Method and device for evaluating eating ability

Abstract

The method for evaluating eating ability has: an acquisition step that acquires myoelectric potential data on a plurality of facial muscles while a subject person chews; a calculation step that calculates the ratio of the amount of work of a first muscle, which is one of the plurality of facial muscles, to the total amount of work of all of the plurality of facial muscles for each unit time based on the acquired myoelectric potential data; and an evaluation step that evaluates the eating ability of the subject person in accordance with the ratio.

Description

Eating ability evaluation method and evaluation device

[0001] The present invention relates to a method and an apparatus for evaluating eating ability.

[0002] As the super-aging society progresses, methods for evaluating chewing movements such as eating ability are being developed to improve the quality of chewing movements in the elderly and solve chewing-related problems.

[0003] A physiological evaluation method using electromyography has been developed to evaluate the series of activities from the moment food is placed in the mouth to the moment it is swallowed.

[0004] Patent Document 1 discloses a method for evaluating the behavior of food in the mouth using the results of measuring dynamic changes over time in the surface myoelectric potential of the left and right masseter muscles and the suprahyoid muscles.

[0005] Patent Document 2 discloses a physiological food texture evaluation device that obtains muscle activity levels correlated with the workload of each muscle from electromyograms of the left and right masseter muscles and suprahyoid muscles, and determines differences in muscle activity levels due to food and differences during the chewing phase, thereby enabling appropriate and objective sensory evaluation of complex foods.

[0006] JP 2020-148692 A JP 2012-139442 A

[0007] To evaluate eating ability, it is conceivable to obtain electromyograms of the left and right masseter muscles and suprahyoid muscles, calculate the area of ​​the electromyogram waveform from the muscle action potential (μV) and activity time (s), and measure the workload (μV·s) of each muscle. However, although it is possible to compare between foods within the same subject in a single measurement, it is difficult to compare measurements taken on different days by the same subject, or between subjects.

[0008] It is conceivable to normalize (standardize) the measurement values ​​in order to compare the measurement values ​​of the same subject on different days or between subjects. However, if an attempt is made to measure the workload at maximum occlusion using the EMG waveform at maximum load for the purpose of normalization (standardization), there is a problem that it is difficult to measure the workload at maximum occlusion in subjects who have difficulty following instructions, such as elderly people or young children, or subjects with oral and maxillofacial diseases.

[0009] For this reason, when measuring the work of each muscle to evaluate eating ability, it is necessary to be able to compare measured values ​​of the same subject on different days and between subjects.

[0010] Therefore, the present invention provides an eating ability evaluation method and evaluation device that can compare measurement values ​​taken on different days by the same subject and between subjects when evaluating eating ability by measuring the workload of each muscle in the left and right masseter muscles and suprahyoid muscles.

[0011] One method for evaluating eating ability includes an acquisition step of acquiring electromyographic data of multiple facial muscles of a target person while they are chewing; a calculation step of calculating, from the acquired electromyographic data, the ratio of the workload of a first muscle, which is one of the multiple facial muscles, to the total workload of all of the multiple facial muscles per unit time; and an evaluation step of evaluating the eating ability of the target person based on the ratio.

[0012] In one method for evaluating eating ability, the plurality of muscles include a masseter muscle and a suprahyoid muscle group, and the first muscle is the masseter muscle.

[0013] In one method for evaluating eating ability, the unit time is from the start of chewing to just before swallowing.

[0014] In one method for evaluating eating ability, the acquisition process acquires data for motion analysis that analyzes the motion of the subject when the electromyography data is measured, and the calculation process excludes the electromyography data from the motion analysis data during periods when the subject is not chewing from the calculation of the ratio.

[0015] In one method for evaluating eating ability, the motion analysis data is video data of the subject taken when the myoelectric potential data is acquired.

[0016] In one method for evaluating eating ability, the motion analysis data is audio recording data of sounds around the subject when the myoelectric potential data is acquired.

[0017] In one method for evaluating eating ability, the evaluation step determines that the eating ability is better when the range between the maximum and minimum values ​​of the ratio over a predetermined time period is wider.

[0018] In one method for evaluating eating ability, the evaluation step determines that the eating ability is better when the median value of the ratio over a predetermined time period is larger.

[0019] In one method for evaluating eating ability, the evaluation step evaluates the eating ability according to the median value and the range between the maximum and minimum values ​​of the ratio at a predetermined time.

[0020] In one method for evaluating eating ability, the evaluation step determines that the eating ability is better when the average value of the ratio over a predetermined time period is larger.

[0021] In one method for evaluating eating ability, the evaluation step determines that the eating ability is better when the mode of the ratio in a predetermined time period is larger.

[0022] In one method for evaluating eating ability, the myoelectric potential data is a measurement value obtained when the subject chews food that includes ingredients of a first hardness, ingredients of a second hardness that is harder than the first hardness, and ingredients of a third hardness that is harder than the second hardness.

[0023] In one method for evaluating eating ability, the myoelectric potential data is a measurement value obtained when the subject chews food that includes ingredients of the first hardness and the third hardness but does not include ingredients of the second hardness, out of ingredients of a first hardness, ingredients of a second hardness that is harder than the first hardness, and ingredients of a third hardness that is harder than the second hardness.

[0024] In one method for evaluating eating ability, ingredients of the first hardness are ingredients that can be processed with the tongue, ingredients of the second hardness are soft ingredients, and ingredients of the third hardness are hard ingredients, and the hardness of ingredients is classified according to the pressure that can crush the ingredients, with ingredients that have a pressure less than a first threshold being classified as ingredients of the first hardness, ingredients that have a pressure equal to or greater than a second threshold that is greater than the first threshold being classified as ingredients of the third hardness, and all other ingredients being classified as ingredients of the second hardness.

[0025] In one method for evaluating eating ability, the plurality of muscles include left and right masseter muscles and suprahyoid muscles, and the workload of the first muscle is the sum of the workloads of the left and right masseter muscles.

[0026] In one method for evaluating eating ability, the plurality of muscles include either the left or right masseter muscle and the suprahyoid muscle group, and the first muscle is either the left or right masseter muscle.

[0027] In one method for evaluating eating ability, the plurality of muscles include the zygomaticus muscle and the suprahyoid muscle group, and the first muscle is the zygomaticus muscle.

[0028] In one method for evaluating eating ability, the plurality of muscles include a temporalis muscle and a suprahyoid muscle group, and the first muscle is a temporalis muscle.

[0029] In one method for evaluating eating ability, the multiple muscles are the suprahyoid muscles as well as one or a combination of the left and right masseter muscles, zygomatic muscles, and temporalis muscles, and the workload of the first muscle is the workload of one of the left and right masseter muscles, zygomatic muscles, and temporalis muscles, or the total workload of the combination.

[0030] In one method for evaluating eating ability, the evaluation process is carried out using an evaluation model, which learns using learning myoelectric potential data and the eating ability data of the person being measured who has measured the learning myoelectric potential data, and generates a threshold value in the learning process.In the evaluation process, the ratio is input, and the eating ability of the target person is output by comparing the generated threshold value with the ratio.

[0031] In one disclosure, when assessing eating ability by measuring the work of each muscle of the left and right masseter muscles and the suprahyoid muscles, it is possible to compare measured values ​​of the same subject on different days and between subjects.

[0032] FIG. 1 is a schematic diagram showing the configuration of an evaluation device according to an embodiment. FIG. 2 is a schematic diagram illustrating the state in which the electromyogram measuring unit for measuring the left and right masseter muscles and suprahyoid muscles of the evaluation device shown in FIG. 1 is attached to a subject. FIG. 3 shows (A) an electromyogram of the right masseter muscle, (B) an electromyogram of the left masseter muscle, and (C) an electromyogram of the suprahyoid muscles, obtained in the first example of FIG. 1. FIG. 4A is an example of a graph showing the workload of the left and right masseter muscles and suprahyoid muscles during a single chewing and swallowing movement of a subject obtained in the first example. FIG. 4B is an example of a graph showing the ratio of the workload of the left and right masseter muscles and suprahyoid muscles during a single chewing and swallowing movement of a subject obtained in the first example. FIG. 5A is a graph showing the ratio of the workload of the left and right masseter muscles and suprahyoid muscles during a single chewing and swallowing movement of a subject with high eating ability obtained in the first example. Figure 5B is a graph showing the ratio of the workload of the left and right masseter muscles and the suprahyoid muscle group during a single chewing and swallowing action of a subject with intermediate eating ability, obtained in the first embodiment. Figure 5C is a graph showing the ratio of the workload of the left and right masseter muscles and the suprahyoid muscle group during a single chewing and swallowing action of a subject with low eating ability, obtained in the first embodiment. Figure 6A is a graph showing the ratio of the workload of the left and right masseter muscles during a single chewing and swallowing action of a subject with high eating ability, obtained in the first embodiment, versus the type of food eaten. Figure 6B is a graph showing the ratio of the workload of the left and right masseter muscles during a single chewing and swallowing action of a subject with high eating ability, obtained in the first embodiment. Figure 6C is a graph showing the mode or median of the ratio of the workload of the left and right masseter muscles on the horizontal axis and the range on the vertical axis. Figure 7A is a graph showing the ratio of the workload of the left and right masseter muscles and the suprahyoid muscle group during a single chewing and swallowing action of a subject with high eating ability, obtained in the second embodiment, versus the type of food eaten. Figure 7B is a graph showing the ratio of the workload of the left and right masseter muscles and the suprahyoid muscles in a single chewing and swallowing action for a subject with medium eating ability, obtained in Example 2, versus the type of food eaten. Figure 7C is a graph showing the ratio of the workload of the left and right masseter muscles and the suprahyoid muscles in a single chewing and swallowing action for a subject with low eating ability, obtained in Example 2, versus the type of food eaten. Figure 7D is a graph showing the ratio of the workload of the left and right masseter muscles in a single chewing and swallowing action for subjects with high, medium, and low eating abilities, obtained in Example 2.FIG. 7E is a graph showing the range of the median value of the ratio of the workload of the left and right masseter muscles in the second embodiment. FIG. 7F is a graph showing the range of the mode value of the ratio of the workload of the left and right masseter muscles in the second embodiment. FIG. 8A is a graph showing the ratio of the workload of the left and right masseter muscles and the suprahyoid muscle group in a single chewing and swallowing action of a subject with high eating ability, obtained in the third embodiment, versus the type of food eaten. FIG. 8B is a graph showing the ratio of the workload of the left and right masseter muscles and the suprahyoid muscle group in a single chewing and swallowing action of a subject with intermediate eating ability, obtained in the third embodiment, versus the type of food eaten. FIG. 8C is a graph showing the ratio of the workload of the left and right masseter muscles and the suprahyoid muscle group in a single chewing and swallowing action of a subject with low eating ability, obtained in the third embodiment, versus the type of food eaten. FIG. 8D is a graph showing the ratio of the workload of the left and right masseter muscles in a single chewing and swallowing action of subjects with high, medium, and low eating abilities, obtained in the third embodiment. FIG. 8E is a graph showing the range of the median value of the ratio of the workload of the left and right masseter muscles in the third embodiment. FIG. 8F is a graph showing the range of the mode value of the ratio of the workload of the left and right masseter muscles in the third embodiment. FIG. 9A is a graph showing the ratio of the workload of the left and right masseter muscles and the suprahyoid muscle group in a single chewing and swallowing action of a subject with high eating ability, obtained in the fourth embodiment, versus the type of food eaten. FIG. 9B is a graph showing the ratio of the workload of the left and right masseter muscles and the suprahyoid muscle group in a single chewing and swallowing action of a subject with intermediate eating ability, obtained in the fourth embodiment, versus the type of food eaten. FIG. 9C is a graph showing the ratio of the workload of the left and right masseter muscles and the suprahyoid muscle group in a single chewing and swallowing action of a subject with low eating ability, obtained in the fourth embodiment, versus the type of food eaten. FIG. 9D is a graph showing the ratio of the workload of the left and right masseter muscles in a single chewing and swallowing action of subjects with high, medium, and low eating abilities, obtained in the fourth embodiment. Fig. 9E is a graph showing the range of the median value of the ratio of the workload of the left and right masseter muscles in Example 4. Fig. 9F is a graph showing the range of the mode value of the ratio of the workload of the left and right masseter muscles in Example 4. Fig. 10A is a graph showing the ratio of the workload of the left and right masseter muscles and the suprahyoid muscles in a single chewing and swallowing movement of a subject with high eating ability obtained in Example 5, versus the type of food eaten.Figure 10B is a graph showing the ratio of the workload of the left and right masseter muscles and the suprahyoid muscle group during a single chewing and swallowing action for a subject with intermediate eating ability, obtained in Example 5, versus the type of food eaten. Figure 10C is a graph showing the ratio of the workload of the left and right masseter muscles and the suprahyoid muscle group during a single chewing and swallowing action for a subject with low eating ability, obtained in Example 5, versus the type of food eaten. Figure 10D is a graph showing the ratio of the workload of the left and right masseter muscles during a single chewing and swallowing action for subjects with high, medium, and low eating abilities, obtained in Example 5. Figure 10E is a graph showing the range of the median of the ratio of the workload of the left and right masseter muscles in Example 5. Figure 10F is a graph showing the range of the mode of the ratio of the workload of the left and right masseter muscles in Example 5. Figure 11A is a graph showing the median of the ratio of the workload of the left and right masseter muscles versus the test score for the evaluation item related to eating ability in Example 6. FIG. 11B is a graph showing the mode of the ratio of the workload of the left and right masseter muscles to the test scores for the evaluation items related to eating ability in Example 6. FIG. 11C is a graph showing the range of the ratio of the workload of the left and right masseter muscles to the test scores for the evaluation items related to eating ability in Example 6. FIG. 11D is a graph showing the range of the median of the ratio of the workload of the left and right masseter muscles in Example 6. FIG. 11E is a graph showing the range of the mode of the ratio of the workload of the left and right masseter muscles in Example 6. FIG. 12 is a diagram explaining the ratio of the workload of the left and right masseter muscles and the workload of the suprahyoid muscles measured during mastication to the workload of the oral muscles required for mastication. (A) shows the case of a subject with high eating ability, and (B) shows the case of a subject with low eating ability. FIG. 13 is a diagram showing examples of ingredients included in the "Pork and Tofu Set." FIG. 14 is a diagram showing examples of the workload ratio of the masseter muscles in Food Pattern 1 (including all ingredients). Fig. 15 is a diagram showing an example of the workload ratio of the masseter muscle in food pattern 2 (excluding ingredients that can be processed with the tongue). Fig. 16 is a diagram showing an example of the workload ratio of the masseter muscle in food pattern 3 (excluding soft ingredients). Fig. 17 is a diagram showing an example of the workload ratio of the masseter muscle in food pattern 4 (excluding hard ingredients). Fig. 18 is a diagram showing examples of ingredients included in a "meal set."

