Anthropometry of the External Ear in Korean Adults: A Multicenter Study

Abstract

Background

Numerous anthropometric studies on the auricle have been conducted in diverse populations, and variations in ear morphology associated with age, sex, and ethnicity have been identified. This study aimed to establish standard anthropometric data for the external ear within the Korean adult population.

Methods

This study included 631 subjects (331 males and 300 females) aged 20 to 92 years, who underwent three-dimensional computed tomography (3D-CT) of the face for various medical purposes at six hospitals in Korea. Soft-tissue landmarks on the ears and face were obtained from 3D-CT reconstruction images. Ear lobule types were classified into the following categories: tapering (≤ 69°), square (70–109°), and pendulate (≥ 110°). The classification was based on the angle between the base of the auricle and a line drawn from the superior otobasion to the inferior otobasion. Age correlations and differences according to sex were analyzed for all measured variables. The average ear length and width were compared with data from previously published reports on other ethnic groups.

Results

Compared with females, males presented greater ear length, ear width, protrusion at the superaurale and tragal levels, and lobular length. All measurements were symmetric on both sides, except for the auricle distance from the inferior orbital rim (IOR). All length measurements (insertion/ear/conchal/lobular length), lobular width, and auricle distance from the IOR were positively correlated with age. The pendulate lobule type was the most prevalent configuration in both sexes, followed by the square and tapering types. Koreans had shorter ear lengths than Indians and Caucasians but longer ear lengths than Africans and Chinese individuals.

Conclusion

Our age-specific auricular anthropometric data for Koreans will serve as a valuable reference for diagnosing congenital abnormalities and guiding surgical reconstructions in the Korean population.

Graphical Abstract

INTRODUCTION

The human ear plays a significant role in defining facial aesthetics, contributing to a naturally balanced and harmonious appearance.1,2 The shape and features of the auricle are influenced by factors such as age, sex and ethnicity.3 When reconstructing the external ear, surgeons often prefer to use the contralateral normal ear as a template.4 Anthropometric data of the average ear provide crucial reference information, especially in cases of bilateral auricular trauma or congenital anomalies when the contralateral ear cannot be used as a template.4 These data aid in determining the ideal ear dimensions, the tissue quantities necessary for reconstruction, and the optimal timing for surgical interventions.4,5 Moreover, they can provide valuable reference information for a range of forensic procedures, including aging assessments for both living and deceased individuals and personal identification.4

While a study conducted in Korea indicated that the length and width of the ear reach 90% of adult dimensions by the age of 14–15 years, suggesting a later maturation pattern than that in Western populations (who reach 90% by 9–12 years), this study focused exclusively on Koreans aged 0–18 years.5 For the purpose of ear reconstruction in Koreans, it is essential to have standardized measurements specific to Koreans. Unfortunately, to date, anthropometric auricle data for the Korean adult population remain considerably limited.

Many existing anthropometric studies on the auricle have employed direct measurement techniques to assess ear dimensions, location, inclination, and level. Traditional dimensional measurements are often prone to inaccuracies due to the distortion of soft tissues and difficulties in locating landmarks on the natural ear.6 Computed tomography (CT) offers a solution to this problem, providing better measurement quality.6 Coward et al.7 used CT to capture three-dimensional (3D) data from the ears of living humans, demonstrating the reliability of this method.8,9

The aim of our study was to establish normative data for ear morphology in the Korean population using a 3D-CT reconstruction technique. We collected various anthropometric parameters of the auricle, including the earlobe, from a sample of 631 Korean adult subjects. We determined age- and sex-related differences and explored potential ethnic variations in these measurements.

METHODS

Study participants

The study included 631 Korean adults who underwent soft tissue reconstruction 3D-CT of the face for various medical purposes at eight participating hospitals in Korea between August 2012 and March 2014. Soft-tissue landmarks on the ears and face were extracted from 3D-CT reconstruction images of 331 males (aged 20–90 years) and 300 females (aged 20–92 years). The age distribution of the subjects was designed to include more than 50 individuals in each ten-year age group for both sexes (Table 1). Medical records were reviewed to exclude individuals with a history of ear trauma, otologic surgery, or tumors in areas extending from the inferior orbital rim (IOR) to the external ear, as well as individuals who were not of Korean ethnicity.

Table 1. Distribution of subjects by age and sex categories.

