Hearing assistance devices with motion sickness prevention and mitigation features

1. A method of preventing or mitigating motion sickness in a subject comprising:

tracking motion of the subject using a first motion sensor;

estimating a vestibular system input based on tracked motion of the subject, wherein estimating the vestibular system input comprises estimating a direction of motion of the subject;

tracking head position of the subject using the first motion sensor;

estimating a visual system input based on tracked head position of the subject, wherein estimating the visual system input comprises estimating a line of gaze of the subject;

estimating consistency between the vestibular system input and the visual system input by calculating an angle between the line of gaze and the direction of motion;

comparing the calculated angle to a threshold value; and

initiating a responsive measure if the estimated consistency crosses the threshold value.

2. The method of claim 1 , the responsive measure comprising prompting the subject to move their head sufficiently to increase consistency between the vestibular system input and the visual system input.

3. The method of claim 1 , the responsive measure comprising providing auditory stimulation.

4. The method of claim 3 , the auditory stimulation comprising a perceptually stationary auditory stimulus.

5. The method of claim 1 , the responsive measure comprising prompting the subject to focus their gaze on the horizon.

6. The method of claim 5 , further comprising using tracked head position of the subject to assess whether the subject focused their gaze on the horizon.

7. The method of claim 1 , the responsive measure comprising displaying video images on a device with a display screen showing motion consistent with tracked motion.

8. The method of claim 7 , wherein the shown motion changes in response to tracked motion changes.

9. The method of claim 1 , wherein estimating visual system input based on tracked head position of the subject comprises estimating a direction of visual focus of the subject.

10. The method of claim 1 , further comprising estimating focal depth of the subject.

11. The method of claim 1 , further comprising tracking eye movement of the subject.

12. The method of claim 1 , further comprising sensing ambient sounds with a microphone as part of a hearing assistance device and classifying current surroundings of the subject based on the ambient sounds.

13. The method of claim 1 , further comprising sensing data with at least one of a magnetic sensor, a telecoil, a wireless radio antenna, and a motion sensor as part of a hearing assistance device and classifying current surroundings of the subject based on ambient sounds.

14. The method of claim 1 , further comprising sensing data with at least one sensor and further comprising classifying current surroundings as one of vehicular, stationary, and non-stationary.

15. The method of claim 14 , further comprising subclassifying vehicular surroundings as one of a passenger vehicle, a bus, a train, a plane, and a boat.

16. The method of claim 15 , further comprising detecting ambient sound, wherein detection of sustained sound at a frequency of less than 200 Hz results in a classification of current surroundings as vehicular and a subclassification as a train.

17. The method of claim 15 , wherein detection of sustained motion at a speed of greater than 150 MPH results in a classification of current surroundings as vehicular and a subclassification as a plane.

18. The method of claim 15 , wherein detection of a change in altitude exceeding a threshold value over less than a threshold amount of time results in a classification of current surroundings as vehicular and a subclassification as a plane.

19. The method of claim 1 , further comprising detecting motion at a frequency of less than 0.5 Hz; wherein detection of sustained oscillating motion at a frequency of less than 0.5 Hz results in a classification of current surroundings as vehicular and a subclassification as a boat.

20. The method of claim 1 , further comprising detecting emesis of the subject.

21. A method of preventing or mitigating motion sickness in a subject comprising:

tracking a direction of motion of the subject using a first motion sensor associated with a hearing assistance device;

tracking a line of gaze of the subject using the first motion sensor;

calculating an angle between the line of gaze and the direction of motion;

sensing ambient sounds with the hearing assistance device;

classifying surroundings based on the tracked motion, tracked head position, and ambient sounds as one of

vehicular;

stationary; and

non-stationary; and

initiating a responsive measure based on the classification of the surroundings and the calculated angle.

22. The method of claim 21 , the responsive measure comprising lifting the subject's head to a horizontal position if the tracked line of gaze is indicated to be below or above horizontal.

23. The method of claim 21 , the responsive measure comprising at least one of

administering aural stimulation to the subject;

prompting the subject to open a vent and/or adjust a fan speed to increase air flow;

prompting the subject to maintain their gaze at a fixed point;

prompting the subject to maintain their gaze at a fixed point on a horizon no less than 30 degrees different than a direction of a vector representing their current motion; and

prompting the subject to breath according to a predetermined cadence.