Underwater Noise Measurement Seminar
Thursday, 13th October 2005
National Physical Laboratory, Teddington
Underwater Noise Seminar Agenda 
(114 KB)
The National Physical Laboratory (NPL), in collaboration with the Society for Underwater Technology (SUT), held a one-day seminar on October 13th 2005 on the subject of the measurement of underwater noise radiated from machinery and platforms. The aim of the event was to increase awareness of the current concerns in this field and its potential for impact on industry, and to examine current best measurement practice for noise assessment.
Seminar Presentations
The seminar consisted of a series of presentations by invited speakers with expertise in this field. The presentations are listed below in the seminar's chronological order.
Disclaimer: The views and opinions expressed in the following presentations are solely those of the authors and are do not necessarily represent the views and opinions of NPL or the SUT.
Presentations, Speakers, and Summaries
(2.06MB) Introduction to issues in the assessment of underwater noise
Stephen Robinson, National Physical Laboratory, Teddington, TW11 0LW
Tel: 020 8943 7152, Email: stephen.robinson@npl.co.uk, Web: www.npl.co.uk/acoustics
Summary
Underwater acoustics plays a key role in the off-shore industry, civil offshore activities being heavily dependent on underwater acoustics as a major underpinning technology. The applications of underwater sound span positioning, communications, navigation, echo-sounding, sub-sea control, petrochemical surveying, water quality measurement, sonar, and tomographic measurements of ocean currents and temperature. These are in addition to the classic military applications such as anti-submarine warfare, and mine counter measures. Most of these applications involve actively transmitting sound into the ocean. Sound is also a by-product of many of man's activities. These activities may include shipping, off-shore construction, oil and gas exploration, drilling, cable and pipeline laying activities, and leisure activities (power boats, jet skis etc). The increasing levels of man-made sounds in the ocean (whether deliberately generated or not) has led to concern over marine noise pollution. In particular, exposure of marine life to underwater man-made noise is of growing concern as the effects of this exposure begin to be understood. Increasingly, an environmental impact assessment is being required before activities which may generate underwater acoustic noise may commence. Of course, not all uses of underwater sound are necessarily harmful and acoustic devices may in fact be used to protect marine life, e.g. by reducing accidental catch of dolphins in fishing nets. In addition, the noise pollution may also have an impact on humans (divers and swimmers), and on other users of acoustic equipment, for example where self-noise of vehicles and platforms may hinder the operation of acoustic positioning systems. This presentation provides a brief overview of the issues surrounding the pollution of the underwater marine environment by man-made noise. A description is given of some typical sources of underwater sound, followed by a brief summary of some of the concerns regarding its environmental impact. Finally, a brief description is given of some of the methods that may be used to measure and characterise underwater noise.
(1.83 MB) Mitigation Measures for Acoustic Effects on Marine Life
Geraint West, Head of UK Ocean Research Services, Ocean Engineering Division National, Oceanography Centre, Southampton, SOUTHAMPTON, SO14 3ZH
Tel: 02380 596147, Email: gerw@noc.soton.ac.uk, Web:www.noc.soton.ac.uk/ and www.noc.soton.ac.uk/OED/
Summary
A review is presented of the current and proposed regulations governing the procedures required to minimise the effects on marine life of anthropogenic noise. The requirements of international conventions and regulations such as UNCLOS, ASCOBANS and the Rio Declaration are described. Also presented are the recommended mitigation measures ranging from soft starts and the use of marine mammal observers, to the use of passive acoustic monitoring. The implication of the above for those involved in maritime operations are discussed.
(431 KB) Impact of noise on the marine environment - a regulatory perspective
Inger Söderström Environmental Manager, Energy and Development Unit, Department of Trade and Industry, Atholl House, 86-88 Guild Street, Aberdeen, AB11 6AR
Email: inger.soderstrom@dti.gov.uk, Web: www.dti.gov.uk and www.og.dti.gov.uk/environment/
Summary
The presentation describes the work of the Environmental Management Team of the Energy Resources and Development Unit of the Department of Trade and Industry (DTI). The aim of the DTI policy is to minimise the impact of oil and gas activities and offshore windfarms on the marine environment. A description is given of the programme of Strategic Environmental Assessments being undertaken for UK waters. The regulatory procedures for Site Specific Assessment is also covered, including the Offshore Petroleum Activities (Conservation of Habitats) Regulations 2001, and the Offshore Petroleum Production and Pipe-lines (Assessment of Environmental Effects) Regulations 1999. These cover activities such as seismic surveys, high resolution seismic site surveys, magnetic surveys, gravity surveys, borehole seismic and shallow drilling. For consent for such work to be obtained, an application (PON 14) requires that the guidelines of the Joint Nature Conservation Committee be followed. A list of web-sites containing guidance for industry is also provided.