Age, yr	Male	Female
20–29	50	50
30–39	66	50
40–49	55	50
50–59	59	50
60–69	50	50
70–92	51	50
Total	331	300

Measurements

The CT images utilized in this study were collected from the databases of eight hospitals using the same helical CT machine (Brilliance 64, 64 slice; Philips, Haifa, Israel). The imaging protocol involved the acquisition of images generated at 3 kV with a 3 mA X-ray. The reconstructed images had a slice thickness of 1 mm and an image matrix size of 512 × 512. 3D-CT images were created, and the measurements were obtained using EBW software V4.53 (Philips). All the measurement points were determined using 3D reconstructed images. Ten anthropometric landmarks on the auricle (Fig. 1A) and the IOR were used (11 landmarks in total). A total of 10 items were measured for each auricle (Fig. 1). The measured values are as follows:

Fig. 1. Auricular Landmarks and Measurement Parameters. (A) Landmarks and measurements of the auricle: a: the lower margin of the inferior orbital rim (not shown); b: porion (superior border of the external auditory meatus); c: otobasion superius; d: otobasion inferius; e: superaurale; f: subaurale; g: concha superior; h: intertragic notch; i: most posterior point from point h, measured vertically to the e–f line; j: most posterior point from point c, measured vertically to the e–f line; and k: most pronounced antihelical curvature. (B) Auricle protrusion measured by the vertical distances from the scalp at the superaurale level (p1) and the tragal level (p2).

• • Auricle distance from the IOR (a) (distance from the lower margin of the IOR (a) to the intersection point of the a–b line and c–d line)

• • Insertion length of the auricle (c–d)

• • Ear length (e–f)

• • Ear width (c–j)

• • Conchal length (g–h)

• • Conchal width (b–k)

• • Lobular length (h–f)

• • Lobular width (h–i)

• • Protrusion at the superaurale level (p1)

• • Protrusion at the tragal level (p2)

The classification of earlobe types depended on the angle formed by the base of the auricle and the line connecting the superior otobasion to the inferior otobasion.10 Earlobes were grouped into three categories: tapering (≤ 69°), square (70–109°), and pendulate (≥ 110°) (Fig. 2).10

Fig. 2. Classification of lobule shape.10 .

We analyzed the anthropometric data obtained from the auricles of Korean adults, and examined aspects such as symmetry, sex-related differences, age-related variations, and lobule shape. Additionally, we conducted comparisons with data from other ethnic groups within the same age and sex categories using previously published data with compatible measuring parameters.3,6 Specifically, we compared the mean ear length of our study cohort with that of individuals from Indian, Caucasian, and African backgrounds within the same age and sex groups. We also compared ear length and lobular length with age- and sex-matched data from the Han Chinese population. For some of the existing studies, including late teens (Alexander et al.3: 15–29 years old, Wang et al.6: 18–40 years old), we exclusively incorporated data from adults (Alexander et al.3: 20–29 years old, Wang et al.6: 20–40 years old) for our analysis.

Statistical analysis

SPSS software (version 20.0; SPSS, Chicago, IL, USA) was used for statistical analysis. All measured anthropometric data followed a normal distribution. The mean and standard deviation for each of the 10 measurements were calculated for each age group in both sexes. A paired t-test was performed to examine bilateral differences. Pearson’s correlation analysis using data measured from the right ear was conducted to investigate age-related changes. Student’s t-test was used to compare the Korean data from our study with age- and sex-matched data from previous studies of other ethnic groups. The χ² test was performed to compare lobule types. A P value < 0.05 was considered to indicate statistical significance.

Ethics statement

This study was approved by the Institutional Review Board (IRB) of Hallym University Sacred Hospital and the requirement for informed consent was waived because of the retrospective nature of the study (IRB No. 2012-I050).

RESULTS

Sexual differences

The means and standard deviations of the 10 measurements, categorized by age and sex, are presented in Table 2. The mean ear length in the right ear was 67.1 mm in males and 64.5 mm in females, while the mean ear width was 29.2 mm in males and 27.3 mm in females, with both sex differences being statistically significant. Significant sex-based differences in ear length, ear width, protrusion at the superaurale level, protrusion at the tragal level, and lobular length were detected for both the right and left ears, all of which were greater in males than in females. Additionally, compared to those in females, male conchal length was greater in the left ear alone, while male conchal width was greater in the right ear alone.

