Patent Grant
11881201
This application is a U.S. National Phase of International Patent Application No. PCT/JP2020/031969 filed on Aug. 25, 2020, which claims priority benefit of Japanese Patent Application No. JP 2019-160508 filed in the Japan Patent Office on Sep. 3, 2019. Each of the above-referenced applications is hereby incorporated herein by reference in its entirety.
The present technology relates to a control apparatus for controlling an audio output apparatus having a tactile presentation function, to a loudspeaker apparatus, and to an audio output method.
In recent years, applications of stimulating the sense of touch via human skin or the like through a tactile reproduction device have been utilized in various scenes.
As tactile reproduction devices therefor, eccentric rotating mass (ERM), linear resonant actuator (LRA), and the like have been currently widely used, and devices with a resonant frequency that is a frequency (about several 100 Hz) that provides good sensitivity for the human sense of touch have been widely used for them (e.g., see Patent Literature 1).
Since the frequency band that provides high sensitivity for the human sense of touch is several 100 Hz, vibration reproduction devices that handle this band of several 100 Hz have been mainstream.
As other tactile reproduction devices, an electrostatic tactile display and a surface acoustic wave tactile display aiming at controlling a friction coefficient of a touched portion and realizing a desired tactile sense have been proposed (e.g., see Patent Literature 2). In addition, an airborne ultrasonic tactile display utilizing an acoustic radiation pressure of converged ultrasonic waves and an electrotactile display that electrically stimulates nerves and muscles that are connected to a tactile receptor have been proposed.
For applications utilizing those devices, especially for music listening, a vibration reproduction device is built in a headphone casing to reproduce vibration at the same time as music reproduction, to thereby emphasize bass sound.
Moreover, wearable speakers that do not take the form of headphones and are used hanging around a neck have been proposed. The wearable speakers include one (e.g., see Patent Literature 3) that transmits vibration to a user from the back together with sound output from the speaker by utilizing their contact with a user's body and one (e.g., see Patent Literature 4) that transmits vibration to a user by utilizing a resonance of a back pressure of speaker vibration.
Headphones and wearable (neck) speakers that perform tactile presentation can interfere with music listening because noise associated with vibration of vibrators provided for tactile presentation or driving of other tactile presentation devices reaches user's ears. Although noise that reaches ears can be reduced through a wearable speaker structure by some degree, noise having a frequency that provides higher sensitivity for human ears is generated, for example, in a case where vibration has higher frequency components for expressing a variety of tactile senses.
In view of the above-mentioned circumstances, the present technology has been made to provide a control apparatus, a loudspeaker apparatus, and an audio output method, by which noise from a tactile presentation device can be reduced.
A control apparatus according to an embodiment of the present technology includes a tactile control section and an audio control section.
The tactile control section generates, on the basis of a tactile signal for tactile presentation, a tactile control signal for driving a tactile presentation unit.
The audio control section generates, on the basis of a first audio signal and a second audio signal, an audio control signal for driving an audio output unit, the second audio signal containing sound components that are in an opposite phase to sound generated on the basis of the tactile signal and generated from the tactile presentation unit.
The audio control section may generate the audio control signal by adding the second audio signal to the first audio signal.
The control apparatus may further include a cancellation signal generation section that generates the second audio signal on the basis of the tactile signal.
The control apparatus may generate the audio control section generates a first signal for driving a first audio output unit that reproduces the first audio signal, and the cancellation signal generation section may generate a second signal for driving a second audio output unit that reproduces the second audio signal.
The cancellation signal generation section may generate the second audio signal on the basis of a frequency response characteristic of the audio output unit, a frequency response characteristic of the tactile presentation unit, and a transform function from vibration generated at the tactile presentation unit into sound.
A loudspeaker apparatus according to an embodiment of the present technology includes a tactile presentation unit, an audio output unit, a tactile control section, and an audio control section.
The tactile control section generates, on the basis of a tactile signal for tactile presentation, a tactile control signal for driving the tactile presentation unit.
