Automation and standardisation of a passive acoustic

Internship Report

Investigation of potential modifications of a passive acoustic monitoring system for a wider commercial use.

Irene Voellmy in partnership with Ultra Electronics Ltd.

Investigation of potential modifications of a passive acoustic

monitoring (PAM) system for a wider commercial use

NERC MRE knowledge exchange internship report

Irene Voellmy

October 2013

NERC MRE internship report Irene Voellmy

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Table of contents

Aim of this internship ......................................................................................................... 3

Part I: Applications of PAM systems ................................................................................... 3

1. Research requirements .............................................................................................................................. 4

2. Regulation and industry requirements ...................................................................................................... 5

3. Requirements reported by PAM users in the questionnaire ...................................................................... 6

4. Implications for Passive Acoustic Monitoring (PAM) devices .................................................................. 15

5. Limitations and gaps of autonomous PAM systems ................................................................................ 16

6. Potential of Ultra Electronics sonobuouys to meet requirements and to fill gaps .................................. 17

Part II: Detection and classification of marine mammals .................................................. 19

1. Humpback whales in Madagaskar .......................................................................................................... 20

2. Dolphin clicks and whistles North Carolina .............................................................................................. 22

3. Ambient noise in Blyth ............................................................................................................................. 24

4. Conclusions .............................................................................................................................................. 26

NERC MRE knowledge exchange internship as a tool to use knowledge acquired by

academic research for commercial interests ..................................................................... 28

Acknowledgements .......................................................................................................... 29

References........................................................................................................................ 30

Appendix 1: Sonobuoy description ................................................................................... 32

Appendix 2: SurveyMonkey questionnaire ....................................................................... 34

Appendix 3: Marine mammal detector settings ................................................................ 41


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Investigation of potential modifications of a passive acoustic

monitoring (PAM) system for a wider commercial use

Aim of this internship

The project aimed to explore potential modifications of a military passive sonar system (SSQ 906G

Low frequency analysis and recording (LOFAR) Sonobuoy, Ultra Electronics, Greenford, UK) for wider

commercial use as a Passive Acoustic Monitoring (PAM) system, including an automated system to

detect, classify and localise (DCL) marine mammals by their emitted sounds. Originally, this system

had been developed for deployment from an aircraft to detect quiet submarines during WWII by

listening to sounds transmitted by the system (Discovery of Sound in the Sea (DOSITS) 2013; see

Appendix 1 for Ultra Electronics LOFAR sonobuoy original description).

The objectives should be achieved by exploring today’s requirements and trends in applications of

PAM systems (part I of this report) and by exploring detection programs in use to create a user-

friendly software package to record and detect marine mammals in real-time to be added to the

modified sonobuoys (part II of this report).

Part I: Applications of PAM systems

Research on marine mammals has increasingly used adapted military passive sonar techniques

during the last few decades for marine mammal research and abundance monitoring, as acoustic

detection of emitted sounds of marine mammals complement limitations of visual surveys, which

can only be made at daylight, in favourable weather conditions based on visual observations of

marine mammals during the short time they emerge from the water surface (Zimmer 2011). More

recently, potential impacts of anthropogenic (man-made) noise emission have been more and more

recognised and described (e.g. Nowacek et al. 2007; Popper & Hastings 2009; Barber et al. 2010).

Moreover, the significance of acoustic environment characterisation to assess habitat quality has

been discovered, as well as the potential to acoustically monitor changes of species composition and

ecosystems induced by human activities (e.g. Blumstein et al. 2011). These developments have

diversified PAM applications and will further increase and diversify usage of PAM devices. Today,

PAM systems are used in research, noise emission monitoring and regulation by academic

institutions, NGOs, policy makers and industry.


4

To enable informed decisions about most effective modifications of Ultra Electronic sonobuoys for

wider commercial use, I assessed most common applications and future trends of using PAM

systems by conducting a short and non-exhaustive literature review as well as by attending a

meeting on marine mammal detection and classification in St. Andrews, a conference on

underwater acoustics in Corfu, and by participating in the IMARES - TNO Workshop on “International

Harmonisation of Approaches to Define Underwater Noise Exposure Criteria” in Budapest to

investigate current use and future trends in PAM system applications. In addition, Peter Dobbins and

I created an internet-based questionnaire to explore current requirements of regulators,

researchers, engineers, and companies using or intending to use PAM systems.

