Revisiting Age-Related Normative Hearing Levels in Korea

Sang-Yoon Han; Hee Won Seo; Seung Hwan Lee; Jae Ho Chung

doi:10.3346/jkms.2025.40.e3

Journal List > J Korean Med Sci > v.40(2) > 1516089435

Go to TopGo to Top Go to BottomGo to Bottom

TOOLS

Han, Seo, Lee, and Chung: Revisiting Age-Related Normative Hearing Levels in Korea

Original Article

Clinical Medicine in Other Specialties

Journal of Korean Medical Science 2025; 40(2): e3.

Published online: 18 October 2024

DOI: https://doi.org/10.3346/jkms.2025.40.e3

Revisiting Age-Related Normative Hearing Levels in Korea

Sang-Yoon Han

, Hee Won Seo

, Seung Hwan Lee

, Jae Ho Chung

Department of Otolaryngology-Head and Neck Surgery, College of Medicine, Hanyang University, Seoul, Korea.

Address for Correspondence: Jae Ho Chung, MD, PhD. Department of Otolaryngology-Head and Neck Surgery, College of Medicine, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 04763, Korea. jaeho.chung.md@gmail.com

Received 28 July 2024 Accepted 12 September 2024

The Korean Academy of Medical Sciences

https://creativecommons.org/licenses/by-nc/4.0/

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (https://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Background

Hearing level reference values based on the results of recent audiometry have not been established for the general population of South Korea. This study aimed to evaluate the mean hearing levels of each age group and to measure the annual progression of hearing loss.

Methods

We used the database of the eighth and ninth Korea National Health and Nutrition Examination Survey from 2020 to 2022, and included participants with normal tympanic membranes and without occupational noise exposure. Mean hearing levels were calculated by averaging hearing levels at 0.5 kHz, 1 kHz, 2 kHz, and 4 kHz. Hearing loss was defined as a hearing level exceeding 25 dB in the better ear, and severity of hearing loss was classified as moderate, moderately severe, severe, and profound, following the World Health Organization classification.

Results

Hearing levels and the proportions of patients with hearing loss increased with age. Hearing levels were 9.11 ± 6.28 dB, 13.33 ± 7.85 dB, 19.90 ± 10.30 dB, and 31.95 ± 13.37 dB in those in their 40s, 50s, 60s, and 70s, respectively, and the proportions of patients with hearing loss were 1.81%, 7.51%, 25.32%, and 63.94%, respectively. The annual increase in hearing level was 0.71 dB, and increases were greater at higher frequencies. Hearing loss was also worse in men.

Conclusion

The present study provides reference values for normal hearing levels by age group, and indirectly reveals the progression of age-related hearing loss. Based on the results, physicians will be able to provide appropriate advice regarding hearing levels and the need for monitoring in the elderly.

Go to :

Graphical Abstract

Go to :

Keywords: Hearing Level, Aging, Elderly, Presbycusis, Hearing Aids, Reference Values

INTRODUCTION

Hearing loss is one of the most common sensory organ diseases, and aging is the most common cause.1 2 3 As hearing levels deteriorate with age, many older individuals experience hearing loss.1 In some age groups, the average hearing level can exceed the threshold for hearing loss, even reaching levels classified as moderate hearing loss.4 5 However, the progression of hearing loss varies between individuals.1

To raise awareness about hearing loss it is important for individuals to know their own hearing levels. Despite undergoing hearing tests, patients often find it challenging to accurately understand their hearing levels. Recently, there has been a campaign to enhance awareness of hearing levels similar to remembering one’s diopter for visual acuity, through a concept called the “Hearing Number.”6 This initiative aims to facilitate easy recollection of one’s hearing status and foster interest in hearing health.6 By providing individuals with their pure-tone audiometry averages, and informing them of normal age-specific hearing ranges and hearing levels requiring hearing aids or cochlear implants, one aims to empower individuals to understand their hearing status and foster interest in auditory rehabilitation

One important part of this initiative is the provision of age-specific normal hearing ranges. Existing epidemiological studies of hearing impairment in the general population based on data from the Korea National Health and Nutrition Examination Survey (KNHANES) between 2010 and 2012 are a decade old.5 7 8 Given societal shifts, and the increased use of personal audio devices that aggravate the risk of noise-induced hearing loss in the young,9 10 11 12 there is a pressing need for updated research on age-specific average hearing levels.13 In addition, the annual mean progression of age-related hearing loss in the general population, based on individuals with normal tympanic membranes, has not yet been assessed using recent audiometric data.

In the present study we provide age- and gender-specific average hearing levels for individuals without a history of occupational noise exposure and with normal tympanic membranes, using data from 2020 to 2022. We also estimate the prevalence of hearing loss, and the annual progression of hearing loss at each frequency in the general population.

