Electric boat underwater radiated noise and its potential impact on species of conservation interest.

Electric boats are thought to be noiseless, but in-situ measurements are generally rare. The Underwater Radiated Noise (URN) of 8-m Trimaran Pontoon Boat with two outboard electric engines was measured in the Miramare Marine Protected Area (Trieste, Italy), together with the URN of a fibreglass 5-m boat, with a outboard gasoline engine, for comparisons. International standards and guidelines for shallow waters were considered. URN were provided in one-third octave band and in narrow band spectra. The electric boat produced a low input of underwater noise at low frequencies. Given a low-frequency hearing sensitivity, the listening space reduction (LSR) was lower when generated by the electric than by combustion engine boat for the brown meagre, a local Teleost fish. No difference was found for the bottlenose dolphin LSR although continuous, tonal, high frequency components generated by the electric boat are expected to be highly detrimental for the bottlenose dolphin.

Airborne Sound Power Levels and Spectra of Noise Sources in Port Areas.

Airborne port noise has historically suffered from a lack of regulatory assessment compared to other transport infrastructures. This has led to several complaints from citizens living in the urban areas surrounding ports, which is a very common situation, especially in countries facing the Mediterranean sea. Only in relatively recent years has an effort been made to improve this situation, which has resulted in a call for and financing of numerous international cooperation research projects, within the framework of programs such as EU FP7, H2020, ENPI-CBC MED, LIFE, and INTERREG. These projects dealt with issues and aspects of port noise, which is an intrinsically tangled problem, since several authorities and companies operate within the borders of ports, and several different noise sources are present at the same time. In addition, ship classification societies have recently recognized the problem and nowadays are developing procedures and voluntary notations to assess the airborne noise emission from marine vessels. The present work summarizes the recent results of research regarding port noise sources in order to provide a comprehensive database of sources that can be easily used, for example, as an input to the noise mapping phase, and can subsequently prevent citizens' exposure to noise.

Characterization of the underwater noise produced by recreational and small fishing boats (<14 m) in the shallow-water of the Cres-Losinj Natura 2000 SCI.

Recreational boats are a dominant source of underwater noise in coastal areas, but reliable boat noise assessment is generally lacking. Here the Underwater Radiated Noise (URN) of seven recreational and small fishing boats moving at two different speeds was measured in the shallow waters of the Cres-Losinj Natura 2000 SCI (Croatia). Measurements were undertaken considering the internationally recognized standards and published guidelines for shallow waters. URN was provided in 1/3 octave band spectra and in narrow band spectra, to highlight the tonal components. Engine power and type rather than the boat length and design result to be more predictive of URN. Highest speeds induce highest noise levels only in a very limited frequency range and different boats with similar speed but different engines show a shift in the spectra. Relevance of the achieved results for the tested area is further discussed.

Source characterization guidelines for noise mapping of port areas.

Maritime transport for both passengers and freight is continuously increasing and, consequently, the global attention toward its sustainability is growing. Ships offer advantages in terms of environmental impact compared to other transportation systems but the increasing traffic volume is expected to increase pollutants. Noise produced in port areas has been neglected for too long, until the INTERREG Maritime programme Italy-France 2014-2020 has brought to light how citizen complaints are emerging for some of the main ports in the Mediterranean. However, port noise prevention and management is difficult as knowledge on specific sources is very limited in the literature. Furthermore, on field measurements are difficult to be performed given the complexity of the port area, where multiple types of sound emitters mix and confuse each other. Noise maps represent the first important step in order to align ports to the requirements set by the Environmental Noise Directive to the transportation infrastructures. Once computed, they are an excellent tool supporting port management towards the reduction of citizens' noise exposure while ensuring traffic growth. The present paper reports a guideline for the characterization of noise sources needed as inputs for the noise maps, as developed in the framework of the INTERREG Maritime programme Italy-France 2014-2020. On the basis of the current state of the art, a procedure has been elaborated for different categories of noise sources acting in port, ranging from stationary to moving ships, from mooring operations to loading/unloading operations, from industrial activities to road and railway traffic.

A novel approach to port noise characterization using an acoustic camera.

Acoustic cameras are powerful instruments combining an optical camera with a microphone array to obtain information about power and location of noise sources. The main aim of this study is to identify key points in the application of an acoustic camera to the characterization of port noise. An experimental campaign was carried out in the seaport of Genoa. Based on this experience, a SWOT (Strengths, Weaknesses, Opportunities, and Threats) analysis was performed. The experimental results confirm the intrinsic complexity of the noise field in ports. Several noise sources were identified and can be categorized by their duration, intensity, location and spectral content; the analysis performed allows us to propose a basic framework for the innovative application of this technique to the port noise context. Acoustic cameras can be considered viable and useful tools to characterize and monitor port noise, following at least the minimum key points highlighted in the proposed framework.