Table 2. Auricular dimensions categorized by sex and age groups (in mm).

Measurements	Sex	Entire group		20–29 yr		30–39 yr		40–49 yr		50–59 yr		60–69 yr		70 yr and older
		Left	Right	Left	Right	Left	Right	Left	Right	Left	Right	Left	Right	Left	Right
Auricle distance from IOR	M	91.3 ± 12.4*	90.0 ± 12.2*	90.2 ± 11.4	88.7 ± 11.3	88.9 ± 15.1	88.6 ± 14.1	90.3 ± 13.1*	88.0 ± 12.7*	91.5 ± 12.7*	90.0 ± 14.1*	91.2 ± 10.0	91.3 ± 9.3	96.0 ± 9.1*	93.7 ± 9.3*
	F	90.6 ± 11.6*	90.0 ± 11.4*	88.6 ± 10.0	87.7 ± 9.0	89.4 ± 9.0	89.6 ± 9.3	86.4 ± 9.2*	84.7 ± 10.2*	88.5 ± 17.9*	90.2 ± 17.6*	94.7 ± 9.2*	92.7 ± 8.7*	96.3 ± 8.8	94.9 ± 8.8
Insertion length	M	54.7 ± 9.6	54.2 ± 10.0	50.9 ± 8.0	50.4 ± 7.3	51.7 ± 10.0	52.2 ± 11.7	54.8 ± 9.7†	53.7 ± 11.7	56.8 ± 9.2	56.1 ± 8.8	54.8 ± 8.3	53.7 ± 7.5	59.7 ± 9.2	59.5 ± 8.8
	F	53.4 ± 8.0	53.7 ± 8.3	50.2 ± 5.5	49.8 ± 6.1	52.0 ± 6.6	52.5 ± 6.4	51.3 ± 6.8†	51.3 ± 7.0	53.3 ± 10.4	54.0 ± 11.6	55.5 ± 6.7	56.0 ± 6.4	58.1 ± 8.6	58.8 ± 7.8
Ear length	M	66.8 ± 10.4†	67.1 ± 9.9†	63.9 ± 8.1†	63.8 ± 7.1†	63.1 ± 9.7	63.7 ± 10.3	66.1 ± 10.7†	66.2 ± 10.1†	68.6 ± 11.1	68.7 ± 11.1	70.2 ± 9.1†	70.2 ± 9.8†	69.5 ± 11.6	70.4 ± 7.7
	F	64.5 ± 10.1†	64.5 ± 9.4†	60.1 ± 5.5†	60.9 ± 5.7†	63.8 ± 12.7	62.3 ± 6.9	62.3 ± 7.8†	62.2 ± 8.2†	66.6 ± 13.8	67.0 ± 14.2	65.4 ± 7.5†	65.9 ± 7.6†	68.1 ± 9.5	68.6 ± 8.9
Ear width	M	28.9 ± 7.3†	29.2 ± 7.5†	28.0 ± 8.6*	29.0 ± 8.7*	27.6 ± 9.0	27.7 ± 8.6	28.5 ± 7.1	28.5 ± 7.2	28.8 ± 6.8	28.8 ± 6.9	31.1 ± 5.8†	32.0 ± 7.4†	29.7 ± 5.1	29.7 ± 5.3
	F	27.5 ± 6.0†	27.3 ± 6.3†	26.5 ± 4.5	26.4 ± 4.4	27.4 ± 5.7	27.4 ± 5.5	27.1 ± 6.9	27.3 ± 7.1	28.9 ± 8.4	28.9 ± 9.1	26.8 ± 5.1*,†	25.5 ± 4.7*,†	28.1 ± 4.7	28.2 ± 5.5
Conchal length	M	28.0 ± 4.0†	28.0 ± 4.8	27.8 ± 3.5†	28.0 ± 3.6†	27.3 ± 3.9	27.3 ± 4.6	28.0 ± 5.2	27.8 ± 4.9	27.6 ± 3.0	27.3 ± 6.4	28.2 ± 4.6	28.5 ± 3.9	28.9 ± 4.1	29.3 ± 4.2