1. Research requirements

PAM is used for a variety of academic and non-academic research fields involving bioacousticians,

physicists, conservationists, consultancies, regulators, and industry.

Research includes investigation of acoustic behaviour of marine mammals, reptiles, anurans (frogs

and toads), fish and invertebrates, as aquatic animals are very difficult to observe directly, but are

acoustically detectable using emitted sounds (e.g. Zimmer 2011). Each species emits its own sounds

with sound frequencies ranging from 5 Hz to 140 kHz and thus comes with its own technical

requirements, such as the ability to record high frequency sounds with minimum sampling frequency

rates of 300 kHz and high data processing capacities, respectively. Moreover, most projects will run

for extended time periods of several months, requiring high data storage capacities and efficient

data processing and analyses. Consequently, many projects on marine mammals involve automated

detection and classification programs, most of which also requiring localisation of vocalising animals

for group size and population density estimation (Zimmer 2011).

As it is increasingly recognised that man-made sound can negatively impact aquatic organisms, PAM

systems are increasingly used for quantification, characterisation and monitoring anthropogenic

noise, and projects investigating effects of human acoustic interference (e.g. Blumstein et al. 2011).

In addition to previously mentioned requirements, work on human sound emissions demands a high

dynamic range not only to capture low level noises from distant ambient noise, but also high level

noises emitted by animals or sounds close to the receiver.

Another fast growing research field is the characterisation of acoustic environments to monitor

species presence and composition, to determine criteria indicating high quality habitats as well as to


5

monitor changes over time, for instance, changes triggered by human interference (e.g. Blumstein et

al. 2011).

It is important to note that many species other than marine mammals detect and rely on particle

motion to various extents, rather than on the sound pressure aspect of sound (e.g. Salmon 1971;

Goodall et al. 1990; Popper & Fay 2011). Since research on taxa other than marine mammals has

intensified substantially over the past decade, there is a need for developing PAMs capable of

quantifying particle motion in addition to sound pressure. Integration of particle motion

measurements will require simultaneous multichannel recordings, as particle motion is directional

within the three dimensional space, consisting of movement components in the x-, y-, and z-axis.

2. Regulation and industry requirements

Regulators and industry use PAM devices for three main purposes: first, to monitor anthropogenic

sound emission, such as noise emitted during seismic surveys, construction and operation of marine

renewable energy converters, or noise emitted by ship and boat traffic (Lucke et al. In Prep.).

Second, PAM devices are used to monitor abundance of marine mammal species in a given habitat,

in some projects including investigating change of species composition with human activities

(Blumstein et al. 2011). Third, PAM systems can serve as a real-time warning tool to alert vessels to

the presence of marine mammals, to minimise or divert ship traffic to different routes, for example,

further away from breeding grounds (Silber & Bettridge 2006). Alerting PAM systems could also be

used for workers to interrupt or minimise seismic surveys, drilling, pile driving and other noise

generating activities while marine mammals are present.

Requirements to monitor anthropogenic noise emission generally overlap with requirements of

researchers investigating acoustic environments. Regulations on how to quantify and monitor

anthropogenic sound emission, however, are still very vague (De Jong et al. 2011; Lucke et al. In

Prep.), as not much is known, for example, for how long a specific area has to be acoustically

monitored to quantify and characterise naturally occurring ambient noise and noise levels added to

the ambient noise by human activities. This issue is currently further addressed by the NERC MRE

internship project by Silvana Neves. Moreover, it is not known which parameters of noise emitted

are triggering most impairing effects in animals, for instance, whether the onset of noise and its

duration, as well as its predictability is determining effects on aquatic organisms rather than sound

levels per se. Specific guidelines and regulations vary substantially between countries (Lucke et al. In

Prep.). As a result specific requirements will differ between countries on how human activities are


6

surveyed, even though several working groups are currently working on harmonisation and

standardisation of monitoring protocols (see Ainslie 2011; De Jong et al. 2011; Lucke et al. In Prep.

for examples).