[0033] The following describes embodiments of the present invention. The embodiments described below are merely examples and can be modified as appropriate within the scope obvious to those skilled in the art.

[0034] 1 is a schematic diagram showing the configuration of an evaluation device of this embodiment. The evaluation device 1 for eating ability includes a first electromyography unit 11 attached to the left and right masseter muscle regions of a subject, a second electromyography unit 12 attached to the suprahyoid muscle region of the subject, and a signal processing unit 14 connected to the first electromyography unit 11 and the second electromyography unit 12.

[0035] The first electromyography measurement unit 11 is attached to the left and right masseter muscle regions of the subject, and transmits the output resulting from electromyography of the left and right masseter muscles of the subject to the signal processing unit 14. Since there are two masseter muscles, one on the left and one on the right, two first electromyography measurement units 11 are attached as a set to the right masseter muscle region and the other to the left masseter muscle region of the subject. The first electromyography measurement unit 11 that measures the electromyography of the left and right masseter muscles of the subject can use an already known electromyograph for the left and right masseter muscles.

[0036] The second electromyography unit 12 is attached to the suprahyoid muscle group of the subject, and transmits an output resulting from electromyography of the suprahyoid muscle group of the subject to the signal processing unit 14. The second electromyography unit 12 that measures the electromyography of the suprahyoid muscle group of the subject can be an already known electromyograph for the suprahyoid muscle group.

[0037] The eating ability evaluation device 1 may further include a swallowing measurement unit 13 attached to the throat of the subject. The swallowing measurement unit 13 is attached to the throat of the subject and measures the timing at which food (drinks or solid objects) that has entered the oral cavity of the subject is swallowed. The swallowing measurement unit 13 may be, for example, a microphone, a surface electromyograph, or a Doppler meter.

[0038] 1 , the signal processing unit 14 includes an electromyogram acquisition unit 21, a left and right masseter muscle workload acquisition unit 22, a suprahyoid muscle group workload acquisition unit 23, a left and right masseter muscle and suprahyoid muscle group workload ratio acquisition unit 24, a discrimination unit 25, an evaluation unit 26, and a memory unit 35. The signal processing unit 14 may be realized by hardware, or may be realized by a combination of hardware and software on a computer including a calculation unit and a control unit. The signal processing unit 14 receives measurement signals measured by the first electromyogram measurement unit 11, the second electromyogram measurement unit 12, and the swallowing measurement unit 13, and performs various calculations. The signal processing unit 14 may be connected to other clients or servers via, for example, the Internet, a LAN, or a wireless LAN so as to be able to exchange information with them.

[0039] The signal processing unit 14 is not limited to a configuration in which all of the components constituting the signal processing unit 14 are integrally formed. For example, the electromyogram acquisition unit 21 may be configured separately from the other components of the signal processing unit 14. In this case, the first electromyogram measurement unit 11, the second electromyogram measurement unit 12, and the electromyogram acquisition unit 21 may be configured as a set of electromyogram data acquisition devices. The left and right masseter muscle work acquisition unit 22, the suprahyoid muscle group work acquisition unit 23, the left and right masseter muscle and suprahyoid muscle group work ratio acquisition unit 24, the discrimination unit 25, the evaluation unit 26, and the storage unit 35 may be realized by cooperation of hardware and software on a single computer.

[0040] The electromyogram acquisition unit 21 acquires electromyograms of the left and right masseter muscles from the signal of the first electromyogram measurement unit 11. It also acquires electromyograms of the suprahyoid muscles from the signal of the second electromyogram measurement unit 12. A pair of first electromyogram measurement units 11 are attached to the right and left masseter muscle regions of the subject, respectively, so that electromyograms of the right and left masseter muscles are acquired as electromyograms of the left and right masseter muscles. Here, the electromyogram is a graph showing the muscle action potential (μV), which is the output of the first electromyogram measurement unit 11 and the second electromyogram measurement unit 12, versus the activity time (s), and the muscle work (μV·s) of each of the left and right masseter muscles and the suprahyoid muscles can be obtained by calculating the area of ​​the electromyogram waveform.

[0041] The left and right masseter muscle workload acquisition unit 22 acquires the muscle workload of the left and right masseter muscles by calculating the area of ​​the electromyogram waveform of the left and right masseter muscles obtained from the signal of the first electromyogram measurement unit 11. Here, the area of ​​the electromyogram waveform is calculated for each of the electromyogram of the right masseter muscle and the electromyogram of the left masseter muscle, and these are added together to determine the muscle workload of the left and right masseter muscles.

[0042] The suprahyoid muscle group workload acquisition unit 23 calculates the area of ​​the electromyogram waveform of the suprahyoid muscle group obtained from the signal of the second electromyogram measurement unit 12 to acquire the workload of the suprahyoid muscle group.

[0043] The workload of the left and right masseter muscles and the workload of the suprahyoid muscles are obtained by, for example, adding up the areas of the waveforms in one chewing and swallowing movement. One chewing and swallowing movement is the movement from when the subject puts food to be eaten in the mouth, chews it, and swallows it. The number of chews may be, for example, multiple times, but may also be one or zero.

[0044] The left and right masseter and suprahyoid muscle group workload ratio acquisition unit 24 calculates the ratio between the muscle workload of the left and right masseter muscles obtained by the left and right masseter muscle workload acquisition unit 22 and the muscle workload of the suprahyoid muscle group obtained by the suprahyoid muscle group workload acquisition unit 23, and acquires the workload ratios of the left and right masseter and suprahyoid muscle groups. The workload ratio of the left and right masseter muscles is the ratio of the workload of the left and right masseter muscles to the oral cavity muscle workload, which is the total workload of the left and right masseter muscles and suprahyoid muscle groups. The workload ratio of the suprahyoid muscle groups is the ratio of the workload of the suprahyoid muscle groups to the oral cavity muscle workload. The workload ratio of the left and right masseter and suprahyoid muscle groups is the ratio of the workload of the left and right masseter muscles and the workload of the suprahyoid muscle groups. The sum of the workload ratios of the left and right masseter muscles and the workload ratio of the suprahyoid muscle groups is 1.

[0045] The determination unit 25 determines which of the left and right masseter muscles and the suprahyoid muscle group makes a dominant contribution to mastication, based on the ratio of the workload of the left and right masseter muscles and the suprahyoid muscle group obtained by the workload ratio acquisition unit 24. The determination based on the ratio of the workload of the left and right masseter muscles and the ratio of the workload of the suprahyoid muscle group may be based on either one of the ratio of the workload of the left and right masseter muscles and the ratio of the workload of the suprahyoid muscle group.

[0046] The evaluation unit 26 evaluates the eating ability based on the ratio of the workload of the left and right masseter muscles and the suprahyoid muscles obtained by the workload ratio acquisition unit 24. The evaluation based on the ratio of the workload of the left and right masseter muscles and the suprahyoid muscles may be based on either the ratio of the workload of the left and right masseter muscles or the ratio of the workload of the suprahyoid muscles. For example, a representative value of the workload ratio of the left and right masseter muscles is calculated, and eating ability is evaluated based on the obtained representative value. Here, the representative value may be a mode (mode Mo), a median (median Me), a mean value, or the like. In evaluating eating ability, it is important to capture the characteristics of the movement of the oral muscles during eating, and the mode, which indicates the most frequently detected value, is preferable. Alternatively, the difference between the maximum and minimum values ​​of the workload ratio of the left and right masseter muscles (range R) may be calculated, and eating ability may be evaluated based on the obtained range. Alternatively, eating ability may be evaluated by calculating the relationship between the representative value and the range of the workload ratio of the left and right masseter muscles. Alternatively, eating ability may be evaluated based on the representative value, range, or the relationship between the representative value and the range of the workload ratio of the suprahyoid muscles.

