Estimating parameter values in a model for rating shooting sounds from field survey data

Laboratory studies show that the annoyance caused by shooting sounds can be predicted from the outdoor A- and C-weighted sound exposure levels (ASELs and CSELs; L_AE and L_CE). For any single event, the rating sound level, L_r,s in decibel, is given by L_r,s = L_AE + 12 + β(L_CE - L_AE)(L_AE - α). On the basis of the laboratory results α = 47 dB and β = 0.015 dB^-1 were recommended. In the present study, parameter values α and β are re-estimated. Subjective reactions to shooting and road-traffic sounds were determined for 400 respondents divided among 15 residential areas. Also, the noise dose for road traffic was calculated and the ammunition spent in the 12 months preceding the administration of the questionnaire was listed. Next, for all impulsive sources, the required ASELs and CSELs received in the residential areas were calculated. Based on the data from the majority of the residential areas, the estimated β in combination with α = 45 dB is equal to 0.025 dB^-1. At the lower and upper limits of the 95% confidence interval of β, as obtained with the help of a bootstrap method, β is equal to 0.013 and 0.037 dB^-1, respectively.