However, trends for future requirements became apparent at the IMARES-TNO workshop in

Budapest, August 2013: regulators are becoming increasingly aware of the necessity of including

sound measurements relevant for non-marine mammals (see above). Thus, integrating

measurements of particle motion and recording on multiple channels simultaneously will become

increasingly important for regulators and industry. Moreover, sound quantification at different

depths, as well as including hydrophones sensitive to different frequency ranges, and sound source

localisation will become iimportant to assess sound exposures of aquatic organisms.

With increasing numbers of offshore marine renewable energy devices, the number of projects

monitoring sound emission in shallow waters will rise as a consequence. Sound propagation patterns

in shallow waters are more complicated and thus more difficult to predict. PAM devices may

become increasingly important for empirical verification and refinements of theoretical sound

propagation models to improve estimation of the extent marine organisms are exposed to

anthropogenic noise emission. Data loggers recording non-acoustic data, such as water temperature

and salinity, will be important to improve sound propagation calculations. Recording additional data

on water quality, such as turbidity, acidity and other chemical parameters will also allow a more

integrative approach taking into account potentially confounding and synergistic effects, for

example, potential effects of bad water quality on animal sound production in addition to increased

ambient noise levels.

Using PAM systems to monitor marine mammal abundance, as well as using real-time PAM

techniques as a warning system to manage human activity, will require similar specifications to

marine mammal research, however, additional automated and robust detection and classification

algorithms that are easily operable by non-specialists will be desirable.

3. Requirements reported by PAM users in the questionnaire

A web-based questionnaire was composed in SurveyMonkey (www.surveymonkey.com) to

investigate further and verify the current state of the art of how PAM systems are used, as well as

specific features sonobuoys need to provide. The questionnaire consisted of a total of eight

questions addressing PAM user’s institutions and working areas, their areas of interest and


7

requirements sonobuoys need to meet (Appendix 2). The questionnaire was distributed through

mailing lists (Bioacoustics List (Cornell University), International Bioacoustics Council, Marine

Mammals Research and Conservation Discussion (MARMAM), Coral List) and sent by email to

specific contacts to reach as many PAM users from as many diverse application fields as possible,

including physicists, bioacousticians, regulators, PAM providers, consultancies, military and

commercial institutions, etc.

A total of 74 PAM users responded to the questionnaire. The majority and almost half of PAM users

answering the questionnaire worked for an academic institution (table 1, fig. 1), while many fewer

users are PAM service providers or researchers funded by the government. Six PAM users work in a

commercial research organisation, and only 3 users are funded independently (table 1, fig. 1). Two

users work for the oil and gas industry, consultancies and NGOs, respectively (table 1, fig. 1). One

person is working for the renewable energy section and one person for an aquarium (table 1, fig. 1).

Although sonobuoys were originally developed for military purposes (Zimmer 2011), none of the

users responding to the questionnaire was working for a military institution. There were also none

using PAM devices for whale watching tours, outreach activities or as a regulatory organisation. It is

possible that the email contacts and mailing lists we have used did not reach representatives of

these sections.

Table 1. Number and percentage of PAM users and their respective organisations and working areas (n = 74).

Organisation/working area Number of PAM users Percentage of PAM users

Academic institution 33 44.6 PAM service provider 13 17.6

Government research organisation 11 14.9

Commercial research organisation 6 8.1

Independent research 3 4.1

Oil and gas industry 2 2.7

Consultancy 2 2.7

NGO 2 2.7

Renewable energy organisation 1 1.4

Aquarium 1 1.4

http://www.ibac.info/


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Figure 1. PAM users and their institutions or work areas (in percentage; n = 74).

The majority of PAM users operate 2 to 5 devices (29 of 71; 40.8%), while 19 of 71 users (26.8%)

operate 10 or more devices, and 10 of 71 users own 6 – 10 PAM devices (14.1%; fig. 2). However,

there are also 13 of 71 PAM users working with one PAM device only (18,3%; fig. 2).

Figure 2. Number of PAM devices used by PAM users (n = 71).