[0047] The evaluation unit 26 evaluates the eating ability based on a comparison between the ratio of the workload of the left and right masseter muscles and suprahyoid muscle groups of the evaluation subject and the ratio of the workload of the left and right masseter muscles and suprahyoid muscle groups of a comparison subject. For example, the eating ability is compared based on a comparison between the mode of the ratio of the workload of the left and right masseter muscles and suprahyoid muscle groups of the evaluation subject and the mode of the ratio of the workload of the left and right masseter muscles and suprahyoid muscle groups of a comparison subject. The ratio of the workload of the left and right masseter muscles and suprahyoid muscle groups of the comparison subject is, for example, the ratio of the workload of the left and right masseter muscles and suprahyoid muscle groups obtained on a different day for the same subject, or the ratio of the workload of the left and right masseter muscles and suprahyoid muscle groups of another subject. Furthermore, a table or the like showing a correlation between the workload ratio of the left and right masseter muscles and suprahyoid muscle groups and eating ability may be created in advance, and the eating ability may be evaluated by referring to the workload ratio of the left and right masseter muscles and suprahyoid muscle groups of the evaluation subject and the table or the like. Tables showing the correlation between the ratio of the workload of the left and right masseter muscles and the suprahyoid muscles and eating ability may be created for each type of food, or data on various foods may be compiled into a single table. For example, the level of eating ability may be classified and evaluated into two levels (high and low), three levels (high, medium, and low), or other multiple levels. The evaluation based on the ratio of the workload of the left and right masseter muscles and the suprahyoid muscles may be based on either the ratio of the workload of the left and right masseter muscles or the ratio of the workload of the suprahyoid muscles.

[0048] The signal processing unit 14 may further include an eating start time measuring unit that measures the time it takes for food to be placed in the oral cavity based on the measurement signal received from either the first electromyography measuring unit 11 or the second electromyography measuring unit 12, and a swallowing time calculation unit that calculates the time required for food to be swallowed based on the measurement signal measured by the swallowing measuring unit 13 and the time measured by the eating start time measuring unit.

[0049] The signal processing unit 14 can store, as necessary, the following data in the storage unit 35: signal data from the first electromyography measuring unit 11, signal data from the second electromyography measuring unit 12, the electromyogram acquired by the electromyogram acquiring unit 21, the workload of the left and right masseter muscles acquired by the left and right masseter muscle workload acquiring unit 22, the workload of the suprahyoid muscles acquired by the suprahyoid muscle group workload acquiring unit 23, the ratio of the workload of the left and right masseter muscles and the suprahyoid muscle group acquired by the ratio acquiring unit 24, the discrimination result obtained by the discrimination unit 25, and the evaluation result obtained by the evaluation unit 26. The data stored in the storage unit 35 can be read out from outside the evaluation device 1, and can also be used for each calculation performed by the signal processing unit 14 as necessary.

[0050] An example of the operation of the eating ability evaluation device of this embodiment will be described below. At the start of operation, the first electromyography measurement unit 11, the second electromyography measurement unit 12, and the swallowing measurement unit 13 are attached to the measurement sites of the subject. When the subject eats food and begins chewing, the subject's left and right masseter muscles and suprahyoid muscles become active.

[0051] When the output signal from the first electromyography measuring unit 11 is input to the signal processing unit 14, electromyograms of the left and right masseter muscles are acquired by the electromyogram acquiring unit 21. Information on the electromyograms of the left and right masseter muscles is transmitted to the left and right masseter muscle work acquiring unit 22, and the areas of the electromyogram waveforms of the left and right masseter muscles are calculated to acquire the muscle work of the left and right masseter muscles.

[0052] On the other hand, when the output signal of the second electromyography measuring unit 12 is input to the signal processing unit 14, an electromyogram of the suprahyoid muscles is acquired by the electromyogram acquiring unit 21. The electromyogram information of the suprahyoid muscles is transmitted to the suprahyoid muscle work acquiring unit 23, and the area of ​​the electromyogram waveform of the suprahyoid muscles is calculated to acquire the muscle work of the suprahyoid muscles.

[0053] The workload of the left and right masseter muscles and the workload of the suprahyoid muscles are transmitted to a workload ratio acquisition unit 24 for the left and right masseter muscles and the suprahyoid muscles, which acquires the workload ratio between the left and right masseter muscles and the suprahyoid muscles. The workload ratio between the left and right masseter muscles and the suprahyoid muscles is transmitted to a discrimination unit 25, which determines which of the left and right masseter muscles and the suprahyoid muscles contributes more predominantly to mastication based on the workload ratio between the left and right masseter muscles and the suprahyoid muscles, and outputs the discrimination result. The workload ratio between the left and right masseter muscles and the suprahyoid muscles is transmitted to an evaluation unit 26, which evaluates eating ability based on the workload ratio between the left and right masseter muscles and the suprahyoid muscles, and outputs the evaluation result.

[0054] The eating start time measuring unit may determine the start of eating based on either or both of the output signal of the first electromyography measuring unit 11 and the output signal of the second electromyography measuring unit 12. Furthermore, the swallowing time calculation unit may calculate the time required for food to be swallowed based on the measurement signal measured by the swallowing measuring unit 13 and the time measured by the eating start time measuring unit. The eating start time and the time required for swallowing can be used to clearly distinguish between types of food being eaten in each example described below, and can also be used for various physiological analyses other than determining which of the left and right masseter muscles and the suprahyoid muscles contributes more predominantly to mastication and evaluating eating ability.

[0055] (Actions and Effects of the Evaluation Device) With conventional electromyographic waveform analysis, it is possible to make comparisons within a subject, but it is difficult to compare measurements taken on different days by the same subject or between subjects. However, we discovered that by calculating the ratio of the workload of the left and right masseter muscles and the suprahyoid muscles from the workload of the left and right masseter muscles and the suprahyoid muscles, it is possible to compare measurements taken on different days by the same subject or between subjects.

[0056] According to the evaluation device of this embodiment, when evaluating eating ability by measuring the workload of each muscle of the left and right masseter muscles and the suprahyoid muscles, it is possible to compare measurement values ​​of the same subject on different days and between subjects.

[0057] Furthermore, because chewing is a complex movement that moves the mandible and suprahyoid muscles back and forth, up and down, and left and right, it has been difficult to grasp the chewing movement in detail based solely on the magnitude of the workload of the left and right masseter muscles and suprahyoid muscles. The evaluation device of this embodiment can grasp chewing movements such as dominance of the left and right masseter muscles and dominance of the suprahyoid muscles, which cannot be evaluated by comparing the magnitude of the workload.

[0058] The evaluation device of this embodiment can evaluate masticatory movements by non-invasive and simple electromyography. This device serves as the basis for the design of physical properties of products aimed at maintaining and improving masticatory ability. Individual masticatory training methods can be proposed using these products or the evaluation device itself, and it is also possible to observe changes in masticatory movements as a result of this training. When used in conjunction with information related to the magnitude of the workload of the left and right masseter muscles and suprahyoid muscles, this can further contribute to improving the quality of masticatory movements.

[0059] (Method for Determining Muscles That Dominately Contribute to Eating) The method for determining muscles that dominantly contribute to eating involves first measuring the electromyograms of the left and right masseter muscles during chewing to obtain the workload of the left and right masseter muscles, and measuring the electromyograms of the suprahyoid muscles to obtain the workload of the suprahyoid muscles. For example, the electromyogram acquisition unit 21 shown in Fig. 1 acquires electromyograms of the left and right masseter muscles from signals from the first electromyogram measurement unit 11, and the left and right masseter muscle workload acquisition unit 22 acquires the workload of the left and right masseter muscles. The electromyogram acquisition unit 21 also acquires electromyograms of the suprahyoid muscles from signals from the second electromyogram measurement unit 12, and the suprahyoid muscle group workload acquisition unit 23 acquires the workload of the suprahyoid muscles.

[0060] Next, the muscle workload ratio, which is the ratio between the workload of the left and right masseter muscles and the workload of the suprahyoid muscles, is calculated. For example, the left and right masseter and suprahyoid muscle workload ratio acquisition unit 24 calculates the ratio between the workload of the left and right masseter muscles and the workload of the suprahyoid muscles, and acquires the workload ratio of the left and right masseter muscles and the suprahyoid muscle group.

[0061] Next, based on the obtained ratio of the workload of the muscles, it is determined which of the left and right masseter muscles and the suprahyoid muscle group contributes predominantly to mastication. For example, the determination unit 25 determines which of the left and right masseter muscles and the suprahyoid muscle group contributes predominantly to mastication based on the ratio of the workload of the left and right masseter muscles and the suprahyoid muscle group.

[0062] (Actions and Effects of the Method for Identifying Muscles That Dominately Contribute to Eating) According to the method for identifying muscles that dominantly contribute to eating of this embodiment, when measuring the workload of each muscle of the left and right masseter muscles and the suprahyoid muscle group to evaluate eating ability, it is possible to compare measured values ​​of the same subject on different days and between subjects, and it can be used in an evaluation method and evaluation device that can evaluate chewing movements by non-invasive and simple electromyography. Furthermore, it is possible to grasp chewing movements such as left and right masseter muscle dominance and suprahyoid muscle group dominance, which cannot be evaluated by comparing the magnitude of the workload of the left and right masseter muscles and the suprahyoid muscle group.

[0063] (Method for evaluating eating ability) The method for evaluating eating ability is similar to the method for determining the muscles that contribute most significantly during eating, in which the workload of the left and right masseter muscles and the workload of the suprahyoid muscles during chewing are obtained, and the ratio between the workload of the left and right masseter muscles and the workload of the suprahyoid muscles is calculated.

[0064] Next, based on the obtained muscle workload ratio, it is determined which of the left and right masseter muscles and the suprahyoid muscle group contributes predominantly to mastication, and eating ability is evaluated. For example, the evaluation unit 26 evaluates eating ability based on the workload ratio of the left and right masseter muscles and the suprahyoid muscle group obtained by the workload ratio acquisition unit 24 for the left and right masseter muscles and the suprahyoid muscle group.

[0065] The evaluation of eating ability is based on the ratio of the workload of the left and right masseter muscles and the suprahyoid muscles obtained by the workload ratio acquisition unit 24 for the left and right masseter muscles and the suprahyoid muscles. The evaluation may be based on either the ratio of the workload of the left and right masseter muscles or the ratio of the workload of the suprahyoid muscles. For example, a representative value such as the mode, median, or mean value of the ratio of the workload of the left and right masseter muscles is obtained, and eating ability is evaluated based on the obtained representative value. A range of the ratio of the workload of the left and right masseter muscles may be obtained, and eating ability may be evaluated based on the obtained range. Alternatively, eating ability may be evaluated by determining the relationship between the representative value and range of the ratio of the workload of the left and right masseter muscles.

[0066] Furthermore, the evaluation of eating ability is based on a comparison between the ratio of the workload of the left and right masseter muscles and suprahyoid muscle groups of the subject to be evaluated and the ratio of the workload of the left and right masseter muscles and suprahyoid muscle groups of a comparison subject. The ratio of the workload of the left and right masseter muscles and suprahyoid muscle groups of the comparison subject is, for example, the ratio of the workload of the left and right masseter muscles and suprahyoid muscle groups obtained on a different day for the same subject, or the ratio of the workload of the left and right masseter muscles and suprahyoid muscle groups of another subject. Furthermore, for the ratio of the workload of the left and right masseter muscles and suprahyoid muscle groups, a table or the like may be created in advance that shows the correlation between eating ability for each type of food, and eating ability may be evaluated by referring to the ratio of the workload of the left and right masseter muscles and suprahyoid muscle groups of the subject to be evaluated and the table or the like.

