As an environmental pollutant, noise is created due to different human activities and the mandatory communication between humans and the world around them(Hammer et al., 2014). Noise waves are considered as necessary factors in daily life and occupational activities, yet in some cases and under certain conditions, hearing these waves is unpleasant. Those noise waves unwittingly emitted into the environment and are annoying to hear are called noise or noise pollution(Brown, 2010, Hammer et al., 2014). Occupational noise is a kind of noise pollution we face in the workplace that is beyond the control and management of the employer and employees. Strong proofs show that industrial noise pollution is an undesirable risk factor for human health(Cantley et al., 2019, Sayler et al., 2019). Indeed, the noise has been introduced as one of the most significant causes of occupational diseases and the second leading cause of occupational injuries in the workplace, as due to the presence of high-speed machines and high-speed mechanical movements, the harmful effects of noise have become more intense in manufacturing industries(Müller and Janssen, 2008). Globally, hearing loss (more than 40 decibels) has risen from 120 to 466 million in the last two decades from 1995 to 2018 because of different causes(Ramsey et al., 2018)with approximately one-third of people over 65 suffering from hearing loss and the number of people with hearing loss will probably increase in the coming years in case of lack of timely care and treatment(Ramos, 2018). According to statistics released in 2018 by World Health Organization (WHO), about 466 million people worldwide suffer from disabling hearing loss (6.1% of the world population), of whom about 432 million (93%) are adults and (7%) are children. According to the estimates made by the Occupational Safety & Health Administration, 17% of manufacturing workers have a hearing impairment(Organization, 2018). Hearing loss due to exposure to workplace noise is of the most significant diseases that can affect the safety and effectiveness of the individual, but its importance is usually neglected(Feder et al., 2017). According to the estimates of WHO, the number of people with hearing loss will reach 630 million by 2030, and this population may even reach more than 900 million by 2050(Laxmi et al., 2019, Punch et al., 2019). The cost of hearing loss due to noise exposure higher than threshold limit value (TLV) is high; for instance, in a country like America, this cost is over hundreds of millions of dollars(BakhshianShahrbabaki et al., 2018). These statistics show the high number of people exposed to noise and the significance of this issue. Undoubtedly, one can state that noise is one of the fundamental problems of the industrial world and the working class, with many people at risk from its adverse effects in the workplace(TAJIK et al., 2009). Noise exposure has always had a devastating impact on human health, which has been recognized for more than 2,500 years(Raja et al., 2019, Basner, 2019). Problems due to the exposure noise do not end with hearing loss. For example, people exposed to more noise than the limit have twice as many family problems as healthy people(Joynes, 2019).
Moreover, the body's response to noise is so similar to the state when the body responds to stress, which over time can impair health(Wendt et al., 2017). Prolonged exposure to noise can lead to hearing loss(Kurabi et al., 2017). There is now evidence claiming that stress-related noise leads to a wide range of mental, psychological, and physiological problems (from allergies to heart disease). Meanwhile, the number of people affected by the environment noise is increasing daily(Sadeghi et al., 2007, Mbuligwe, 2004). Noise exposure can affect a person's ability to work, especially the mental work(Fausti et al., 2019). Moreover, like a warning signal sudden, noise can affect the brain in several ways that trigger the response to stress(Jafari et al., 2018). Noise-related health effects are bad mood, lack of concentration, weakness and fatigue, and poor performance(Shan and Neis, 2020), impaired speech and verbal communication, hearing loss, sleep disorder, cardiovascular effects, changes in physiological-psychological and cardiovascular levels, changes in stress hormone levels, blood magnesium levels, changes in the functioning of the body's immune system, gastrointestinal tract, decreased productivity, increased incidents, the effect on social behavior, increased aggressive behaviors, mental states, helplessness and confusion that occurs in individuals depending on the job conditions(Organization, 2019). The physiological and psychological effects of exposure to noise on humans usually appear gradually with negative psychological consequences in the long run(Jafari et al., 2019a, Mohammadi et al., 2019). Among the individual differences relative to noise, one can state that noise is more annoying for some people than the others. The performance of people with an anxious personality type is more than the performance of those with a non-anxious personality type(Ljungberg and Neely, 2007). Personality traits are the first guides for determining the cognitive and emotional status of individuals and affect emotional-social maps and interpersonal or occupational behaviors of individuals(Marinova et al., 2019). To Eysenck, the main reason for the difference between extroverts and introverts is their level of cerebral arousal(Netter et al., 2020). In other words, introverts and extroverts differ in a part of their brain functions(Revelle, 2016). Another effect of noise as a stressor is an occupational cognitive impairment (reaction time, attention, comprehension of warning signs, and so on), as the slightest delay in reaction of the individuals in sensitive occupations can increase the likelihood of an accident and the risk of irreversible incidents(Zare et al., 2017). Depression and anxiety are strongly interrelated, and usually, these two disorders are experienced side by side(Januzzi et al., 2000). There is a difference between stress and anxiety in terms of mental health, stress is a reaction to a threat, and anxiety response to stress is a threat(Moussa et al., 2017), and If people are exposed to stress for a long time, they may experience discomfort or depression(Beutel et al., 2016). Among the valid scales for examining the physiological and psychological effects of noise in the areas of cognitive processing and stress and anxiety, respectively, are Cognitive Processing Inventory (CPI) and Depression, Anxiety, Stress, Scale (DASS)(Monroe and Simons, 1991). Measuring the severity of the main symptoms of depression, anxiety, stress, and disorder in employee information processing exposed to harmful noise is done using the psychological and mental scales of CPI and DASS (Habibi et al., 2017, Sahebi et al., 2005). Mood and emotional states affect cognitive processes as well. Many of our cognitive processes like attention, learning, memory, judgment, inference, and interpretation are affected by our moods(Canter et al., 2016). The effect of moods on the processing pattern is that in different mood states, information is processed in different ways(Forgas et al., 2012). When someone is in a particular mood, one pays more attention to the stimuli, subjects, images, and situations emotionally compatible with one's emotional state, thus processing them better and learning better(Christianson, 2014).
Noise is present in almost all occupational activities, yet certain types of material produce noise more strong intensity in some activities. Those working in the manufacturing, transportation, mining, construction, agriculture, and military industries have the highest risk of hearing loss as a result of noise (Berger, 2000, Goelzer et al., 2001). Given the special equipment and systems like pumps, compressors, furnaces, motors, air blower systems and cooling towers, ducts and gas and steam valves, arc furnaces, rolling units, and the fans used for ventilation in the steel industry, high nose threatens the health of the employees (Golmohamadi et al., 2013).
The existence of extensive studies on the effects of noise shows that this detrimental factor can affect the health of employees and their mental health components. Studies in Iranian literatures show that little examine the impact of noise and cognitive effects in industrials. Therefore, in the one of Iranian steel industrial the simultaneous effect of harmful noise on the nine psychological components and mental processing of individuals is done.