Most PAM devices were used to collect long term data with collecting periods exceeding a year (20

of 72 PAM users; 27.8%; fig. 3), or 9 months to a year (18 of 72 PAM users; 25.0%; fig. 3). Only 2

PAM users collected acoustic data for less than a week (2.8%; fig. 3).

0 10 20 30 40 50

Renewable energy organisation

Aquarium

Oil and gas industry

Consultancy

NGO

Independent research

Commercial research organisation

Government research organisation

PAM service provider

Academic institution

0 10 20 30 40 50

10 +

6-10

2-5

1

% PAM users

% PAM users


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Figure 3. Time period PAM users collect data (n = 71).

Most PAM users are involved in projects focusing on marine mammal sounds (59 of 70; 84.3%; fig. 4)

and anthropogenic noise (53 of 70; 75.7%; fig. 4). Most PAM projects address multiple topics (57 of

70; 81.4%). This is not surprising, as many of these interests also require investigation of other

related areas, such as monitoring and assessing impacts of anthropogenic noise requires monitoring

naturally occurring ambient noise, as well as monitoring aquatic organism presence and abundance.

Figure 4. PAM user’s areas of interests (n = 70).

0 5 10 15 20 25 30

more than a year

9 months to a year

6-9 months

3-6 months

1-3 months

week to a month

less than a week

0 10 20 30 40 50 60 70 80 90

Sound propagation model evaluation

Acoustic environment/soundscape

Anthropogenic noise

Other natural abiotic noise

Seismic noise

Anuran monitoring

Bird monitoring

other aquatic organism sounds

Marine mammal sounds

% PAM users

% PAM users


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PAM users monitor a wide range of marine mammals (table 5, fig. 5). However, the majority focuses

on cetaceans, and fewer monitor pinnipeds, of which the vast majority of projects seem to focus on

species of the Northern hemisphere (table 5, fig. 5). Only one PAM device user reported to monitor

Dugongs (table 5, fig.5).

Table 5. Species of interest for PAM users (n = 60)

Species of interest Number of users Percentage of users

Porpoises 31 51.7

Oceanic Dolphins 35 58.3

River Dolphins 7 11.7

Orcas 24 40.0

Sperm Whales 32 53.3

Beaked Whales 28 46.7

Belugas and Narwhals 14 23.3

other odontocetes 10 16.7

Right and Bowhead Whales 25 41.7

Rorquals 57 95.0

Dugong 1 1.7

Arctic pinnipeds 32 53.3

Antarctic pinnipeds 3 5.0

Figure 5. Species of interest for PAM users (n = 60)

0 10 20 30 40 50 60 70 80 90 100

Antarctic pinnipeds

Arctic pinnipeds

Dugong

Rorquals

Right and Bowhead Whales

other odontecetes

Belugas and Narwhals

Beaked Whales

Sperm Whales

Orcas

River Dolphins

Oceanic Dolphins

Porpoises

% PAM users


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For most PAM device users, it is important that sonobuoys are recoverable and reusable with a

rechargeable battery to avoid littering the coast or seabed using one-way PAM devices, as is the case

for most sonobuoys developed for military purposes (table 6, fig.6). Most PAM users would like to

locate sonobuoys using GPS (table 6, fig.6). One user also suggested an AIS (Automatic Identification

System) transmission system on board and another suggested increasing visibility and locatability

using an acoustic pinger or a flashing light to increase the chance of retrieving sonobuoys. Three

quarters of PAM users answering the questionnaire record sound up to 20kHz, but almost 60% also

record up to 150 kHz to include marine mammals emitting ultrasonic sound, such as porpoise or

dolphin clicks. The majority of PAM users would also prefer on-board hard disk recording of full

bandwith signals for ultrasonic recordings (table 6, fig.6). Less important, but still regarded as

preferable by most PAM users, are small lightweight sonobuoys which can be deployed by one

person from a small boat (table 6, fig.6). There seems to no clear-cut preference of specific

hydrophone depths, as some PAM users record acoustic data near the shoreline, while some use

their sonobuoys in the open and deep ocean (table 6, fig.6). The same seems true for directional

hydrophones, as most localisations are achieved using PAM arrays, not by directional hydrophones

