Dharma Raj Paudel, Lecturer, Department of Physics, Midwestern University, Surkhet, Nepal.

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1 A Study of noise levels inside pre-primary classrooms in the Surkhet Valley Dharma Raj Paudel, Lecturer, Department of Physics, Midwestern University, Surkhet, Nepal. Abstract: Noise is the undesirable sound. The continuous imposition of sound is harmful. In nursery schools, pupils are more vulnerable to high sound level. The basic purpose of this research is to increase the concerns of noise pollution inside the classroom showing how it affects the children s learning activities. The measurement of sound levels inside the active classrooms is taken in different schools at their pre-primary classes in the month of January, The measurement shows that noise level inside classrooms is in the maximum level than the noise level standard recommended by WHO and other international organizations. Keywords: Noise level, Decibel, Classroom, Children, Speech Interference. INTRODUCTION Noise is a variety of sound. According to World Health Organization (WHO), noise is unwanted sound. The intensity of sound is measured in a logarithmic unit called decibel (db). Young D. (2007) had defined the intensity level of sound by the equation β= db log I I 0 where is the reference intensity, chosen to be /,which is equal approximately the threshold of human hearing at 1000 Hz and be the intensity level at the point under consideration. However, sound exposure level in decibels is not much used in noise measurement. Instead time-averaged value is used which is called the equivalent continuous sound level, symbol L eq.since there is no any unique method of assessing noise and its effect, is most common way utilized in most of the country. Pierre. B (2015) defines steady sound pressure level which, over a given period of time, has the same total energy as the actual fluctuating noise. Mathematically it is given by =., where T is the time period and is the noise level of i th sample. For the discrete methodology, =., where N is the total number of data taken, and be the fraction of time that the sound level is in the h interval which is taken as one second usually for slow response mode of sound level meter device (Bhattrai, L.2012). A Sound level meter also called decibel is a simple instrument which is used to find the sound level at a place. It is usually set to measure intensity of sound by special setting called A-setting in which the sound level meter responds as same manner as human ear to the sound intensity. Then expressed in A-setting is denoted as or simply (dba)

2 Table:1 ANSI S (America n National standard of Acoustical performance criteria for schools) Australian and New Zealand Standard, AS/NZ 2107: , where 35 is satisfactory and 45 is maximum. Institutions (dba) /Standard WHO 35 Source: Bridget M.(2003) Table (1) shows the standard value of inside class rooms by different institutions. In pre-primary schools, since we are adopting day by day new technique of learning, for example Montessori based teaching method that involves activities related learning which encourage students to communicate with each other. So good hearing conditions are crucial for the children to communicate easily. Basic problems related to the noise inside classroom for children The noisy environment which cross the standard as given in table (1) causes different noise related problems. Following are some of the problems: (a) Concentration: For teaching and other activities demanding steady concentrations, maximum sound level exposure during normal class is 40 db(a). The study carried out by Ko. (1979) and Kryter (1985) reveals that above that value, the children loss concentration. The study also found that teachers in noisy schools reported more concentration problems in student than did teachers in quieter schools. Without getting concentration, student learning activities are affected badly. (b) Hearing loss: The long term exposure to high sound levels may destroy the hair cells of inner ear resulting in a cochlear hearing loss (Johansson, 2003). However, the risk of noise induced hearing loss depends on the duration of the exposure time also. The critical level based on the is set at 85 db(a) for 8 hours per day (Pa r L.. When there is increase in the decibel value, there must be decreased in the time of exposure. (c) Biochemical effect: Due to exposure of high noise level for long term results increase in blood pressure (Andrenet al. 1978) and other circulatory effects (Borg 1981). Children also becomes tired due to the long time exposure of noise. Irritation, discomfort are also the common symptoms due to the noise exposure. According to P. To avoid such symptoms, noise levels should not cross above 40 db(a). (d) Speech interference: It is one of the most important problems that are faced specially by children. Speech interference is the specific situation where speech is masked by another sound. Children have generally a less precise speech, a more limited vocabulary and less familiarity with language rules than adults. Masking effects of noise may therefore be