	F	27.0 ± 4.5*,†	27.4 ± 4.4*	25.7 ± 2.5†	26.1 ± 2.9†	26.8 ± 3.6	27.1 ± 3.8	26.2 ± 4.3	26.4 ± 3.6	27.8 ± 5.9	27.9 ± 6.0	27.6 ± 4.6	27.5 ± 4.2	28.1 ± 4.8*	29.1 ± 5.0*
Conchal width	M	18.7 ± 4.6	18.8 ± 4.6†	18.2 ± 6.0	18.5 ± 5.9	18.7 ± 5.5	18.5 ± 5.6	18.8 ± 4.7†	19.1 ± 4.8	19.1 ± 4.1	19.1 ± 3.6	18.6 ± 4.1	18.7 ± 3.8	18.5 ± 2.8	18.9 ± 2.8
	F	18.2 ± 4.0	18.1 ± 4.0†	18.7 ± 3.3	18.7 ± 3.2	19.4 ± 3.4*	18.6 ± 3.2*	17.0 ± 4.4†	17.4 ± 4.9	18.0 ± 5.4	18.2 ± 5.7	18.1 ± 3.3	17.5 ± 3.3	18.0 ± 3.6	18.2 ± 3.0
Protrusion at the superaurale level	M	9.9 ± 3.7†	9.7 ± 3.7†	9.9 ± 2.5†	10.3 ± 2.9†	9.1 ± 2.8†	8.9 ± 3.0	9.6 ± 4.2	9.2 ± 3.7	8.8 ± 3.3	8.5 ± 3.1	10.3 ± 4.2†	10.3 ± 4.4†	12.1 ± 4.2*,†	11.2 ± 4.2*,†
	F	8.3 ± 3.1†	8.5 ± 3.2†	7.8 ± 2.6†	7.6 ± 2.5†	8.0 ± 3.1†	8.4 ± 2.8	8.5 ± 2.7	8.9 ± 3.0	8.4 ± 3.4	8.3 ± 3.5	8.2 ± 3.6†	8.3 ± 3.3†	8.9 ± 3.3†	9.5 ± 3.6†
Protrusion at the tragal level	M	19.5 ± 4.5†	19.4 ± 4.1†	19.3 ± 4.0†	19.6 ± 3.4†	18.7 ± 3.7†	18.7 ± 4.0†	19.1 ± 4.5†	19.3 ± 4.2†	18.9 ± 4.5	19.0 ± 4.8†	20.1 ± 3.9†	19.6 ± 4.1	21.1 ± 6.2	20.3 ± 4.3†
	F	17.3 ± 4.6†	17.1 ± 4.6†	16.7 ± 3.3†	17.3 ± 3.2†	16.7 ± 4.0†	16.8 ± 4.0†	16.8 ± 4.0†	16.3 ± 3.8†	17.4 ± 6.2	16.5 ± 4.7†	17.5 ± 4.3†	18.0 ± 6.7	19.0 ± 4.8*	18.0 ± 4.3*,†
Lobular length	M	25.3 ± 4.9*,†	25.6 ± 4.5*,†	24.4 ± 4.6†	24.5 ± 4.1†	24.0 ± 5.2*	24.6 ± 4.6*,†	24.6 ± 4.7†	25.0 ± 4.7†	25.0 ± 5.1	25.1 ± 4.6	27.6 ± 4.8†	27.7 ± 4.6†	26.5 ± 4.0	26.8 ± 3.7
	F	23.5 ± 4.3†	23.7 ± 4.5†	22.3 ± 3.2†	22.4 ± 3.5†	22.8 ± 4.0	22.9 ± 4.5†	22.8 ± 3.5†	22.9 ± 3.7†	24.6 ± 4.9	24.7 ± 6.1	23.4 ± 4.8†	23.6 ± 4.3†	24.9 ± 4.7	25.4 ± 4.2
Lobular width	M	21.6 ± 10.0	21.5 ± 8.2	19.7 ± 8.1	20.0 ± 8.7	19.0 ± 6.9	18.5 ± 6.7	19.8 ± 4.4	19.7 ± 3.5	21.2 ± 4.8	21.8 ± 4.6	25.7 ± 13.0†	26.7 ± 13.2†	24.9 ± 16.7	23.2 ± 7.6
	F	20.8 ± 6.9	21.1 ± 6.9	18.5 ± 4.1	18.1 ± 4.4	18.7 ± 5.2	19.0 ± 4.4	19.9 ± 6.2	21.2 ± 7.7	24.1 ± 11.9	24.1 ± 11.8	21.1 ± 3.4†	21.3 ± 3.5†	22.4 ± 5.3	22.6 ± 4.5

The mean values are presented with their corresponding standard deviations.