Go to :

METHODS

Study population

The KNHANES, which was initiated in 1998, is designed to periodically assess the health and nutritional status of the non-institutionalized population of South Korea. The survey employs a mobile examination unit, which includes medical professionals including otolaryngologists and ophthalmologists, as well as nurse examiners, to conduct health assessments across the country. These assessments encompass interviews, physical examinations, and detailed otolaryngological evaluations, including auditory tests, tailored to participants of various ages. Each year the survey targets approximately 4,600 households chosen from the National Census by a multistage, clustered, and stratified random sampling method.

Historical rates of participation in the KNHANES have been robust, typically ranging between 76% and 82%, and the survey methodology leverages sample weighting to enhance representativeness. This involves three stages: computing the base weight as the inverse probability of selection, adjusting for nonresponses, and applying post-stratification adjustments to align with census population figures.

The present study used the database of the eighth and ninth KNHANES from 2020 to 2022. From among the 20,714 participants in these surveys, we included 10,028 individuals for whom there was information on age, gender, history of occupational noise exposure, pure tone audiometry, and tympanic membrane status to establish age-normal hearing levels (Fig. 1). In the end, we retrieved 8,392 individuals for whom there was information on air-conduction hearing levels, and who had normal tympanic membranes evaluated by tympanometry with no history of occupational noise exposure (Fig. 1).

Fig. 1

Flow diagram of subject inclusion.

KNHANES = Korea National Health and Nutrition Examination Survey, TM = tympanic membrane.

The mean age of the subjects was 59.79 ± 11.87, and 3,319 (39.55%) of the subjects were male and 5,073 (60.45%) female.

Otological and audiometric evaluation

In the eighth and ninth KNHANES, all otologic evaluations were performed by four trained nurses affiliated with the Korean Society of Otorhinolaryngology-Head and Neck Surgery under the supervision of otorhinolaryngologists. Tympanic membrane status was evaluated by tympanometry performed with a Titan IMP440 screener (Interacoustics, Assens, Denmark), and hearing level was measured with an AD629 audiometer (Interacoustics) compliant with international standards14 in a double-wall soundproof booth. The audiometer and Titan IMP 440 screener were calibrated prior to the KNHANES.

Air-conduction pure tone audiometry was performed at frequencies of 0.5 kHz, 1 kHz, 2 kHz, 4 kHz, and 8 kHz. Cases with out-of-scale or missing values were excluded.

Tympanic membranes and middle ear status were evaluated by tympanometry. Only individuals with type A tympanometry were included in this study.

Mean hearing levels were calculated as the averages of levels at 0.5 kHz, 1 kHz, 2 kHz, and 4 kHz. The data were taken from the better ear, and subjects were stratified into four age categories: 40–49, 50–59, 60–69, and 70 years and above. In addition, these groupings were further subdivided by gender.

Hearing loss was defined as a mean hearing level in the better ear in excess of 25 dB, and severity of hearing loss was classified by the mean hearing level in the better ear as follows: mild: between > 25 dB and 40 dB; moderate: between > 40 dB and 55 dB; moderately severe: between > 55 dB and 70 dB, severe to profound: > 70 dB.

Statistical analysis

Weighted hearing levels for each participant were divided by 3 to calculate one-year average hearing levels over three years, and estimated frequencies of hearing loss in the general population. We performed descriptive statistical analyses of hearing levels for each 10-unit age category. Student’s t tests were used to analyze differences in continuous variables, and the χ² test was used to evaluate difference in categorical variables. We also conducted linear regression analyses to evaluate annual decreases in mean hearing level at each frequency in the general population. All statistical analyses were performed using IBM SPSS Statistics 25.0 (IBM Corp., Armonk, NY, USA).

Ethics statement

This study was conducted based on the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines. The eighth and ninth KNHANES were performed in accordance with the guidelines provided by the Korean Disease Control and Prevention Agency (KDCA). The KNHANES were also approved by the Institutional Review Board (IRB) of KDCA (IRB No. 2018-01-03-4C-A, 2018-01-03-2C-A, 2018-01-03-5C-A). All participants gave informed consent to participating in the KNHANES.

Go to :

RESULTS

Hearing levels of individuals with normal tympanic membranes by age group

Hearing levels at each frequency, and mean hearing levels, increased with age (Tables 1 and 2, Fig. 2A and B). Mean hearing levels were 9.11 ± 6.28 dB, 13.33 ± 7.85 dB, 19.90 ± 10.30 dB, and 31.95 ± 13.37 dB in individuals in their 40s, 50s, 60s, and 70s, respectively.

Fig. 2

Mean hearing levels (A), and hearing levels at each frequency, in the general population (B), in males (C), in females (D) and by age.

Statistically significant difference between males and females: ^***P < 0.001.

