Earphone and method for identifying whether earphone is inserted into user's ear

Abstract

The invention relates to a headset having a proximity sensor, an acceleration sensor and a signal analysis processing device. The proximity sensor is configured to generate a proximity sensor signal. The acceleration sensor is configured to generate an acceleration sensor signal. The signal analysis processing device is configured to identify, using the proximity sensor signal, an approaching movement of the headset towards an object. Further, the signal analysis processing device determines whether the approaching movement is a movement of the headset towards an ear of a user, wherein fluctuations in a course of change over time of the proximity sensor signal are analyzed and taken into account. By filtering the acceleration sensor signal, the signal analysis processing device generates a high-pass filtered acceleration signal and a low-pass filtered acceleration signal. Further, the signal analysis processing device determines, using the low-pass filtered acceleration signal, an end time of the approaching movement based on a stabilization of the acceleration. The signal analysis processing device confirms, based on a change of the high-pass filtered acceleration signal after the determined end time of the approaching movement, that the approaching movement is a movement of the headset towards the ear of the user.

Description

Technical Field

[0001] This invention relates to an earphone and a method for identifying whether the earphone is inserted into a user's ear. Background Technology

[0002] To improve user experience, an increasing number of sensors are being incorporated into audible devices (i.e., headphones with added functionality). One important function is recognizing whether headphones are being worn. This can, for example, facilitate the activation or deactivation of specific headphone components to conserve energy, or enable mono / stereo matching for a better music experience.

[0003] The identification of whether the earphone is in the user's ear can be performed based on proximity sensor data, as known from WO19039894 A1, US2017 / 244821A, US2016 / 198251A, US2015 / 382098A, US2015 / 281826A, US10306350 B and CN110012376 A.

[0004] Here, a proximity sensor can determine the proximity of the headphones to the user's ear by measuring distance or light intensity. Proximity sensor-based recognition yields many true positive results, many true negative results, and a small number of false negative results. However, proximity sensors also produce many false positives, exhibiting a high error rate regarding in-ear positioning. Therefore, for example, a low light intensity or short distance might lead to the conclusion that the headphones are in the ear. This is problematic because headphones can also be located in a trouser pocket, handbag, or hand.

[0005] Therefore, other sensors, especially biosensors, touch sensors, or additional proximity sensors, can also be considered, as known from US2016 / 205475A, US2016 / 050474A, US2015 / 281421A, US2015 / 078573A, US2011 / 286615A, CN208971758U, and CN108810788A. However, such sensors consume relatively more power, thus reducing the headset's runtime. Summary of the Invention

[0006] This invention provides an earphone with the features of the independent patent claims and a method for identifying whether the earphone is inserted into a user's ear.

[0007] The preferred embodiments are the subject of the various dependent claims.

[0008] According to a first aspect, the present invention thus relates to an earphone having a proximity sensor, an accelerometer, and a signal analysis and processing device. The proximity sensor is configured to generate a proximity sensor signal. The accelerometer is configured to generate an acceleration sensor signal. The signal analysis and processing device is configured to identify, using the proximity sensor signal, an approach motion of the earphone toward an object. Further, the signal analysis and processing device determines whether the approach motion is a motion of the earphone toward a user's ear, wherein fluctuations in the temporal variation of the proximity sensor signal are analyzed and considered. By filtering the accelerometer signal, the signal analysis and processing device generates a high-pass filtered acceleration signal and a low-pass filtered acceleration signal. Further, the signal analysis and processing device determines the end time of the approach motion based on the stability of the acceleration when using the low-pass filtered acceleration signal. The signal analysis and processing device confirms that the approach motion is a motion of the earphone toward the user's ear based on the change of the high-pass filtered acceleration signal after the determined end time of the approach motion.

[0009] According to a second aspect, the present invention thus relates to a method for identifying whether an earphone is inserted into a user's ear. Using a proximity sensor signal from the earphone's proximity sensor, a proximity motion of the earphone toward an object is identified. It is determined whether the proximity motion is a motion of the earphone toward the user's ear, wherein fluctuations in the temporal variation of the proximity sensor signal are analyzed, processed, and considered. The acceleration sensor signal from the earphone's acceleration sensor is filtered to generate a high-pass filtered acceleration signal and a low-pass filtered acceleration signal. Using the low-pass filtered acceleration signal, the end time of the proximity motion is determined based on the stability of the acceleration. Based on the change in the high-pass filtered acceleration signal after the determined end time of the proximity motion, it is confirmed that the proximity motion is a motion of the earphone toward the user's ear.