The audio control section generates, on the basis of a first audio signal and a second audio signal, an audio control signal for driving the audio output unit, the second audio signal containing sound components that are in an opposite phase to sound generated on the basis of the tactile signal and generated from the tactile presentation unit.
The loudspeaker apparatus may further include a storage section that stores the tactile signal and the first audio signal.
The loudspeaker apparatus may further include a communication section that is capable of communicating with a server that stores the tactile signal and the first audio signal.
The audio output unit may include a common loudspeaker unit that reproduces the first audio signal and the second audio signal.
The audio output unit may include a first loudspeaker unit that reproduces the first audio signal and a second loudspeaker unit that reproduces the second audio signal.
The audio output unit may include a right loudspeaker and a left loudspeaker, and
the loudspeaker apparatus may further include a coupler for hanging around a neck, the coupler coupling the right loudspeaker with the left loudspeaker.
The tactile presentation unit may include a vibration device.
Alternatively, the tactile presentation unit may include an ultrasonic wave generator, an electrical muscle stimulator, or an air flow generator.
An audio output method according to an embodiment of the present technology acquires a tactile signal for tactile presentation and a first audio signal. A tactile signal for tactile presentation and a first audio signal are acquired. A tactile control signal for driving a tactile presentation unit is generated on the basis of the tactile signal. A second audio signal containing sound components in an opposite phase to sound generated from the tactile presentation unit on the basis of the tactile signal is generated. An audio control signal for driving an audio output unit is generated on the basis of the first audio signal and the second audio signal.
Hereinafter, each of embodiments according to the present technology will be described with reference to the drawings.
(Basic Configuration of Loudspeaker Apparatus)
The loudspeaker apparatus 100 includes a right loudspeaker 100R, a left loudspeaker 100L, and a coupler 100C that couples the right loudspeaker 100R with the left loudspeaker 100L. The coupler 100C is formed in an arbitrary shape capable of hanging around the neck of the user U, and the right loudspeaker 100R and the left loudspeaker 100L are positioned on both shoulders or upper portions of the chest of the user U.
The right loudspeaker 100R and the left loudspeaker 100L include, for example, audio output units 250, tactile presentation units 251, and casings 254 that house them. The right loudspeaker 100R and the left loudspeaker 100L typically reproduce audio signals by a stereo method. Reproduction sound is not particularly limited as long as it is reproducible sound or voice that is typically a musical piece, a conversation, a sound effect, or the like.
The audio output units 250 are electroacoustic conversion-type dynamic speakers. The audio output units 250 includes a diaphragm 250a, a voice coil 250b wound around the center portion of the diaphragm 250a, a fixation ring 250c that retains the diaphragm 250a to the casing 254, and a magnet assembly 250d arranged facing the diaphragm 250a. The voice coil 250b is arranged perpendicular to a direction of a magnetic flux produced in the magnet assembly 250d. When an audio signal (alternate current) is supplied into the voice coil 250b, the diaphragm 250a vibrates due to electromagnetic force that acts on the voice coil 250b. By the diaphragm 250a vibrating in accordance with the signal waveform of the audio signal, reproduction sound waves are generated.
The tactile presentation unit 251 includes a vibration device (vibrator) capable of generating tactile vibration, such as an eccentric rotating mass (ERM), a linear resonant actuator (LRA), and a piezoelectric element. The tactile presentation unit 251 is driven when a tactile signal for tactile presentation prepared in addition to a reproduction signal is input. The amplitude and frequency of the vibration are also not particularly limited. The tactile presentation unit 251 is not limited to a case where it is constituted by the single vibration device, and the tactile presentation unit 251 may be constituted by a plurality of vibration devices. In this case, the plurality of vibration devices may be driven at the same time or may be driven individually.
The casing 254 has an opening potion (sound input port) 254a for passing audio output (reproduction sound) to the outside, in a surface opposite to the diaphragm 250a of the audio output unit 250. The opening potion 254a is formed in a straight line shape to conform to a longitudinal direction of the casing 254 as shown in
The tactile presentation unit 251 is, for example, arranged on an inner surface on a side opposite to the opening potion 254a of the casing 254. The tactile presentation unit 251 presents tactile vibration to the user via the casing 254. In order to improve the transmissivity of tactile vibration, the casing 254 may be partially constituted by a relatively low rigidity material. The shape of the casing 254 is not limited to the shape shown in the figure, and an appropriate shape such as a disk-shape and a rectangular parallelepiped-shape can be employed.
