Noise Induced Hearing Loss among Industrial Workers in North India: A Tale of Various Influencing Factors

Abstract

To study the prevalence and determinants of Noise Induced Hearing Loss (NIHL) among industrial workers. To access the benefit of Distortion Product Oto Acoustic Emissions (DPOAEs) in its early detection as compared to Pure Tone Audiometry (PTA). Detailed in-person questionnaires were filled followed by general and otological examination viz. local and otoscopic examination. NIHL was assessed by tuning fork test, PTA and DPOAEs. 360 participants aged 20–55 years from 6 industries 4 at noise level of 81–90 dBA and 2 at 91–100 dBA. Prevalence of NIHL at 81–90 dBA and 91–100 dBA was 48% and 59% on PTA. Overall Prevalence from 81 to 100 dBA was 49.45% on PTA and 67% on DPOAEs. NIHL was more prevalent at higher noise level, age group higher than 40 years, duration of service greater than 16 years of exposure and continuous noise type. Noise Induced Permanent Threshold Shift (NIPTS) was found to gradually increase at higher noise level and with increase in duration of service. Noise exposure monitoring at work place, engineering controls to reduce noise levels, provision of hearing protection devices, periodic audiometric evaluation of employees and employee’s education regarding NIHL are some of the significant aspects to be considered to prevent NIHL.

Introduction

Occupational noise is one of the most universal occupational hazards that affects the hearing system [1]. The reduction in auditory acuity associated with excessive noise exposure is termed as noise-induced hearing loss (NIHL). NIHL is characterized as sensorineural hearing loss which is generally bilateral, irreversible and progresses as the noise exposure continues. The hearing loss may be described as temporary threshold shift (TTS) [2]. Repeated TTS may lead to permanent hearing loss known as permanent threshold shift (PTS) [3]. NIHL begins and succeeds towards higher frequencies of 3, 4, 6 and 8 kHz and progresses further to low frequencies of 2, 1, 0.5, 0.25 kHz on PTA with a dip or Notch at 4 kHz being the first sign, with recovery at 6 and 8 kHz [4]. The World Health Organization (2018) estimates that approximately 466 million people worldwide suffer from hearing loss and approximately 1.1 billion young people (aged between 12 and 35 years) face hearing loss as a result of noise (WHO guidelines, 2018) [5].

Although the sensitivity of each individual is different, sound intensity over 85 dB can cause noise-induced hearing loss. Such high levels of noise exposure usually come from occupational noise such as factories and industries. It has been reported that people exposed to sound over and above 89 dB for more than 5 h per week can undergo irreversible hearing damage in due course of time [6]. A continuous noise exposure of 90 dBA for 8 h is the maximum noise limit recommended by the Directorate General of Factories Advisory Services and Labour Institutes of India. Noise level in several industries in the developing countries including India, which provide employment to millions of workers exceed this 90-dBA limit in routine. Examples of such industries are the metal, textile, woodworker, marble, ceramic and some other industries [7]. Studies carried out by the National Institute of Occupational Health, India, showed that the sound pressure levels were very high in various Indian industries [8].

NIHL is a multifactorial and complex situation. Hair cells are highly differentiated cells which are not able to regenerate. The main pathological change of noise-induced hearing loss is mechanical damage to the cochlea. Noise energy transmitted to the inner ear causes the perilymph and endolymph to oscillate aggressively. The basilar membrane and the tectorial membrane which separates the cilia from the inner and outer hair cells shear and compress robustly, making it difficult for the hair cells to obtain effectual vibration stimulation. The fluctuation or oscillation of the lymph can also detach the hair cells from the basilar membrane, resulting in the disruption of ribbon synapses. Consequently, the residual synapses cannot maintain optimal function and the encoding ability of hair cells becomes faulty. Hence this leads to trouble in understanding and verbal communication in a raucous location [9, 10]. If loud noise repeatedly acts on the inner ear, then demolition of these inner hair cells (responsible for perceiving the vibration) as well as outer hair cells (responsible for amplifying the sound) occurs and act as a ground for sensorineural hearing loss. So, preventing powerful noise exposure is very imperative and should be highly emphasized [11].

