Anthropometric characteristics and product categorization of Chinese auricles for ergonomic design

The purpose of this study is to provide summarized anthropometric data and ergonomic characteristics about Chinese auricles and categorization modes of anthropometric measurements and ear-related wearable products. 700 male and female volunteers aged 15–90 were recruited, a new measurement has been proposed and 19 ear measurements were measured in this study. 93% volunteers were right-handed people, 15 linear measurements and 3 angular measurements were taken directly on the auricle, and the angle between tragus and medial concha was measured by scanning. Most measurements increase steadily with age, auricular length has highest correlation with age (0.753, p < 0.01). There have been a decrease in ear protrusion, concho-mastoid angle, tragal height and conchal depth of higher age groups, respectively. Most ear measurements of males were larger than females’, however, some of the differences were not significant. The overall growth rates of females are higher than those of males in most linear measurements, which were achieved by linear regression analysis with age. Some age groups showed no significant differences in ear measurements and this phenomenon appeared mainly in 30–39 and 40–49, 50–59 and 60–69. Except for tragal height of males, there was no significant difference achieved between left- and right-side ears for both genders. Principal component analysis determined distinct factors which were associated with the variation of ear shape (i.e. overall contour, cavum concha, ear protrusion), and the relationships between measurements become orderly and obviously. Further, a product categorization mode was proposed based on the results of principal component analysis. This mode simplified the process of data matching for different types of products.