Patent Publication Number: US-11659316-B2

Title: Acoustic device and method for controlling acoustic device

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a U.S. National Phase of International Patent Application No. PCT/JP2019/028289 filed on Jul. 18, 2019, which claims priority benefit of Japanese Patent Application No. JP 2018-162786 filed in the Japan Patent Office on Aug. 31, 2018. Each of the above-referenced applications is hereby incorporated herein by reference in its entirety. 
     TECHNICAL FIELD 
     The present technology relates to an acoustic device to be used in listening to music and the like, and a method for controlling this acoustic device. 
     BACKGROUND ART 
     Hitherto, as well known, acoustic devices such as earphones and headphones are not always fitted to earholes. Even if sound is played back in such a state, a user cannot listen to the sound, and power of the acoustic devices is wasted. 
     In order to solve this problem, according to the technology disclosed in Patent Literature 1, whether the earphones are in a fitting state of being fitted to the earholes, or in a non-fitting state of not being fitted to the earholes is detected by contact switches, and the sound is played back on the basis of results of the detection. With this, for example, processes in accordance with the fitting states of the acoustic devices, such as a process of stopping the sound playback in the non-fitting state, are automatically executed. As a result, the power is supposed to be prevented from being wasted. 
     CITATION LIST 
     Patent Literature 
     
         
         Patent Literature 1: Japanese Patent Application Laid-open No. 2004-153350 
       
    
     DISCLOSURE OF INVENTION 
     Technical Problem 
     However, the technology disclosed in Patent Literature 1 is disadvantageous in that the contact switches need to be provided in the earphone portion to detect the fitting state and the non-fitting state of the earphones, and in that the number of components to prevent the waste of the power needs to be increased in the earphone portion. 
     In view of such circumstances, the present technology has been made to achieve an object to provide an acoustic device that is capable of reducing power consumption even without increasing the number of components in an earphone portion, and a method for controlling this acoustic device. 
     Solution to Problem 
     In order to achieve the above-mentioned object, according to an embodiment of the present technology, there is provided an acoustic device including an operating portion and a control unit. 
     The operating portion generates information for determining whether a state of an earphone portion is 
     a wearing state in which the earphone portion is worn by the user, or 
     a non-wearing state in which the earphone portion is not worn by the user. 
     The control unit 
     determines whether the earphone portion is in the wearing state or in the non-wearing state on the basis of output from the operating portion, and 
     implements a function based on a result of the determination. 
     The control unit may implement, in accordance with a determined one of the wearing state and the non-wearing state of the earphone portion, 
     a wearing function in the wearing state, and 
     a non-wearing function in the non-wearing state. 
     The control unit may implement a noise cancelling function as the wearing function. This enables the user to listen to sound from which the noise is removed, and to have a realistic sense of immersion. 
     The control unit may implement an energy-saving function as the non-wearing function. This prevents the sound from being played back under the state in which the earphone portion is not worn by the user. Thus, power consumption can be reduced. In addition, in this case, for example, if the noise cancelling function is being implemented, by stopping this function, power consumption can be further reduced. 
     The operating portion may include a detection unit for determining whether the earphone portion is in the wearing state or in the non-wearing state. With this, a size of the earphone portion can be reduced to be smaller than that in a case where the earphone portion includes the built-in detection unit, and the number of wires (core wires) connecting the earphone portion and the operating portion to each other can be reduced. Thus, the acoustic device can be configured even without increasing the number of components in the earphone portion. 
     The operating portion may be provided at a position near the earphone portion. With this, whether the earphone portion is in the wearing state or in the non-wearing state can be clearly distinguished. As a result, false detection of the state of the earphone portion is suppressed. 
     The operating portion may include a tilt sensor as the detection unit. With this, power need not be separately supplied to the tilt sensor itself. Thus, power consumption and the number of wires (core wires) can be reduced to be smaller than those in utilizing other sensors. 
     In order to achieve the above-mentioned object, according to another embodiment of the present technology, there is provided a method for controlling an acoustic device, the method including: 
     determining whether a state of an earphone portion is 
     a wearing state in which the earphone portion is worn by the user, or 
     a non-wearing state in which the earphone portion is not worn by the user; and 
     implementing, in accordance with a determined one of the wearing state and the non-wearing state of the earphone portion, 
     a wearing function in the wearing state, and 
     a non-wearing function in the non-wearing state. 