[0010] Advantages of the invention

[0011] Not only using proximity sensors, but also using accelerometers, the system identifies whether headphones are inserted into a user's ear. This combination of sensors significantly reduces false positives. Therefore, it can better identify and rule out, for example, the process of a user putting headphones in their pocket. Thus, such a process is no longer incorrectly identified as headphones being inserted into the user's ear. This is achieved by first identifying the possible approach of the headphones towards the user's ear based on proximity sensors. Based on sensor data from the accelerometer, this hypothesis is confirmed or rejected. While maintaining a high proportion of true positives, a high proportion of true negatives, and a low proportion of false negatives, the proportion of false positives can also be significantly reduced.

[0012] According to the present invention, the “end time” of the proximity motion can correspond to a moment at which the proximity sensor signal identifies that the earphone is located in the ear and / or the low-pass filtered contribution of the acceleration signal begins to stabilize.

[0013] Compared to other sensors such as touch sensors and biosensors, the use of accelerometers has significantly lower power consumption. This significantly increases the operating time of the headphones.

[0014] Furthermore, data from the accelerometer can also be used to monitor the user's current movement or activity. Thus, for example, it can be determined whether the current movement or activity is caused by the user's head movement with a high or low probability.

[0015] Furthermore, it is advantageous that modern headphones are typically equipped with (three-axis) accelerometer sensors, for example, to provide activity recognition, pedometer functions, posture monitoring, etc. Therefore, no additional functions are needed to provide functionality in assessing whether the headphones are being oriented towards the user's ears. In addition, this eliminates the need for additional structural space within the headphones.

[0016] According to one embodiment of the headphones, a signal analysis and processing device is configured to determine and consider the monotonicity of the temporal variation of the proximity sensor signal in order to analyze and process fluctuations in the variation process of the proximity sensor signal. When the headphones move toward a user's ear, the proximity sensor signal typically exhibits a monotonic and smooth variation process. When the headphones move into the user's pocket, larger fluctuations occur in the proximity sensor signal due to the movement of the headphones in the pocket. For example, a measure of the monotonicity of the temporal variation of the proximity sensor signal, such as a probability, can be calculated. If this measure is higher than a predetermined threshold, the variation process of the proximity sensor signal is therefore sufficiently monotonic, and thus the movement of the headphones toward the user's ear can be determined.

[0017] According to one embodiment of the headphones, the signal analysis and processing device is configured to confirm that the approach motion is a movement of the headphones toward the user's ear if the measure of change in the high-pass filtered acceleration signal after a predetermined end time of the approach motion is higher than a pre-defined first threshold. The high-pass filtered acceleration signal corresponds to a small acceleration of the headphones that is caused after the headphones are inserted into the user's ear by the headphones continuing to move slightly in the user's ear until they reach their final position. This is caused, for example, by the flexible material of the headphones, which causes a slight change in the position of the headphones even after they are inserted into the user's ear. Vibration may decrease, or the position or location of the headphones in the ear may change slightly. Therefore, such a stable phase can be identified based on the acceleration signal.

[0018] According to one embodiment of the headphones, the signal analysis and processing device is configured to identify that the approach motion is not a movement of the headphones toward the user's ear if the measure of change of the high-pass filtered acceleration signal after the determined end time of the approach motion is lower than a predetermined second threshold. Therefore, it is possible to infer, for example, a process in which the headphones are placed in the user's pocket, wherein the aforementioned matching process does not occur.

[0019] According to one embodiment of the headphones, the signal analysis and processing device is configured to determine, based on the proximity sensor signal, whether the headphones have been removed from the user's ear again. For example, a distance can be determined, and if the determined distance is higher than a predetermined threshold, it is identified that the headphones have been removed from the user's ear.

[0020] According to one embodiment of the headphones, the signal analysis and processing device is configured to identify the absence of motion based on the acceleration sensor signal, and, if identified, to place the headphones in an out-of-ear mode. The headphones thus automatically enter out-of-ear mode when they are stationary, for example, when placed on a solid surface. To determine whether identification is possible, the higher order of the derivative of the acceleration is equal to zero.