PTA is presently the gold standard test for detecting and monitoring NIHL in different industries where the daily noise exposure levels exceed 85 dBA. But the sensitivity of PTA is questioned in detecting subclinical noise-induced cochlear function changes. NIHL in its early stages primarily affects the outer hair cells in the cochlea whereas PTA measures the integrity of the whole auditory pathway. Hearing damage is only detected when permanent irreversible damage has already happened. Subsequently, there is no timely prevention of outer hair cell damage from occupational noise exposure. Moreover, PTA testing requires the cooperation of the employee. These are some noteworthy limitations for using PTA as the only hearing screening technique in occupational health surveillance programmes. Several studies have specified that otoacoustic emissions (OAEs) could be a more appropriate diagnostic tool for the early detection of cochlear function changes from excessive noise exposure, allowing detection of cochlear damage before it is evident through PTA [12]. Otoacoustic emissions (OAE) are resonances produced from the cochlea and conveyed across the middle ear to the external ear, where these can be recorded [13].

Ranga et al (2014) studied NIHL in 100 Iron steel Industry workers exposed to 87.3 dBA of noise level and reported overall prevalence of 38% at 4 kHz [14]. Biswas and Kumar (2018) reported that half of the Industrial workers under study had NIHL audiometric patterns [15]. Dube et al reported that 86% of ginning industry workers exposed to 89–106 dBA suffered hearing loss [16]. Significant association between NIHL and age was reported in industrial workers by Khare et al (2017) [17]. Routine monitoring of work place noise levels and hearing protection for workers in noisy settings were recommended by Sakhare and Chakravarty et al (2019) in a study involving 100 construction industrial workers [18].

The literature on occupational noise induced hearing loss in India are limited. Till date there is paucity of data indicating the noise pollution caused by industrial setups, prevalence of NIHL and factors affecting NIHL in workers exposed to such high noise intensities in India. There is a lack of awareness regarding the fact that NIHL is a preventable disease.

In view of above facts, a study was conducted on 360 participants (industrial workers) by ENT department of Government Medical College and Rajindra Hospital (GMC & RH) Patiala, Punjab to evaluate the prevalence and determinants of noise induced hearing loss in industrial workers.

Methods

Study Population

This cross-sectional study undertaken was conducted from February, 2021 to October, 2022. A total of 450 workers of age group 20–55 years were randomly selected from the list of workers present on the day of visit from 6 industries (food, automobile, spare part, combine industries with noise level 81–90 dBA and iron mills with noise level 91–100 dBA). Out of total 450 workers who underwent in-person questionnaires, 42 workers refused to give written informed consent for examination. Total 48 individuals who had history of congenital hearing loss, ear disease, systemic diseases or history of ototoxic medication were excluded from the study. The sample size was calculated using the formula suggested by WG (1963) [19]. A total of 384 participants were needed, we took 15% more participants to account for non-responders and those not fulfilling the inclusion criteria.

Selection of Study Participants

The study involved 360 male and female workers of age group 20–55 years. 297 participants worked in food, automobile, spare part and combine industries with noise level 81–90 dBA and 63 participants worked in iron mills with noise level 91–100 dBA. Written consent of all 360 factory workers was taken for examination. This study was approved by Research Committee and Institutional Ethics Committee, Government Medical College, Patiala and Faculty of Medical Sciences, Baba Farid University of Health Sciences, Faridkot, (Punjab) with approval number: BFUHS/2K21p-TH/14744 dated 15-12-2021 and this study was performed in accordance with the ethical standards as laid down in the 1964 Declaration of Helsinki and its later amendments.

Noise Measurements at the Work Place

Noise measurements were carried out in all the industries with the help of a sound Level Meter SL101 (Sigma). This was a portable type and had “A” Weighting frequency feature with frequency response range of 31.5 Hz-8 kHz. It had a range from 30 to 130 dBA with ± 1.5dB accuracy and resolution of 0.1dB. Noise levels were measured at various working areas in all industries using this Sound Level Meter. Additionally, the iNVH mobile application developed by Bosch Global Software Technologies Private Limited was also used for the measurement of noise levels of various industrial establishments. This application comes with an auto-calibrated module for the noise level measurement. This versatile application can measure sounds in the range of 30–120 dBA.