     Advantageous Effects of Invention 
     As described above, according to the present technology, the acoustic device that is capable of reducing power consumption even without increasing the number of components in the earphone portion, and the method for controlling this acoustic device can be provided. Note that, the above-described advantages should not be construed restrictively. Together with the above-described advantages or instead of the above-described advantages, any of the advantages described herein or other advantages that can be understood from the present application may be obtained. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    A schematic view illustrating a configuration example of an acoustic device of the present technology. 
         FIG.  2    A block diagram illustrating a configuration example of the acoustic device. 
         FIG.  3    An enlarged schematic view of the remote-control portion of the acoustic device. 
         FIG.  4    A circuit diagram showing an example of a resistive divider of the remote-control portion. 
         FIG.  5    A circuit diagram showing another example of the resistive divider of the remote-control portion. 
         FIG.  6    A schematic view illustrating another configuration example of the acoustic device. 
         FIG.  7    A schematic view illustrating a still another configuration example of the acoustic device. 
         FIG.  8    A flowchart showing a typical operation procedure of the acoustic device 
         FIG.  9    A view illustrating a wearing state in which the acoustic device is worn by the user. 
         FIG.  10    A view illustrating a non-wearing state in which the acoustic device is not worn by the user. 
     
    
    
     MODE(S) FOR CARRYING OUT THE INVENTION 
     Hereinbelow, with reference to the drawings, an embodiment of a case where the present technology is applied to Bluetooth (trademark) earphones is described. 
     [Configuration of Acoustic Device] 
       FIG.  1    is a schematic view illustrating a configuration example of an acoustic device  100  of the present technology.  FIG.  2    is a block diagram illustrating a configuration example of the acoustic device  100 . As illustrated in  FIG.  1   , the acoustic device  100  includes an earphone portion  10 , a remote-control portion  20  (operating portion), a main-unit portion  30 , a battery portion  40 , and a cable  50 . 
     (Earphone Portion) 
     The earphone portion  10  is connected to the cable  50 , specifically, is connected electrically to the remote-control portion  20  and the battery portion  40  via the cable  50 . A right-hand earphone of the earphone portion  10  includes a built-in Rch speaker  101 R, and a left-hand earphone of the same includes a built-in Lch speaker  101 L. 
     The Rch speaker  101 R and the Lch speaker  101 L are connected to a Bluetooth (trademark) module  308 , and are configured to output sound by converting an electrical signal acquired via this module  308  to air vibration (sound). Note that, “R” and “L” in the reference symbols respectively represent the right and left as viewed from a user wearing the acoustic device  100 . 
     (Remote-Control Portion) 
     The remote-control portion  20  is connected to the cable  50 , specifically, is connected electrically to the earphone portion  10  and the main-unit portion  30  via the cable  50 . The remote-control portion  20  of this embodiment is provided between the earphone portion  10  and the main-unit portion  30 , specifically, at a position near the earphone portion  10 . 
       FIG.  3    is an enlarged schematic view of the remote-control portion  20 . The remote-control portion  20  includes a casing  21  and a resistive divider  208  built in the casing  21 . Although a material of the casing  21  is not limited in particular, typically, the casing  21  is made of a synthetic resin such as plastic. 
       FIG.  4    is a circuit diagram showing an example of the resistive divider  208 . The resistive divider  208  is an analog circuit including resistors R 1  to R 6  connected in series. The resistive divider  208  includes a PLAY/PAUSE/FF/FR/CALL key  203 , a Vol.Up key  202 , a Vol.down key  201 , an NC (Noise Cancelling) key  204 , and a tilt sensor (detection unit). The resistive divider  208  outputs output currents (analog signals) based on various different output voltages according to the resistive divider rule to the main-unit portion  30  (A/D interface  304 ). 
     When the user presses the PLAY/PAUSE/FF/FR/CALL key  203 , sound is played back, stopped, paused, fast-forwarded, or rewound under control by a CPU  301 . When the user presses the Vol.Up key  202  and the Vol.down key  201 , volume of the sound to be output from the earphone portion  10  is increased or reduced under the control by the CPU  301 . 
     In addition, when the user presses the NC key  204 , the CPU  301  implements a noise cancelling function (NC function) to reduce nose by generating an acoustic wave component in a phase reverse to that of noise picked up by microphones in the earphone portion  10 . 