[0021] According to one embodiment of the headphones, the signal analysis and processing device is configured to identify, based on an accelerometer signal, the following movement of the headphones and, if identified, to place the headphones in an off-ear operating mode: the movement being of such intensity that it cannot be generated by head movement.

[0022] According to one implementation of the headphones, once the headphones are identified as being in the user's ear and once the user's movement (e.g., walking or periodic movement) is detected, it is possible to determine whether the headphones are still in the user's ear based solely on proximity sensor signals.

[0023] According to one implementation of the headphones, the accelerometer is a triaxial accelerometer.

[0024] According to one embodiment of the headphones, the signal analysis and processing device is configured to calculate the maximum and minimum values ​​of acceleration along three axes, and to take into account the maximum and minimum values ​​if it is confirmed that the approach motion is a movement of the headphones toward the user's ear. Attached Figure Description

[0025] The attached diagram shows:

[0026] Figure 1 A schematic block diagram of an earphone according to one embodiment of the present invention;

[0027] Figure 2a The change in the proximity sensor signal as the earphone moves toward the user's ear;

[0028] Figure 2b The change in the proximity sensor signal as the earphone moves into the user's pocket;

[0029] Figure 3a The change in the proximity sensor signal as the earphone moves toward the user's ear;

[0030] Figure 3b The change in the contribution of the low-pass filtered acceleration signal as the headphones move toward the user's ear;

[0031] Figure 3c The change in the contribution of the proximity sensor's acceleration signal after high-pass filtering as the headphones move toward the user's ear;

[0032] Figure 3d The minimum and maximum values ​​of the acceleration signal from the three-axis accelerometer change as the headphones move toward the user's ear;

[0033] Figure 3e The minimum and maximum values ​​of the contribution of the low-pass filtered acceleration signal change as the headphones move toward the user's ear;

[0034] Figure 3f The minimum and maximum values ​​of the contribution of the acceleration signal after high-pass filtering change as the headphones move toward the user's ear;

[0035] Figure 4a The change in the proximity sensor signal as the earphone moves into the user's pocket;

[0036] Figure 4b The change in the contribution of the acceleration signal after low-pass filtering as the headphones move into the user's pocket;

[0037] Figure 4c The change in the contribution of the proximity sensor's acceleration signal after high-pass filtering as the earphone moves into the user's pocket;

[0038] Figure 4d The minimum and maximum values ​​of the acceleration signal from the triaxial accelerometer change as the earphone moves into the user's pocket;

[0039] Figure 4e The minimum and maximum values ​​of the contribution of the low-pass filtered acceleration signal change as the earphone moves into the user's pocket;

[0040] Figure 4f The changes in the minimum and maximum values ​​of the high-pass filtered contribution of the acceleration signal as the earphone moves into the user's pocket; and

[0041] Figure 5 A flowchart of a method for identifying whether an earphone is inserted into a user's ear according to one embodiment of the present invention.

[0042] The numbering of method steps is for clarity and should generally not imply a specific chronological order. In particular, multiple method steps can be performed simultaneously. Detailed Implementation

[0043] Figure 1 A schematic block diagram of an earphone 1 according to an embodiment of the present invention is shown. The earphone 1 includes a proximity sensor 2, which generates a proximity sensor signal, for example based on a speed measurement or a brightness measurement, the proximity sensor signal corresponding to or at least associated with the distance between the earphone 1 and an object.

[0044] Furthermore, the earphone 1 includes an accelerometer 3, which in particular can involve a triaxial accelerometer. The accelerometer 3 generates an accelerometer signal, which can, for example, include the acceleration of the earphone 1 along each of the three axes.

[0045] Finally, the earphone 1 includes a signal analysis and processing unit 4, which is coupled to the proximity sensor 2 and the accelerometer 3. The signal analysis and processing unit 4 includes a computing device, such as a microprocessor, integrated circuit, etc. The signal analysis and processing unit 4 identifies the earphone's approaching motion towards an object using the proximity sensor signal, if the distance to the earphone 1 decreases substantially to zero.

[0046] Furthermore, the signal analysis and processing device 4 determines whether the approach motion is a movement of the earphone 1 toward the user's ear, wherein fluctuations in the temporal variation of the proximity sensor signal are analyzed and considered. For this purpose, monotonicity in the temporal variation of the proximity sensor signal can be determined, for example. If sufficient monotonicity exists, the signal analysis and processing device 4 establishes the hypothesis that there is movement of the earphone toward the user's ear. This hypothesis is confirmed or rejected based on the acceleration signal from the accelerometer 3.