Table 1

Mean hearing levels (dB hearing loss) in total subjects, and males and females by age

Gender	Frequency	Age group, yr				Total
Gender	Frequency	40–49	50–59	60–69	70–79	Total
Total	0.5 kHz	8.05 ± 6.88	10.23 ± 6.92	14.76 ± 9.23	24.79 ± 13.50	13.08 ± 10.66
	1 kHz	7.23 ± 7.06	9.83 ± 8.16	15.06 ± 10.75	25.93 ± 14.60	12.97 ± 11.86
	2 kHz	8.95 ± 8.21	13.00 ± 10.13	20.12 ± 12.82	32.35 ± 16.13	16.68 ± 14.14
	4 kHz	12.22 ± 12.10	20.25 ± 16.20	29.67 ± 18.92	44.75 ± 19.37	24.09 ± 19.89
	8 kHz	17.57 ± 16.13	28.58 ± 19.37	43.41 ± 21.24	64.66 ± 18.42	34.71 ± 24.98
	MHL	9.11 ± 6.28	13.33 ± 7.85	19.90 ± 10.30	31.95 ± 13.37	16.70 ± 12.18
Male	0.5 kHz	8.07 ± 6.86	10.41 ± 7.36	14.09 ± 9.25	23.25 ± 13.33	12.40 ± 10.13
	1 kHz	7.52 ± 7.03	10.44 ± 8.75	15.11 ± 10.95	25.16 ± 15.11	12.74 ± 11.61
	2 kHz	9.33 ± 8.31	13.71 ± 11.04	21.09 ± 13.99	33.91 ± 17.82	16.97 ± 14.80
	4 kHz	16.32 ± 14.04	26.52 ± 18.80	37.19 ± 20.39	53.02 ± 19.82	29.59 ± 21.84
	8 kHz	21.98 ± 18.19	34.42 ± 21.54	49.23 ± 21.76	68.89 ± 17.72	38.89 ± 25.63
	MHL	10.31 ± 6.59	15.27 ± 8.77	21.87 ± 10.91	33.84 ± 13.85	17.92 ± 12.43
Female	0.5 kHz	8.03 ± 6.89	10.07 ± 6.51	15.29 ± 9.18	25.75 ± 13.50	13.62 ± 11.03
	1 kHz	6.99 ± 7.07	9.30 ± 7.58	15.01 ± 10.59	26.42 ± 14.25	13.16 ± 12.05
	2 kHz	8.63 ± 8.11	12.39 ± 9.21	19.34 ± 11.74	31.37 ± 14.88	16.44 ± 13.58
	4 kHz	8.70 ± 8.71	14.78 ± 10.91	23.66 ± 15.19	39.55 ± 17.15	19.68 ± 16.92
	8 kHz	13.79 ± 12.99	23.49 ± 15.58	38.75 ± 19.61	62.00 ± 18.36	31.36 ± 23.91
	MHL	8.08 ± 5.80	11.64 ± 6.50	18.33 ± 9.50	30.77 ± 12.93	15.72 ± 11.88
P value^a		< 0.001	< 0.001	< 0.001	< 0.001	< 0.001

Statistically significant differences are highlighted in bold.

^aComparing mean hearing levels in males and females in each age group.

Table 2

Hearing threshold (dB hearing loss) percentiles in males and females in each age group

Hearing level	Hearing threshold percentiles	Age group, yr/Gender
		40–49		50–59		60–69		70–79
		Male	Female	Male	Female	Male	Female	Male	Female
0.5 kHz	5%	0.00	0.00	0.00	0.00	0.00	5.00	5.00	10.00
	10%	0.00	0.00	0.00	0.00	5.00	5.00	10.00	10.00
	25%	5.00	5.00	5.00	5.00	10.00	10.00	15.00	15.00
	50%	10.00	5.00	10.00	10.00	15.00	15.00	20.00	25.00
	75%	10.00	10.00	15.00	15.00	20.00	20.00	30.00	30.00
	90%	15.00	15.00	20.00	20.00	25.00	30.00	40.00	45.00
	95%	20.00	20.00	25.00	20.00	30.00	30.00	50.00	50.00
1 kHz	5%	0.00	0.00	0.00	0.00	0.00	0.00	5.00	5.00
	10%	0.00	0.00	0.00	0.00	5.00	5.00	10.00	10.00
	25%	5.00	5.00	5.00	5.00	10.00	10.00	15.00	15.00
	50%	5.00	5.00	10.00	10.00	15.00	15.00	25.00	25.00
	75%	10.00	10.00	15.00	15.00	20.00	20.00	35.00	35.00
	90%	15.00	15.00	20.00	20.00	30.00	30.00	45.00	45.00
	95%	20.00	20.00	25.00	25.00	35.00	35.00	50.00	50.00
2 kHz	5%	0.00	0.00	0.00	0.00	5.00	5.00	10.00	10.00
	10%	0.00	0.00	5.00	5.00	5.00	5.00	10.00	15.00
	25%	5.00	5.00	5.00	5.00	10.00	10.00	20.00	20.00
	50%	10.00	10.00	10.00	10.00	20.00	20.00	30.00	30.00
	75%	15.00	10.00	20.00	15.00	30.00	25.00	45.00	40.00
	90%	20.00	20.00	25.00	25.00	40.00	35.00	60.00	50.00
	95%	20.00	25.00	35.00	35.00	45.00	40.00	65.00	60.00
4 kHz	5%	0.00	−5.00	5.00	0.00	10.00	5.00	20.00	15.00
	10%	0.00	0.00	5.00	5.00	15.00	5.00	25.00	20.00
	25%	5.00	5.00	15.00	10.00	20.00	15.00	40.00	25.00
	50%	15.00	10.00	20.00	15.00	35.00	20.00	55.00	40.00
	75%	20.00	15.00	35.00	20.00	50.00	30.00	65.00	50.00
	90%	30.00	20.00	55.00	30.00	65.00	45.00	75.00	60.00
	95%	45.00	25.00	65.00	35.00	75.00	50.00	85.00	70.00
8 kHz	5%	0.00	0.00	5.00	5.00	15.00	10.00	35.00	25.00
	10%	5.00	0.00	10.00	5.00	20.00	15.00	45.00	35.00
	25%	10.00	5.00	20.00	10.00	30.00	25.00	60.00	50.00
	50%	15.00	10.00	30.00	20.00	50.00	35.00	70.00	65.00
	75%	30.00	20.00	45.00	30.00	65.00	55.00	85.00	75.00
	90%	50.00	30.00	65.00	45.00	75.00	65.00	90.00	85.00
	95%	60.00	40.00	75.00	50.00	90.00	70.00	90.00	90.00
Mean^a	5%	1.25	1.25	3.75	3.75	7.50	6.25	15.00	12.50
	10%	3.75	2.50	6.25	5.00	10.00	8.75	17.50	15.00
	25%	6.25	3.75	8.75	7.50	13.75	11.25	23.75	21.25
	50%	10.00	7.50	13.75	10.00	20.00	16.25	32.50	28.75
	75%	13.75	10.00	20.00	15.00	27.50	23.75	42.50	38.75
	90%	17.50	15.00	27.50	20.00	36.25	30.00	52.50	48.75
	95%	21.25	17.50	32.50	23.75	41.25	36.25	57.50	55.00

