In this study, an earphone-type interface named “earable TEMPO” was developed for hands-free operation, wherein the user can control the device by simply pushing the tongue against the roof of the mouth for about one second. This interface can be used to start and stop the music from a portable audio player. The earable TEMPO uses an earphone-type sensor equipped with a light emitting diode (LED) and a phototransistor to optically measure shape variations that occur in the external auditory meatus when the tongue is pressed against the roof of the mouth. To evaluate the operation of the earable TEMPO, experiments were performed on five subjects (men and women aged 22–58) while resting, chewing gum (representing mastication), and walking. The average accuracy was 100% while resting and chewing and 99% while walking. The precision was 100% under all conditions. The average recall value of the five subjects was 92%, 90%, and 48% while resting, masticating, and walking, respectively. All subjects were reliably able to perform the action of pressing the tongue against the roof of the mouth. The measured shape variations in the ear canal were highly reproducible, indicating that this method is suitable for various applications such as controlling a portable audio player.

Abstract:In this study, we describe a technique for estimating meal times using an earphone-type wearable sensor. A small optical sensor composed of a light-emitting diode and phototransistor is inserted into the ear hole of a user and estimates the meal times of the user from the time variations in the amount of light received. This is achieved by emitting light toward the inside of the ear canal and receiving light reflected back from the ear canal. This proposed technique allowed "meals" to be differentiated from having conversations, sneezing, walking, ascending and descending stairs, operating a computer, and using a smartphone. Conventional devices worn on the head of users and that measure food intake can vibrate during running as the body is jolted more violently than during walking; this can result in the misidentification of running as eating by these devices. To solve this problem, we used two of our sensors simultaneously: one in the left ear and one in the right ear. This was based on our finding that measurements from the left and right ear canals have a strong correlation during running but no correlation during eating. This allows running and eating to be distinguished based on correlation coefficients, which can reduce misidentification. Moreover, by using an optical sensor composed of a semiconductor, a small and lightweight device can be created. This measurement technique can also measure body motion associated with running, and the data obtained from the optical sensor inserted into the ear can be used to support a healthy lifestyle regarding both eating and exercise.Keywords: wearable device; ear canal; meal time estimation; body vibration on running; dietary support Background and ObjectiveThe use of wearable devices is growing in popularity in the field of healthcare [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. Wristwatch-type wearable devices are particularly widespread and estimate the amount of exercise by measuring body temperature and heart rate, thereby supporting a user's diet by presenting these estimates. In dietary support, the use of measured results for meals is just as important as support that uses measured results for the amount of exercise. Calorie control is the main form of support for meals; however, support using meal time management has recently received growing attention. Irregular meal times and eating before bedtime have been found to be some of the factors that promote the onset and progression of lifestyle-related diseases [17]. However, support for ordinary individuals

We intend to develop earphone-type wearable devices to measure occlusal force by measuring ear canal movement using an ear sensor that we developed. The proposed device can measure occlusal force during eating. In this work, we simultaneously measured the ear canal movement (ear sensor value), the surface electromyography (EMG) of the masseter muscle and the occlusal force six times from five subjects as a basic study toward occlusal force meter development. Using the results, we investigated the correlation coefficient between the ear sensor value and the occlusal force, and the partial correlation coefficient between ear sensor values. Additionally, we investigated the average of the partial correlation coefficient and the absolute value of the average for each subject. The absolute value results indicated strong correlation, with correlation coefficients exceeding 0.9514 for all subjects. The subjects showed a lowest partial correlation coefficient of 0.6161 and a highest value of 0.8286. This was also indicative of correlation. We then estimated the occlusal force via a single regression analysis for each subject. Evaluation of the proposed method via the cross-validation method indicated that the root-mean-square error when comparing actual values with estimates for the five subjects ranged from 0.0338 to 0.0969.

We aim to develop earphone type wearable devices for measuring occlusal force. In this article, we investigated the correlation between occlusal force and the movement of the ear canal as a basic study to estimate the occlusion force. The proposed estimation method uses the least squares method and the weighted average. We developed an experimental device for simultaneously measuring occlusal force and the movement of the ear canal. This device primarily consists of an occlusal force sensor and a wearable ear sensor, and converts analog signals from both sensors into digital signals using an analog‐to‐digital (AD) converter, then records the data as signals associated with measurement time. The experiment involved six subjects, who performed chewing of the occlusal force sensor five times, for 2 seconds. The occlusal force sensor was placed at the right second molar, with the wearable ear sensor placed on the right ear. Through the experiment, the occlusion and the ear canal movement were found to have a strong correlation. The average correlation coefficients consistently exceeded 0.89 for all subjects.