Next, a control system of the loudspeaker apparatus 100 will be described.
The loudspeaker apparatus 100 includes a control apparatus 1 that controls driving of the audio output units 250 and the tactile presentation units 251 of the right loudspeaker 100R and the left loudspeaker 100L. The control apparatus 1 and other elements to be described later are built in the casing 254 of the right loudspeaker 100R or the left loudspeaker 100L. Alternatively, the control apparatus 1 may be configured as an external apparatus connected to the right loudspeaker 100R and the left loudspeaker 100L with a wire or wirelessly.
As shown in
The control apparatus 1 can be realized by hardware components used in a computer, such as a central processing unit (CPU), a random access memory (RAM), and a read only memory (ROM), and necessary software. Instead of or in addition to the CPU, a programmable logic device (PLD) such as a field programmable gate array (FPGA) or a digital signal processor (DSP) or other application specific integrated circuit (ASIC) and the like may be used. The control apparatus 1 executes a predetermined program, such that the audio control section 13, the tactile control section 14, and the cancellation signal generation section 17 are configured as functional blocks.
The loudspeaker apparatus 100 includes storage (storage section) 11, a decoding section 12, an audio output section 15, a tactile output section 16, and a communication section 18 as other hardware.
On the basis of the tactile signal for tactile presentation, the tactile control section 14 generates a tactile control signal for driving the tactile output section 16. The tactile signal is, as will be described later, data for tactile presentation (tactile data) stored in the storage 11 or an external server device 50 such as a cloud server. The tactile output section 16 includes the tactile presentation unit 251 shown in
On the basis of a first audio signal and a second audio signal, the audio control section 13 generates an audio control signal for driving the audio output section 15. In this embodiment, the audio control section 13 generates the audio control signal by adding the second audio signal to the first audio signal.
Here, the first audio signal is an audio signal of a musical piece or the like. The second audio signal is an audio signal that is generated on the basis of the tactile signal and includes sound components that are in an opposite phase to sound generated from the tactile output section 16. The first audio signal is data for audio reproduction (audio data) stored in the storage 11 or the server device 50. Moreover, the second audio signal is equivalent to a cancellation signal for cancelling the sound generated at the time of driving the tactile output section 16 and is generated by the cancellation signal generation section 17.
The cancellation signal generation section 17 is configured to be capable of generating the second audio signal on the basis of the tactile signal. The tactile signal is data for tactile presentation (vibration data) stored in the storage 11 or the server device 50. In this embodiment, the second audio signal is configured to be generated in the cancellation signal generation section 17, though not limited thereto. The second audio signal may be stored in the storage 11 or the server device 50 together with the first audio signal and the tactile signal.
The storage 11 is a storage device capable of storing the first audio signal and the tactile signal, such as a nonvolatile semiconductor memory. In this embodiment, the first audio signal and the tactile signal are stored in the storage 11 as digital data encoded as appropriate.
The decoding section 12 decodes the first audio signal and the tactile signal stored in the storage 11. The decoding section 12 may be configured as a functional block that forms a part of the control apparatus 1.
The communication section 18 is constituted by a communication module connectable to a network 10 with a wire or wirelessly. The communication section 18 is configured to be capable of communicating with the server device 50 via the network 10 and capable of acquiring the first audio signal and the tactile signal stored in the server device 50.
The audio output section 15 includes the audio output units 250 of the right loudspeaker 100R and the left loudspeaker 100L shown in
The tactile output section 16 includes the tactile presentation units 251 shown in
(Operation of Loudspeaker Apparatus)
Next, a typical operation of the loudspeaker apparatus 100 configured in the above-mentioned manner will be described.
The control apparatus 1 acquires digital signals (first audio signal and tactile signal) for outputting sound and a tactile sense by receiving the digital signals from the server device 50 or reading the digital signals from the storage 11.