[0067] For example, when a single food is being eaten, electromyography of the left and right masseter muscles and the suprahyoid muscles may be performed, and based on the ratio of the workload of the left and right masseter muscles to the workload of the suprahyoid muscles, it may be determined which of the left and right masseter muscles and the suprahyoid muscles contributes more significantly to mastication, thereby evaluating eating ability. Furthermore, when a plurality of different types of food is being eaten, electromyography of the left and right masseter muscles and the suprahyoid muscles may be performed, and based on the ratio of the workload of the left and right masseter muscles to the workload of the suprahyoid muscles, it may be determined which of the left and right masseter muscles and the suprahyoid muscles contributes more significantly to mastication, thereby evaluating eating ability. The same applies when at least one of a representative value and a range of the ratio of the workload of the left and right masseter muscles and the workload of the suprahyoid muscles is calculated and eating ability is evaluated based on at least one of these.

[0068] (Functions and Effects of the Method for Evaluating Eating Ability) According to the evaluation method of this embodiment, when evaluating eating ability by measuring the workload of each muscle of the left and right masseter muscles and the suprahyoid muscles, it is possible to compare measurements taken on different days by the same subject and to compare between subjects. Furthermore, it is possible to grasp chewing movements such as left and right masseter dominance or suprahyoid muscle dominance, which cannot be evaluated by comparing the magnitude of the workload of the left and right masseter muscles and the suprahyoid muscles.

[0069] The evaluation method of this embodiment evaluates eating ability by measuring electromyography when a single food or multiple different types of foods are eaten, and can evaluate differences in mastication movements when eating the single food or multiple different types of foods. Furthermore, eating ability can be evaluated by monitoring mastication movements when consecutively ingesting foods during a series of meals. Furthermore, eating ability can be evaluated by reflecting differences in multiple mastication movements, which cannot be fully grasped by the amount of work required when ingesting a single food, and mastication ability during a series of meals.

[0070] 1, the first electromyogram measuring unit 11 and the second electromyogram measuring unit 12 were attached to 10 subjects, and electromyograms were obtained by measuring the electromyograms of the left and right masseter muscles and the suprahyoid muscles when the subjects ate the same meal. In this example, the meal was a curry and rice set (a set consisting of green beans, a salad containing ham, curry and rice containing potatoes, pickled vegetables, and a peach for dessert).

[0071] 2 is a schematic diagram illustrating the state in which the electromyography measuring units for the left and right masseter muscles and the suprahyoid muscles of the evaluation device 1 in FIG. 1 are attached to a subject. A pair of first electromyography measuring units 11 are attached to the left and right masseter muscles of the subject, and a second electromyography measuring unit 12 is attached to the suprahyoid muscles of the subject.

[0072] 3A to 3C show examples of electromyograms acquired in this example: (A) an electromyogram of the right masseter muscle, (B) an electromyogram of the left masseter muscle, and (C) an electromyogram of the suprahyoid muscles. The vertical axis of each electromyogram represents the electromyograph output signal (unit: μV), and the horizontal axis represents time (unit: s). In the electromyogram acquisition unit 21, each electromyogram is acquired from the signal of the first electromyogram measurement unit 11 or the signal of the second electromyogram measurement unit 12. In FIGS. 3A to 3C, each electromyogram signal is divided by the type of food eaten, and shows a signal fa when curry rice is eaten, a signal fb when fukujinzuke is eaten, and a signal fc when kidney beans are eaten.

[0073] The areas of the electromyogram waveforms of the right and left masseter muscles were calculated from the electromyogram data in Figures 3(A) and (B), and the areas of the waveforms for one chewing and swallowing movement were added together to obtain the muscular work of the left and right masseter muscles for one chewing and swallowing movement. Furthermore, the areas of the electromyogram waveforms of the suprahyoid muscles were calculated from the electromyogram data in Figure 3(C), and the work of the suprahyoid muscles for one chewing and swallowing movement was obtained.

[0074] When the 10 subjects were eating to obtain electromyograms, several experts, including dentists, simultaneously tested the subjects' eating behavior to assess the eating ability of the subjects. The eating ability of the 10 subjects was assessed based on the total score of each item and categorized into three levels: high, medium, and low. The details of the assessment items, the scores of each subject, and the assessment of eating ability are summarized in Table 1.

[0075]

[0076] The evaluation items related to eating ability were items such as "difficulty eating hard foods (chunks of meat)" and "difficulty eating hard foods (thinly sliced ​​meat)," as shown in Table 1. The evaluation items are not limited to these, and items other than those shown in Table 1 may be included. For each evaluation item, 2 points were awarded if it applied, 1 point if it somewhat applied, and 0 point if it did not apply. Subjects who scored 0 to 3 points when the scores for each item were added up (subject numbers 6, 1, and 9) were classified into the high eating ability group, subjects who scored 4 to 7 points (subject numbers 7, 11, 8, and 2) were classified into the medium eating ability group, and subjects who scored 8 to 11 points (subject numbers 10, 4, and 5) were classified into the low eating ability group.

[0077] 4A is an example of a graph showing the muscle workload (μV·s) of the left and right masseter muscles and suprahyoid muscles during a single chewing and swallowing action of a subject. The graphs of each workload are shown for each type of food eaten, corresponding to a signal fa when eating curry rice, a signal fb when eating fukujinzuke pickles, and a signal fc when eating kidney beans.

[0078] 4B is an example of a graph showing the ratio of the muscle workload of the left and right masseter muscles and the suprahyoid muscle group during one chewing and swallowing movement of a subject. The ratio of the muscle workload of the left and right masseter muscles and the suprahyoid muscle group was obtained from the data on the muscle workload of the left and right masseter muscles and the suprahyoid muscle group in FIG. 4A.

[0079] 5A is a graph showing the ratio (%) of the workload of the left and right masseter muscles and suprahyoid muscles during a single chewing and swallowing movement for a subject who was classified as a high-ability group based on the results of the test for the evaluation items related to eating ability. The graph of each workload ratio is shown for each type of food eaten, corresponding to the signal fa when eating a curry rice set, the signal fb when eating fukujinzuke, and the signal fc when eating green beans.

[0080] The ratio of the workload of the left and right masseter muscles and suprahyoid muscles when eating a curry rice set was also obtained for subjects who were classified as having medium eating ability and subjects who were classified as having low eating ability based on the results of the test on evaluation items related to eating ability.

[0081] Figure 5B is a graph showing the ratio of the workload of the left and right masseter muscles and the suprahyoid muscles during a single chewing and swallowing action of a subject with intermediate eating ability, obtained in this example. Figure 5C is a graph showing the ratio of the workload of the left and right masseter muscles and the suprahyoid muscles during a single chewing and swallowing action of a subject with low eating ability, obtained in this example. The graphs of the workload ratios are shown separately for each type of food eaten, corresponding to the signal fa when eating curry rice, the signal fb when eating fukujinzuke, and the signal fc when eating green beans.

[0082] A comparison of Figures 5A to 5C confirmed that, when eating the curry rice set, subjects in which the ratio of work load between the left and right masseter muscles was high at around 70% to 80% had high eating ability, subjects in which the ratio of work load between the left and right masseter muscles was low at around 40% to 60% had low eating ability, and subjects in which the ratio of work load between the left and right masseter muscles was intermediate had intermediate eating ability.

[0083] 6A is a graph showing the ratio of the workload of the left and right masseter muscles during a single chewing and swallowing action of a subject with high eating ability obtained in this example, versus the type of food eaten. The horizontal axis shows the ratio of the workload of the left and right masseter muscles and the suprahyoid muscles during a single chewing and swallowing action of the food shown. When the horizontal axis shows an action instead of a food, it shows the ratio of the workload of the left and right masseter muscles and the suprahyoid muscles during that action.

[0084] 6B is a graph showing the ratio of the workload of the left and right masseter muscles in a single chewing and swallowing movement of a subject with high eating ability obtained in Example 2. The mode Mo, median Me, and range R of the workload of the left and right masseter muscles shown in FIG. 6B were calculated to evaluate eating ability.

[0085] FIG. 6C is a diagram showing the mode or median of the ratio of the workload of the left and right masseter muscles on the horizontal axis and the range on the vertical axis. From the graph obtained by plotting the mode Mo or median Me of the ratio of the workload of the left and right masseter muscles obtained above and the range R on the diagram shown in FIG. 6C, the following judgments can be made in relation to the evaluation of eating ability. For example, if the mode Mo or median Me of the ratio of the left and right masseter muscles is high and the range R is large (first quadrant of FIG. 6C), it can be determined that the left and right masseter muscles are dominant and that there is a large variety of movement. If the mode Mo or median Me of the ratio of the left and right masseter muscles is low and the range R is large (second quadrant of FIG. 6C), it can be determined that the suprahyoid muscles are dominant and that there is a large variety of movement. If the mode Mo or median Me of the ratio of the left and right masseter muscles is low and the range R is small (third quadrant of FIG. 6C), it can be determined that the suprahyoid muscles are dominant and that there is a small variety of movement. When the mode Mo or median Me of the ratio of the left and right masseter muscles is high and the range R is small (fourth quadrant in Figure 6C), it can be determined that the left and right masseter muscles are dominant and there is little movement variety.

[0086] <Second Example> Using the evaluation device 1 shown in Figure 1, an eating test was conducted to obtain electromyograms of subjects with high, medium, and low eating abilities when they ate a curry rice set, and to obtain the ratio of the workload of the left and right masseter muscles and the suprahyoid muscles for each type of food eaten.

[0087] Fig. 7A is a graph showing the ratio of the workload of the left and right masseter muscles and the suprahyoid muscles during a single chewing and swallowing action of a subject with high eating ability, obtained in this example, versus the type of food eaten. Fig. 7B is a graph showing the ratio of the workload of the left and right masseter muscles and the suprahyoid muscles during a single chewing and swallowing action of a subject with medium eating ability, obtained in this example, versus the type of food eaten. Fig. 7C is a graph showing the ratio of the workload of the left and right masseter muscles and the suprahyoid muscles during a single chewing and swallowing action of a subject with low eating ability, obtained in this example, versus the type of food eaten. Each graph shows the ratio of the workload of the left and right masseter muscles and the suprahyoid muscles during a single chewing and swallowing action of the food shown on the horizontal axis. When the horizontal axis shows an action rather than a food, it shows the ratio of the workload of the left and right masseter muscles and the suprahyoid muscles during that action.

[0088] When comparing the three figures (Figures 7A to 7C), although the type of food eaten and the movements were not the same, in subjects with high eating ability, the ratio of the workload of the left and right masseter muscles was generally higher than the ratio of the workload of the suprahyoid muscles regardless of the type of food or movement (the left and right masseter muscles were dominant), whereas in subjects with low eating ability, the ratio of the workload of the left and right masseter muscles and the ratio of the workload of the suprahyoid muscles were similar (the left and right masseter muscles and the suprahyoid muscles were similar).In addition, subjects with intermediate eating ability had results that were intermediate between the above.