^aAverage of hearing thresholds at 0.5 kHz, 1 kHz, 2 kHz, and 4 kHz.

When we broke down the data into subgroups according to gender, males had higher hearing levels at each frequency, and higher mean hearing levels, than females (Tables 1 and 2, Fig. 2A, C and D). Mean hearing levels were 10.31 ± 6.59 dB, 15.27 ± 8.77 dB, 21.87 ± 10.91 dB, and 33.84 ± 13.85 dB for males in their 40s, 50s, 60s, and 70s, respectively. And they were 8.08 ± 5.80 dB, 11.64 ± 6.50 dB, 18.33 ± 9.50 dB, and 30.77 ± 12.93 dB for females in their 40s, 50s, 60s, and 70s, respectively. In addition, left-side hearing levels (40s: 12.43 ± 8.12 dB; 50s: 17.83 ± 10.12 dB; 60s: 24.53 ± 12.01 dB; 70s: 36.85 ± 15.28 dB) were much poorer than right-side levels for males in all age groups (40s: 13.04 ± 8.54 dB, P < 0.001; 50s: 18.45 ± 11.06 dB; 60s: 25.50 ± 12.90 dB; 70s: 38.16 ± 15.63 dB, P < 0.001), whereas for females, hearing levels on the left side in each age group (40s: 9.88 ± 7.24 dB; 50s: 14.07 ± 7.68 dB; 60s: 21.30 ± 11.95 dB; 70s: 34.14 ± 14.21 dB) were better than on the right side (40s: 10.21 ± 7.13 dB, P < 0.001; 50s: 13.77 ± 8.54 dB, P < 0.001; 60s: 21.17 ± 11.61 dB P < 0.001; 70s: 34.05 ± 15.06 dB P < 0.001) (see Discussion section).

Prevalence of hearing loss by age

Overall rates of hearing loss were 1.81%, 7.51%, 25.32%, and 63.94% in people in their 40s, 50s, 60s, and 70s, respectively. Hearing loss patients accounted for 19.45% of all middle-aged and older individuals (Fig. 3A). In terms of severity of hearing loss rates of mild hearing loss were 1.47%, 6.30%, 21.54%, and 39.52% in their 40s, 50s, 60s, and 70s, respectively, with an overall incidence of 13.95%. Frequencies of moderate hearing loss were 0.34%, 1.12%, 3.15%, and 18.93% in their 40s, 50s, 60s, and 70s, respectively, and 4.39% in all individuals (Fig. 3B). Moderately severe hearing loss occurred in 0.00%, 0.09%, 0.45%, and 4.82% of individuals in their 40s, 50s, 60s, and 70s, respectively, and 0.96% in all individuals (Fig. 3A). In addition, severe-to-profound hearing loss accounted for 0.00%, 0.00%, 0.18%, and 0.67% of individuals in their 40s, 50s, 60s, and 70s, respectively, with an overall prevalence of 0.16% (Fig. 3A).