from a single PAM device (table 6, fig.6). Radio telemetry does not seem essential for many PAM

users, as not all users need real-time data monitoring, and PAM users recording ultrasound will have

to use wireless data transfer facilities (table 6, fig.6). In contrast to supposed future trends to

integrate non-acoustic data to allow for a more holistic approach, most users classify data loggers

collecting additional non-acoustic data about water quality as not essential. Similarly, even though

particle motion quantifications and measurements at different depths using different hydrophones

seem to become increasingly important and high numbers of simultaneous radio channels does not

seem a widespread requirement (table 6, fig.6). However, most devices used to date are either not

collecting real-time data (e.g. devices by Wildlife Acoustics Inc., Concord, MA, USA), or transmit data

by wireless internet connections, instead of radio channels (e.g. devices by RTsys, Caudan, France).


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Table 6. Interest of PAM users in specific hardware specifications. “Yes” denotes specifications essential for

user’s to meet their requirements, “not essential” denotes specifications helpful for additional or future data

collection, but not essential for fulfilling projects, “no” denotes specifications not necessary for users.

Proposed hardware specifications Total answers

Yes (%) Not essential (%)

No (%)

Recoverable, reusable, rechargeable battery 50 78.0 16.0 6.0

HiFi quality signal 10Hz – 20kHz 49 75.5 16.3 8.2

Hydrophone suspension to minimise recording noise 48 70.8 20.8 8.3

GPS/compass positioning 50 68.0 26.0 6.0

On-board full bandwidth backup recording 50 64.0 30.0 6.0

Compressed signal 10kHz – 150kHz 50 58.0 24.0 18.0

Small, lightweight for hand deployment 50 56.0 40.0 4.0

Hydrophone depth selectable 15/30/60 m 48 45.8 33.3 20.8

FM radio telemetry 48 45.8 29.2 25.0

Maximum depth more than 60 m 47 42.6 31.9 25.5

Directional hydrophones 50 42.0 42.0 16.0

Maximum depth more than 300 m 49 40.8 30.6 28.6

Data logger recording temperature, salinity, pH 49 36.7 53.1 10.2

Up to 100 selectable independent transmission channels 49 16.3 46.9 36.7


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Figure 6. Interest of PAM users in specific hardware specifications. “Yes” denotes specifications essential for

user’s to meet their requirements, “not essential” denotes specifications helpful for additional or future data

collection, but not essential for fulfilling projects, “no” denotes specifications not necessary for users.

Over 75% of PAM users would prefer devices with adjustable recording levels to meet the

requirements of wide dynamic range to record very quiet ambient sounds, but also much louder

sounds, such as noise emitted by pile driving activities or ship traffic. However, only some users

indicate they would need an interactive device control to change settings during recording sessions

(table 7). Also, the majority of users would like to monitor acoustic data in real-time, but not only

rely on recording data via data transfer but also have an on-board hard-disk in addition to ensure

back-up data storage (table 7). Some users also commented on the fragility of real-time data

transmission using radio signals or a wireless connection, causing data losses. For most applications,

0 10 20 30 40 50 60 70 80

Up to 100 selectable independent transmission channels

Data logger recording temperature, salinity, pH

Maximum depth more than 300 m

Directional hydrophones


FM radio telemetry

Hydrophone depth selectable 15/30/60 m

Small, lightweight for hand deployment

Compressed signal 10kHz – 150kHz

On-board full bandwidth backup recording

GPS/compass positioning

Hydrophone suspension to minimise recording noise

HiFi quality signal 10Hz – 20kHz

Recoverable, reusable, rechargeable battery

Yes

Not essential

No

%


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3D sound source localisation will be required, preferably using a single buoy (table 7). Most users

will also need real-time detection and classification of marine mammals for their applications. Some

would require an alerting function included when marine mammal sounds are detected, but only

some would need these detections displayed (table 7). However, one PAM device user commented

that they would prefer open source software rather than getting black boxes of ready-to-use

detection programs delivered by the PAM system provider, which they expect to be more difficult to

control and adjust in case of suboptimal detection performance.