IOR = inferior orbital rim.

^*P < 0.05 for bilateral difference; ^†P < 0.05 for sex difference.

Bilateral differences

The mean distance from the right IOR to the right auricle was 90.0 mm in both male and female adults, which was significantly shorter than the distance from the left IOR to the left auricle (90.6–91.3 mm). In the subgroup analysis across different age groups, we observed statistically significant bilateral differences in auricle distance from the IOR, with the left side most often being greater than the right, especially among individuals aged 40 years and older. Additionally, the mean conchal length of females and the mean lobular length of males were significantly greater on the right side than on the left side; however, these differences were less than 0.5 mm. In the entire age group, no interaural differences were observed for the other parameters. While some bilateral differences in specific measurements were observed within certain age and sex subgroups, the disparities were minimal, ranging from 0.6 to 1.3 mm. In summary, the overall anthropometry of the ears, except the auricle distance from the IOR, can be described as symmetrical (Table 2).

Age correlation

Six out of the 10 measurements showed significant positive correlations with age in both sexes, although the strengths of these correlations were generally weak (Table 3). In both sexes, all length measurements, including insertion length, ear length, conchal length, and lobular length, demonstrated an age-related increase, with the strongest associations found for insertion length (R = 0.354) and ear length (R = 0.283).

Table 3. Linear correlation analysis of measurements with age.

Measurements	Male		Female
	R	P value	R	P value
Auricle distance from IOR	0.141	0.010*	0.226	< 0.001*
Insertion length	0.250	< 0.001*	0.354	< 0.001*
Ear length	0.270	< 0.001*	0.283	< 0.001*
Ear width	0.101	0.022*	0.038	0.099
Conchal length	0.116	0.036*	0.193	0.001*
Conchal width	0.026	0.632	−0.049	0.397
Protrusion at the superaurale level	0.120	0.033*	0.115	0.377
Protrusion at the tragal level	0.083	0.487	0.065	0.249
Lobular length	0.221	< 0.001*	0.214	< 0.001*
Lobular width	0.241	< 0.001*	0.223	< 0.001*

R = Pearson correlation coefficient, IOR = inferior orbital rim.

^*Statistically significant.

Lobule morphology

With respect to lobule configuration, the pendulate type was the most prevalent configuration in both males (73.28%) and females (79.62%), followed by the square type and the tapering type (Table 4). There were no statistically significant differences between males and females in terms of lobule type (Table 4).

Table 4. Distribution of lobule types.

Types	Male	Female	P value
Pendulate	73.28%	79.62%	0.296
Square	25.16%	18.76%
Tapering	1.54%	1.60%

Ethnic disparities

Korean males had shorter ear lengths than Indian males across all age groups. Korean males also had shorter ear lengths than Caucasian males, with statistical significance observed only in the middle-aged group (30–44 years old). Similarly, Korean females presented shorter ear lengths than Indian and Caucasian females, but the difference was statistically significant only in comparison with middle-aged Indian females. In contrast, compared with Africans, Koreans generally had longer ear lengths, although these differences were not statistically significant (Table 5). Furthermore, compared with the Han Chinese population, Koreans consistently had longer ear length and lobular length in all age groups (18–60 years) for both sexes (Table 6).

Table 5. Comparison of Korean ear length with Indian, Caucasian, and African ear length.

Ethnic groups	Ear length, mm
	Age 15–29 yr		Age 30–44 yr
	Male	Female	Male	Female
Korean	63.7 ± 9.8	59.8 ± 8.7	64.2 ± 9.1	62.2 ± 6.9
Indian	68.9 ± 3.9	60.9 ± 3.7	70.5 ± 4.0	64.7 ± 4.3
	P < 0.001*	P = 0.310	P < 0.001*	P = 0.002*
Caucasian	65.2 ± 4.2	60.4 ± 3.2	68.0 ± 4.5	63.5 ± 4.6
	P = 0.149	P = 0.606	P < 0.001*	P = 0.104
African	62.7 ± 2.8	60.4 ± 2.1	62.7 ± 4.0	60.8 ± 4.4
	P = 0.302	P = 0.606	P = 0.109	P = 0.076

The values are presented in means ± standard deviations. Data from Indian, Caucasian, and African populations were sourced from the literature.3

^*Statistically significant.

