Fatigue is a state of reduced mental or physical capability caused by sleep loss, disrupted circadian rhythm, or increased workload in the workplace. Fatigue can be either acute or chronic, and both forms affect organizational performance. ¹ Acute, cumulative and circadian fatigue can pose a significant risk to worker safety and health, leading to an increased risk of work accidents, hypertension, stroke, heart attack, menstrual disorders, cancer, mental disorders, and gastrointestinal, neurological, and chronic pain sequelae. ² These adverse effects are associated with mental and physical strain, such as fatigue. ³ Fatigue at work is a significant issue that is currently being widely discussed in various countries around the world. According to a survey, 32.8% of the 58,115 workers who experienced work accidents reported that the accidents were caused by fatigue at work. ^{4, 5} The magnitude of losses due to fatigue on workers’ health and safety is an important factor that must be studied and resolved.

Fatigue at work can be caused by various factors, including personal and work environmental factors. Personal factors may include age, sex, genetics, mental and physical health, nutritional status, sleep debt, circadian phase. ⁶ Work environmental factors can encompass poor lighting, exposure to noise and vibration, lack of ventilation, and working in a hot climate. ⁷ Many studies have indicated that noise exposure is the primary cause of work fatigue in many industries. ^{8, 9}

Numerous studies on workplace noise control have been conducted due to the detrimental effects of noise on a range of human health issues. One such study examines the use of personal protective equipment. ^{10, 11} The use of earmuffs and earplugs is the choice of workers to protect themselves from noise exposure, even though their use can disrupt comfort at work. ^{12, 13}

The weaving process poses a very high level of noise hazard originating from the movement of machines. The workers at IT Co. Ltd carry out weaving work for 8 hours/day, 40 hours a week. Based on the results of noise intensity measurements, it was found that the average in the weaving room was 103.06 dB, far exceeding the required safe limit 85 dB. Weaving workers in IT Co. Ltd are reluctant to use earmuffs because they interfere with comfort while working. Many previous studies have only discussed the relationship between noise and its effects on health, without providing interventions for improvement. ^{14– 16}

Other studies emphasize the importance of using ear protection to reduce the risk of fatigue among textile workers. Most previous research on occupational noise exposure has primarily focused on long-term auditory outcomes, such as hearing loss. However, short-term non-auditory fatigue responses related to the use of hearing protection have not been thoroughly examined. ^{17– 21} Specifically, there is limited evidence concerning daily fatigue responses during the initial period of using earmuffs, which is crucial for ensuring worker comfort and compliance. This study addresses this gap by investigating short-term fatigue responses over consecutive workdays. We assessed daily fatigue to capture potential fluctuations during the early phase of earmuff use in high noise levels. Our evaluation of daily short-term fatigue associated with earmuff use represents a novel contribution to the literature on occupational health and safety. Using a quasi-experimental design with daily fatigue measurements over six consecutive workdays, this study aimed to investigate the short-term adaptation process to hearing protection devices by examining daily fatigue fluctuations during the initial exposure period. By analysing daily fatigue during the early stages of earmuff use, this study enhances our understanding of the short-term adaptation processes related to hearing protection in high-noise work environments.

This study was conducted at IT Co. Ltd in Surakarta, Indonesia from August 1 to September 29, 2025. This quasi-experimental study used a non-equivalent control group design approach and was approved by the Health Research Ethics Committee of Dr. Moewardi General Hospital with Protocol ID Number 1.167/VII/HREC/2025 on July 22, 2025. The research focused on production workers at IT Co. Ltd, specifically those in the weaving rooms. The sample comprised 100 workers who met certain inclusion criteria, which included willingly participating as respondents by signing an informed consent form, working morning shifts, being female, having over one year of employment, and maintaining normal nutritional status. The selection of female participants was a primary consideration because 98% of weaving machine operators are women. This criterion was applied to avoid research bias related to gender, as studies have shown that fatigue can have different effects on men and women. Prior to participation, all eligible workers received a comprehensive overview of the study’s goals, methods, potential risks, and benefits. Each participant signed the informed consent form before data collection began. Participation was entirely voluntary, and individuals were informed that they could withdraw from the study at any time without any impact on their career or working conditions. The exclusion criteria for this study included temporary workers and those not present during the data collection period.

The study involved 33 workers in the Intervention Group (IG) who used earmuffs to protect their hearing from high noise levels, and 67 workers in the Control Group (CG) who did not use any hearing protection. On the first day, none of the participants wore earmuffs to observe trends before and after the intervention. This study has limitations regarding the proportionality between the number of participants in the intervention and control groups. The two groups were not equally matched due to the availability of workers willing to participate in the full six-day intervention program, and some workers opted not to take part. Specifically, only 33 participants in the intervention group committed to completing the entire six-day earmuff usage program, while 67 workers in the control group did not receive the intervention but were able to follow the entire process correctly.

To minimize research bias stemming from interactions between the intervention and control groups, participants were assigned to groups based on their workspaces: weaving room A for the intervention group and weaving room B for the control group. Although both groups are located within the same division, specifically the weaving production division, partitions were installed as separators to help prevent interactions. This approach aligns with the design of a non-equivalent control group study, which aims to evaluate differences in average fatigue scores between the intervention and control groups. The research team worked closely with the supervisors of the weaving machine operators to train and monitor the use of earmuffs in accordance with established standards throughout the study. If any participant in the intervention group failed to comply with PPE guidelines, the weaving worker supervisor promptly addressed the issue by reprimanding the worker to ensure proper and correct use of earmuffs.