Next, the decoding section 12 performs suitable decoding processing on the acquired data to thereby take out audio data (first audio signal) and tactile data (tactile signal), and inputs the audio data (first audio signal) and the tactile data (tactile signal) into the audio control section 13 and the tactile control section 14, respectively.
The audio control section 13 and the tactile control section 14 performs various types of processing on the input data. Output (audio control signal) of the audio control section 13 is input into the audio output section 15 and output (tactile control signal) of the tactile control section 14 is input into the tactile output section 16. The audio output section 15 and the tactile output section 16 each include a D/A converter, a signal amplifier, and a reproduction apparatus (equivalent to the audio output units 250 and the tactile presentation units 251). The D/A converter and the signal amplifier may be included in the audio control section 13 and the tactile control section 14. The signal amplifier may include a volume control section that is controlled by the user U.
The tactile control section 14 sends the tactile data to the cancellation signal generation section 17. The cancellation signal generation section 17 generates a cancellation signal (second audio signal) for cancelling noise output from the tactile output section 16 and sends the cancellation signal to the audio control section 13. The cancellation signal includes sound components that are generated on the basis of the tactile data and are in an opposite phase to the sound (noise) generated from the tactile output section 16. A method of generating the cancellation signal will be described later in detail.
On the basis of the input tactile data, the tactile control section 14 generates a tactile control signal for driving the tactile output section 16. On the basis of the input audio data and cancellation signal, the audio control section 13 generates an audio control signal for driving the audio output section 15. Accordingly, the audio output section 15 outputs reproduction sound that contains sound components for cancelling the sound (noise) generated from the tactile output section 16.
(Noise Cancellation Principle)
Next, the cancellation signal generated in the cancellation signal generation section 17 will be described. Here, a case of reproducing content including an audio signal and a vibration signal for presenting a tactile sense through a vibration speaker provided with a vibrator for tactile presentation, which is capable of being actively driven, and listening a musical piece with a vibration will be described.
Vibration transmitted to the user's body (skin) from the vibration speaker is vibration output from the vibrator driven in accordance with the vibration signal. On the other hand, sound that is transmitted to the user's ear from the vibration speaker is not only sound from the loudspeaker driven in accordance with the audio signal but also sound transformed from vibration of the vibrator driven in accordance with the vibration signal, i.e., the sum of both. Those components as the sound transformed from vibration, which are added to the sound from the loudspeaker, often interfere with the user's music experience as noise.
As shown in
On the other hand, with respect to a Fourier transform F2 of a vibration signal f2, vibration Z output from a vibrator 21 is a signal multiplied by a frequency response characteristic H2 of the vibrator 21, and it is transmitted to the skin as the vibration Z. In addition, sound subjected to transform (transform function H3) from vibration into sound is generated from the vibrator 21 and is transmitted to the user's ear.
Thus, the sound Y that reaches the ears of the user U is as follows:
Y=H1F1+H3H2F2. [Expression 1]
The frequency response characteristic H1 of the loudspeaker section 20 is, for example, a frequency response characteristic of the loudspeaker section 20 itself or one obtained by multiplying this frequency response characteristic by a gain or the like of a signal amplifier provided on the previous stage of the loudspeaker section 20.
The frequency response characteristic H2 of the vibrator 21 is also defined similar to the frequency response characteristic H1 of the loudspeaker section 20. The transform function H3 from vibration into sound is, for example, defined as a function (characteristic) based on mechanical structure and arrangement of the vibrator 21.
On the other hand,
The audio control section 13 that has received the cancellation signal F3 adds the cancellation signal F3 to the audio signal f1, sends it to the loudspeaker section 20 (audio output section 15), and sound is output at the loudspeaker section 20. The cancellation signal F3 is generated to cancel only sound of sound that reaches the ears of the user U, which is generated from the vibrator 21. As a result, the user U is able to perceive the vibration Z output from the vibrator 21 (tactile output section 16) as it is, and to listen sound with the noise sound generated from the vibrator 21 cancelled.