[0089] 7D is a graph showing the ratio of the workload of the left and right masseter muscles during a single chewing and swallowing movement for subjects with high, medium, and low eating ability, obtained in this example. The mode Mo of the ratio of the workload of the left and right masseter muscles for subjects with high eating ability was 66%, the median Me was 64%, and the range R was 39.55. The mode Mo of the ratio of the workload of the left and right masseter muscles for subjects with intermediate eating ability was 56%, the median Me was 57%, and the range R was 36.36. The mode Mo of the ratio of the workload of the left and right masseter muscles for subjects with low eating ability was 56%, the median Me was 52%, and the range R was 19.37.

[0090] Fig. 7E is a graph showing the range of the median of the ratio of the workload of the left and right masseter muscles in this example. Fig. 7F is a graph showing the range of the mode of the ratio of the workload of the left and right masseter muscles in this example. Generally, the higher the eating ability, the larger the median Me, mode Mo, and range R of the workload of the left and right masseter muscles, indicating a relatively high dominance of the left and right masseter muscles and a greater variety of exercise. The lower the eating ability, the smaller the median Me, mode Mo, and range R of the workload of the left and right masseter muscles, indicating a relatively low dominance of the left and right masseter muscles and a less variety of exercise.

[0091] As described above, by calculating and comparing the ratio of the workload of the left and right masseter muscles and the suprahyoid muscles, it was possible to make comparisons between subjects when evaluating eating ability. It was also possible to compare measurements taken on different days for the same subject. In addition, it was possible to understand chewing movements such as dominance of the left and right masseter muscles or dominance of the suprahyoid muscles, which could not be evaluated by comparing the magnitude of the workload of the left and right masseter muscles and the suprahyoid muscles.

[0092] In assessing the above-mentioned eating ability, for example, a table showing the correlation between the ratio of the workload of the left and right masseter muscles and the suprahyoid muscles for each type of food and eating ability may be prepared in advance, and eating ability may be evaluated by referring to the ratio of the workload of the left and right masseter muscles and the suprahyoid muscles obtained by measuring the subject and the table. For example, the table shows a correlation in which, when eating a curry and rice set, the ratio of the workload of the left and right masseter muscles was generally higher than the ratio of the workload of the suprahyoid muscles (the left and right masseter muscles were dominant), regardless of the type of food or movement, while the ratio of the workload of the left and right masseter muscles was similar to the ratio of the workload of the suprahyoid muscles for subjects with low eating ability (the left and right masseter muscles and the suprahyoid muscles were similar). Once the table is prepared, eating ability can be evaluated based on the workload of the left and right masseter muscles and the suprahyoid muscles by referring to the table if the types of food are similar.

[0093] Example 3: In a similar manner to Example 2, an eating test was conducted in which electromyograms were obtained from subjects with high, medium, and low eating abilities when they ate a somen noodle set, and the ratio of the workload of the left and right masseter muscles and the suprahyoid muscles was obtained for each type of food eaten. The somen noodle set consisted of somen noodles containing chicken breast, etc., salad with rape blossoms, stir-fried radish, and pineapple for dessert.

[0094] Fig. 8A is a graph showing the ratio of the workload of the left and right masseter muscles and the suprahyoid muscles in a single chewing and swallowing action of a subject with high eating ability, obtained in this example, versus the type of food eaten. Fig. 8B is a graph showing the ratio of the workload of the left and right masseter muscles and the suprahyoid muscles in a single chewing and swallowing action of a subject with medium eating ability, obtained in this example, versus the type of food eaten. Fig. 8C is a graph showing the ratio of the workload of the left and right masseter muscles and the suprahyoid muscles in a single chewing and swallowing action of a subject with low eating ability, obtained in this example, versus the type of food eaten. Each graph shows the ratio of the workload of the left and right masseter muscles and the suprahyoid muscles in a single chewing and swallowing action of the food shown on the horizontal axis. When the horizontal axis shows an action rather than a food, it shows the ratio of the workload of the left and right masseter muscles and the suprahyoid muscles during that action.

[0095] 8A to 8C, although the type of food eaten and the movements were not the same, in subjects with high eating ability, the ratio of the workload of the left and right masseter muscles was generally higher than the ratio of the workload of the suprahyoid muscles regardless of the type of food or the movement (the left and right masseter muscles were dominant), whereas in subjects with low eating ability, the ratio of the workload of the left and right masseter muscles and the ratio of the workload of the suprahyoid muscles were similar (the left and right masseter muscles and the suprahyoid muscles were similar).In addition, subjects with intermediate eating ability had results that were intermediate between the above.

[0096] 8D is a graph showing the ratio of the workload of the left and right masseter muscles during a single chewing and swallowing movement for subjects with high, medium, and low eating ability, obtained in this example. The mode Mo of the ratio of the workload of the left and right masseter muscles for subjects with high eating ability was 60%, the median Me was 60%, and the range R was 33.19. The mode Mo of the ratio of the workload of the left and right masseter muscles for subjects with intermediate eating ability was 60%, the median Me was 52%, and the range R was 34.15. The mode Mo of the ratio of the workload of the left and right masseter muscles for subjects with low eating ability was 50%, the median Me was 50%, and the range R was 15.41.

[0097] Fig. 8E is a graph showing the range of the median of the ratio of the workload of the left and right masseter muscles in this example. Fig. 8F is a graph showing the range of the mode of the ratio of the workload of the left and right masseter muscles in this example. Generally, the higher the eating ability, the larger the median Me, mode Mo, and range R of the workload of the left and right masseter muscles, indicating a relatively high dominance of the left and right masseter muscles and a greater variety of exercise. The lower the eating ability, the smaller the median Me, mode Mo, and range R of the workload of the left and right masseter muscles, indicating a relatively low dominance of the left and right masseter muscles and a less variety of exercise.

[0098] As described above, by calculating and comparing the ratio of the workload of the left and right masseter muscles and the suprahyoid muscles, it was possible to make comparisons between subjects when evaluating eating ability. It was also possible to compare measurements taken on different days for the same subject. In addition, it was possible to understand chewing movements such as dominance of the left and right masseter muscles or dominance of the suprahyoid muscles, which could not be evaluated by comparing the magnitude of the workload of the left and right masseter muscles and the suprahyoid muscles.

[0099] Example 4: In a similar manner to Example 2, an eating test was conducted to obtain the ratio of the workload of the left and right masseter muscles and the suprahyoid muscles for each type of food consumed by subjects with high, medium, and low eating abilities, while they were eating a stir-fried pork and broccoli salad set. The stir-fried pork and broccoli salad set consisted of stir-fried pork containing green peas, onion, pork, etc., rice, broccoli salad, pickles, miso soup, and navel oranges for dessert.

[0100] Figure 9A is a graph showing the ratio of the workload of the left and right masseter muscles and the suprahyoid muscles during a single chewing and swallowing action of a subject with high eating ability, as determined in this example, versus the type of food eaten. Figure 9B is a graph showing the ratio of the workload of the left and right masseter muscles and the suprahyoid muscles during a single chewing and swallowing action of a subject with intermediate eating ability, as determined in this example, versus the type of food eaten. Figure 9C is a graph showing the ratio of the workload of the left and right masseter muscles and the suprahyoid muscles during a single chewing and swallowing action of a subject with low eating ability, as determined in this example, versus the type of food eaten. Each graph shows the ratio of the workload of the left and right masseter muscles and the suprahyoid muscles during a single chewing and swallowing action of the food shown on the horizontal axis. When an action, rather than a food, is shown on the horizontal axis, the ratio of the workload of the left and right masseter muscles and the suprahyoid muscles during that action is shown. In the case of the subject with intermediate eating ability shown in Figure 9B, rice was replaced with porridge.

[0101] 9A to 9C, although the types of food eaten and movements were not the same, in subjects with high eating ability, the ratio of the workload of the left and right masseter muscles was generally higher than the ratio of the workload of the suprahyoid muscles regardless of the type of food or movement (the left and right masseter muscles were dominant), whereas in subjects with low eating ability, the ratio of the workload of the left and right masseter muscles and the ratio of the workload of the suprahyoid muscles were similar (the left and right masseter muscles and the suprahyoid muscles were similar).In addition, subjects with intermediate eating ability had results that were intermediate between the above.

[0102] 9D is a graph showing the ratio of the workload of the left and right masseter muscles during a single chewing and swallowing movement for subjects with high, medium, and low eating ability, obtained in this example. The mode Mo of the ratio of the workload of the left and right masseter muscles for subjects with high eating ability was 78%, the median Me was 69%, and the range R was 51.73. The mode Mo of the ratio of the workload of the left and right masseter muscles for subjects with intermediate eating ability was 50%, the median Me was 54%, and the range R was 35.82. The mode Mo of the ratio of the workload of the left and right masseter muscles for subjects with low eating ability was 44%, the median Me was 47%, and the range R was 43.51.

[0103] 9E is a graph showing the range of the median of the ratio of the workload of the left and right masseter muscles in this embodiment. FIG. 9F is a graph showing the range of the mode of the ratio of the workload of the left and right masseter muscles in this embodiment. Generally, subjects with high eating ability had large median Me, mode Mo, and range R of the workload of the left and right masseter muscles, indicating a relatively high dominance of the left and right masseter muscles and a wide variety of exercise. Because subjects with intermediate eating ability replaced rice with porridge, the order was reversed in some areas. However, subjects with low or intermediate eating ability had small median Me, mode Mo, and range R of the workload of the left and right masseter muscles, indicating a relatively low dominance of the left and right masseter muscles and a low variety of exercise.

[0104] As described above, by calculating and comparing the ratio of the workload of the left and right masseter muscles and the suprahyoid muscles, it was possible to make comparisons between subjects when evaluating eating ability. It was also possible to compare measurements taken on different days for the same subject. In addition, it was possible to understand chewing movements such as dominance of the left and right masseter muscles or dominance of the suprahyoid muscles, which could not be evaluated by comparing the magnitude of the workload of the left and right masseter muscles and the suprahyoid muscles.

[0105] Example 5: In a similar manner to Example 2, an eating test was conducted in which electromyograms were obtained when subjects with high, medium, and low eating abilities ate a set of fried and chilled pork tofu, and the ratio of the workload of the left and right masseter muscles and the suprahyoid muscles was obtained for each type of food eaten. The fried and chilled pork tofu set included fried pork containing cabbage, carrots, eggplant, green peppers, meat, etc., served with chilled tofu (tofu), and clear soup (shellfish).

[0106] Figure 10A is a graph showing the ratio of the workload of the left and right masseter muscles and the suprahyoid muscles during a single chewing and swallowing action of a subject with high eating ability, as acquired in this example, versus the type of food eaten. Figure 10B is a graph showing the ratio of the workload of the left and right masseter muscles and the suprahyoid muscles during a single chewing and swallowing action of a subject with intermediate eating ability, as acquired in this example, versus the type of food eaten. Figure 10C is a graph showing the ratio of the workload of the left and right masseter muscles and the suprahyoid muscles during a single chewing and swallowing action of a subject with low eating ability, as acquired in this example, versus the type of food eaten. Each graph shows the ratio of the workload of the left and right masseter muscles and the suprahyoid muscles during a single chewing and swallowing action of the food shown on the horizontal axis. When an action rather than a food is shown on the horizontal axis, the ratio of the workload of the left and right masseter muscles and the suprahyoid muscles during that action is shown. In the case of the subject with intermediate eating ability shown in Figure 10B, rice was replaced with porridge.