Fig. 3

Frequencies of different levels of hearing loss in the total population (A), males (B), and females (C).

HL = hearing loss, mod = moderate, sev = severe, prof = profound.

In males, rates of mild hearing loss were 2.23%, 10.21%, 26.98%, and 38.86% in those in their 40s, 50s, 60s, and 70s, respectively. Mild hearing loss patients constituted 15.68% of all middle-aged and older males (Fig. 3B). Moderate hearing loss patients accounted for 0.35%, 1.93%, 4.47%, and 23.19% of those in their 40s, 50s, 60s, and 70s, respectively, and the overall incidence of moderate hearing loss was 5.15% (Fig. 3B). Additionally, rates of moderately-severe hearing loss were 0.00%, 0.20%, 0.72%, and 5.73% among those in their 40s, 50s, 60s, and 70s, respectively, and 1.08% in the total male population (Fig. 3B), while severe-to-profound hearing loss affected 0.00%, 0.00%, 0.24%, and 1.01% of males in their 40s, 50s, 60s, and 70s, respectively, and 0.20% of all males (Fig. 3B).

Among females, rates of mild hearing loss were 0.82%, 2.89%, 17.20%, and 39.94% in those in their 40s, 50s, 60s, and 70s, respectively, and the rate of mild hearing loss among middle-aged to older females was 12.56% (Fig. 3C). In addition, rates of moderate hearing loss were 0.34%, 0.41%, 2.09%, and 16.25% in females in their 40s, 50s, 60s, and 70s, respectively, and the overall prevalence was 3.78% (Fig. 3C). Rates of moderately severe hearing loss were 0.00%, 0.00%, 0.23%, and 4.24% among the 40s, 50s, 60s, and 70s, respectively, with an overall rate of 0.86% (Fig. 3C).

In females, severe-to-profound hearing loss was observed in 0.00%, 0.00%, 0.13%, and 0.46% of individuals in their 40s, 50s, 60s, and 70s, respectively, with an overall rate of 0.12% in the middle and older age groups (Fig. 3C).

In all age groups, there was a higher proportion of mild hearing loss in males than in females (P < 0.001), and the same was true for moderate and moderate-to-severe hearing loss in individuals aged 50 or over (P < 0.001 for the 50s, 60s and 70s). In addition, severe-to-profound hearing loss was more common in males than females in the over-60s (P < 0.001 in 60s and 70s).

Annual hearing deterioration at each frequency

General population

Linear regression analysis of hearing levels with age at each frequency showed that hearing levels were linearly correlated with age at all frequencies (P < 0.001 for all frequencies). Annual increments of hearing level at 0.5 kHz, 1 kHz, 2 kHz, 4 kHz, and 8 kHz, respectively, were 0.51 dB (95% confidence interval [CI], 0.51–0.51 dB), 0.57 dB (95% CI, 0.57–0.57 dB), 0.73 dB (95% CI, 0.73–0.73 dB), 1.02 dB (95% CI, 1.02–1.02 dB), and 1.49 dB (95% CI, 1.49–1.49 dB). Additionally, mean hearing levels increased by 0.71 dB per year (95% CI, 0.71–0.71 dB; P < 0.001) (Table 3).

Table 3

Annual increments of hearing level at each frequency in males, females and total subjects

Frequency	0.5 kHz	1 kHz	2 kHz	4 kHz	8 kHz	Mean
Males, dB/yr	0.46 (0.45–0.46)	0.54 (0.54–0.54)	0.76 (0.76–0.76)	1.15 (1.15–1.15)	1.50 (1.50–1.50)	0.73 (0.73–0.73)
Females, dB/yr	0.55 (0.55–0.55)	0.60 (0.60–0.60)	0.71 (0.71–0.72)	0.96 (0.96–0.96)	1.51 (1.51–1.51)	0.71 (0.71–0.71)
Total, dB/yr	0.51 (0.51–0.51)	0.57 (0.57–0.57)	0.73 (0.73–0.73)	1.02 (1.02–1.02)	1.49 (1.49–1.49)	0.71 (0.71–0.71)

Values are means (95% confidence interval).

Males

Hearing levels in males also increased linearly with age (P < 0.001 for all frequencies) (Table 3), with an annual deterioration of approximately 0.46 dB (95% CI, 0.45–0.46 dB), 0.54 dB (95% CI, 0.54–0.54 dB), 0.76 dB (95% CI, 0.76–0.76 dB), 1.15 dB (95% CI, 1.15–1.15 dB), and 1.50 dB (95% CI, 1.50–1.50 dB) at 0.5 kHz, 1 kHz, 2 kHz, 4 kHz, and 8 kHz, respectively, while the mean hearing level worsened by approximately 0.73 dB per year (95% CI, 0.73–0.73 dB; P < 0.001) (Table 3).