     The tilt sensor  205  is configured to be capable of detecting a tilt of the acoustic device  100  (remote-control portion  20 ). The tilt sensor  205  includes, for example, a built-in metal ball. When the tilt sensor  205  is tilted in a certain direction, the ball comes into contact with a metal terminal to establish conduction between a power supply (VDD) and the ground. When the tilt sensor  205  is tilted to an opposite side, the ball and the metal terminal separate from each other to insulate the power source and the ground. An example of such a configuration of the tilt sensor  205  is disclosed, for example, in Japanese Patent Application Laid-open No. 2000-173420 (refer to FIG. 6). 
     Although a type of the tilt sensor  205  is not limited in particular, typically, a one-directional tilt type in which the ball rolls in a certain direction is employed. Note that, the exemplary circuit diagram of  FIG.  4    is that of a case where the tilt sensor  205  is incorporated in the resistive divider  208 . 
     The tilt sensor  205  need not necessarily be incorporated in the resistive divider  208  as in this embodiment, and a gravity sensor may be incorporated instead of the tilt sensor  205 .  FIG.  5    is a circuit diagram showing an example in which the gravity sensor is incorporated in the resistive divider  208 . A type of the gravity sensor is not limited, and, for example, a three-axis acceleration sensor that measures acceleration in three-axis directions orthogonal to each other, or the like may be used. 
     Note that, as a matter of course, a configuration of the remote-control portion  20  is not limited to the configuration illustrated in  FIG.  3   , and sizes, shapes, arrangements, and the like of the various keys may be changed as appropriate. 
     (Main-Unit Portion) 
     The main-unit portion  30  is connected to the cable  50 , specifically, is connected to the remote-control portion  20  and the battery portion  40  via the cable  50 . As shown in  FIG.  2   , the main-unit portion  30  includes the CPU (Central Processing Unit)  301  (control unit), a RAM (Random Access Memory)  302 , a ROM (Read Only Memory)  303 , the A/D interface  304  (A/D converter), a parallel I/O interface  305 , a serial interface  306 , an antenna  307 , a Bluetooth (trademark) module  308 , a microphone  309 , an LED light source  310 , a power key  311 , and a bus  312 . 
     The CPU  301  functions as an arithmetic processing device and a control device, and controls all or ones of operations of the acoustic device  100  in accordance with various programs stored in the RAM  302  or the ROM  303 . The CPU  301  is configured to be capable of implementing a wearing function to be implemented when the acoustic device  100  (earphone portion  10 ) is worn by the user, and a non-wearing function to be implemented when the acoustic device  100  (earphone portion  10 ) is not worn by the user. 
     The CPU  301  is connected to the RAM  302 , the ROM  303 , the A/D interface  304 , the parallel I/O interface  305 , and the serial interface  306  via the bus  312 . 
     The CPU  301  of this embodiment performs the control on the basis of various output voltages generated by dividing by the resistive divider  208 . Specifically, on the basis of the various output voltages generated by the dividing by the resistive divider  208 , the CPU  301  determines which of the keys is pressed, and performs the control in response to operations to the various keys. 
     In addition, on the basis of the output from the remote-control portion  20  (resistive divider  208 ), the CPU  301  determines whether or not the acoustic device  100  (earphone portion  10 ) is worn by the user. 
     The acoustic device  100  of this embodiment may include, instead of or together with the CPU  301 , a processing circuit such as a DSP (Digital Signal Processor), an ASIC (Application Specific Integrated Circuit), or an FPGA (Field-Programmable Gate Array). 
     The RAM  302  temporarily stores, for example, the programs to be executed by the CPU  301 , and parameters to vary as appropriate in accordance with the execution. The ROM  303  stores, for example, the programs and arithmetic parameters to be used by the CPU  301 . 
     The A/D interface  304  is an electronic circuit that is connected to the resistive divider  208 , converts the output currents (analog signals) output from the resistive divider  208  to digital signals, and then outputs these signals to the CPU  301 . 
     The parallel I/O interface  305  is connected to the power key  311  and the LED light source  310 . The parallel I/O interface  305  is a connection interface configured to be capable of transmitting a plurality of signals in parallel to and simultaneously with each other. 
     The serial interface  306  is connected to the Bluetooth (trademark) module  308 . The serial interface is a connection interface of a serial-transfer-type connection interface that exchanges data via a single signal line. 
     The antenna  307  receives radio waves from an arbitrary device synchronized with (connected to) the Bluetooth (trademark) module  308 , such as a smartphone. 
