Simultaneous Measurement of Ear Canal Movement, Electromyography of the Masseter Muscle and Occlusal Force for Earphone-Type Occlusal Force Estimation Device Development

Abstract

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.

Bite Force Transducers and Measurement Devices

“…Kurosawa et al developed a headset-type wearable device to indirectly measure bite force by measuring ear canal movement through ear sensors (Kurosawa et al, 2019). Chewing causes changes in the shape of the masticatory muscles and the ear canal near the temporomandibular joint.…”

Validation of Earphone-Type Sensors for Non-Invasive and Objective Swallowing Function Assessment

“…Because the device is small and lightweight, it can be used not only in hospitals but also in residences for older adults, home-based medical care, and nursing care facilities. Furthermore, it has been verified that the earphone-type sensor can measure mastication and breathing rate [ 20 , 21 , 22 , 23 , 24 ]. The combined use of earphone-type sensors and other non-invasive devices may enable continuous evaluation of swallowing function.…”

“…The earphone-type sensor is very easy to mount, and various information can be provided simply by inserting the earphones into the ear canal. It is a highly reliable apparatus that can allow measurements of mastication count [ 20 ], respiratory rate [ 21 ], occlusal force [ 22 ], mealtime [ 23 ], and tongue movement [ 24 ]. The earphone-type sensor developed for this study ( Figure 1 A) had a longer elastic region than conventional earphone-type sensors that measure mastication rate, respiratory rate, occlusal force, mealtime, or tongue movement.…”

Earable Ω (OMEGA): A Novel Clenching Interface Using Ear Canal Sensing for Human Metacarpophalangeal Joint Control by Functional Electrical Stimulation

“…Earable is an earphone-type wearable device that has a reflective photosensor in the earpiece’s center. It can measure clenching force by sensing ear canal deformation [ 42 , 43 , 44 ]. Earable is shown in Figure 1 .…”

“…Therefore, we propose an earphone-type clenching sensor interface for FES, unlike existing ones that require the placement of sensors around the mouth. We have developed an earphone-type ear canal movement sensor [ 35 , 36 , 37 , 38 , 39 , 40 , 41 ] and showed its application in measuring clenching occlusal force [ 42 , 43 , 44 ]. We use this earphone-type ear canal movement sensor, an earphone-type occlusal measurement device (earable (OMEGA)), for an FES interface to make the mouth free from sensors by measuring the clenching motion in the ear canal.…”