Noise is described as “unwanted sound," which can cause several health effects for a community (Anizar 2009). Environmental noise is the accumulation of noise pollution from outside, caused by transportation, industrial and recreational activities. This noise is generally present in all areas of human activity. According to Indonesian Statistics Agency, passengers of a train in Indonesia has increased in the past two years 254,309 in 2014 and 325,945 in 2015, respectively. Besides, railways are also used for cargo transport such as petroleum and goods. However, there are negative impacts caused this kind of transportation, which is environmental noise. Noise generated by train is intermittent (Suma'mur 1996).
People who have been exposed to this kind of noise can have health problems, both auditory and non-auditory effects. Also, noise causes hearing loss, noise exposure leads to annoyance, disturbs sleep and causes daytime sleepiness, increases the occurrence of hypertension and cardiovascular disease, and impairs the cognitive performance of children in school (Eriksson 2013; Basner et al. 2013).
Several studies have been conducted to measure the level of environmental noise in residential areas around Surabaya. Hariyanto (2012) had measured noise level (Ldn) in Bungurasih residential area, which is directly adjacent to the bus terminal and has high traffic level. The result was 78 dB(A). Another research had measured noise level (Ldn) in a residential area near a railroad track. The effect of environmental noise (Ldn) was 85.5 dB(A) at the residential area which had a distance less than 11 m from railroad track (Agustini 2012). Environmental quality standards for a residential area has been established by the Indonesian's Ministry of the Environment as high as 55 dB(A) (KepMenLH No. 48/1996). Both studies showed that noise in residential near the transportation activities had exceeded the Environmental Quality Standards.
Poor urban planning in some areas in Surabaya causes some residential exposing environmental noise due to railway activities such as inNgagel Rejo. This settlement was only about 3 meters from double rail track connecting two stations of Wonokromo and Gubeng. The number of a train which crossing the railroad was about 92 trips. The railway system in Surabaya was more or less a passenger-oriented system, and there were few freight services, due to the limited capacity of the tracks. Train schedule at both stations was started at 00:22 am until 23:08 pm. The settlement in Ngagel Rejo had known as a dense residential area for many years. Based on these circumstances there were some possibilities for someone to suffer from environmental noise. This study aimed to measure the level of environmental noise and identify the hearing loss that might occur in the community who lived near the railroad in Ngagel Rejo, Surabaya.
This study was an observational research with a cross-sectional approach. This study was conducted in Ngagel Rejo, Surabaya which is near the railroad, on May 2016. The population of this research were housewives with inclusion criteria 25-50 years old, stayed in 8 hours a day at home, had resided in research area at least five years, and willing to be a participant in this research. The sample size was calculated using Cochran formula (1977) for simple random sampling method. The sample size was 25 housewives who lived 3 meters from the railroad and 25 homemakers who lived 100 meters from the railroad. This study was approved by the Institutional Ethics Board of the Universitas Airlangga School of Public Health, Surabaya, and all participants gave informed consent.
Noise level measurement used in this research was Extech DigitalSound Level Meter Model 407730. Environmental noise was measured in the house, for 24 hours (L ) with permission. Audiometry test was conducted to a housewife who willing to be participants. Audiometry test was performed in a closed room that had noise less than 40 dB(A). Respondents were asked to wear a headset and gave a response when they heard the sound. Each respondent had an autograph from this test, which was interpreted by professionals. Data were analyzed using descriptive statistic, and chi-square produces for explaining the relationship between respondent characteristics and incidence of hearing loss.
Environmental noise was a measurement of the noise exposure in the respondent house that was caused by noise exposure from the train activities and others. Noise level was 24 hours measurement (L ). The noise level in a respondent house was shown in Table 1.
The noise levels were measured at 65.89 dB(A) to the house within 3 meters of the railway and 51.35 dB(A) for a home within 100 meters of the railway. Based on the noise measurement, the primary source of noise exposure at Ngagel Rejo was railway activities.
Age and residence time were respondent's characteristics to be observed. The frequency of distribution of age and residence time of respondent is shown in Table 2.
|40 years old||34||68|
|40 years old||16||32|
Age can affect a person's physiological function of hearing. Commonly, the aging process begins at 40 years old, and it also decreases the hearing function. Only 32% of respondent in this study were above 40 years old; the most past was 48. Residence time described the exposure time of noise from railway activities. As a residential area, Ngagel Rejo is part of the old city in Surabaya. In this study, 86% of respondents had lived in this area of more than ten years, in fact, some respondents had been liveing in this area since they were very young.