[0047] By filtering the accelerometer signal, the signal analysis and processing unit 4 generates a high-pass filtered acceleration signal and a low-pass filtered acceleration signal. The low-pass filtered acceleration signal corresponds to the linear acceleration of the earphone 1.

[0048] Furthermore, the signal analysis and processing device 4 determines the near-end moment of motion based on the stability of the acceleration when using a low-pass filtered acceleration signal. For example, if the fluctuation of the low-pass filtered acceleration signal is below a predetermined threshold, the end moment is identified. The low-pass filtered acceleration signal essentially still only contains the component of gravitational acceleration.

[0049] If the change in the high-pass filtered acceleration signal after the determined end time of the approach motion is measured to be higher than a predetermined first threshold, then the signal analysis and processing device 4 confirms that the approach motion is the movement of the earphone 1 toward the user's ear. Conversely, if the change in the high-pass filtered acceleration signal is less than or equal to the predetermined first threshold or a predetermined second threshold, then the signal analysis and processing device 4 rejects the assumption that the approach motion is the movement of the earphone 1 toward the user's ear.

[0050] Figure 2a The diagram illustrates the change in the proximity sensor signal A of proximity sensor 2 as earphone 1 moves toward the user's ear. In the first time period B1, earphone 1 is outside the user's ear and does not move. In the second time period B2, earphone 1 is guided toward the user's ear, during which the temporal change of the proximity sensor signal is monotonically alternating, i.e., continuously increasing. In the third time period B3, the earphone is inside the user's ear.

[0051] Figure 2b The diagram illustrates the change in proximity sensor signal A from proximity sensor 2 as earphone 1 moves into the user's pocket. In the second time period B2, significantly larger fluctuations occur, meaning the temporal change of proximity sensor signal A is no longer as pronounced as in the previous time period. Figure 2a It's not as monotonous as it is.

[0052] Figure 3aThe diagram illustrates the change in the proximity sensor signal A of proximity sensor 2 as earphone 1 moves toward the user's ear. This change essentially corresponds to the change in... Figure 2a The process of change is shown in the figure.

[0053] Figure 3b The diagram illustrates the variation of the low-pass filtered acceleration signal contribution AccMagLP (i.e., the low-pass filtered acceleration amplitude that combines the contributions from all three axes) as the earphone 1 moves toward the user's ear. The moment t_f near the end of the motion corresponds to a time when the low-pass filtered acceleration signal stabilizes, i.e., the fluctuation is less than a pre-defined threshold.

[0054] Figure 3c The diagram illustrates the variation of the high-pass filtered contribution AccMagHP (i.e., the high-pass filtered acceleration amplitude combining the contributions of all three axes) of the proximity sensor's acceleration signal as the earphone moves toward the user's ear. It can be seen that fluctuations in the high-pass filtered acceleration signal occur in the third time period B3, originating from the matching motion of the earphone within the user's ear.

[0055] Figure 3d The diagram illustrates the changes in the minimum and maximum values ​​(AccMinMax) of the acceleration signal, measured with respect to each axis of the triaxial accelerometer 3, as the earphone 1 moves toward the user's ear. The moments in the third time period B3 at which the minimum and maximum values ​​of the acceleration signal are reached are identified.

[0056] Figure 3e The minimum and maximum values ​​of the low-pass filtered acceleration signal (i.e., the low-pass filtered acceleration amplitude that combines the contributions of all three axes) are shown as the earphone 1 moves toward the user's ear.

[0057] Figure 3f The diagram illustrates the changes in the minimum and maximum values ​​(AccMinMaxHP) of the high-pass filtered acceleration signal (i.e., the high-pass filtered acceleration amplitude that combines the contributions from all three axes) as the earphone 1 moves toward the user's ear. Even when the low-pass filtered contribution of the acceleration signal is stable, i.e., does not change between the minimum and maximum values, the high-pass filtered contribution still varies drastically, causing large changes in the minimum and maximum values.

[0058] Figure 4a The diagram illustrates the change in the proximity sensor signal as the earphone moves into the user's pocket, which essentially corresponds to the change in... Figure 2b The process of change is shown in the figure.

[0059] Figure 4bThis shows how the low-pass filtered acceleration signal (i.e., the low-pass filtered acceleration amplitude that combines the contributions from all three axes) changes as the earphone moves into the user's pocket.