History and General Physical Examination

Detailed history of the participants was taken on a performa checklist that included the details related to their general information, work/work related environment, residential conditions, history of any addiction, history of any ailment like diabetes, hypothyroidism, cardiovascular diseases, renal failure, Human Immunodeficiency Virus, chronic Urinary Tract Infection (on aminoglycosides), arthritis (on Methotrexate), high cholesterol, hypertensives on loop-diuretics and ototoxic drug use.

The factory-based general physical examination of the individual was done as per the performa. After doing the general physical examination, local examination of the ear was done, followed by otoscopic examination of external auditory canal and tympanic membrane.

Hearing Assessment

Assessment of hearing of the participants was done by performing the following tests as per standard procedures.

Tuning Fork Test

Rinne’s test and Weber’s test were performed.

Pure Tone Audiometry

The hearing thresholds were tested using a commercially available ALPS advanced digital audiometer AD2100 for speech frequencies and higher frequencies audiometry. Hearing thresholds were assessed by PTA. Bone and air conduction thresholds were tested at frequencies between 250 and 8000 Hz. NIHL was defined as a hearing threshold level greater than 25 db hearing loss at 3K, 4K or 6K kHz [20].

Oto Acoustic Emissions

Otoacoustic emission (OAEs) are defined as the acoustic energy produced by the cochlea and recorded in the outer ear canal which relates to the health and function of the outer ear canal and thus to the health and function of the outer hair cells (OHCs). It is generally recognized that evoked OAEs are more sensitive in revealing early NIHL, easy to perform and require minimal co-operation from patients. Otoacoustic emissions were carried out using systems developed by MAICO DIAGNOSTICS ERO-SCAN Item No.8106838. Distortion product OAE (DPOAE) were performed for each patient. DPOAE were recorded by DPgram method. The f2/f1 ratio was held at 1.2. The stimuli level was held constant at L1=65 dBA Sound Pressure Level (SPL) and L2= 55 dBA SPL. The level amplitude and signal to noise ratio (SNR) of the DPOAE occurring at 2f1-f2 frequency were measured with f2 frequency in half-octave-band frequencies of 1,2,3,4,6 and 8kHz. The decorum set for the instrument identified a “Pass” when DPOAEs were detected at a 6 dBA signal-to-noise ratio for three out of four test frequencies f2 (2, 3, 4, and 5 kHz). If the “Pass” status was not met, the instrument showed a “Refer” status on the testing. A “Refer” was considered as an absent DPOAE.

Statistical Analysis

Results observed among the participants were compared and analysed statistically using IBM, SPSS statistical software. Descriptive statistics were done for all data and were reported in terms of mean, S.D. and percentages. Appropriate statistical tests of comparison were applied. Categorical variables were analysed with the help of chi square/fisher exact test. Statistical significance was taken as p<0.05.

Results

Demographic Profile

The mean age of the participants was found to be 39.61±7.89 years, median age 40 years and the range of age was 20–55 years. 14.45% participants were under age group of 20–30 years. Highest number of participants were recorded in the age group 31–40 (38.89%) followed by 41–50 years (36.66%). Least number of participants i.e. 10 were under 51–60 years age category. The male to female ratio in this study was 97:3. 174 participants hailed from rural areas and 186 participants resided in urban localities.

Symptoms Related to NIHL Reported by Participants.

Hearing loss with difficulty in social communication was reported by 14.4 % participants. Tinnitus was reported by 9.4% participants.

Prevalence of NIHL at Different Noise Levels on PTA

High Frequency Hearing Loss (HFHL) was detected in 36.9%, HFHL with 4 kHz Notch was observed in 7.2% and Low Frequency Hearing Loss (LFHL) was observed in 5.2% out of total 360 participants. Overall prevalence of NIHL was 49.4% (Fig. 1a).