Table 6. Comparison of ear length and lobular length between Koreans and the Han Chinese population.

Measurements	Ethnic group	Age 18–40 yr		Age 41–60 yr
		Male	Female	Male	Female
Ear length, mm	Korean	63.6 ± 8.7	61.6 ± 6.4	67.7 ± 10.7	64.7 ± 11.6
	Han Chinese	58.1 ± 2.3	55.9 ± 3.3	61.2 ± 3.1	59.1 ± 3.6
	P value	< 0.001*	< 0.001*	< 0.001*	< 0.001*
Lobular length, mm	Korean	18.9 ±7.1	18.7 ± 4.6	21.1 ± 5.1	22.7 ± 9.8
	Han Chinese	17.2 ± 2.7	16.8 ± 2.2	19.3 ± 2.1	18.4 ± 2.4
	P value	0.004*	< 0.001*	< 0.001*	< 0.001*

The values are presented in means ± standard deviations. Data from Indian, Caucasian, and African population were sourced from the literature.6

^*Statistically significant.

DISCUSSION

Our study revealed significant sex differences in various ear dimensions, including ear length, ear width, protrusion at the superaurale and tragal levels, and lobular length, all of which were greater in males. This observation is consistent with previous studies, which have frequently reported larger measurements in males. Sforza et al.4 reported that all ear dimensions, including ear width, length, and area, were significantly greater in men. This sexual disparity in ear size seems to begin during postnatal growth, as nearly all studies indicate that there are no differences between boys and girls within the first two years of life.4 According to Meijerman et al.,11 auricle expansion, in terms of both lengthening and widening, starts more slowly in early adulthood but continues to occur at an older age (over 70 years) in females compared to males. This sex discrepancy in the relative pace of auricle expansion is more pronounced for width than for length.11 Additionally, a pediatric study by Chae et al.5 revealed that males had a greater auricle length than females after the age of 12.

However, contradictory evidence in the literature exists. For example, Brucker et al.1 reported that total ear length was longer in men than in women by 6.5%, but they reported no variation in earlobe size (lobule length and width) between men and women. Similarly, Wang et al.6 concluded that there were no significant sex differences in lobular length, lobular width, or protrusion.

The measurements obtained in our study generally exhibited good symmetry between the right and left ears, which was consistent with the findings of previous studies.3,6 However, one notable exception was observed in the auricle distance from the IOR, where the distance on the left side was greater than that on the right side in both sexes. The greater auricle distance from the IOR on the left side aligns with findings from studies on facial asymmetry, which reported left-side dominance in facial size.12,13 This may result from asymmetric brain development, specifically greater growth of the left temporal lobe, which influences facial structures, especially in right-handed individuals.12 In the analysis by sex, we observed bilateral differences in conchal length among females and in lobular length among males, with the right side exhibiting greater dimensions than the left. However, because these measurements were not significantly different in the opposite sex, we considered conchal length and lobular length to be predominantly symmetric. The proper size and symmetric positioning of the auricles are considered more crucial factors than angular inclinations or protrusion levels in creating a natural facial appearance.5 Alexander et al.3 discovered greater symmetry in linear measurements than in angular measurements assessing prominence or protrusion, underscoring the importance of ensuring that linear measurements correlate with those of the contralateral ear as the primary determinant for achieving symmetry after reconstruction.

Notably, insertion length, ear length, lobular length, and lobular width exhibited particularly strong positive correlations with age in both sexes (R values ranging from 0.214 to 0.354, all P < 0.001). Although all the length measurements were positively correlated with age, conchal length exhibited a relatively weak correlation (R values ranging from 0.116 to 0.193). These findings suggest that as individuals age, all length measurements (insertion length, ear length, and lobular length) and lobular width tend to increase, whereas other dimensions, such as ear width, conchal width, and protrusion at the superaurale and tragal levels, may remain relatively stable. The increase in these dimensions may be attributed to factors such as reduced skin resilience and elasticity, decreased tensile strength of connective tissue, and gravitational force exerted on the ear over time.2,6