Females

There were also linear increments of hearing loss with age among females across all frequencies (P < 0.001) (Table 3), with annual increases of hearing level of approximately 0.55 dB at 0.5 kHz (95% CI, 0.55–0.55 dB), 0.60 dB at 1 kHz (95% CI, 0.60–0.60 dB), 0.71 dB at 2 kHz (95% CI, 0.71–0.72 dB), 1.02 dB at 4 kHz (95% CI, 1.02–1.02 dB), 1.49 dB at 8 kHz (95% CI, 1.49–1.49 dB), and an overall increase of 0.71 dB in mean hearing level (95% CI, 0.71–0.71) (P < 0.001 for all frequencies and mean hearing level) (Table 3).

Comparison with the results of a previous study

We compared mean hearing levels at each frequency in a previous study using data from KNHANES from 2010 to 2012 with those reported in the present study. Mean hearing levels at 1 kHz and 2 kHz for individuals in their 40s were poorer in the present study, but not at 1 kHz for females in their 50s (Table 4). Those in their 70s also had worse hearing than those in the previous study (Table 4). Hearing levels at other frequencies for various age groups in 2020–2022 were better than those in 2010–2012 (Table 4).

Table 4

Comparison of hearing levels at each frequency in 2020–2022 and 2010–2012

Age, yr	0.5 kHz, dB				1 kHz, dB				2 kHz, dB				4 kHz, dB
	Male		Female		Male		Female		Male		Female		Male		Female
	2010–2012	2020–2022	2010–2012	2020–2022	2010–2012	2020–2022	2010–2012	2020–2022	2010–2012	2020–2022	2010–2012	2020–2022	2010–2012	2020–2022	2010–2012	2020–2022
40–49	8.6	8.07	9.4	8.03	6.1	7.52	6	6.99	7.9	9.33	7.6	8.63	21.5	16.32	8.6	8.7
50–59	11.1	10.41	12	10.07	9.4	10.44	9.6	9.3	13.1	13.71	11.5	12.39	29.8	26.52	15.1	14.78
60–69	15.7	14.09	16.9	15.29	15.5	15.11	16	15.01	22.1	21.09	19.7	19.34	42	37.19	25.1	23.66
70–80	22.5	23.25	26.2	25.75	23	25.16	25.6	26.42	31.4	33.91	30	31.37	50.9	53.02	38.9	39.55

Hearing levels that were poorer in 2020–2022 than in 2010–2012 are depicted in dark gray.

Go to :

DISCUSSION

In the present study we analyzed mean hearing levels across different age groups using recent KNHANES data, and assessed overall annual increments of hearing loss at each frequency.

As aging progresses, mean hearing levels deteriorate, with males exhibiting a greater decline in hearing than females. By their 70s, approximately 65% of individuals experience some degree of hearing loss, with 25% suffering from what is defined as more than moderate hearing loss. Annually, hearing level increases by approximately 0.71 dB, and hearing deteriorates more rapidly at higher frequencies.

In the United States, age-norm hearing levels are characterized by “Hearing Number” in decibels, and average hearing levels are 5 dB, 9 dB, 16 dB, and 25 dB at ages 20, 40, 60, and 80, respectively. Prescription hearing aids are recommended for individuals with hearing numbers between 20 dB and 90 dB, while cochlear implants are recommended for individuals with hearing numbers > 60 dB. The present study found similar extents of hearing loss in individuals in their 40s and 60s. In addition, mean hearing level was higher than 20 dB in males of 60 and over, and about 30 dB in people in the general population in their 70s. Moreover, the mean hearing level of those in the 70s with one standard deviation added reached 40 dB, which is considered a disabling level calling for consideration of a hearing aid.15 Recent studies have demonstrated that hearing levels and hearing aids are crucial for the elderly in terms of social communication, life satisfaction, and cognitive function.16 17 18 19 Therefore, our findings imply that regular evaluation of hearing levels and appropriate hearing rehabilitation should be provided for persons in their 70s. Furthermore, since men suffered more extensive hearing loss than women, the hearing levels of elderly males should be especially carefully monitored.

In clinical practice it is difficult to distinguish age-related hearing loss from hearing loss caused by other factors including otitis media and choleseteatoma.1 15 However, information on expected hearing levels can be provided to patients with age-related hearing loss, and such information enables patients to compare their hearing status with peers in the same age group, which can be invaluable during consultations. Health policymakers can also use the information to design or modify public health interventions aimed at preventing hearing loss in the aging population. Furthermore, the availability of data can help audiologists and healthcare providers to provide more effective, age-specific hearing conservation programs and rehabilitation procedures.

Hearing levels at each frequency in our study differed across all age groups by about 1–5 dB from those reported in a previous study using the fifth KNHANES.5 These differences may be due to differences between manual and automated audiometry.8 20 21 22 Moreover, previous studies have shown that the accuracy of automated audiometry can decrease in older individuals.21 22 Therefore, our data will provide valuable reference values for interpreting manual audiometry-based normative hearing level in South Korea.