[0060] Figure 4c This illustrates the change in the high-pass filtered acceleration signal from the proximity sensor (i.e., the high-pass filtered acceleration amplitude combining contributions from all three axes) as the earphone moves into the user's pocket. Figure 3c Unlike before, the fluctuations in the high-pass filtered acceleration signal now occur primarily only during the first and second time periods, B1 and B2. These fluctuations occur before the end time t_f.

[0061] Figure 4d This illustrates the changes in the minimum and maximum values ​​of the acceleration signal from the triaxial accelerometer as the earphone 1 moves into the user's pocket. Figure 3d In contrast, the minimum and maximum values ​​remain almost unchanged after the end time t_f.

[0062] Figure 4e This illustrates the changes in the minimum and maximum values ​​of the low-pass filtered acceleration signal (i.e., the low-pass filtered acceleration amplitude combining the contributions from all three axes) as the earphone 1 moves into the user's pocket. Figure 3e In contrast, the absolute values ​​in the first and second time periods B1 and B2 are greater than the absolute value in the third time period B3.

[0063] Figure 4f The diagram illustrates the changes in the minimum and maximum values ​​of the high-pass filtered acceleration signal (i.e., the high-pass filtered acceleration amplitude combining the contributions of all three axes) as the earphone moves into the user's pocket. The minimum and maximum values ​​of the high-pass filtered acceleration signal cease to change after the end time t_f (i.e., after the low-pass filtered contribution of the acceleration signal has stabilized).

[0064] exist Figures 3a to 3f or Figures 4a to 4f All signal change processes shown can be mathematically analyzed and processed, for example, by calculating the probability of movement toward the user's ear.

[0065] The low-pass filtered contribution of the acceleration values ​​corresponds to linear acceleration. The high-pass filtered contribution of the acceleration values ​​corresponds to the rotation and position change of the headphones. The minimum and maximum values ​​of the low-pass filtered acceleration values ​​indicate when linear acceleration occurs or ends and how much it changes. The high-pass filtered acceleration values, along with the minimum and maximum values ​​of the three axes, indicate when acceleration occurs or ends due to rotation or position change and how much it changes.

[0066] Linear acceleration corresponds to motion-based acceleration and is primarily represented by the low-pass filtered acceleration amplitude. Linear acceleration corresponds to the low-pass filtered acceleration amplitude minus the contribution of gravity. If the value of linear acceleration is close to zero, the termination moment is identified. After the termination moment, no linear acceleration occurs when moving towards the user's ear or into the user's pocket. Even when linear acceleration is zero, the acceleration itself can still change. In this case, Equal to the contribution of gravity, where, It is the contribution in the x, y, and z directions. This relationship also applies when the headphones rotate, ensuring that no linear acceleration occurs, although the accuracy... x，y，z Changes occur. Such motion can be identified from the high-pass filtered contribution of the acceleration amplitude.

[0067] It is determined whether the high-pass filtered contribution of acceleration, or the maximum and minimum values ​​of acceleration, changes after the low-pass filtered amplitude roughly corresponds to the contribution of gravity and almost no linear acceleration occurs, i.e., after the end time. If this is the case, it involves movement toward the ear; otherwise, it involves movement, for example, into a pocket.

[0068] Figure 5 A flowchart illustrating a method for identifying whether earphone 1 is inserted into a user's ear is shown. Earphone 1, as described above, can be used in this method.

[0069] In the first method step S1, the accelerometer 3 generates an accelerometer signal.

[0070] In method step S2, the magnitude of acceleration is determined based on the acceleration sensor signal, and when using a triaxial acceleration sensor 3, the magnitude is determined for each of the three axes.

[0071] In method step S3, the accelerometer signal is filtered using a high-pass filter to generate a high-pass filtered acceleration signal.

[0072] In method step S4, the accelerometer signal is filtered using a low-pass filter to generate a low-pass filtered acceleration signal.

[0073] In step S5 of the method, a proximity sensor signal is generated by proximity sensor 2.

[0074] In method step S6, acceleration data analysis is performed using proximity sensor signals, high-pass filtered acceleration signals, and low-pass filtered acceleration signals.

[0075] In method step S7, motion monitoring of the user is also performed based on the high-pass filtered acceleration signal and the low-pass filtered acceleration signal.