(793 KB) Techniques and terminologies of airborne noise assessment
Andrew Bullmore Hoare Lea Consultants, Glen House, 200-208 Tottenham Court Road, London, W1T 7PL
Tel: 01454 201020, Email: andrewbullmore@acoustics.hoarelea.com, Web: www.hoarelea.com/
Summary
This presentation covers the rationale behind noise assessment in air acoustics. This includes the methodology used to describe noise, and the fundamentals of human hearing. The decibel scale is described along with the rationale for the dB(A) unit which takes account of the human audiological response. A description is given of the factors affecting received noise level including transmission effects. The descriptors used to characterise a source are presented along with a review of methods used for noise level calculations. The presentation provides an overview of the methodology used in the assessment of airborne noise for those unfamiliar with the field, highlighting the numerous instances where direct analogies exist with the issues of concern in underwater noise.
(3.21 MB) Estimation of underwater noise - a simplified method
Richard Hazelwood, R&V Hazelwood Associates LLP, 14 Ash Grove, Guildford, GU2 8UT
Tel: 01483 568646, Email dick@r-vhazelwood.co.uk
Summary
A set of procedures have been developed to allow preliminary estimates to be made of underwater noise and its effects on marine species. They do not require detailed acoustic survey data, either of the site or of the proposed plant. However, they still facilitate the comparison of different project proposals to assist in the optimisation of equipment layout and routing. Noise may be due to specific sources, such as ships and marine equipment, or assessed as a general background level. Some aspects of acoustic analysis applicable to more detailed environmental impact assessments are also described, particularly relevant when comparing noise spectra with audiometry data appropriate to different species of wildlife.
For further information on this topic please refer to the following paper:
Estimation of underwater noise - a simplified method, RA HAZELWOOD R&V Hazelwood Associates LLP, Guildford, UK and J CONNELLY Metoc plc, Liphook, UK
(2.08MB) Hydroacoustic measurements of piling operations in the north sea, and PAMGUARD - Passive Acoustic Monitoring Guardianship open-source software
Ron McHugh, Heriot Watt University, Electrical, Electronic & Computer Engineering School of Engineering & Physical Sciences, Edinburgh, EH14 4AS
Tel: 0131 451 3355, Email: R.McHugh@hw.ac.uk, Web: www.hw.ac.uk and www.ece.eps.hw.ac.uk/Research/oceans
Summary
There is a need to increase our knowledge of the noise levels associated with underwater operations in shallow water environments. In the summer of 2004 hydroacoustic recordings were made close to a sea floor pile driving operation. Two hydrophones recorded data at depths of 20m and 65m in water of approximately 95m deep. This paper presents the analysis of the data recorded. Through combining recorded acoustic data with hydroacoustic modelling, peak source levels of 210 dB//µPa @1m were estimated for the percussive pile hammering signatures. Also presented is the PAMGUARD project; its motivations, provenance and plans. During maritime operations that produce high levels of sound, legislation requires that the presence of marine mammals is monitored for mitigation purposes Traditionally, human observers have helped in this process and there already exists mature Passive Acoustic Monitoring (PAM) software to augment their efforts by listening for cetacean vocalisations. However, the existing software is closed-source and supported by only a few enthusiasts. This slows down innovation at a critical time when computer technology, legislation and marine mammal research are changing rapidly. Building on the skills and success of the extant PAM software communities, and leveraging the virtues of open-source development, we are developing a new versatile platform we call PAMGUARD, which will see best-of-breed functionality combined with an extensible architecture.