Fig. 1.

a Overall prevalence of NIHL b Prevalence of NIHL at different noise levels

Out of 297 participants exposed to 81–90 dBA, HFHL, HFHL with 4 kHz Notch and LFHL was detected in 37%, 6% and 5% participants respectively. Out of 63 participants exposed to 91–100 dBA, HFHL, HFHL with 4 kHz Notch and LFHL was detected in 38%, 13% and 8% participants respectively. Statistically significant difference is observed in the distribution of participants on the basis of hearing status (NH, HFHL, HFHL with 4 kHz Notch and LFHL) by Tukey’s multiple comparison test at each noise level i.e. either 81–90 dBA or 91–100 dBA (P<0.001) (Fig. 1b).

Prevalence of NIHL in Workers Working in Different Industries

Among the industries at noise level of 81–90 dBA and 91–100 dBA, the prevalence of NIHL was found to be 47.47% and 58.73% respectively (Table 1).

Table 1.

Prevalence of NIHL in different industries in the present study

S. no.	Type of industry	Noise level	No. of participants	Participants with NIHL	Prevalence of NIHL (%)	Overall prevalence of NIHL (%)
1.	Food industry	81–90 dBA	189	86	45.5	47.47
2.	Automobile industry		29	16	55.1
3.	Spare part manufacturing industry		57	27	47.36
4.	Combine manufacturing industry		22	12	54.54
5.	Iron mill	91–100 dBA	63	37	58.73	58.73

Prevalence of NIHL in Workers at Different Age Groups

At noise level of 81–90 dBA, in 21–30 years age group, HFHL, HFHL with 4 kHz Notch and LFHL was observed in 4.8%, 2.4% and 4.8% cases respectively. In 31–40 years, age group, HFHL, HFHL with 4 kHz Notch and LFHL was detected in 18.4%, 4.8% and 1.6% cases respectively. In 41–50 years, age group, HFHL, HFHL with 4 kHz Notch and LFHL was observed in 60.7%, 10.7% and 4.9% cases. In age group of 51–60 years, HFHL and LFHL was observed in 75.8%, and 17.2% cases respectively. But no case of HFHL with 4 kHz Notch was observed in this age group. The differences of hearing status among different age groups at 81–90 dBA noise level were highly statistically significant at p value <0.0001(Fig. 2a).

Fig. 2.

a Distribution of participants with hearing loss based on age groups at noise level of 81–90 dBA b Distribution of participants with hearing loss based on age groups at noise level of 91–100 dBA

Out of 63 participants at noise level of 91–100 dBA, no case of hearing loss was detected in 21–30 years age group. In 31–40 years, age group, HFHL, HFHL with 4 kHz Notch and LFHL was detected in 13.3%, 20% and 6.6% cases respectively. In 41–50 years, age group, HFHL, HFHL with 4 kHz Notch and LFHL was observed in 56.6%, 16.6% and 6.6% cases. In age group of 51–60 years, HFHL and LFHL was observed in 71.4%, and 28.5% cases respectively. But no case of HFHL with 4 kHz Notch was observed in this age group. The differences of hearing status among different age groups at 91–100 dBA noise level were highly statistically significant at p value <0.0001(Fig. 2b).

Prevalence of NIHL in Workers Based on Duration of Service

Participants exposed to 81–90 dBA noise level were studied for effect of duration of service on prevalence of NIHL. With duration of service of <6 years, HFHL was observed in 5.5% participants, while none of them had HFHL with 4 kHz Notch and LFHL. In 6–10 years of duration of service, 10.7%, 2.9% and 1.9% participants were found to have HFHL, HFHL with 4 kHz Notch and LFHL respectively. In 11–15 years of duration of service, 44% and 4% participants were found to have HFHL and LFHL respectively. But no case of HFHL with 4 kHz Notch was observed. In 16–20 years of service HFHL, HFHL with 4 kHz Notch and LFHL was observed in 47.4%, 10.3% and 6.1% respectively. Similarly, in >20 years of service 72.7%, 9% and 9% participants were found to have HFHL, HFHL with 4 kHz Notch and LFHL respectively (Fig. 3a). The difference in distribution of participants on the basis of duration of service was highly significant statistically at p <0.0001.