[0076] In method step S8, data analysis of the proximity sensor signal is performed.

[0077] In method step S9, it is determined whether the earphone has been inserted into the user's ear. Here, the approach motion is identified based on the temporal change of the proximity sensor signal, and it is determined whether this is the earphone moving towards the user's ear. This hypothesis is confirmed or rejected using both low-pass and high-pass filtered acceleration signals. For this purpose, the determination is performed specifically at the end of the approach motion.

[0078] In method step S10, the operating mode of the headphones is selected based on the decision, namely, external ear operating mode or internal ear operating mode.

Claims

1. An earphone (1) having: Proximity sensor (2), the proximity sensor being configured to generate a proximity sensor signal; Accelerometer (3), the accelerometer being configured to generate an accelerometer signal; and Signal analysis and processing device (4), the signal analysis and processing device being configured to: a. Identify the approaching motion of the earphone (1) toward the object using the proximity sensor signal; b. Determine whether the approach motion is the movement of the headphones (1) toward the user's ear, wherein, The fluctuations in the proximity sensor signal over time are analyzed, processed, and considered. c. Generate a high-pass filtered acceleration signal and a low-pass filtered acceleration signal by filtering the acceleration sensor signal; d. Using the low-pass filtered acceleration signal, determine the end time of the approach motion based on the stability of the acceleration; and e. Based on the change of the high-pass filtered acceleration signal after the determined end time of the approach motion, confirm that the approach motion is the movement of the earphone (1) toward the user's ear.

2. The earphone (1) according to claim 1, wherein, The signal analysis and processing device (4) is configured to determine and consider the monotonicity of the temporal variation of the proximity sensor signal in order to analyze and process the fluctuations in the change process of the proximity sensor signal of the proximity sensor (2).

3. The earphone (1) according to claim 1 or 2, wherein, The signal analysis and processing device (4) is configured to confirm that the approach motion is the movement of the earphone (1) toward the user's ear if the measure of the change of the high-pass filtered acceleration signal after the determined end time of the approach motion is higher than a pre-given first threshold.

4. The earphone (1) according to claim 3, wherein, The signal analysis and processing device (4) is configured to identify that the approach motion is not a motion of the earphone (1) toward the user's ear if the measure of the change of the high-pass filtered acceleration signal after the determined end time of the approach motion is lower than a predetermined second threshold, wherein the predetermined second threshold is less than or equal to the predetermined first threshold.

5. The earphone (1) according to claim 1 or 2, wherein, The signal analysis and processing device (4) is configured to determine, based on the proximity sensor signal, whether the earphone (1) has been removed from the user's ear again.

6. The earphone (1) according to claim 1 or 2, wherein, The signal analysis and processing device (4) is configured to identify the absence of motion based on the acceleration sensor signal, and, if identified, to place the earphone (1) in an external ear operation mode.

7. The earphone (1) according to claim 1 or 2, wherein, The signal analysis and processing device (4) is configured to identify, based on the acceleration sensor signal, the following movement of the earphone (1) and, if identified, to place the earphone (1) in an external ear operation mode: the movement is not generated by head movement due to its intensity.

8. The earphone (1) according to claim 1 or 2, wherein, The acceleration sensor (3) is a triaxial acceleration sensor (3).

9. The earphone (1) according to claim 8, wherein, The signal analysis and processing device (4) is configured to calculate the maximum and minimum values ​​of acceleration along three axes, and to take into account the maximum and minimum values ​​if it is confirmed that the approach motion is the movement of the earphone (1) toward the user's ear.

10. A method for identifying whether an earphone (1) is inserted into a user's ear, the method comprising the steps of: The proximity sensor signal of the proximity sensor (2) of the earphone (1) is used to identify the approaching movement of the earphone (1) toward the object; Determine whether the approach motion is the movement of the headphones (1) toward the user's ear, wherein, The fluctuations in the proximity sensor signal over time are analyzed, processed, and considered. The acceleration sensor signal of the accelerometer sensor (3) of the earphone (1) is filtered to generate a high-pass filtered acceleration signal and a low-pass filtered acceleration signal. Using the low-pass filtered acceleration signal, the end time of the approach motion is determined based on the stability of the acceleration; and Based on the change of the high-pass filtered acceleration signal after the determined end time of the approach motion, it is confirmed that the approach motion is the movement of the earphone (1) toward the user's ear.

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