Noise intensity was measured using an EXTECH sound level meter at 100 locations where weaving workers worked. This instrument was routinely calibrated in the OHS laboratory before use at the study site. Fatigue was evaluated using a questionnaire with 19 self-administered questionnaire assessing subjective work-related fatigue symptoms adapted from the study by Novitasari and Sarah. The questionnaire covers physical, mental, and general fatigue symptoms, including head heaviness, whole-body fatigue, sleepiness, musculoskeletal discomfort, cognitive disturbance, and general malaise. Each question has two answer choices: “yes” and “no.” For favourable questions, a “yes” answer is worth 2 points, and a “no” answer is worth 1 point. Validity testing conducted on 30 participants in textile workers Surakarta Indonesia showed that all items had item–total correlation coefficients (r) exceeding the critical value (r table = 0.361). Reliability analysis demonstrated Cronbach’s alpha values greater than 0.70, indicating that the questionnaire was valid and reliable for use as a research instrument. The Mann-Whitney test was used with SPSS 23 to compare fatigue scores between the intervention group (IG) and the control group (CG) separately for each measurement day (day 1 to day 6). This non-parametric test was chosen because the normality test indicated that the data did not meet the assumptions required for parametric tests.

This study involved 100 weaving machine operator participants. An overview of participant characteristics and measurements of noise intensity can be seen in Table 1. Table 2 shows the effect of using earmuffs on fatigue in weaving operators during the 6 days of measurement.

Table 2 indicates a significant difference (p-value <0.05) between the average fatigue scores on IG and CG before and after the intervention. This difference is particularly visible on days 4 and 5. The intervention appeared to increase the fatigue, this can be seen from the average value which increased compared to the first day to the sixth day. Day 6 obtained the highest average fatigue score, while Day 1 yielded the lowest average score.

Work fatigue is a well-known non-auditory reaction to noise at work that happens when physical stressors and how a person perceives them interact in a complicated way. ^{21– 23} In this study, daily comparisons between the intervention group (wearing earmuffs) and the control group revealed no significant differences in fatigue scores on days 1–3. However, significant differences were noted on day 4 (p = 0.029) and day 5 (p = 0.011), with no significant difference observed on day 6. This pattern indicates that the impact of earmuff usage on perceived fatigue was not uniform across all days, but may fluctuate during the initial usage period, necessitating a thorough examination of short-term responses instead of solely depending on endpoint measurements.

Most previous studies on occupational noise have concentrated on auditory outcomes and general work fatigue in group comparisons, often without examining short-term variability during intervention periods. ^{22, 24} For instance, other studies have demonstrated that exposure to occupational noise correlates with heightened self-reported fatigue and various symptoms, including tinnitus and stress, across a range of work settings, suggesting significant effects of noise that extend beyond auditory impairment. ^{25– 28} Noise exposure has been associated with auditory fatigue and other self-reported symptoms, such as workplace stress and annoyance, which are conceptually connected to fatigue outcomes in noisy environments. ^{29– 31}

The changing fatigue pattern observed here highlights the importance of measuring daily progress in intervention studies. The effects of early intervention may not be immediately evident following implementation, and reactions to protective equipment may change over time. ^{32, 33} This highlights a subtlety frequently neglected when fatigue is assessed solely at isolated time intervals preceding and following an intervention period. Daily measurements facilitate the identification of temporal trends that may signify adaptation, initial discomfort, or other ephemeral alterations in perception. ^{34– 37}

Some mechanisms may elucidate the daily fluctuations in fatigue scores, including physical discomfort from extended use, disruption of communication, or psychological adaptation to personal protective equipment. However, these factors were not directly evaluated in the present study and therefore cannot be established as causal. ^{38, 39} In the workplace, subjective fatigue is affected by a number of factors, such as the speed of work, the difficulty of the tasks, psychosocial stress, and how well each person can handle stress. Consequently, the current findings should be construed as identifying correlations rather than determining direct causations. ^{40, 41}

The practical implication of these findings is that employers and occupational health professionals must recognize that workers’ short-term experiences with hearing protection may vary. ^{42, 43} In the first few days of using hearing protection, workers might not feel a significant difference in their fatigue levels, and daily fluctuations could indicate that they are still acclimating to the equipment. This information can help develop training and acclimatization programs that increase workers’ comfort and ensure adherence to hearing protection guidelines.

This study has several limitations, including intervention duration was comparatively brief, differences in the number of intervention and control groups, use of non-parametric tests, constraining conclusions regarding the long-term effects of earmuff usage. Fatigue was assessed through a self-reported questionnaire, which may introduce subjective bias. Moreover, this study did not account for possible confounding variables, including sleep quality, workload intensity, heat exposure, psychosocial stress, menstrual cycle effects and other environmental stressors. Lastly, the analytical method, which includes daily comparisons between groups, restricts more general causal inferences. Subsequent research should integrate objective fatigue metrics (such as physiological indicators), extended intervention durations, and evaluations of comfort and compliance to enhance the understanding of short-term fatigue responses associated with hearing protection.

This study suggests that fatigue responses among weaving workers may vary during the initial adaptation to wearing hearing protection devices. Over the first three days, no significant differences in fatigue levels were found between earmuff users and non-users. However, noticeable differences emerged by days four and five, indicating a temporary increase in fatigue as workers adjusted to wearing earmuffs in high-noise environments. These results should be interpreted cautiously, as they do not establish causation due to the quasi-experimental design and reliance on subjective fatigue assessments. While hearing protection is essential for preventing noise-induced hearing loss, further research with longer observation periods and objective measurements is needed to better understand the short-term non-auditory responses to hearing protection.