Fig. 3.

a Distribution of participants with hearing loss based on duration of service at 81–90 dBA b Distribution of participants with hearing loss based on duration of service at 91–100 dBA c NIPTS at both noise levels based on average duration of service

At 91–100 dBA noise level, with <6 years of service, no participant was found to have hearing loss. In 6–10 years of service 18.1% and 9% participants were found to have HFHL, HFHL with 4 kHz Notch and no case of LFHL was observed. In 11–15 years of service 71.4% and 14.2% participants were found to have HFHL, HFHL with 4 kHz Notch and no case of LFHL was observed. In 16–20 years of service HFHL, HFHL with 4 kHz Notch and LFHL was observed in 56.2%, 31.2% and 6.2% respectively. Similarly, in >20 years of service 57.1%, 7.1% and 28.5% participants were found to have HFHL, HFHL with 4 kHz Notch and LFHL respectively (Fig. 3b). The difference in distribution of participants on the basis of duration of service was highly significant statistically p <0.0001.

Noise Induced Permanent Threshold Shift (NIPTS) in Participants Corresponding to Duration of Service

Noise induced permanent threshold shift was calculated taking the average of duration of service at two different noise levels and compared. Figure 3c clearly indicates that as the duration of service in industrial workers increases, the NIPTS also increases. Moreover, NIPTS is higher at 91–100 dBA noise level in comparison to that at 81–90 dBA noise level (Fig. 3c) Two-way ANOVA reveals that the difference between NIPTS at different noise levels and between different duration of service was highly significant at p <0.0001.

Prevalence of NIHL Based on Type of Noise Exposure (Continuous/Intermittent)

In our study, out of the 254 participants working in a continuous noise of 81–90 dBA, 48.8% participants were found to have hearing loss. While out of the 43 participants working in intermittent noise, 39.5% were found to have hearing loss. Similarly, out of the 57 participants working in a continuous noise of 91–100 dBA, 61.4% participants were found to have hearing loss and out of the 6 participants working in intermittent noise, 33% were found to have hearing loss. NIHL was more prevalent in workers exposed to continuous noise type. Statistically no significant difference was found in NIHL affected participants working in continuous and intermittent noise type.

Hearing Assessment of Participants by Means of DPOAE

When hearing status was assessed using DPOAEs, it was observed that out of total 297 participants working at noise level of 81–90 dBA, 199 participants had hearing loss out of which 155 have Bilateral Refer and 44 have Unilateral Refer on DPOAEs. Out of total 63 participants working at a noise level of 91–100 dBA, 42 participants had Hearing Loss out of which 35 had Bilateral Refer and 7 had Unilateral Refer on DPOAE. The overall prevalence of hearing loss was 67% on DPOAEs.

In this study hearing loss was detected among 49.5% of participants as per PTA and 67% as per DPOAE out of total 360 participants. These differences between PTA and DPOAE are statistically highly significant at p <0.0001 (Table 2).

Table 2.

Detection of normal hearing and NIHL by PTA and DPOAE and their comparison at noise level of 81–100 dBA

Hearing status	PTA (%)	DPOAE (%)
Normal hearing/pass	182 (50.55)	119 (33.00)
Hearing loss /refer	178 (49.45)	241 (67.0)
Total	360	360
Chi-square (χ2)	22.66
p value	<0.0001
Statistically significant

Distribution of Participants Based on Use of Hearing Protection Device

Among the 360 participants, only 31(8.6%) reported use of hearing protection devices during working h.

Discussion

Out of 360 participants, hearing loss was found in 49.4% workers. Nyarubeli et al (2019) observed hearing loss in 10% workers. Hong et al (1998) reported that among plywood industry workers working at 85.5 dBA noise level, 10.2% workers had hearing loss. However, Chen et al (2010) reported hearing loss in 28 % workers in oil refinery workers working at noise level of 73–89 dBA [21].