     The Bluetooth (trademark) module  308  is a module that is connected to the antenna  307 , the microphone  309 , the Rch speaker  101 R, the Lch speaker  101 L, and the serial interface  306 , and that performs wireless communication with the arbitrary device such as the smartphone by utilizing the radio waves. 
     The Bluetooth (trademark) module  308  converts the radio waves received by the antenna  307  to a digital signal, and outputs this signal to the CPU  301 . In addition, the Bluetooth (trademark) module  308  converts an electrical signal output from the microphone  309  to the digital signal, and outputs this signal to the CPU  301 . 
     The microphone  309  is configured to be capable of acquiring sound information (such as voice of the user and the like). The microphone  309  converts this sound information to the electrical signal, and outputs this signal to the Bluetooth (trademark) module  308 . 
     The LED light source  310  is connected to the parallel I/O interface  305 , and is connected to the bus  312  via this interface. Under the control by the CPU  301 , the LED light source  310  emits light when the acoustic device  100  is activated, and is turned off when the acoustic device  100  is deactivated. The LED light source  310  indicates states of the acoustic device  100  by being turned on, turned off, or flashing. 
     A type of the LED light source  310  is not limited, and, for example, a through-hole type, a Flux type, an SMD (Surface Mount Device) type, a COB (Chip On Board) type, or the like may be employed. 
     The power key  311  in the main-unit portion  30  is connected to the parallel I/O interface  305 , and is connected to the bus  312  via this interface. The power key  311  is a key for activating or deactivating the acoustic device  100 . 
     (Battery Portion) 
     The battery portion  40  is connected to the cable  50 , specifically, is connected to the earphone portion  10  and the main-unit portion  30  via the cable  50 . The battery portion  40  is configured to be capable of accumulating a power supply for operating the acoustic device  100 , and of supplying the power to the acoustic device  100 . As the battery portion  40 , rechargeable batteries such as a lithium-ion battery are employed. 
     (Cable) 
     The cable  50  contains wires (not shown) that electrically connect the earphone portion  10  and the battery portion  40  to each other, the battery portion  40  and the main-unit portion  30  to each other, the main-unit portion  30  and the remote-control portion  20  to each other, and the remote-control portion  20  and the earphone portion  10  to each other. With this, the earphone portion  10 , the remote-control portion  20 , the main-unit portion  30 , and the battery portion  40  are electrically connected to each other via the cable  50 . 
     In this embodiment, the cable  50  may be configured to be contained in a band portion  60  between the main-unit portion  30  and the battery portion  40  (refer to  FIG.  9    and  FIG.  10   ). 
     The band portion  60  is configured to be wrapped around the neck of the user, and, for example, has flexibility of being curved substantially with a predetermined curvature as a whole. Although a material of the band portion  60  is not limited in particular, for example, a synthetic resin or the like is employed. 
     [Other Configurations of Acoustic Device] 
       FIG.  6    and  FIG.  7    are each a schematic view illustrating another configuration example of the acoustic device  100  of this embodiment. A configuration of the acoustic device  100  is not limited to the configuration illustrated in  FIG.  1   . For example, the acoustic device  100  may be configured to include the remote-control portion  20  not only between the earphone portion  10  and the main-unit portion  30 , but also between, as illustrated in  FIG.  6   , the earphone portion  10  and the battery portion  40 . 
     Alternatively, the acoustic device  100  may be configured to include, as illustrated in  FIG.  7   , only the earphone portion  10 , the remote-control portion  20 , and the cable  50 . In this case, hardware necessary for the operations of the acoustic device  100 , such as the CPU  301 , the RAM  302 , and the ROM  303 , are provided in the earphone portion  10 . 
     [Method for Controlling Acoustic Device] 
       FIG.  8    is a flowchart showing a typical operation procedure of the acoustic device  100 . In addition,  FIG.  9    is a view illustrating a wearing state in which the acoustic device  100  is worn by the user, and  FIG.  10    is a view illustrating a non-wearing state in which the acoustic device  100  is not worn by the user. 
     In a method for controlling the acoustic device  100  according to this embodiment, various processes are triggered by an interruption process that is executed if voltage fluctuation via the A/D interface  304  occurs. Hereinbelow, with reference to  FIG.  8    to  FIG.  10    as appropriate, the method for controlling the acoustic device  100  is described. 
