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To fulfil the airport safety requirements as stated in International Civil Aviation Organization document, ICAO 9137-3 AN part 3 – Airport Services Manual, Wildlife control and reduction, especially the bird stike control programme, the Sam Ratulangi International Airport is decided to apply the auditory method to control the birds in aerodrome area. Study on this need have been carried out using the sound energy approach, more specifically on inverse square law theory in free field. The theory said that by doubling the distance between the speaker and the sound level meter will decrease in sound pressure level of around 6 dB. From the field measurement results, the measured sound pressure level were 85 dB and 79 dB at the distance of 50 m and 100 m from the speaker. Both levels and distance were used in trials of repelling birds at 1600 Hz to 3150 Hz in frequencies. The use of long range acoustic device, LRAD speakers, that genereate 156 dB at a distance of 1 m in front of the speaker can effectively reach longer distances.

Design and characterization for an acoustic comparison coupler has been carried out at Deputy of National Measurement Standard-BSN by Research Group for Acoustics and Vibration. The aim of this work is to contrive a design and characterize this prototype that has an ability to be used either as the portable of calibration medium or as the sound source for calibration of the acoustic instruments. This prototype is consists of two main sections that made from aluminum material. The first section is a body part that is assembled some components such as a super low noise connector, a glass wool, and a loudspeaker. Meanwhile for a head part as the second section, it is formed a concave space inside, and a coupler hole of microphones. In addition, some stages of testing of this prototype are also reported in this paper, consists of measurement of insulation level, frequency response, maximum of sound pressure level (SPL), long term stability, and total harmonic distortion (THD), respectively. From the first stage, the difference of SPL between the two rooms and its background noise is not significant where it shown that the deviation of SPL values are 15.0 dB and 0.9 dB, respectively. Subsequently, the SPL maximum and long-term stability test is obtained at range of SPL of 118.0 dB -124.0 dB, and 0.1 dB -0.5 dB respectively at the frequency of 63 Hz -8000 Hz in one third octave band. Moreover, the total harmonic distortion that measured in the final stage is still in a tolerance limit, where it has a value as 1.88 % for the aforementioned frequencies.

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