The frequency of distribution of respondent for hearing loss was shown in Table 3 below.
Based on audiometry test, 14% of respondent suffered from hearing loss, 12% left ear and 10% right ear. The type of hearing loss was determined by comparing the results of audiometric parts AC and BC. The symbol "o" and "x": two symbols for inspecting air (air conduction / AC). The symbol "o" to the right ear, and the symbol "x" to the left ear. The symbol " " and " ": two symbols for examining bone (bone conduction / BC). The symbol " " for the right ear and the symbol " " to the left ear. Examination by a special headset section installed behind the earlobe.
Audiogram of the respondent with normal hearing threshold described in Figure 1, AC and BC graphic was in normal position at 25 dB. Respondent did not have hearing loss in the outer, middle and inner ear.
The example of conductive mild hearing loss audiogram was shown in Figure 2. AC line showed uplift of hearing threshold and BC were in normal range. There was a hearing loss at the outer ear or middle ear, but inner ear was normal. Conductive hearing loss can be caused by many different causes, such as malformation of external ear, ear canal, or middle ear structures, fluid in the middle from colds, ear infection in the middle ear, allergies, poor Eustachian tube function, perforated eardrum, impacted earwax, infection in the ear canal, foreign body in the ear, and otosclerosis (HLAA 2016).
The relationship between age and resident time with hearing loss
Association of respondent characteristics (age and residence time) with hearing loss were shown in Table 4 and Table 5.
|Normal||Conductive middle hearing loss|
|40 years old||34||100.0||0||0||34||100|
|40 years old||9||56.3||7||43.8||16||100|
|p value =0.000 0.05|
Above 40 years old respondents Conductive middle hearing loss was suffered by. There was a significant relationship between age and hearing loss.
|Residence time||Hearing type||Total|
|Normal||Conductive middle hearing loss|
|p value 0.250 0.05|
There was no relationship between residence time and the hearing loss. According to this, the incidence of hearing loss was not due to noise exposure. Hearing loss due to noise is determined by the noise exposure during a person's life; all age groups can be affected. It can also be affected by the type of sound. Exposure to various types of noise from early childhood may have a cumulative effect on hearing the loss in adults (Welch et al. 2013).
Ngagel Rejo residential area which was within 3 meters of the railroad, exposed to the noise above the environmental quality standard for residential areas. The high level of noise could be related by the rail traffic passing through Ngagel Rejo, the distance between the house and the railroad, and also a quality of home's wall. Permanent house built of brick relatively able to reduce noise from outside (Christi 2016).
Environmental noise at residential near the railroad in this study agreed with the previous studies done by Suryani (2015) and Agustini (2012), in which the environmental noise level hit 70.73 dB (A) and 85.5 dB (A) respectively. The result of measurements of environmental noise in houses within 100 m of the railroad was still below the environmental quality standard for residential areas. Based on this study, the government should have the regulation about minimum distance between houses and the railroad, so that the public can be protected from noise exposure caused by trains. Besides that, controlling noise environment due to train activity can be done using the wall barrier, housing relocation, used electric train rather than diesel, used wall silencer and adjust the layout rooms in the house (Suherwin 2004 in Agustini 2012).
In this study, age had a significant relationship with hearing loss, as compared with resident time. According to Baktiansyah (2004), they were hearing function of someone who waw 40 years old starting to decrease (presbycusis). This hearing loss usually began at 40 years old with an average decline of 0.5 dB (A) per year (Rais 2003). This study implied that exposure to environmental noise due to the nearness of the house to the railroad did not cause auditory effects. However, although it didn't cause acoustic effects, many related studies found that that environmental noise induced non-auditory effects such as annoyance, disturbed the sleep and causeddaytime sleepiness, increased the occurrence of hypertension and cardiovascular disease, which could reduce quality of life (Basner et al. 2014; Welch et al. 2013).
It could be concluded that the residential area within 3 meters of the railroad in Ngagel Rejo, Surabaya was exposed with the noise above the environmental quality standard. However, the incidence of hearing loss in this area was not caused by the environmental noise from railway activities. Further research about non-auditory effects caused by railway activities should be conducted to find the significant relationship between environmental sound with a quality of life, especially in the urban community.