     In response to the input to the various keys (interruption) by the user (Step S 101 ), the CPU  301  determines whether or not the acoustic device  100  is in the state of being worn by the user. Specifically, on the basis of whether or not the digital signal generated by converting the output voltage that is generated when the conduction between the power supply (VDD) and the ground is established in the tilt sensor  205  is acquired from the A/D interface  304 , the CPU  301  determines whether the acoustic device  100  is in the wearing state of being worn by the user. 
     Specifically, if the digital signal from the A/D interface  304  is within a range of preset values (thresholds), the CPU  301  determines that the acoustic device  100  (earphone portion  10 ) is in the state of being worn by the user (refer to  FIG.  9   ) (YES in Step S 102 ). Then, in response to the key operation by the user, the CPU  301  implements the function (wearing function) based on the state via the Bluetooth (trademark) module  308 . 
     In this embodiment, as the function to be implemented under the state in which the acoustic device  100  (earphone portion  10 ) is worn by the user, if the user has selected the NC function by making an input to the NC key  204  for switching the NC function (ON in Step S 103 ), the NC function is implemented (Step S 104 ). Note that, “State of NC (Noise Cancelling)” of Step S 103  in  FIG.  8    represents “State of NC that has been set in response to the key operation by the user,” that is, does not represent how the NC is being implemented, but represents “Has the NC set by the user been turned ON or turned OFF?” 
     When the sound such as music or the like is played back by the acoustic device  100 , first, sound containing noise is picked up by the microphones in the earphone portion  10 . Then, this sound is converted to the digital signal by the Bluetooth (trademark) module  308  (hereinafter, referred to as a signal A). 
     Next, the radio waves received from the arbitrary device via the antenna  307  are converted to the digital signal (such as an audio signal) by the Bluetooth (trademark) module  308 . 
     After that, the Bluetooth (trademark) module  308  calculates a difference between the signal A and a signal B (signal component except a signal component of the noise), thereby extracting the signal component of the noise, and generating a signal in a phase reverse to that of this signal (hereinafter, referred to as a signal C). Then, the Bluetooth (trademark) module  308  synthesizes the signal A and the signal C with each other. In this way, a digital signal in which the noise component of the signal A has been cancelled is generated. In other words, sound from which the noise is eliminated is played back. This enables the user to listen to sound from which the noise is removed, and to have a realistic sense of immersion. 
     Note that, in this embodiment, even when the CPU  301  determines that the acoustic device  100  (earphone portion  10 ) is in the state of being worn by the user, if the user has not selected the NC function by making the input to the NC key  204  for switching the NC function (OFF in Step S 103 ), the NC function is not implemented, and the procedure shifts to a state of waiting for the input to the various keys by the user (Step S 109 ). 
     Meanwhile, if the digital signal from the A/D interface  304  is out of the range of the preset values (thresholds), the CPU  301  determines that the acoustic device  100  (earphone portion  10 ) is in the state of not being worn by the user (refer to  FIG.  10   ), and implements the function based on this state (non-wearing function). 
     In this embodiment, as the function to be implemented under the state in which the acoustic device  100  (earphone portion  10 ) is not worn by the user, an energy-saving function is implemented. By this energy-saving function, for example, if the music is being played back by the acoustic device  100  (YES in Step S 105 ), this music is paused (Step S 106 ). This prevents the music from being played back under the state in which the acoustic device  100  (earphone portion  10 ) is not worn by the user. Thus, power consumption can be reduced. 
     Then, for example, if the NC function has been selected (ON in Step S 107 ) in response to the key operations by the user, the above-described NC function is implemented, and if the NC function has not been selected (OFF in Step S 107 ) in response to the key operations by the user, the procedure shifts to the state of waiting for the input to the various keys by the user (Step S 109 ). Note that, “State of NC (Noise Cancelling)” of Step S 107  in  FIG.  8    represents, similar to that of Step S 103 , “State of NC that has been set in response to the key operation by the user,” that is, does not represent how the NC is being implemented, but represents “Has the NC set by the user been turned ON or turned OFF?” 
     Note that, in this embodiment, under the state in which the acoustic device  100  (earphone portion  10 ) is not worn by the user (NO in Step S 102 ), even if the NC function has been selected, by not implementing the NC function (ON in Step S 107 ), both the music playback and the NC function can be stopped. With this, power consumption can be further reduced. 