[0107] 10A to 10C, although the types of food eaten and movements were not the same, in subjects with high eating ability, the ratio of the workload of the left and right masseter muscles was generally higher than the ratio of the workload of the suprahyoid muscles regardless of the type of food or movement (the left and right masseter muscles were dominant), whereas in subjects with low eating ability, the ratio of the workload of the suprahyoid muscles was higher than the ratio of the workload of the left and right masseter muscles (the suprahyoid muscles were dominant).In addition, subjects with intermediate eating ability had results that were intermediate between the above.

[0108] 10D is a graph showing the ratio of the workload of the left and right masseter muscles during a single chewing and swallowing movement for subjects with high, medium, and low eating ability, obtained in this example. The mode Mo of the ratio of the workload of the left and right masseter muscles for subjects with high eating ability was 52%, the median Me was 55%, and the range R was 57.02. The mode Mo of the ratio of the workload of the left and right masseter muscles for subjects with intermediate eating ability was 53%, the median Me was 44%, and the range R was 28.33. The mode Mo of the ratio of the workload of the left and right masseter muscles for subjects with low eating ability was 38%, the median Me was 35%, and the range R was 24.93.

[0109] Fig. 10E is a graph showing the range of the median of the ratio of the workload of the left and right masseter muscles in this example. Fig. 10F is a graph showing the range of the mode of the ratio of the workload of the left and right masseter muscles in this example. Generally, subjects with high eating ability had large median Me, mode Mo, and range R of the workload of the left and right masseter muscles, indicating a relatively high dominance of the left and right masseter muscles and a wide variety of exercise. Subjects with low or intermediate eating ability had small median Me, mode Mo, and range R of the workload of the left and right masseter muscles, indicating a relatively low dominance of the left and right masseter muscles and a low variety of exercise.

[0110] As described above, by calculating and comparing the ratio of the workload of the left and right masseter muscles and the suprahyoid muscles, it was possible to make comparisons between subjects when evaluating eating ability. It was also possible to compare measurements taken on different days for the same subject. In addition, it was possible to understand chewing movements such as dominance of the left and right masseter muscles or dominance of the suprahyoid muscles, which could not be evaluated by comparing the magnitude of the workload of the left and right masseter muscles and the suprahyoid muscles.

[0111] Example 6 Figure 11A is a graph showing the median Me of the ratio of the workload of the left and right masseter muscles to the test scores for the evaluation items related to eating ability in this example. The data for the median Me of the ratio of the workload of the left and right masseter muscles in the graph shown in Figure 11A includes data measured in a total of five eating tests for subjects with high eating ability, data measured in a total of five eating tests for subjects with intermediate eating ability, and data measured in a total of five eating tests for subjects with low eating ability, including the data from Examples 2 to 5 above. The median Me of the ratio of the workload of the left and right masseter muscles tended to decrease as the score for the evaluation items related to eating ability increased. The figure shows a straight line y = -1.4407x + 62.428 obtained by the least squares method. Here, x is the score for the evaluation item related to eating ability, and y is the median Me of the ratio of the workload of the left and right masseter muscles. If the total score of the test for the evaluation items related to eating ability is 3 points or less, the eating ability group is high, if it is 8 points or more, the eating ability group is low, and the range between them is intermediate eating ability group, then if the median value Me of the ratio of the workload of the left and right masseter muscles is 58.1% or more, the eating ability group is high, if the median value Me of the ratio of the workload of the left and right masseter muscles is 50.9% or less, the eating ability group is low, and if the median value Me of the ratio of the workload of the left and right masseter muscles is more than 50.9% and less than 58.1%, the eating ability group is intermediate. From the data in Figure 11A, a table showing the correlation between the median value Me of the ratio of the workload of the left and right masseter muscles and the suprahyoid muscles and eating ability can be created in advance. When the workload ratio of the left and right masseter muscles and the suprahyoid muscles to be evaluated is obtained, the eating ability can be evaluated by referring to the above table.

[0112] 11B is a graph showing the mode Mo of the ratio of the workload of the left and right masseter muscles versus the test score for the evaluation item related to eating ability in this example. The data for the mode Mo of the ratio of the workload of the left and right masseter muscles in the graph shown in FIG. 11B was measured in the same manner as the data shown in FIG. 11A. The mode Mo of the ratio of the workload of the left and right masseter muscles tended to decrease as the score for the evaluation item related to eating ability increased. The graph shows a straight line y = -1.6547x + 65.369 obtained by the least squares method. Here, x is the score for the evaluation item related to eating ability, and y is the mode Mo of the ratio of the workload of the left and right masseter muscles. If the total score of the test for the evaluation items related to eating ability is 3 points or less, the eating ability group is high, if it is 8 points or more, the eating ability group is low, and the range between them is intermediate eating ability group, then if the mode Mo of the ratio of the workload of the left and right masseter muscles is 60.4% or more, the eating ability group is high, if the mode Mo of the ratio of the workload of the left and right masseter muscles is 52.1% or less, the eating ability group is low, and if the mode Mo of the ratio of the workload of the left and right masseter muscles is more than 52.1% and less than 60.4%, the eating ability group is intermediate. From the data in Figure 11B, a table showing the correlation between the mode Mo of the ratio of the workload of the left and right masseter muscles and the suprahyoid muscles and eating ability can be created in advance. When the workload ratio of the left and right masseter muscles and the suprahyoid muscles to be evaluated is obtained, the eating ability can be evaluated by referring to the above table.

[0113] 11C is a graph showing the range R of the ratio of the workload of the left and right masseter muscles relative to the test score of the evaluation item related to eating ability in this example. The data for the range R of the workload of the left and right masseter muscles in the graph shown in FIG. 11C was measured in the same manner as the data shown in FIG. 11A. The range R of the workload of the left and right masseter muscles tended to decrease as the score of the evaluation item related to eating ability increased. The graph shows a straight line y = -1.9781x + 47.659 obtained by the least squares method. Here, x is the score of the evaluation item related to eating ability, and y is the range R of the workload of the left and right masseter muscles. If the total score of the test for the evaluation items related to eating ability is 3 points or less, the eating ability group is high, if it is 8 points or more, the eating ability group is low, and the range between them is intermediate eating ability, then if the range R of the ratio of the workload of the left and right masseter muscles is 41.7 or more, the eating ability group is high, if it is 31.8 or less, the eating ability group is low, and if it is more than 31.8 but less than 41.7, the eating ability group is intermediate. From the data in Figure 11C, a table showing the correlation between the range R of the workload of the left and right masseter muscles and the suprahyoid muscles and eating ability can be created in advance. When the workload ratio of the left and right masseter muscles and the suprahyoid muscles to be evaluated is obtained, the eating ability can be evaluated by referring to the above table.

[0114] Fig. 11D is a graph showing the range R relative to the median Me of the ratio of the workload of the left and right masseter muscles in this embodiment. The data for the median Me and range R of the ratio of the workload of the left and right masseter muscles in the graph shown in Fig. 11D are the same as the data shown in Figs. 11A and 11C. In Fig. 11D, thick lines are shown at the points of 58.1% and 50.9% of the median Me of the ratio of the workload of the left and right masseter muscles, which are the boundaries separating high, medium, and low eating abilities from Fig. 11A. In addition, thick lines are shown at the points of 41.7 and 31.8 of the range R of the ratio of the workload of the left and right masseter muscles, which are the boundaries separating high, medium, and low eating abilities from Fig. 11C.

[0115] Fig. 11E is a graph showing the range R for the mode Mo of the ratio of the workload of the left and right masseter muscles in this embodiment. The data for the mode Mo and range R of the ratio of the workload of the left and right masseter muscles in the graph shown in Fig. 11E are the same as the data shown in Figs. 11B and 11C. In Fig. 11E, thick lines are shown at the points of 60.4% and 52.1% of the mode Mo of the ratio of the workload of the left and right masseter muscles, which are the boundaries separating high, medium, and low eating abilities from Fig. 11B. In addition, thick lines are shown at the points of 41.7 and 31.8 of the range R of the ratio of the workload of the left and right masseter muscles, which are the boundaries separating high, medium, and low eating abilities from Fig. 11C.

[0116] As shown in Figures 11D and 11E, it was confirmed that, generally, the higher the eating ability, the larger the median Me, mode Mo, and range R of the left and right masseter muscle work, the relatively higher the dominance of the left and right masseter muscles, and the greater the movement variety. Furthermore, it was confirmed that, the lower the eating ability, the smaller the median Me, mode Mo, and range R of the left and right masseter muscle work, the relatively lower the dominance of the left and right masseter muscles, and the less movement variety. This is thought to correspond to the fact that, as shown in Figure 6C, the higher the eating ability, the higher the mode Mo or median Me of the ratio of the left and right masseter muscles, the larger the range R, the data is closer to the first quadrant, the left and right masseter muscles are dominant, and the greater the movement variety. On the other hand, as the eating ability is lower, the lower the mode Mo or median Me of the ratio of the left and right masseter muscles, the smaller the range R, the data is closer to the third quadrant, the less dominance of the left and right masseter muscles, and the less movement variety.

[0117] 12A and 12B are diagrams illustrating the ratio of the workload of the left and right masseter muscles and the suprahyoid muscles measured during mastication to the workload of the oral muscles (left and right masseter muscles and suprahyoid muscles) required for mastication, where (A) shows the case of a subject with high eating ability, and (B) shows the case of a subject with low eating ability. The horizontal axes of Fig. 12A and 12B represent the workload of the oral muscles required for mastication, and the vertical axes represent the workload of the left and right masseter muscles and the suprahyoid muscles measured during mastication. As shown in Fig. 12A, a subject with high eating ability can masticate up to a predetermined maximum masticatory capacity. For example, when eating food A for evaluating masticatory ability with a predetermined hardness, the workload of the left and right masseter muscles and the workload of the suprahyoid muscles are indicated by the length of the area crossed by the dotted line A. When eating food B for evaluating chewing ability, which is harder than food A for evaluating chewing ability, the amount of work done by the left and right masseter muscles and the amount of work done by the suprahyoid muscles is indicated by the length of the part where dotted line B crosses at a position different from dotted line A.

[0118] As shown in Figure 12 (B), the maximum masticatory capacity of subjects with low eating ability is smaller than that of subjects with high eating ability. Furthermore, when eating the food A for evaluating masticatory ability, the ratio of the workload of the left and right masseter muscles to the workload of the suprahyoid muscles, which is indicated by the length of the area crossed by the dotted line A, is smaller than that in Figure 12 (A), and the ratio of the workload of the suprahyoid muscles is larger. Even in the case of the food B for evaluating masticatory ability, which has a different hardness, the ratio of the workload of the left and right masseter muscles to the workload of the suprahyoid muscles, which is indicated by the length of the area crossed by the dotted line B, is smaller than that in Figure 12 (A), and the ratio of the workload of the suprahyoid muscles is larger. It is considered that as eating ability decreases, the ratio of the workload of the left and right masseter muscles decreases and the ratio of the workload of the suprahyoid muscles increases for foods of any hardness.

