Acoustical characteristics of device system for chasing away birds at Ngurah Rai International Airport Denpasar Bali

Abstract

Ngurah Rai International Airport Denpasar Bali has two models of the device for chasing away birds these are Mobile Model and Fixed Model. Acoustical characteristics of the device for chasing away birds is determined by two parameters: SPL and Frequency Responses as well as sound propagation in the free field outdoor acoustics, thus to analyze sound properties radiated by the device for chasing away birds must be using a theoretical approach of Inverse Distance Law. Measurement results on Mobile Model that decreasing value of SPL by moving microphone position into the position of double distances from an original distance were somewhat 6 dB, it is nearly agreed with Inverse Distance Law. While measurement results on Fixed Model using the same mechanism of changing the distance the decreasing value of SPL does not comply Inverse Distance Law since the decreasing is about 10 dB. From results of measurement of decreasing SPL, both two models of the device for chasing away birds can be only used effectively to disperse some birds in which their position is very near the speaker that is about 4 - 8 m. Based on a calculation using Inverse Distance Law, the value of SPL at the distance of 1 m from the speaker is below 100 dB. Measurement results on Frequency Spectrum for Mobile Model was dominant at the frequency of 500 Hz to 3150 Hz, while for Fixed Model was dominant at the frequency of 500 Hz to 2500 Hz. At the end, the device for chasing away birds using acoustical method needs a system of sound generator and speaker which can generate the sound wave with very high of sound power level and it has a flat form of frequency responses with a wide range of frequencies. With the high sound power level, the sound will reach very far away this kind of device is called Long Range Acoustic Device (LRAD).