Underwater noise of commercial vessels in Nusakambangan Strait and the relationship with distance

Amron Amron,Ratna Juita Sari,Rizqi Rizaldi Hidayat,Yessy Hurly Sefnianti

doi:10.20884/1.oa.2021.17.1.902

Abstract

The existence of shipping activities can produce noise with certain characteristics as a main source of noise pollution in the waters. This research aimed to study the sound characteristics (frequency and sound pressure levels) of various type of commercial vessels crossing the Nusakambangan Strait, its relationship to the distance, and their potential impact to the marine biota. Noise frequency and sound pressure level were determined by spectral and envelope analysis from sound recording by hydrophone, while the type of vessel that produces noise and the distance from receiver were analyzed based on video recording. Relationship between frequency and sound pressure level to the distance were analyzed using simple linear regression. Results showed that frequency of noise is varied more clearly compared to the sound pressure level (1,7 – 20 kHz and 93.8 -117.8 dB re 1 μPa respectively) for each type of vessel (ro-ro ferry, small fishing boat, small ferry, tug boat and pilot boat) based on the size of the ship, engines type and power, loading capacity and vessels speed. Sound characteristics changed based on distance, where the frequency of sound increases (0.04 – 34.28 Hz.m-1) and different things for sound pressure level (0.04 – 0.11 dB dB re 1 μPa m-1). Estimated source level also differ from one ship to another (105 – 128 dB dB re 1 μPa). The existence of ship noise has the potential impacts on the presence of marine biota in these waters.

Highlights

IntroductionIndonesia is an archipelago country that has diverse resources requires vessel as a sea transportation to optimize the potential
The main objective of this research was to explore the sound characteristics of both frequency and sound pressure levels of various types of ships crossing the Nusakambangan Strait, Cilacap, Indonesia
The type of commercial vessels equipped with various size, engine types and power, loading capacity, and operation speed influenced the characteristics of the noise emitted

Summary

Introduction

Indonesia is an archipelago country that has diverse resources requires vessel as a sea transportation to optimize the potential. As a main source of noise pollution in the waters, the sound of vessel is generally produced by propeller, main engine, auxiliary engine, flow noise, etc. Variations of ship noise depend heavily on the propulsion system, and the propeller (Ross, 2005). This mechanical system produces noise based on the characteristics of the ship and engine type (McKenna et al, 2012). Small ships that have high-speed engines and propellers generally produce higher frequency (Erbe, 2002), while large ships produce lower frequency noise (McKenna et al, 2012). The sound of the ship will become more complex when the ship is operating (Kozaczka et al, 2007), where propellers and various types of engines and their parts will work together that cause noise is a combined effect from various sources (Zhang & Meng, 2018). The sound characteristics of both frequency and intensity will change in line with the change in distance due to the operation of the vessel (see Sutin et al, 2010; Fillinger et al, 2011; McKenna et al, 2012; Halliday et al, 2017; Jones et al, 2017; Ahmad et al, 2018 Peng et al, 2018; Enguix et al, 2019)

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