[0119] The method for evaluating eating ability according to this embodiment allows for the understanding of eating movements from the beginning to the end of a meal. When consuming a curry and rice set containing curry rice, pickled vegetables, green bean salad, and canned peaches, the ingredients vary in size and physical properties, including the viscous curry roux, the hard potatoes contained within, the chewy pickled vegetables, the fibrous green beans, and the peaches, which are bitten off with the front teeth to adjust the bite size. A person with high eating ability can eat at their own pace, enjoying the various textures and adjusting the bite size without being affected by the differences in physical properties. In other words, the masseter muscle is used predominantly for mastication, and the ratio of work load between the masseter muscle and the suprahyoid muscles is stable. On the other hand, a person with low masticatory ability may be unable to adapt to the differences in the physical properties of each ingredient, such as eating rice and curry roux separately, leaving some pickled vegetables, chopping the potatoes finely and eating them separately from the curry roux and rice, or chewing the green beans several times before swallowing them with water. This can result in longer meal times and fatigue, leading to more food waste. In other words, the ratio of work load between the left and right masseter muscles and the suprahyoid muscles is unstable, and foods that are difficult to chew using the left and right masseter muscles have a low ratio of work load to the masseter muscles.With the exception of noodles that you eat by sucking them, cold tofu that you can crush with your tongue, and soups, the ratio of work load between the masseter muscles and the suprahyoid muscles is not easily affected by chewing ability.

[0120] From the above, the above-mentioned method of evaluating eating ability, which allows for comparison of chewing movements when multiple foods are eaten and monitoring chewing movements when eating successive foods, is able to reflect chewing ability over a series of meals, which cannot be fully grasped by the amount of work done when eating a single food.

[0121] In the above-described embodiment and modified examples, various modifications can be made as follows without departing from the spirit of the present invention.

[0122] In the above embodiment, the evaluation device determines which of the left and right masseter muscles and the suprahyoid muscles contributes more to mastication based on the ratio of the muscle workload of the left and right masseter muscles to the muscle workload of the suprahyoid muscles, and evaluates eating ability, but this is not limited to the above. For example, the evaluation device may perform only one of determining which of the left and right masseter muscles and the suprahyoid muscles contributes more to mastication and evaluating eating ability. It may also not perform both, in which case the device simply outputs the muscle workload ratio. For example, the level of eating ability may be classified into two levels (high and low) or multiple levels other than three levels.

[0123] Seventh Example A seventh example will be described. The seventh example relates to ingredients that constitute the food eaten by the subject.

[0124] In another example, the evaluation device 1 measures myoelectric potential data when a subject chews a certain food, and evaluates the subject's eating ability based on the measured myoelectric potential data. In a seventh example, in evaluating eating ability, the type of ingredients that are preferable for the food to be eaten was examined. Note that the following examination is performed by the tester.

[0125] The tester will conduct an experiment using, for example, a "pork and tofu set" as the food. Food includes a single dish or a set of dishes. For example, a "pork and tofu set" is a meal set that includes the main dish ingredient ("stir-fried pork"), as well as the staple food "porridge" and the side dish "tofu," i.e., a meal set that includes pork and tofu. Furthermore, even if some ingredients are removed in the following experiment and the "pork and tofu set" no longer contains "pork" or "tofu," it will still be referred to as a "pork and tofu set."

[0126] Fig. 13 is a diagram showing examples of ingredients included in the "pork and tofu set." In Fig. 13, the names of ingredients are shown in the left column, and the hardness of the ingredients is expressed in units of pressure (N / cm) in the right column. 2The hardness is expressed in units of Newtons per square centimeter. This pressure is, for example, a pressure that can crush the food material (or the food material begins to crush). The hardness in FIG. 13 is, for example, a value measured on a selected food material after cooking.

[0127] In the following experiments, food materials were classified into three levels according to their hardness. Level 1 was the softest food material, with a hardness of 1 N / cm 2 Foods that are soft enough to require chewing are called "foods that can be processed by the tongue." The second level is foods that are soft enough to require chewing, and have a force of 1 N / cm 2 More than 30N / cm 2 Food materials with a strength of less than 30N / cm are called "soft food materials." The third level is the hardest food material, with a strength of 30N / cm 2 The above ingredients are called "hard ingredients."

[0128] 1. Experimental Procedure The experimental procedure will be described below. The experiment involves, for example, the following steps.

[0129] <1.1 Food Preparation Process> The food preparation process is a process for preparing the food "pork tofu." The tester prepared four patterns of "pork tofu" for each ingredient contained in the food. Food pattern 1: Includes all ingredients Food pattern 2: Does not include "ingredients that can be processed by the tongue" Food pattern 3: Does not include "soft ingredients" Food pattern 4: Does not include "hard ingredients" The tester first prepared "pork tofu" as food pattern 1. Then, by removing ingredients at each stage shown in Figure 13 from "pork tofu" as food pattern 1, the tester prepared "pork tofu" as food patterns 2 to 4.

[0130] <1.2 Myoelectric potential measurement process> The myoelectric potential measurement process is a process of measuring the myoelectric potential of the subject when chewing. The measurement locations are, for example, the left and right masseter muscles and the suprahyoid muscles, as in the first embodiment. The tester prepares, for example, one or more subjects with high eating ability, one or more subjects with medium eating ability, and one or more subjects with low eating ability. Note that the eating ability is assumed to be, for example, the same as in the above embodiment.

[0131] The tester had each subject eat "pork and tofu" from food patterns 1 to 4, and measured the myoelectric potential during mastication. The myoelectric potential measurement was carried out, for example, using evaluation device 1. The tester obtained myoelectric potential data for the target muscles for each combination of subject with eating ability and food pattern.

[0132] The tester also recorded video of the test subject while they were eating, synchronized with the measurement of EMG. By analyzing the video data, the tester can recognize when the test subject is performing actions other than eating, and can remove noise data from the EMG data. The data to be analyzed (motion analysis data) only needs to be able to identify the test subject's chewing movements, and may be, for example, audio data recorded from around the test subject (e.g., around the mouth).

[0133] The myoelectric potential measurement step may be performed by a different tester or device than the tester or evaluation device that performs the myoelectric potential data analysis step described below. For example, the tester may obtain myoelectric potential data measured at a different location or device and use the data for analysis. Alternatively, the tester may obtain myoelectric potential data by receiving data measured in Japan or a foreign country via communication over the Internet, for example.

[0134] <1.3 Myoelectric Potential Data Analysis Process> The myoelectric potential data analysis process is a process of calculating feature quantities of the myoelectric potential data for each of the subject's eating ability and food patterns. The tester divided the measured myoelectric potential data into unit time periods and calculated the muscle workload ratio. The unit time includes, for example, a predetermined time period or the time required for a series of chewing movements (e.g., the time required to chew one bite or the time required to complete the entire (predetermined amount of) food from the start of eating). The workload is a numerical value indicating how much a certain muscle is moving, such as a myoelectric potential (measured value). The workload ratio is the ratio of the workload of a certain muscle (first muscle) to the total workload of all measured muscles, and is expressed as a percentage (%), for example. The workload may also be the workload in other embodiments.

[0135] The tester judged from the video footage whether the subject was eating the object (in this case, "pork tofu"), and determined that the period from when the subject put the food in their mouth and started chewing (determined, for example, from the characteristic myoelectric potential of the masseter muscles) to just before swallowing (determined, for example, from the characteristic myoelectric potential of the suprahyoid muscles) constituted a series of chewing movements, and extracted the myoelectric potential data to be analyzed.

[0136] The tester further analyzed the recorded video to exclude the following EMG data as noise data: ・When eating multiple foods at the same time (e.g., rice and pork) ・When eating while drinking something (e.g., rice and tea) ・When not chewing (because EMG is measured even when not chewing) ・When talking while eating (because EMG is measured even when not chewing; talking while chewing is also excluded) ・Other actions, such as wiping the mouth (because EMG is measured even when not chewing) The tester classified the extracted EMG data into combinations of chewing ability and food pattern and calculated feature quantities to be analyzed. The feature quantities to be analyzed are, for example, range and median. Note that if there are multiple test subjects with each chewing ability, the tester may use EMG data from one test subject or the same number of test subjects for each eating ability when calculating the feature quantities.

[0137] <2. Experimental Results> The experimental results will be explained below. The experimental results will be explained for each food pattern. In the experiment, the ratio of the workload is the ratio of the workload of the left and right masseter muscles to the total workload. In addition, in the experiment, one subject was used for each chewing ability.

[0138] 2.1 Food Pattern 1 Figure 14 is a diagram showing an example of the workload ratio of the masseter muscle for food pattern 1 (including all ingredients). The graph in Figure 14 shows the workload ratio on the vertical axis and the eating ability of each subject on the horizontal axis. In Figure 14, "Me" indicates the median of the workload ratio, and "R" indicates the range of the workload ratio. This also applies to the graphs in the following figures.

[0139] According to Figure 14, the range for subjects with high eating ability is 57.0, with a median of 55.1%. The range for subjects with intermediate eating ability is 28.3, with a median of 43.8%. The range for subjects with low eating ability is 25.0, with a median of 25.4%.

[0140] In the myoelectric potential measurements using food pattern 1, the higher the eating ability, the wider the range. This phenomenon can be assumed to be due to the fact that people with higher eating ability change their chewing method depending on the hardness of the food (ingredient).

[0141] Furthermore, in the myoelectric potential measurements using food pattern 1, the median value increased with increasing eating ability. This phenomenon can be assumed to be due to the fact that people with higher eating ability use their masseter muscles more frequently (perform frequent chewing movements).

[0142] 2.2 Food Pattern 2 FIG. 15 is a diagram showing an example of the workload ratio of the masseter muscle in food pattern 2 (excluding ingredients that can be processed with the tongue).

[0143] 15, the range for subjects with high eating ability is 55.0, with a median of 55.4%. The range for subjects with intermediate eating ability is 24.9, with a median of 45.9%. The range for subjects with low eating ability is 25.0, with a median of 37.7%.

[0144] In the myoelectric potential measurements using food pattern 2, the median value increased as the eating ability increased.

[0145] However, in the EMG measurements using food pattern 2, the range was the widest for subjects with high eating ability, but was lower for subjects with intermediate eating ability than for subjects with low eating ability. In other words, it may not necessarily be true that the range increases with increasing eating ability.

[0146] 2.3 Food Pattern 3 FIG. 16 is a diagram showing an example of the workload ratio of the masseter muscle for food pattern 3 (excluding soft food ingredients).

[0147] 16, the range for subjects with high eating ability is 54.2 with a median of 66.7%, the range for subjects with intermediate eating ability is 28.3 with a median of 44.0%, and the range for subjects with low eating ability is 25.0 with a median of 33.1%.

[0148] In the myoelectric potential measurement using food pattern 3, the range is wider as the eating ability is higher.

[0149] Furthermore, in the myoelectric potential measurements using food pattern 3, the median value increases as the eating ability increases.

[0150] 2.4 Food Pattern 4 FIG. 17 is a diagram showing an example of the workload ratio of the masseter muscle for food pattern 4 (excluding hard ingredients).

[0151] 17, the range for subjects with high eating ability is 57.0 with a median of 52.4%. The range for subjects with intermediate eating ability is 23.7 with a median of 40.4%. The range for subjects with low eating ability is 24.5 with a median of 35.8%.

[0152] In the myoelectric potential measurements using food pattern 4, the median value increased as the eating ability increased.