Despite the fact that direct comparison between previous data and recent data is not recommended by the KDCA due to differences in measuring methods—automatic in the previous survey and manual in the recent one—hearing levels were consistently worse in the latter at all frequencies in individuals in their 70s, whereas the hearing levels in other age groups did not show a consistent trend at all frequencies. In addition, as average life expectancy has increased, the mean age of individuals in their 70s has also risen, potentially contributing to higher hearing levels in this age group.23 24 25 Furthermore, when compared to a previous study that used ISO 7029 data to assess normal hearing ranges for each age group and presented median hearing levels for various countries, including South Korea,26 the median values obtained in our study were about 0.5–4 dB higher than those obtained in that study over the decades from the 40s to the 60s. From the findings of the fifth KNHANES and the ISO 7029 data together with those of our study, we can conclude that overall hearing ability has declined. Societal shifts and increased use of personal audio devices are probably leading to heightened risk of noise-induced hearing loss in the young.9 10 11 12 Thus, our findings can be useful in providing updated information on age- and gender-specific average hearing levels.

Surprisingly, we found that females had better hearing on their left side, while the opposite pattern was seen in males, However, this finding is consistent with the conclusion of a previous study that low-frequency hearing in adults is better in the left ear than the right, whereas high-frequency hearing, often affected by noise-induced hearing loss, is poorer in the left ear27; because Korean males are required to serve in the army in their 20s and left side hearing is more susceptible to gunshot noise due to the head shadow effect28 this may explain why Korean males (but not females) have worse hearing on the left side.

This study aimed to evaluate the hearing levels of individuals who did not have histories of occupational noise exposure, and had normal tympanic membranes, to address age-normative hearing levels in the general population. Other diseases or conditions such as cardiovascular comorbidities that might affect hearing levels were not considered. A previous study demonstrated that cardiovascular comorbidity can increase hearing thresholds by about 5.5 dB at low frequencies and by 1.8 dB at high frequencies.29 Additionally, these aggravated hearing thresholds may increase further with additional comorbidities.29 Therefore, when clinicians evaluate hearing levels in patients with other conditions, they need to consider such combined effects.

This study has the limitation commonly associated with KNHANES. It was conducted using a cross-sectional design for the general population. Although annual hearing deterioration was calculated for the general population, the results were based on combining the results for different age groups. Further longitudinal studies evaluating annual changes in hearing levels within the same population could provide more accurate information on annual hearing deterioration. Another limitation was the absence of information on the hearing levels of individuals below 40, as the eighth and ninth KNANES did not include this data. Studies of individuals below 40 may be helpful in evaluating recent trends in hearing level.

Finally, the hearing tests were conducted by four different examiners at various locations in South Korea. Although the audiometric equipment was calibrated before each test, and the examinations were performed according to standardized protocols, differences in testing environments may have influenced the results.

The present study provides reference values for normative hearing levels in different age groups. Based on our study, physicians can offer appropriate consultations regarding hearing levels and the need to monitor hearing levels in the elderly.

Go to :

Notes

Funding: This work is funded by Korea Institute of Science and Technology (KIST) Institutional Program (2E32993 and 2E32990).

Disclosure: The authors have no potential conflicts of interest to disclose.

Author Contributions:

Conceptualization: Han SY, Chung JH.
Data curation: Han SY, Seo HW.
Formal analysis: Han SY.
Investigation: Han SY, Lee SH.
Methodology: Han SY, Chung JH.
Writing - original draft: Han SY, Chung JH.
Writing - review & editing: Seo HW, Lee SH, Chung JH.

Go to :

References

1. Michels TC, Duffy MT, Rogers DJ. Hearing loss in adults: differential diagnosis and treatment. Am Fam Physician. 2019; 100(2):98–108. PMID: 31305044.

2. Raviv D, Dror AA, Avraham KB. Hearing loss: a common disorder caused by many rare alleles. Ann N Y Acad Sci. 2010; 1214(1):168–179. PMID: 21175685.

3. Choi J, Kim T, Kim S, Kim Y, Kim DK. Effect of aging on speech discrimination. J Audiol Otol. 2022; 26(4):198–201. PMID: 36111451.

4. Humes LE. Hearing thresholds for unscreened U.S. adults: data from the National Health and Nutrition Examination Survey, 2011-2012, 2015-2016, and 2017-2020. Trends Hear. 2023; 27:23312165231162727. PMID: 36919308.

5. Park HJ, Yoo MH, Baek SY, Kim SW, Cho YS. Normative hearing threshold levels in Koreans with normal tympanic membranes and estimated prevalence of hearing loss. Clin Exp Otorhinolaryngol. 2017; 10(2):129–136. PMID: 27464516.

6. Hearing Number. Updated 2024. Accessed July 28, 2024. https://hearingnumber.org/about/ .

7. Kim S, Park JM, Han JS, Seo JH, Han KD, Joo YH, et al. Age-related hearing loss in the Korea National Health and Nutrition Examination Survey. PLoS One. 2020; 15(12):e0243001. PMID: 33259558.