(1.07 MB) Anthropogenic noise measurements and impacts for assessments of the marine environment
Paul Lepper, Applied Signal Processing Group, Dept. Electronic & Electrical Engineering, Loughborough University, Loughborough, Leicestershire, LE11 3TU
Tel: 01509 227080, Fax: 01509 227648, Email: p.a.lepper@lboro.ac.uk, Web: www.lboro.ac.uk andsonar-fs.lboro.ac.uk
Summary
The laboratory and in-situ assessment of various man-made noise sources can be made. The context of these measurements in terms of a real and variable marine environment and impacts and perception on marine species is highly complicated. Development of monitoring and assessment tools, the understanding of physiological and behavioural effects on marine species and the development of a fuller perception of current limitations play a vital role in the development of a better understanding of the marine acoustic environment and how best to operate within it.
(0.745 MB) The dBht; a metric for estimating the behavioural effects of noise on marine species
Jeremy Nedwell, Subacoustech Ltd, Chase Mill, Winchester Road Bishops Waltham Hampshire, SO32 1AH
Tel: 01489 891849, Email: jeremy.nedwell@subacoustech.com, Web:www.subacoustech.com
Summary
Concerns over the environmental effects of offshore seismic shooting using airguns prompted the author to propose a perception scale for application to a wide range of species (Nedwell and Turnpenny 1998). The dBht(Species) provides a measurement of sound that relates to its p[otential for an adverse effect by accounting for inter-species differences in hearing ability. Analogously to the dB(A) for human effects of sound, the measured sound is passed through a filter that mimics the hearing ability of a given species thus indicating the "loudness" of the sound for that species. Similar criteria for those used for humans may then be used to determine whether a sound is "unacceptably loud" to a species. The benefit of this approach is that it enables a single number (the dBht(Species)) to describe the effects of the sound on that species. Simple statements such as "levels of sound of 90 dBht(Species) or more may cause significant avoidance behaviour" are possible. "Species sound level meters" enable simple measurements of noise to be made in biologically meaningful units by non acoustically expert users such as MMOs. The current limits of the metric are reviewed, and some recent examples of the use of the scale in assessing offshore noise are reviewed.
(2.33 MB) Torpedoes and AUVs - impact of radiated noise in the context of background noise - to measure or to model that is the question?
Stephen Jones QinetiQ, Technology Centre, Winfrith Newburgh, Dorchester, Dorset, DT2 8XJ
Email: SAJONES@qinetiq.com, Web:www.qinetiq.com
Summary
This paper provides details of a how QinetiQ have tried to understand the environmental issues of radiated noise from unmanned military capability such as torpedoes and AUVs in context of the background noise field. This understanding has looked at a range of approaches, some novel in origin, to providing this understanding via measurement and or modelling of these two noise fields.
(2.71 MB) Acoustic measurements performed at advanced subsea oil and gas installations
Svein Haugen NAXYS AS, Hegrenesveien 42, 5042 Bergen, Norway
Tel.: +47 55 36 48 80, Fax: +47 55 36 48 81, E-mail: sah@naxys.no, Web: www.naxys.no
Summary
Acoustic emissions form subsea installations have proven to contain abundant information that can be used for condition monitoring. Demonstrations of this have been carried out at the Troll Pilot subsea Separation and Water. Injection plant, the Troll PTG Valve skid and at the Åsgard B export Riser Base. The presentation will provide an overview of the measurements that has been performed and will discuss: a) Installations that has been subject to acoustic monitoring; b) Monitoring system; c) Measurements, level, frequency and various presentation forms; d) Extract of condition information provided; e) Further plans
(1.00 MB) Limits for underwater noise exposure of human divers and swimmers
Steven Parvin, Subacoustech Ltd, Chase Mill, Winchester Road, Bishops Waltham, Hampshire, SO32 1AH
Tel: 01489 891849, Email: steve.parvin@subacoustech.com, Web: www.subacoustech.com
Summary
The effects of underwater noise on human swimmers and divers may range from startle or avoidance at the lowest levels, to death or serious injury when in the vicinity of high level sources. With the increasing recreational use of the sea, and the introduction of long endurance breathing equipment, the risk of divers encountering a noise source is increasing. European Directives becoming active in 2006 will also place an obligation on employers and those generating underwater noise to consider its effects on divers. The current state of knowledge is reviewed, with particular emphasis on the increasing interest in non-lethal effects such as noise induced deafness in divers. The classes of effect of noise are reviewed, along with the appropriate metric for its evaluation. Typical examples of its use are given.