[0153] However, in the EMG measurements using food pattern 2, the range was widest for subjects with high eating ability, but was lower for subjects with intermediate eating ability than for subjects with low eating ability. In other words, the relationship that the higher the eating ability, the wider the range may not be.

[0154] 2.5 Comparison by Food Pattern When using food patterns 2 and 4, the median value increases as the eating ability increases. However, the range does not necessarily increase as the eating ability increases. When using food patterns 2 and 4, evaluation using the median value is possible, but evaluation using the range may not be accurate.

[0155] On the other hand, when food patterns 1 and 3 were used, the median value increased with increasing eating ability, and the range increased with increasing eating ability. In other words, when food patterns 2 and 4 were used, evaluation could be performed using both the median and range indicators, which is expected to enable more accurate evaluation than when food patterns 2 and 4 were used.

[0156] Food Pattern 1 and Food Pattern 3 will be compared and examined. Below, the differences in values ​​between subjects with high and intermediate eating ability, and between subjects with intermediate and low eating ability will be compared and examined.

[0157] For food pattern 1, the difference in range between subjects with high and intermediate eating ability was 28.7 (57.0-28.3), and the difference in range between subjects with intermediate and low eating ability was 3.3 (28.3-25.0). On the other hand, for food pattern 3, the difference in range between subjects with high and intermediate eating ability was 25.9 (54.2-28.3), and the difference in range between subjects with intermediate and low eating ability was 3.3 (28.3-25.0). For both food patterns, the difference in range was close. In other words, when using food pattern 1 and food pattern 3, there was almost no difference in the evaluation of range, and it can be assumed that equivalent evaluations can be performed.

[0158] Furthermore, for food pattern 1, the difference in median scores between subjects with high and intermediate eating ability was 11.3 (55.1-43.8), and the difference in median scores between subjects with intermediate and low eating ability was 8.4 (43.8-35.4). On the other hand, for food pattern 3, the difference in median scores between subjects with high and intermediate eating ability was 22.7 (66.7-44.0), and the difference in median scores between subjects with intermediate and low eating ability was 10.9 (44.0-33.1). The difference in median scores was somewhat more pronounced when using food pattern 3, especially between subjects with high and intermediate eating ability. In other words, it can be assumed that food pattern 3 can provide an evaluation using medians that is as accurate as or even more accurate than food pattern 1.

[0159] To summarize the results of the comparison, food patterns 1 and 3 can be evaluated using medians and ranges, and are therefore superior to food patterns 2 and 4. On the other hand, food pattern 3 is either equivalent to food pattern 1 or superior, as the difference in medians is more pronounced.

[0160] Eighth Example An eighth example will be described. In the eighth example, the muscle for measuring the myoelectric potential is changed from that in the other examples.

[0161] In another embodiment, the left and right masseter muscles and suprahyoid muscles are the measurement targets. The measurement targets may be the zygomaticus muscles (either the zygomaticus major or zygomaticus minor, or both) and the suprahyoid muscles. The measurement targets may also be the temporalis muscles and the suprahyoid muscles. Furthermore, the measurement targets may be either the left or right masseter muscles and suprahyoid muscles. The zygomaticus muscles and temporalis muscles are muscles involved in human mastication, and the myoelectric potential data shows similar characteristics to the masseter muscles. Furthermore, since there is little difference between the right and left masseter muscles (they show similar trends), it may be sufficient to measure just one of them.

[0162] Furthermore, the measurement targets may be a combination of the left and right masseter muscles, zygomatic muscles, and temporalis muscles in addition to the suprahyoid muscles. The zygomatic muscles and temporalis muscles show similar characteristics to the masseter muscles, but are not exactly the same. Therefore, combining multiple muscles involved in mastication improves the accuracy of the evaluation.

[0163] Ninth Example For example, in the seventh example, a first threshold value for distinguishing between subjects with high and intermediate eating abilities and a second threshold value for distinguishing between subjects with intermediate and low eating abilities are set for one or both of the range and the median, and the subject's eating ability is evaluated. These first and second threshold values ​​are set, for example, by acquiring a large amount of experimental data and based on the acquired data. The setting and evaluation of these threshold values ​​may be performed, for example, by an evaluation AI (artificial intelligence) (hereinafter referred to as the evaluation model).

[0164] The evaluation model is trained using training data including, for example, feature values ​​of the EMG data (e.g., median or range, which may also include mean or mode) and the subject's eating ability (e.g., high, medium, or low, which may also be a scored value). Note that the EMG data itself may be used instead of the feature values ​​of the EMG data. In this case, the feature values ​​of the EMG data are calculated in the internal processing of the threshold generation model.

[0165] When the trained threshold generation model receives input of data to be judged that includes electromyography data or features of the electromyography data, it generates a first threshold and a second threshold through internal processing, and outputs the eating ability (high, medium, or low, or a score) of the subject of the data to be judged.

[0166] The evaluation model may be trained using evaluation results from actual operation, for example. This allows the amount of training data to increase as the operation progresses, thereby improving the evaluation accuracy of the evaluation model.

[0167] Furthermore, by using the evaluation model, it becomes easy to increase or decrease the types of feature quantities, calculate feature quantities, and calculate threshold values, thereby reducing the workload of the tester.

[0168] Although the myoelectric potential data described above was data obtained during the mastication of a "pork and tofu set," myoelectric potential data may also be obtained using, for example, a plurality of types of food or food sets. Fig. 18 is a diagram showing examples of ingredients included in a certain meal set. Fig. 18 shows examples of ingredients included in a "pork and tofu set," a "curry set," a "somen noodle set," and a "pork and broccoli set."

[0169] The subject may eat meals over multiple days or multiple times, for example, eating a "pork and tofu set" on the first day, a "curry set" on the second day, a "somen noodle set" on the third day, and a "pork and broccoli set" on the fourth day. The meal set used in the experiment may be composed of, for example, a combination of a single food and a food set. Ingredients of each hardness level do not necessarily have to be included in a single food or food set, but may be eaten multiple times in a meal set such as that shown in FIG. 18.

[0170] REFERENCE SIGNS LIST 1 Evaluation device 11 First electromyogram measuring unit 12 Second electromyogram measuring unit 13 Swallowing measuring unit 14 Signal processing unit 21 Electromyogram acquiring unit 22 Left and right masseter muscle work acquisition unit 23 Suprahyoid muscle group work acquisition unit 24 Left and right masseter muscle and suprahyoid muscle group work ratio acquisition unit 25 Discrimination unit 26 Evaluation unit 35 Storage unit

Claims

1. A method for evaluating eating ability, comprising: an acquisition step of acquiring electromyographic data of a plurality of facial muscles when a target person is chewing; a calculation step of calculating, from the acquired electromyographic data, the ratio of the workload of a first muscle, which is one of the plurality of facial muscles, to the total workload of all of the plurality of facial muscles per unit time; and an evaluation step of evaluating the eating ability of the target person according to the ratio.

2. The method for evaluating eating ability according to claim 1, wherein the plurality of muscles include a masseter muscle and a suprahyoid muscle group, and the first muscle is the masseter muscle.

3. The method for evaluating eating ability according to claim 1, wherein the unit time is from the start of chewing to just before swallowing.

4. The eating ability evaluation method according to claim 1, wherein the acquisition step acquires data for motion analysis that analyzes the motion of the subject when the electromyography data is measured, and the calculation step excludes the electromyography data from the motion analysis data during periods when the subject is not chewing from the calculation of the ratio.

5. The eating ability evaluation method according to claim 4, wherein the motion analysis data is video data of the subject taken when the myoelectric potential data was acquired.

6. The eating ability evaluation method according to claim 4, wherein the data for motion analysis is audio data obtained by recording sounds around the subject when the myoelectric potential data is acquired.

7. The eating ability evaluation method according to claim 1, wherein the evaluation step determines that the eating ability is better when the range between the maximum and minimum values ​​of the ratio over a given time period is wider.

8. The eating ability evaluation method according to claim 1, wherein the evaluation step determines that the eating ability is better when the median value of the ratio over a predetermined time period is larger.

9. The method for evaluating eating ability according to claim 1, wherein the evaluation step evaluates the eating ability according to the median value and the range between the maximum and minimum values ​​of the ratio at a predetermined time.

10. The eating ability evaluation method according to claim 1, wherein the evaluation step determines that the eating ability is better when the average value of the ratio over a predetermined time period is larger.

11. The eating ability evaluation method according to claim 1, wherein the evaluation step determines that the greater the mode of the ratio in a given time period, the better the eating ability.

12. The eating ability evaluation method according to claim 1, wherein the myoelectric potential data is a measurement value obtained when the subject chews food containing ingredients of a first hardness, ingredients of a second hardness harder than the first hardness, and ingredients of a third hardness harder than the second hardness.

13. The eating ability evaluation method according to claim 1, wherein the myoelectric potential data is a measurement value when the subject chews food that includes ingredients of the first hardness and the third hardness but does not include ingredients of the second hardness, out of ingredients of a first hardness, ingredients of a second hardness harder than the first hardness, and ingredients of a third hardness harder than the second hardness.

14. The eating ability evaluation method according to claim 13, wherein the ingredients of the first hardness are ingredients that can be processed with the tongue, the ingredients of the second hardness are soft ingredients, and the ingredients of the third hardness are hard ingredients, and the hardness of ingredients is classified according to the pressure that can crush the ingredients, with ingredients that have a pressure less than a first threshold being classified as ingredients of the first hardness, ingredients that have a pressure greater than the first threshold and equal to or greater than a second threshold being classified as ingredients of the third hardness, and all other ingredients being classified as ingredients of the second hardness.

15. The method for evaluating eating ability according to claim 1, wherein the plurality of muscles include the left and right masseter muscles and the suprahyoid muscles, and the workload of the first muscle is the sum of the workload of the left and right masseter muscles.

16. The method for evaluating eating ability according to claim 1, wherein the plurality of muscles include either the left or right masseter muscle and the suprahyoid muscle group, and the first muscle is either the left or right masseter muscle.

17. The method for evaluating eating ability according to claim 1, wherein the plurality of muscles include the zygomaticus muscle and the suprahyoid muscle group, and the first muscle is the zygomaticus muscle.

18. The method for evaluating eating ability according to claim 1, wherein the plurality of muscles include the temporalis muscle and the suprahyoid muscle group, and the first muscle is the temporalis muscle.

19. The method for evaluating eating ability according to claim 1, wherein the plurality of muscles are one or a combination of the left and right masseter muscles, zygomatic muscles, and temporalis muscles in addition to the suprahyoid muscles, and the workload of the first muscle is the workload of one of the left and right masseter muscles, zygomatic muscles, and temporalis muscles, or the total workload of the combination.

20. The eating ability evaluation method according to claim 1, wherein the evaluation process is carried out using an evaluation model that learns using learning myoelectric potential data and eating ability data of the person being measured who has measured the learning myoelectric potential data, and generates a threshold value in the learning process, and in the evaluation process, the ratio is input and the eating ability of the subject person is output by comparing the generated threshold value with the ratio.

21. An eating ability evaluation device having: an acquisition unit that acquires electromyographic data of multiple facial muscles when a target person is chewing; a calculation unit that calculates, from the acquired electromyographic data, the ratio of the workload of a first muscle, which is one of the multiple facial muscles, to the total workload of all of the multiple facial muscles per unit time; and an evaluation unit that evaluates the eating ability of the target person according to the ratio.