8. Mahomed F, Swanepoel W, Eikelboom RH, Soer M. Validity of automated threshold audiometry: a systematic review and meta-analysis. Ear Hear. 2013; 34(6):745–752. PMID: 24165302.

9. Jiang W, Zhao F, Guderley N, Manchaiah V. Daily music exposure dose and hearing problems using personal listening devices in adolescents and young adults: a systematic review. Int J Audiol. 2016; 55(4):197–205. PMID: 26768911.

10. World Health Organization (WHO). Hearing Loss Due to Recreational Exposure to Loud Sounds: A Review. Geneva, Switzerland: WHO;2015.

11. World Health Organization (WHO). World Report on Hearing: World Health Organization. Geneva, Switzerland: WHO;2021.

12. Gopal KV, Mills LE, Phillips BS, Nandy R. Risk assessment of recreational noise-induced hearing loss from exposure through a personal audio system-iPod Touch. J Am Acad Audiol. 2019; 30(7):619–633. PMID: 30395532.

13. Goman AM, Reed NS, Lin FR. Addressing estimated hearing loss in adults in 2060. JAMA Otolaryngol Head Neck Surg. 2017; 143(7):733–734. PMID: 28253386.

14. Suh MJ, Lee J, Cho WH, Jin IK, Kong TH, Oh SH, et al. Improving accuracy and reliability of hearing tests: an exploration of international standards. J Audiol Otol. 2023; 27(4):169–180. PMID: 37872752.

15. Olusanya BO, Davis AC, Hoffman HJ. Hearing loss: rising prevalence and impact. Bull World Health Organ. 2019; 97(10):646–646A. PMID: 31656325.

16. Han SY, Kim YH. Effects of economic status on changes in social networks and mental health after using hearing aids. Laryngoscope. 2024; 134(5):2387–2394. PMID: 37987221.

17. Lin FR, Pike JR, Albert MS, Arnold M, Burgard S, Chisolm T, et al. Hearing intervention versus health education control to reduce cognitive decline in older adults with hearing loss in the USA (ACHIEVE): a multicentre, randomised controlled trial. Lancet. 2023; 402(10404):786–797. PMID: 37478886.

18. Cosh S, Helmer C, Delcourt C, Robins TG, Tully PJ. Depression in elderly patients with hearing loss: current perspectives. Clin Interv Aging. 2019; 14:1471–1480. PMID: 31616138.

19. Choi Y, Go J, Chung JW. Association between hearing level and mental health and quality of life in adults aged >40 years. J Audiol Otol. 2024; 28(1):52–58. PMID: 37953515.

20. Shojaeemend H, Ayatollahi H. Automated audiometry: a review of the implementation and evaluation methods. Healthc Inform Res. 2018; 24(4):263–275. PMID: 30443414.

21. Liu H, Fu X, Li M, Wang S. Comparisons of air-conduction hearing thresholds between manual and automated methods in a commercial audiometer. Front Neurosci. 2023; 17:1292395. PMID: 38188027.

22. Hoff M, Göthberg H, Tengstrand T, Rosenhall U, Skoog I, Sadeghi A. Accuracy of automated pure-tone audiometry in population-based samples of older adults. Int J Audiol. 2024; 63(8):622–630. PMID: 37335133.

23. Kontis V, Bennett JE, Mathers CD, Li G, Foreman K, Ezzati M. Future life expectancy in 35 industrialised countries: projections with a Bayesian model ensemble. Lancet. 2017; 389(10076):1323–1335. PMID: 28236464.

24. Baek JY, Lee E, Jung HW, Jang IY. Geriatrics fact sheet in Korea 2021. Ann Geriatr Med Res. 2021; 25(2):65–71. PMID: 34187140.

25. Kim I, Bae H. Age- and cause-specific contributions to increase in life expectancy at birth in Korea, 2000-2019: a descriptive study. BMC Public Health. 2024; 24(1):431. PMID: 38341549.

26. Jin IK, Lee D, Jeong Y, Seo YJ, Kong TH, Suh MJ, et al. Trends in distributions of hearing threshold levels by ages: a comparison of the ISO 7029 and newly available country-specific data. J Audiol Otol. 2024; 28(1):1–9. PMID: 38254303.

27. Pirilä T, Jounio-Ervasti K, Sorri M. Left-right asymmetries in hearing threshold levels in three age groups of a random population. Audiology. 1992; 31(3):150–161. PMID: 1642566.

28. Le TN, Straatman LV, Lea J, Westerberg B. Current insights in noise-induced hearing loss: a literature review of the underlying mechanism, pathophysiology, asymmetry, and management options. J Otolaryngol Head Neck Surg. 2017; 46(1):41. PMID: 28535812.

29. Wattamwar K, Qian ZJ, Otter J, Leskowitz MJ, Caruana FF, Siedlecki B, et al. Association of cardiovascular comorbidities with hearing loss in the older old. JAMA Otolaryngol Head Neck Surg. 2018; 144(7):623–629. PMID: 29902313.

Go to :

TOOLS

Similar articles