In
(Specific Example of Noise Cancellation)
Hereinafter, processing for cancelling sound noise will be described specifically.
It is desirable that the cancellation signal F3 be sound having the inverted phase with respect to the sound noise from the vibrator 21 when the cancellation signal F3 is output from the loudspeaker section 20.
Thus, in order to generate the cancellation signal F3 from the vibration signal f2, it is sufficient to estimate sound (H3 H2 F2) generated from the vibrator 21 in view of the frequency response characteristic H2 of the vibrator 21 itself and the transform function H3 from vibration of the vibrator 21 into sound and then overcome the frequency response characteristic H1 of the loudspeaker section 20.
Accordingly, as the generated cancellation signal F3 is expressed by a formula, it is G1 H3 H2 F2. Here, G1 is a frequency response characteristic having an inverse characteristic that can overcome the characteristic of the frequency response characteristic H1 of the loudspeaker section 20.
Information regarding the respective characteristics H1, H2, and H3 is essential for calculating this cancellation signal F3, and therefore it is necessary to measure them in advance. Known methods represented by a method of identifying characteristics of acoustic apparatuses and the like are used for this measurement method.
Moreover, envisaging a situation where this loudspeaker apparatus 100 is worn by the user U, the transform function H3 from vibration into sound is desirably measured in a state in which the loudspeaker apparatus 100 is worn by a mannequin, a subject, or the like.
The calculation processing of this cancellation signal F3 can be realized by multiplication of the respective frequency response characteristics G1, H3, H2, and F2 subjected to Fourier transform, for example. Alternatively, the calculation processing of this cancellation signal F3 may be realized by the vibration signal f2 and the inverse Fourier transform of the frequency response characteristics G1, H3, H2, i.e., convolution of impulse responses g1, h3, h2 of each system. Alternatively, the calculation processing of this cancellation signal F3 may be realized by implementing a filter having a characteristic (−G1 H3 H2) in the cancellation signal generation section 17 as hardware.
A technology (ANC: active noise control) in which a vibration speaker provided with a microphone senses sound from a vibrator through the microphone and utilizes the sensing signal as a cancellation signal has also been known. However, in this embodiment, a highly accurate noise cancellation function can be realized by feed-forward control utilizing a vibration signal that is input into the tactile output section 16 without such a microphone. It is because a structural device to prevent noise from the tactile output section 16 from reaching the ears of the user U can be made in the loudspeaker apparatus 100, sound noise from the tactile output section 16, which is measured in advance, can be predicted by some degree unlike environment noise including random noise wished to be cancelled, and the like.
Therefore, in accordance with the loudspeaker apparatus 100 of this embodiment, since a microphone for noise sensing is unnecessary, the apparatus configuration can be simplified or a reduction in size can be achieved. Moreover, by utilizing a buffered vibration signal before output from the network 10 or the storage 11, noise can be cancelled without any delay as the feed-forward control.
Since the tactile output section 16 is configured as a unit separated from the audio output section 15 in the loudspeaker apparatus 100 of this embodiment, the degree of freedom in the design of the tactile output section 16 increases, and a variety of tactile vibrations can be presented to the user. In addition, since the cancellation signal F3 is reproduced in synchronization with driving of the tactile output section 16, noise associated with driving of the tactile output section 16 can be effectively removed. In addition, content to present a tactile sense at a timing different from that of output sound from the audio output section 15 or in a band wider than that of sound can also be reproduced.
For sensitivity control in the loudspeaker apparatus 100, the audio output section 15 may be provided with a single limiter that sets a maximum value of the cancellation signal or a plurality of limiters of weak/middle/strong, for example, in units of dB, for example. Accordingly, the user U him or herself is able to select a noise cancellation level.
As shown in
The audio control section 13 adds this cancellation signal F3 to an audio signal f1 (first audio signal), to thereby generate an audio control signal for driving the audio output section 15. At this time, an amplification scale to be applied to each of the audio signal f1 and the vibration signal f2 at the time of reproduction may be considered. For example, in a case of amplifying the audio signal f1 by a1 times, amplifying the vibration signal f2 by a2 times, and outputting them to the loudspeaker section 20 and the vibrator 21, respectively, the cancellation signal generation section 17 receives information about those amplification scales from the audio control section 13 and the tactile control section 14 and multiplies the cancellation signal F3 by their amplification ratio (a2/a1) in Step S103.