3 particularly critical both for the knowing of children s speech and for the children s perception of speech delivered by the teachers. Children and teachers are unable to communicate with each other clearly. According to Dejoy(1983)- Exposure to high levels of noise during the period in which the children are acquiring speech, language and listening skills may have effects on scholastic performance. The average voice level for a teacher is 57 db (A) (Pekkarinen and Viljanen 1990). In environments with a sound level exposure representing a typical sound level in an occupied class rooms were 60 db(a) as reported by Berg et al. (1996) and noise levels as high as 70 db(a) as reported by Markides (1986). Inside the classrooms, in Spain, seven out of ten schools exceeded the standard permissible noise level of 40 db established by Spanish regulations. Taking the WHO standard which is 35 db (A), nine out of ten schools in Spain, fail to meet the recommended levels. Safety measures To get the good acoustic environment we can take some steps, for example, floors, walls and ceilings should be covered with carpets or rubber foam, windows should have drapes especially of velour. Drapes and rubber foam are good sound absorber. However, it is noted that some countries (e.g. Switzerland) do not recommend the use of carpets in classrooms because of their findings that their use results in a significant rise in the incidence of asthma and allergies in children (Wilson O. 2002). We can also maintain good sound level inside by limiting the background sound. According to Wilson O. (2002), the limit of sound level of unoccupied state is 35 db(a). Further ceilings tiles instead of concrete in the roof can reduce sound intensity inside the room. Lubman et al 1999 presented data which showed that the top rated ceiling tile is quite efficient at absorbing sound particularly in the low frequency sound. Objectives To know the intensity level of sound inside the classroom of different schools To know the effects of noise on teaching learning activities To know health issues related to children inside the class rooms To deliver what the safety measures of noise pollution inside the class rooms. METHODOLOGY Study site Surkhet is One of seventy-five districts of Nepal located about 600 kilometers (373 mi) west of the national capital Kathmandu. Birendranagar is the district headquarter which is located in the Surkhet Valley and is a principal township in the western hills regions. It has population 47,914 according to National population census It is also a centre of academic excellence in this region including Mid-western university at the heart of Birendranagar. According to district education office Surkhet, valley contains total of 51 private schools including primary, secondary and higher secondary schools. The research is focused on the noise intensity levels inside the class rooms taking six private schools in their nursery classes. The schools are chosen randomly,they are (i)eager bridge higher secondary school, Bulbule(ii)Surkhet Horizon academy, Birendrangar-6 (iii) Dv niketan secondary School,Birendranagar -8,Itram (iv) Heuristic secondary school,birendranagar-11, Kunaghat.(v) South Asian Scholars academy(sasa),uttarganga (vi) Saraswoti Montessori,Birendranagar-10,Kalinchok.

4 Techniques of data collection The intensity levels are measured by a decibel of version , android based A- weighting (ANSI S 1.4) device. The data are taken inside the class rooms in the normal conditions where children are taking class from their teachers showing normal activities including oral and listening activities. Children are allowed to communicate, read and perform normally during testing period. The decibel is set in to a slow response mode and sound levels was measured at the 5 h second in the interval of 5 h seconds for 10 minutes. Each sample site gives 40 data inside the class room. The measurements are carried out at the normal atmospheric conditions having no rain fall, high wind speed, no high traffic along the road joining the school s premises, no background activities outside the classroom. Each classroom has normal area about 4 4 m 2 to 4 5 m 2 (small sized rooms) and number of students inside the classes vary from 21 to 30, one exception 49 students in Eagerbrige school. They have floors, walls as well as ceiling all made up of concrete. The floors are covered by carpets specially jute carpets. There is no effective sound absorbing materials in the ceilings and in walls of the room. However, no schools have utilized sound amplifying device like mike inside the rooms. RESULT AND DISCUSSION Inside the nursery classroom, pupils are continuously communicating to the teacher and with each other during the active class. They play, read as well as listen what teachers teach to them.

5 Hence there is quite noisy environment. Figure (1) shows the intensity levels in terms of value in db(a) of the six schools inside the class rooms comparing with WHO standard. The results show that most schools cross the limit (table 1) set by different organization. For DV Niketan, value is 80.2 db (A) with maximum and minimum values and db (A) fig 2(b). For Surkhet horizon Academy, has value 78.22dB (A) while the maximum and minimum sounds are and 63.4 db (A), fig 2 (c). For Saraswoti Montessori be db(a) while the maximum and minimum values are 87.5 and 50 db (A) fig 2 (d). South Asian Scholar Academy has value db (A) while maximum and minimum values are and db(a) fig 2 (e). Heuristic Schools has db (A), the maximum and minimum sound which were observed were 87.5 db(a) and db (A), fig 2 (f). (a) EagerBridge (b) Dv Niketan (c) Surkhet Horizon Academy Figure 1: The noise levels for different Schools, showing they have to accommodate classes with good acoustic environment. The values at the top of each represents the value in db (A) of each. (d) Saraswoti Montessori (e) South Asian Scholars Academy(SASA) (f) Heuristic Boarding School.

