Method of checking earphone wearing state

1. An information processing apparatus comprising:

circuitry configured to

detect an output from a 3-axis acceleration sensor included in an earphone unit worn by a user while the user is in a still state;

monitor the output of the 3-axis acceleration sensor while a nodding gesture is performed by the user;

detect a time when an angle of the nodding gesture reaches a maximum by detecting an extremum in the output for a specific axis of the 3-axis acceleration sensor that varies during the nodding gesture; and

determine an earphone wearing state based on the output from the 3-axis acceleration sensor in the still state and the output from the 3-axis acceleration sensor at the time of detecting the maximum nodding angle.

2. The information processing apparatus of claim 1 , wherein the circuitry is configured to:

detect the time when the angle of the nodding gesture reaches the maximum by detecting a zero-crossing of a gyroscope included in the earphone unit that varies during the nodding gesture.

3. The information processing apparatus of claim 1 , wherein the circuitry is configured to:

determine whether the earphone unit is being worn on the user's left ear or right ear based on whether an output corresponding to a specific axis of the 3-axis acceleration sensor that varies during the nodding gesture exhibits convex variation or concave variation.

4. The information processing apparatus of claim 1 , wherein

provided that three mutually orthogonal axes of an earphone unit-specific three-dimensional coordinate system are an Xs axis, a Ys axis, and a Zs axis, that mutually orthogonal axes of a three-dimensional coordinate system in which the user is disposed are an Xu axis, a Yu axis, and a Zu axis, in which the Xs axis corresponds to a front and back direction of the earphone unit, the Ys axis corresponds to a top and bottom direction of the earphone, the Zs axis is orthogonal to the Xs axis and the Ys axis, the Xu axis corresponds to a front and back direction of the user, the Yu axis corresponds to a top and bottom direction of the user, and the Zu axis is orthogonal to the Xu axis and the Yu axis, and

provided that φ is a tilt angle of the Ys axis with respect to the Yu axis about the Z axis in both coordinate systems, that ψ is a tilt angle of the Ys axis with respect to the Yu axis about the X axis in both coordinate systems, and that θ is a tilt angle of the Xs axis with respect to the Xu axis about the Y axis in both coordinate systems when the user is wearing the earphone unit,

the circuitry is further configured to:

compute a maximum nodding angle α based on the extremum;

compute the angles φ and ψ based on gravitational acceleration and an output of the 3-axis acceleration sensor while the user is in the still state; and

compute the angle θ based on the angles φ, ψ, and α as well as the output of 3-axis acceleration sensor when the extremum is detected for the specific axis of the 3-axis acceleration sensor that varies during the nodding gesture.

5. A method comprising:

detecting an output from a 3-axis acceleration sensor included in an earphone unit worn by a user while the user is in a still state;

monitoring the output of the 3-axis acceleration sensor while a nodding gesture is performed by the user;

detecting a time when an angle of the nodding gesture reaches a maximum by detecting an extremum in the output for a specific axis of the 3-axis acceleration sensor that varies during the nodding gesture; and

determining, by circuitry, an earphone wearing state based on the output from the 3-axis acceleration sensor in the still state and the output from the 3-axis acceleration sensor at the time of detecting the maximum nodding angle.

6. The method of claim 5 , wherein

detecting the time when the angle of the nodding gesture reaches the maximum includes detecting a zero-crossing of a gyroscope included in the earphone unit that varies during the nodding gesture.

7. The method of claim 5 , further comprising:

determining whether the earphone unit is being worn on the user's left ear or right ear based on whether an output corresponding to a specific axis of the 3-axis acceleration sensor that varies during the nodding gesture exhibits convex variation or concave variation.