In the present study, tinnitus was reported by 34 (9.4%) workers out of total 360 workers. Nyarubeli et al (2019), Edward et al (2016) and Chen et al (2010) observed tinnitus in 8.6%, 29% and 32.2% workers.

Determination of Prevalence of NIHL by PTA

At noise level of 81–90 dBA, 43% had HFHL and 5% had LFHL. It is in concordance with the study carried out by Karimi et al (2010) at noise level of 83–90 dBA, 45% participants had HFHL, 12.6% had LFHL. Similar findings have been reported by Chen et al (2003) as HFHL in 38.3% participants and LFHL in 9.6% workers. Hong et al (1998) reported airport workers exposed to >85 dBA noise level, 49.4% participants affected by HFHL and 7% participants affected by LFHL [22]. Ranga et al (2014) studied NIHL in 100 Iron steel Industry workers exposed to 87.3 dBA of noise level and reported overall prevalence of 38% out of which 12% was HFHL and 26% was HFHL at 4 kHz notch which was lower than other reported incidences of NIHL.

At noise level of 91–100 dBA, 51% had HFHL and 8% had LFHL. At noise level of 90–100 dBA, Satish and Kashyap (2008) had HFHL prevalence of 62.4% (41% HFHL and 21.4% HFHL at 4 kHz Notch) and 18.8% of LFHL which is in accordance to our study [23].

Prevalence of NIHL Based on Different Noise Levels at Work Place

Among the industries at noise level of 81–90 dBA i.e. food industry, automobile industry, spare parts and combine manufacturing industry, the prevalence of NIHL was found to be 45.5%, 55.1%, 47.36% and 54.54% respectively. The overall prevalence at this noise level was 47.47%.

The prevalence of NIHL in our study at noise level of 91–100 dBA (Iron mills) was found to be 59% which is in accordance with study conducted by Satish and Kashyap at the noise level of 90–110 dBA reporting overall HFHL prevalence of 62.4% [23]. Nilsson (1977) reported NIHL in 58.1% shipbuilding workers at 88–94 dBA [24], Omokhodian (2007) reported 56% NIHL in mill workers [25] and Nyarubeli et al (2019) reported NIHL in 48% Iron and steel industry workers at 92 dBA [26]^.

Prevalence of NIHL Based on Age Group

Out of 178 participants suffering from hearing loss, 76.85 % participants were of 40 years of age and above. These results are consistent with the results presented in the study by Masilamani et al (2012) and Rachiotis et al (2006) where workers of 40 years and above were found to suffer from NIHL in higher number. Edward et al (2016) also reported that plywood workers working in noise level of 80.5 dBA, NIHL was more prevalent in age group more than 40 years [27].

Prevalence of NIHL Based on Duration of Service

The prevalence of NIHLwas found to increase with increase in the duration of service. This trend was observed at both 81–90 dBA and 91–100 dBA noise level. NIHL was observed to be more prevalent after 16 years of duration of service at both the noise levels.

Accordingly, Omokhodion et al (2007) reported that hearing impairment was highest among the mill workers with more than 20 years of service. Similarly, higher NIHL in electroproduction workers with 14 years of service at a noise level of 91 dBA was reported by Rachiotis et al (2006) [28]. Chen et al (2003) also reported High Frequency Hearing loss increased in workers exposed to chronic noise levels for more than 15 years of service.

Exposure to loud noise can result in temporary threshold shifts (TTS) and/or permanent threshold shifts (PTS) [29]. Hearing loss after a PTS is irreversible. Thus, NIHL refers to PTS. In the present study, NIPTS is higher at 91–100 dBA noise level in comparison to that at 81–90 dBA noise level (Fig. 3c). As the duration of service or exposure to noise increases, the NIPTS also increases. Two-way ANOVA reveals that the difference between NIPTS at different noise levels and between different duration of service is highly significant at p<0.0001. Lie et al (2016) reported the same results as ours i.e. for same duration of service, NIPTS is more at higher noise level as compared to lower noise level [30]. Also, as the duration of service increases, the NIPTS also increases gradually.