Subsequently, in Step S104, the audio control section 13 generates the audio control signal by adding the cancellation signal (f3×(a2/a1)) multiplied by the amplification ratio to a sound signal f1. Accordingly, the sound Y whose noise is not perceived by the user U is output from the audio output section 15.
In the above description, the vibrator 21 has been exemplified as the tactile presentation device (tactile presentation units 251) in the tactile output section 16. The vibrator 21 can be similarly applied to tactile presentation devices other than the vibrator (e.g., an airborne ultrasonic wave generator, an electrical muscle stimulator, an air flow generator, and the like).
Next, a second embodiment of the present technology will be described.
In the above-mentioned first embodiment, the audio output section 15 (audio output units 250) is configured such that the audio signal (first audio signal) and the cancellation signal (second audio signal) are reproduced through the common loudspeaker unit (loudspeaker section 20). In this regards, in this embodiment, the audio signal (first audio signal) and the cancellation signal (second audio signal) are configured to be reproduced through separate loudspeakers, respectively.
In this embodiment, a cancellation signal generation section 27 outputs, to the loudspeaker section 22, a control signal for reproducing the cancellation signal F3 from a loudspeaker section 22. Assuming that a frequency response characteristic having an inverse characteristic that can overcome a frequency response characteristic H4 of the loudspeaker section 22 is denoted by G4, the cancellation signal F3 is represented by the expression of (−G4 H3 H2 F2). Accordingly, synthesized sound of reproduction sound of the audio signal f1 output from the loudspeaker section 20 and reproduction sound of the cancellation signal F3 output from the loudspeaker section 22 is presented to the user U. As a result, sound from the vibrator 21 can be cancelled.
Also in this embodiment, action and effect similar to those of the first embodiment can be obtained. In particular, in accordance with this embodiment, since the loudspeaker section 22 that reproduces the cancellation signal F3 can be configured with specifications different from that of the loudspeaker section 20 that reproduces the audio signal f1, the degree of freedom of the design of each loudspeaker section 20, 22 can increase.
Although the descriptions have been given exemplifying the case where the tactile output section 16 is the vibration device (vibrator 21) in each of the above-mentioned embodiments, a case where the tactile output section 16 is a tactile presentation device other than the vibration device will be described in this embodiment.
Examples of the tactile presentation device other than the vibration device can include one (air flow generator) that sends an air flow toward the user U by driving of a diaphragm, one (ultrasonic wave generator) that provides an acoustic radiation pressure with an ultrasonic wave array focused on the body of the user U, and one (electrical muscle stimulator) that directly stimulates a tactile receptor or muscle of the user U by electric stimulation. In other words, the tactile presentation device may be other devices not aiming at directly vibrating skin along with the vibration.
Also in those tactile presentation devices, noise sound can be generated along with driving of the tactile presentation devices and interfere with music listening in many cases. In view of this, the noise sound is cancelled by generating a cancellation signal with characteristics of each device and outputting the cancellation signal from the loudspeaker. Regarding a transform function from driving of the tactile presentation device into sound, as shown in
In
For example, in each of the above-mentioned embodiments, the wearable loudspeaker apparatus used hanging around the user's neck has been described as an example of the loudspeaker apparatus, though not limited thereto. The present technology can also be applied to headphones or earphones that are mounted on the user's head. In this case, the tactile presentation unit may be configured as an apparatus different from the loudspeaker apparatus. In this case, the tactile presentation unit can be placed at any position, and therefore a tactile sense can be presented to a desired position of the user's body.
It should be noted that the present technology may also take the following configurations.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2019-160508 | Sep 2019 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2020/031969 | 8/25/2020 | WO |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2021/044901 | 3/11/2021 | WO | A |
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| Number | Date | Country | |
|---|---|---|---|
| 20220277726 A1 | Sep 2022 | US |