Some studies have concluded that the primary factor contributing to the increase in auricle length is the elongation of the lobular portion.1,2 For example, a cross-sectional study conducted on Americans by Brucker et al.1 found that lobular length was the only ear structure with a significant age-related increase (coefficient of 0.25). Additionally, the lobular width decreases with age, indicating that the typical lobule changes from a wide and short morphology in young people to a narrower and longer shape as individuals age.1 This finding indicates that aesthetic earlobe contouring surgery for patients with elongated earlobes can achieve a more youthful appearance by shortening the lobule.1,14 However, our findings suggest that both lobular length and width increase with age (coefficients of 0.214–0.241). Alexander et al.3 also reported that total ear length increased with age regardless of ethnicity, with lengthening of the lobule accounting for most, but not all, of the increase, suggesting that there is a significant increase not only in the lobule but also in the cartilaginous part of the auricle.

Brucker et al.1 reported results that contrast with our findings, but more studies have presented results that are consistent with our observations. These studies revealed that the postmature growth of the auricle continues in both sexes without an apparent stopping point.2,3,4 Wang et al.6 reported that various parameters, including ear length, ear width, lobular length, lobular width, insertion length, and tragus length, all increase with age. Alexander et al.3 reported that ear width continues to increase and reaches a plateau after 74 years of age and that the lobular width continues to increase throughout life. This result is partially consistent with our findings, as we observed a relatively strong correlation with age in lobular width but not in ear width. Purkait and Singh2 reported that all linear measurements (length and width of the auricle, lobule, and concha) steadily increased with age, with more elongation than widening (3.2 times greater in women, 2.8 times greater in men).4

Our findings on the distribution of lobule types were consistent with the findings of Kollali et al.,15 who reported a similar prevalence of the pendulate type (65%), followed by the square type (23.5%). In contrast, Wang et al.6 observed an even distribution of the three earlobe types among both men and women. Purkait and Singh2 emphasized that the dimensions of the lobule, including its length and width, depend on the shape and attachment of the lobule to the cheek, with pendulous earlobes being significantly longer and less symmetrical than nonpendulous earlobes. These variations may account for the differences in lobule dimensions across studies conducted in different populations. Azaria et al.14 reported that sex and age were the primary factors contributing to earlobe length, and the creation of nonpendulous earlobes during reconstruction is recommended to avoid postoperative ptosis, which can result in an aged appearance.

The largest ear size, including both length and width, is commonly reported in Indians, followed by Caucasians and Afro-Caribbeans.3 Studies have also reported longer earlobes in Ashkenazi and Sephardic Jews than in Ethiopian, Asian, and American Jews, and shorter earlobes in black individuals.14 Previous studies conducted on Koreans have shown that Korean ears mature later than those of Western individuals.5 Korean ears increase in length and width by 53.8% and 75.1%, respectively, by the age of 15, resulting in an overall round auricle shape with a broader width compared to that of Western individuals.5 By comparing our findings with those of the study by Wang et al.6 on a Han Chinese ethnic group, which constitutes the majority of China’s population, we observed that Koreans exhibit greater ear length and lobular length. The findings of our study suggest that Koreans have smaller ears in terms of auricle length than Indians and Caucasians but larger ears than Africans and Chinese people.

Our findings can serve as a database for the quantitative description of ear morphology in normal Korean adults, considering age- and sex-related variations. This study has potential implications in various fields, including the diagnosis of congenital anomalies and syndromes, as well as acquired deformities of the auricle.2 Using an objective approach for diagnosis, which involves precise measurements rather than relying on physicians’ impressions of physical traits, can enhance the ability to detect minor defects in a metric analysis that may be overlooked through visual inspection.2 These measurements can also serve as useful references for planning cosmetic surgery, designing hearing aid instruments, and forensic applications.2,4,6

There are several limitations to our study. First, in our analysis of age correlations, we only assessed the degree of linear relationships between the two variables. To fully understand the extent of changes in the dependent variable for each unit change in the independent variable, further research is needed. Second, when comparing our findings with data from different ethnic groups, we relied on previous studies. The variations in the precision of the measurement methods across different studies may have introduced errors into our comparisons. Additionally, minor differences between 3D-CT measurements and actual ear measurements may exist, representing another limitation of our study. Furthermore, owing to differences in the age groups included in each study, we were unable to compare all the ethnic groups simultaneously. For more comprehensive results, future research should include multiple ethnic groups, use standardized measurement methods, and control for confounding variables (e.g., age, sex, ethnicity) to minimize biases.