     [Functions] 
     In the acoustic device  100  of this embodiment, typically, the remote-control portion  20  includes the built-in tilt sensor  205 . With this, a size of the earphone portion  10  can be reduced to be smaller than that in a case where the earphone portion  10  includes the built-in tilt sensor  205 , and the number of wires (core wires) connecting the earphone portion  10  and the remote-control portion  20  to each other can be reduced. Thus, the acoustic device  100  can be configured even without increasing the number of components in the earphone portion  10 . 
     In particular, the tilt sensor  205  has a simple structure of switching the conduction/insulation between the power supply (VDD) and the ground to each other by repeating the contact/separation of the built-in metal ball and the terminal in conjunction with the tilting of the tilt sensor  205  itself. With this, power need not be separately supplied to the tilt sensor  205  itself that detects the state of the acoustic device  100 . Thus, power consumption and the number of wires (core wires) can be reduced to be smaller than those in utilizing other sensors. 
     In addition, in this embodiment, the remote-control portion  20  is provided at the position near the earphone portion  10  (refer to  FIG.  1    and  FIG.  9   ). With this, a movable range of the remote-control portion  20  in switching the wearing state (refer to  FIG.  9   ) and the non-wearing state (refer to  FIG.  10   ) of the acoustic device  100  (earphone portion  10 ) is expanded. In accordance therewith, a movable range of the tilt sensor  205  is also expanded. Thus, whether the acoustic device  100  (earphone portion  10 ) is in the wearing state or in the non-wearing state can be clearly distinguished. As a result, false detection of the state of the acoustic device  100  (earphone portion  10 ) is suppressed. 
     &lt;Modifications&gt; 
     As a matter of course, the present technology is not limited to the embodiment described hereinabove, and may be changed as appropriate. 
     For example, the music playback need not necessarily be paused by the energy-saving function as in the embodiment described hereinabove. A call may be hung up if the CPU  301  determines that the acoustic device  100  (earphone portion  10 ) is in the non-wearing state. 
     Further, unlike the embodiment that is described hereinabove on a premise that the acoustic device  100  is the Bluetooth (trademark) earphones, the present technology is applicable to other acoustic devices such as headphones, and its use purpose is not limited in particular. 
     Still further, the NC function need not be implemented in response to the key operation by the user as in the embodiment described hereinabove. The NC function may be automatically implemented/stopped in accordance with the wearing states of the acoustic device  100  (earphone portion  10 ). 
     Note that, the present technology may also employ the following configurations. 
     (1) An acoustic device, including: 
     an operating portion that generates information for determining whether a state of an earphone portion is 
     a wearing state in which the earphone portion is worn by the user, or 
     a non-wearing state in which the earphone portion is not worn by the user; and 
     a control unit 
     that determines whether the earphone portion is in the wearing state or in the non-wearing state on a basis of output from the operating portion, and 
     that implements a function based on a result of the determination. 
     (2) The acoustic device according to (1), in which 
     the control unit implements, in accordance with a determined one of the wearing state and the non-wearing state of the earphone portion, 
     a wearing function in the wearing state, and 
     a non-wearing function in the non-wearing state. 
     (3) The acoustic device according to (2), in which 
     the control unit implements a noise cancelling function as the wearing function. 
     (4) The acoustic device according to (2) or (3), in which 
     the control unit implements an energy-saving function as the non-wearing function. 
     (5) The acoustic device according to any one of (1) to (4), in which 
     the operating portion includes a detection unit for determining whether the earphone portion is in the wearing state or in the non-wearing state. 
     (6) The acoustic device according to any one of (1) to (5), in which 
     the operating portion is provided at a position near the earphone portion. 
     (7) The acoustic device according to (5) or (6), in which 
     the operating portion includes a tilt sensor as the detection unit. 
     (8) A method for controlling an acoustic device, the method including: 
     determining whether a state of an earphone portion is 
     a wearing state in which the earphone portion is worn by the user, or 
     a non-wearing state in which the earphone portion is not worn by the user; and 
     implementing, in accordance with a determined one of the wearing state and the non-wearing state of the earphone portion, 
     a wearing function in the wearing state, and 
     a non-wearing function in the non-wearing state. 
     REFERENCE SIGNS LIST 
     
         
           10  earphone portion 
           20  remote-control portion (operating portion) 
           100  acoustic device 
           301  CPU (control unit) 
           205  tilt sensor (detection unit) 
           208  resistive divider (analog circuit)