Evaluation of Individual and Environmental Sound Pressure Level and Drawing Noise-Isosonic Maps Using Surfer V.14 and Noise at Work V.5.0

Noise pollution is one of the common physical harmful factors in many work environments.The current study aimed to assess personal and environmental sound pressure level and project the sound-Isosonic map in one of the Razavi Khorasan Paste manufacture using Surfer V.14 and Noise at work V.5.0.This cross-sectional,descrip-tive study is analytical that was conducted in 2018 in the Paste factory that contains Canister,production and Brewing unit.Following ISO 9612:2009,Casella Cel-320 was used to measure personal sound pressure level,while CEL-450 sound level meter(manufactured by Casella-Cel,the UK)was employed to assess environmental sound pressure level.Statistical analyzes was done using SPSS V.18 and Linear Regression test.The sound-isosonic maps were projected using Surfer V.14 and Noise at work V.5.0.The results of assessing personal sound pressure level indicated that the highest received dose(172.21%)and personal equivalent sound level(87.36 dBA)were recorded for workers in the Canister unit.According to results of measuring of the environmental sound pressure level,out of 16 measurement stations in this unit,overall 87.5%were regarded as danger and caution areas.The lowest and highest sound pressure levels in this units were 61 dBA and 92 dBA that belong to Brewing and Canister units respectively.Results indicate Over 75%of the Canister and production units had a sound pressure level greater than 85 dBA and these two units were regarded as the most dangerous area in terms of noise pollution.It is there-fore necessary to implement noise control measures,apply hearing protection program and auditory tests among workers in these units.

Presenting a Signal to Noise Ratio Model Based on the Combined Effect ofSound Pressure Level/frequency, Exposure Time and Oral Potassium:Experimental Study in Rats

Exposure to noise can lead to anatomical,nonauditory,and auditory impacts.The auditory influence of noise exposure is manifested in the form of Noise-induced hearing loss(NIHL).The current study aimed at present a signal to noise ratio model of otoacoustic emission of rats’ears in the light of the combined effect of sound pressure level,sound frequency,exposure time,and potassium concentration of the used water.In total,36 adult male rates,whose age varied from 3 to 4 months and had a weight of 200±50 g,were randomly divided into 12 groups,with each group consisting of 3 rats.The rats in both groups(case and control groups)were exposed to SPLs of 85,95,and 105 dB,emitted from sources that generated white noise.A distortion product otoacoustic emission(DPOAE)machine(4000 I/O manufactured by Homoth of Germany)was utilized to gauge the signal to noise ratio(SNR)of otoacoustic emissions of rats’ears at various frequencies in an acoustic room.The inclusion criterion was SNR≥6 dB.The collected data were fed into the Statistical Package for Social Sciences(SPSS)version 18,followed by conducting descriptive and inferential data analysis procedures.The results of SNR analysis indicated that over 82%of all data had SNRs that were equal to or greater than 6 dB.These data were considered as acceptable response.Furthermore,SPL and sound frequency had significant associations with SNR(P<0.0001).Exposure time also significantly correlated with SNR(P=0.008).However,the potassium concentration of the used water had no significant correlation with SNR(P=0.97).High sound pressure levels result in lower DPOAE.Furthermore,higher frequency leads to higher SNR.On the contrary,longer exposure time reduces SNR.Finally,the potassium concentration of the used water has no effect on SNR.