8. The method of claim 5 , wherein

provided that three mutually orthogonal axes of an earphone unit-specific three-dimensional coordinate system are an Xs axis, a Ys axis, and a Zs axis, that mutually orthogonal axes of a three-dimensional coordinate system in which the user is disposed are an Xu axis, a Yu axis, and a Zu axis, in which the Xs axis corresponds to a front and back direction of the earphone unit, the Ys axis corresponds to a top and bottom direction of the earphone, the Zs axis is orthogonal to the Xs axis and the Ys axis, the Xu axis corresponds to a front and back direction of the user, the Yu axis corresponds to a top and bottom direction of the user, and the Zu axis is orthogonal to the Xu axis and the Yu axis, and

provided that φ is a tilt angle of the Ys axis with respect to the Yu axis about the Z axis in both coordinate systems, that ψ is a tilt angle of the Ys axis with respect to the Yu axis about the X axis in both coordinate systems, and that θ is a tilt angle of the Xs axis with respect to the Xu axis about the Y axis in both coordinate systems when the user is wearing the earphone unit,

the method further comprising:

computing a maximum nodding angle α based on the extremum;

computing the angles φ and ψ based on gravitational acceleration and an output of the 3-axis acceleration sensor while the user is in the still state; and

computing the angle θ based on the angles φ, ψ, and α as well as the output of 3-axis acceleration sensor when the extremum is detected for the specific axis of the 3-axis acceleration sensor that varies during the nodding gesture.

9. A non-transitory computer readable medium including computer-program instructions, which when executed by an information processing apparatus, cause the information processing apparatus to:

detect an output from a 3-axis acceleration sensor included in an earphone unit worn by a user while the user is in a still state;

monitor the output of the 3-axis acceleration sensor while a nodding gesture is performed by the user;

detect a time when an angle of the nodding gesture reaches a maximum by detecting an extremum in the output for a specific axis of the 3-axis acceleration sensor that varies during the nodding gesture; and

determine an earphone wearing state based on the output from the 3-axis acceleration sensor in the still state and the output from the 3-axis acceleration sensor at the time of detecting the maximum nodding angle.

10. The non-transitory computer readable medium of claim 9 , the computer-program instructions causing the information processing apparatus to:

detect the time when the angle of the nodding gesture reaches the maximum by detecting a zero-crossing of a gyroscope included in the earphone unit that varies during the nodding gesture.

11. The non-transitory computer readable medium of claim 9 , the computer-program instructions causing the information processing apparatus to:

determine whether the earphone unit is being worn on the user's left ear or right ear based on whether an output corresponding to a specific axis of the 3-axis acceleration sensor that varies during the nodding gesture exhibits convex variation or concave variation.

12. The non-transitory computer readable medium of claim 9 , wherein

provided that three mutually orthogonal axes of an earphone unit-specific three-dimensional coordinate system are an Xs axis, a Ys axis, and a Zs axis, that mutually orthogonal axes of a three-dimensional coordinate system in which the user is disposed are an Xu axis, a Yu axis, and a Zu axis, in which the Xs axis corresponds to a front and back direction of the earphone unit, the Ys axis corresponds to a top and bottom direction of the earphone, the Zs axis is orthogonal to the Xs axis and the Ys axis, the Xu axis corresponds to a front and back direction of the user, the Yu axis corresponds to a top and bottom direction of the user, and the Zu axis is orthogonal to the Xu axis and the Yu axis, and

provided that φ is a tilt angle of the Ys axis with respect to the Yu axis about the Z axis in both coordinate systems, that ψ is a tilt angle of the Ys axis with respect to the Yu axis about the X axis in both coordinate systems, and that θ is a tilt angle of the Xs axis with respect to the Xu axis about the Y axis in both coordinate systems when the user is wearing the earphone unit,

the computer-program instructions causing the information processing apparatus to:

compute a maximum nodding angle α based on the extremum;

compute the angles φ and w based on gravitational acceleration and an output of the 3-axis acceleration sensor while the user is in the still state; and

compute the angle θ based on the angles φ, ψ, and α as well as the output of 3-axis acceleration sensor when the extremum is detected for the specific axis of the 3-axis acceleration sensor that varies during the nodding gesture.