Prevalence of NIHL Based on Type of Noise (Continuous/ Intermittent)

In a continuous noise of 81–90 dBA, 48.8%, while in intermittent noise, 39.5% participants were found to have hearing loss. Similarly, in a continuous noise of 91–100 dBA, 61.4% and in intermittent noise, 33% participants were found to have hearing loss. NIHL was more prevalent in workers exposed to continuous noise type. These observations are complemented by the study reported by Suvorov et. al. 2001, where greater risk of NIHL was found in the people working in continuous noise as compared to those working in intermittent noise.

Determination of Prevalence of NIHL by DPOAE

DPOAE test was performed for screening of hearing loss and its applicability for early detection of hearing loss. Overall hearing loss on DPOAE was detected in 67% of participants. Mohammadi et al (2018) [31], Attias et al (2001) [32] and Moepeng et al (2017) also recommended use of DPOAEs for early detection of NIHL as compared to PTA.

Distribution of Participants Based on Hearing Loss by PTA and DPOAE

When the findings of PTA and DPOAE were compared, hearing loss was detected among 49.5% of participants as per PTA and 67% as per DPOAE.

In the study done by Attias et al (2001) OAEs were found to be more sensitive to noise damage than audiometry. On OAE hearing loss was found in subjects with normal audiogram but with history of noise exposure. Another study by Blioskas et al (2018).also concludes that OAEs provide objectivity and greater sensitivity complementing the pure tone audiometry [33].

Distribution of Participants Based on Usage of Hearing Protection Device (HPD) Among Study Participants

Only 8.6% participants reported use of hearing protection devices in working hours. Reasons were either the employer didn’t make HPD available to the employees or workers found HPDs uncomfortable or unnecessary. One reason might be lack of awareness among workers of role of HPDs in Noise induced hearing loss protection in work settings with high noise levels.

Kitcher et al (2014) reported that only 5% of their study participants used HPDs [34]. Dube et al (2011) and Edward et al (2016) reported that no participant in their study used HPDs and no one knew health effects associated with noise exposure. However, Hong et al (1998b) revealed in their study that 60.8% workers regularly used HPDs. In this study, a clear protective effect was revealed indicated by significantly lower prevalence of hearing loss in the continuous HPD users.

Conclusion

With the rise in industrial sector in the past two decades, there is substantial increase in noise induced hearing loss. NIHL which is an irreversible but preventable sensorineural hearing loss, is still an underestimated public health concern. Although it is not a life-threatening issue, but it causes profound effect on individual’s quality of life.

In the present study undertaken, high prevalence of NIHL was observed. Along with studying various factors affecting NIHL we observed potential benefit of OAE in early detection of noise induced hearing loss over PTA. As the duration of service in industrial settings increases, the Noise Induced Permanent Threshold Shift (NIPTS) also increases. Periodic noise exposure monitoring, engineering controls to reduce noise levels, provision of hearing protection devices, periodic audiometric evaluation of employees and employee’s education regarding NIHL are some of the important factors to be considered to prevent NIHL.

Authors Contribution

Rao Varinder Singh: study design, data collection, data compilation, manuscript writing, manuscript submission. Sanjeev Bhagat: supervision, data filtering and manuscript revision. Dimple Sahni: supervision and manuscript editing. Sangeeta Aggarwal: data collection and manuscript editing. Tanveer Kaur: write up and data analysis.

Funding

This research didn’t receive any funding.

Data Availability

All the data obtained in this study has been included in this article.

Declarations

Conflict of interest

The author(s) declare no conflict of interest.

Ethics Approval

This study was approved by Research Committee and Institutional Ethics Committee, Government Medical College, Patiala and Faculty of Medical Sciences, Baba Farid University of Health Sciences, Faridkot, (Punjab) with approval number: BFUHS/2K21p-TH/14744 dated 15-12-2021.

Consent to Participate

Informed consent to participate in the study was obtained from all the participants.