6 Figure 2: Variation of sound intensity inside the Class rooms for different schools., and represents the variations in maximum, 15 second average and minimum curve respectively within 10-minute time. The values at left side of the curve at top and bottom represents the maximum and minimum value during the measurements. CONCLUSIONS All schools on the observations have sound intensity levels well above the recommended values set by WHO and other institutions (table 1). Numerous researches shows that specially children are more vulnerable to the noise pollution. The equivalent continuous sound level ( ) status which is nearly around 80 db for all classrooms are not accepted for good learning environment. In such environment, children feel the problems such as losing concentration, irritation, discomfort, fatigue, increase in blood pressure and other circulatory effect and more likely the speech interference, children may not understand what the teacher says which degrade their scholastic performances. However, risk of hearing damage during classes must be considered low as they are well below the limit i.e. 85 db(a) for 8 hours daily. The high value of the noise level is due to not having good acoustic environment i.e. no any effective sound absorbing materials inside the room but concrete s wall and ceilings, children s activities like reading, talking, playing etc., more number of students according to the size of the rooms, background noises etc. Since no schools are applying safety measures for noise pollution, they must accommodate with good acoustic environment. RECOMMENDATIONS (a) Absorbent materials such as acoustic foams, acoustic cotton can be used in the walls, ceilings. Carpets (of foam rubber) on the walls and floor, drapes specially of velour on the window or on the walls are better options for sound absorption inside the room. Ceiling made up of tiles are also good option for reducing the sound level inside the classroom. (b) Classrooms should be set away from the noise source example roads, playgrounds, site for the speech, morning pray etc. (c) Classrooms should be designed to get good acoustic environment for example it should not cross the sound level of 35 db(a) in the unoccupied state. (d) School staffs and administration should be made aware of the risk of noise entering the classroom from outside. (e) Teacher training should be conducted on this topics of noise pollution regarding different adverse effects on children. REFRENCES 1. Berg,F.S.,Blair, J.C., and Benson,P.U.(1996), Classroom acoustics: The problem, impact, and solution. Language, Speech and Hearing Services in shools.27,16-20.

7 2. Borg, E. (1985) Physical and Pathogenic effects of sound. Acta otolaryngologica. Suppl DeJoy,D.M.(1983) Environmental noise an children: Review of recent findings. The journal of Auditory Research. 23, District Education Office Surkhet, 2 th February Johansson, M. (2003) On noise and hearing loss: Prevalence and reference data. Thesis. Department of Neuroscience and locomotion, Division of Technical Audiology, Link ping University. Sweden. 6. KO, N.W.M. (1979) Response of teachers to aircraft noise, Journal of Sound and Vibration. 62, Kryter, K.D. (1970) The effects of noise on man. Academic Press, New York and London. 8. Lubman D (1999) Correspondence in Classroom Acoustic Website, classroomacoutics@onelist.com 8/12/1999, retrieved on 20 th January Markides,A.(1986) Speech levels and Speech-to noise ratio. British Journal of Audiology National population census 2011 SURKHET, retrieved from website retrieved on 2 th February P r Lundquist (2003), Classroom Noise-Exposure and Subjective response among pupils, UMEA University Medical dissertations, SE Umeå, Sweden. Retrieved from website umu.diva-portal.org, retrieved on 21 th January Pierre B. (date not specified), Br el and KJaer application notes, Br el & kjaer Denmark. 13. Shield, M., Dorcell E J. (2003). The effect of noise on children at school: A review, Scientific research 10(2),97-106,2003, retrieved from on 25 th January Study carried out by Spanish Organization of Consumer and User, OCU (date not specified), retrieved from website retrieved on 26 th January WHO (1999), Guidelines for Community Noise, World Health Organization. 16. Wilson O. (2002), Class room Acoustics: A New Zealand Perspective, Scientific research, , retrieved from website retrieved on 27 th January Young D.,Freedman A.(2007), University physics; Pearson Education, Dorling Kindersley India.