the control unit 101 may decrease the smoothness when smoothing. Further, the control unit 101 may perform control to change the display state of the image according to the vibration level, such as increasing the brightness of the image when the vibration level is increased and decreasing the brightness of the image when the vibration level is decreased.

[0062] Note that the display unit for displaying an image is not limited to the HUD 80, and may be another type of display unit such as an HMD (Head Mounted Display) or smart glasses worn by the user.

[0063] When the audio system 200 of the present embodiment plays content including a video signal, in addition to outputting sound, it displays a video at a position in the same direction as the position of the sound image caused by the sound. In this way, the audio system 200 of the present embodiment can improve the sense of presence by displaying an image in addition to playing sound. For example, if a phenomenon such as a performance or conversation is reflected in the image and a sound that seems to be generated by this phenomenon is heard, the user recognizes that this sound is generated from the position of the image. At this time, while the user can clearly recognize the position of the phenomenon seen with the eyes, the position of the sound image heard with the ears is relatively ambiguous. Therefore, when there is a deviation between the position of the image and the position of the sound image, the user tends to adjust their recognition so that the position of the sound image coincides with the position of the image (hereinafter also referred to as synchronization). In the present embodiment, since the image is displayed so as to be visible in front of the front window, the user feels that the sound image is also located on the front side in synchronization with the position of this image, and can feel a wider spread of sound. Therefore, the audio system 200 of the present embodiment can enhance the sense of spread of sound.

[0064] Note that when playing surround content including an image, the position of the image seen by the user is clearly perceived, while the position of the sound image perceived by the ears is relatively ambiguous, and the way of feeling the image and the way of feeling the sound image are very different. Therefore, the audio system 200 of the present embodiment blurs and displays the image to be displayed on the HUD 80 in accordance with the sound image. Thereby, the audio system 200 can reduce the difference between the way of feeling the sound image and the way of feeling the image, and improve the sense of presence.

Description of Reference Numerals

[0065] 1: Vehicle 10, 10A: Head Unit 11: Sound Source Acquisition Unit 12: Sound signal generation unit 13: Vibration signal generation unit 14: Output control unit 15: ANC unit 16: AVC unit 20: Speaker unit 23: Right rear seat 24: Center rear seat 25: Left rear seat 30: Excitator 40: Actuator 50: ECU for AVC 60: Display unit 80: Head-up display (HUD) 81: Projection unit 82: Half mirror 90: User 100, 200: Audio system 101: Control unit 102: Memory 103: Input / output IF 104: Amplifier 110: Connection bus

Claims

1. A vibration signal generation method for generating a vibration signal for controlling an exciter that generates vibration, comprising: performing a vibration generation process including a delay process of delaying a sound source signal and a level adjustment process of adjusting a level within an extended range obtained by extending a reference range in which reverberation sound obtained from the law of the first wavefront exists in the long delay direction, and generating the vibration signal; Vibration signal generation method.

2. The vibration generation process is: a process of generating the vibration signal by stretching the reverberation sound generated from the sound source signal in the time direction; The vibration signal generation method according to Claim 1.

3. The vibration generation process is: performing signal processing for delaying and adjusting the level of the sound source signal a plurality of times, and generating the vibration signal by adding outputs of each of the plurality of signal processings; The vibration signal generation method according to Claim 1.

4. The vibration signal generation method according to Claim 1, wherein the sound source signal is analyzed to obtain a sense of spread of the sound source, and the vibration signal is generated such that the level of vibration increases as the sense of spread of the sound source becomes stronger.

5. The vibration signal generation method according to Claim 1, further comprising obtaining a driving environment of a vehicle in which a user is riding and setting a vibration level of the vibration signal according to the driving environment.

6. The vibration signal generation method according to Claim 1, wherein when using a surround function during content reproduction, at least one of active noise control and active vibration control is not performed.

7. generating a sound signal based on a sound source signal, generating the vibration signal by the vibration signal generation method according to any one of Claims 1 to 6, outputting sound based on the sound signal from a speaker, and outputting vibration based on the vibration signal from an exciter; Audio device.

8. An audio system including an audio device, a speaker that outputs sound based on a sound signal from the audio device, and an exciter that outputs vibration based on a vibration signal from the audio device, wherein the audio device generates a sound signal based on a sound source signal, and generates the vibration signal by the vibration signal generation method according to any one of Claims 1 to 6.

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