Abstract
A quantitative study comprising of physical measurements of helicopter noise levels in Mgbuoshimini Community was conducted. The grid method was employed to determine the sampling points and noise measurements were taken for a week each at twenty different locations from 7 am to 5 pm using a TES 1358E Sound Analyzer IEC 61672-1 Class 1 standard, Real time 1/1-Octave and 1/3-Octave analyzer. Location coordinates for noise mapping were obtained using a Garmin Oregon 700 Handheld GPS; and ambient temperature, relative humidity, and wind speed for each location were measured using the SHAHE Portable Digital Anemometer. Results showed a range of noise indices across the twenty locations from lowest to highest as follows: Leq (70.23 to 82.15 dBA); L10 (53.81 to 81.66 dBA); L50 (50.04 to 73.28 dBA); L90 (47.34 to 69.98 dBA); NPL (56.72 to 87.22 dBA); PNL (78.20 to 94.95 PNdB); and SIL (52.42 to 66.92 dBA). From these results, it was found that helicopter flyover noise exceeded the WHO recommended dose of 55 dBA for day-time and also the Nigerian environmental noise standard of 50 dBA for day-time noise limit for residential areas. Consequently, it was deduced that residents of Mgbuoshimini Community may be exposed to psychological and physiological damage as a result of excessive helicopter noise with serious speech interference. In conclusion a noise model which was a function of the number of flyovers above 70 dBA, temperature, wind speed and relative humidity was developed for noise prediction and the coefficient of regression was found to be 0.73

Key words: helicopter noise; noise indices; annoyance; speech interference; noise mapping.