Some PAM device users pointed out that the main problems to be solved by PAM device software

are the decreasing computer efficiency caused by the large quantity of data generated and

associated increasing system instabilities. This is especially the case when working with ultrasonic

sounds. Moreover, PAM devices come with high costs. PAM users also reported problems to detect

low frequency calls using towed arrays or in presence of low frequency anthropogenic noise.

Table 7. Interest of PAM users in specific software and receiver specifications. “Yes” denotes specifications

essential for user’s to meet their requirements, “not essential” denotes specifications helpful for additional or

future data collection, but not essential for fulfilling projects, “no” denotes specifications not necessary for

users.

Specifications for the receiver/software Total answers

Yes (%)

Not essential (%)

No (%)

Adjustable recording levels 49 77.6 22.4 0.0

Direct data transfer and back-up on hard disk 50 68.0 30.0 2.0

Localisation in range, bearing and depth 49 65.3 28.6 6.1

Real-time displays of signal waveforms, spectra and spectrograms

49 59.2 32.7 8.2

In-built detection algorithms of marine mammal vocalisations

49 59.2 28.6 12.2

In-built marine mammal species identification in addition to detection

49 59.2 30.6 10.2

Bearing localisation with single buoy 49 59.2 30.6 10.2

Programmable alerts for presence of cetaceans 49 53.1 34.7 12.2

Choice of single or multi-channel (up to 8) FM receiver 50 52.0 42.0 6.0

Interactive device control 48 45.8 47.9 6.3

Plan and waterfall displays for detections 49 36.7 51.0 12.2


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Figure 7. Interest of PAM users in specific software and receiver specifications. “Yes” denotes specifications

essential for user’s to meet their requirements, “not essential” denotes specifications helpful for additional or

future data collection, but not essential for fulfilling projects, “no” denotes specifications not necessary for

users.

4. Implications for Passive Acoustic Monitoring (PAM) devices

The above examples and the questionnaire illustrate that there is a wide range of potential

requirements and purposes PAM devices are used. The questionnaire indicates that the majority of

PAM device users currently uses 2 - 5 PAM devices to collect long-term data of a year and longer, to

monitor marine mammal and anthropogenic sounds. In general, PAM devices will need to include a

high dynamic range, the capability to record data on multiple channels continuously for an extended

period of time including high data storage capacities. These tasks should preferably be met in a

highly cost effective, data processing and storage-effective way. Moreover, the majority of users

0 10 20 30 40 50 60 70 80

Plan and waterfall displays for detections

Interactive device control

Choice of single or multi-channel (up to 8) FM receiver

Programmable alerts for presence of cetaceans

Real-time displays of signal waveforms, spectra and spectrograms

In-built detection algorithms of marine mammal vocalisations

In-built marine mammal species identification in addition to detection

Bearing localisation with single buoy

Localisation in range, bearing and depth

direct data transfer and back-up on hard disk

Adjustable recording levels

Yes

Not essential

No

%


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prefer retrievable devices with rechargeable batteries to meet requirements of long-term data

collection and to minimise littering the seabed.

Many users work with computer software detecting and classifying marine mammals to facilitate

analysis of long-term data. However, not all users monitoring marine mammals would accept an in-

built software device, as some prefer data post-processing to real-time monitoring and open source

software to avoid the black-box nature of ready-to-use software with limited control over detection

algorithms. This is especially true for research projects. However, some projects will require real-

time monitoring, for instance, projects using PAM systems as warning devices to stop drilling/pile

driving or to divert ship traffic in presence of marine mammals. This application can be highly

demanding, as many marine mammals, such as Humpback whales (Megaptera novaeangliae) and

Bottlenose dolphins (Tursiops truncatus) emit highly variable sounds and thus are difficult to detect

and classify by detection programs robust enough to be operated by non-bioacousticians.

Almost 78% of PAM users would prefer devices offering adjustable recording levels to increase

dynamic range, as not only quiet ambient noise is of interest, but also sounds emitted by human

activities. PAM users seem to operate their devices at many different depths, thus, hydrophone

depths may best be tailored to specific customer needs.

Research focusing on soundscapes and sounds emitted by animals other than marine mammals is

increasing. Thus, the use of sonobuoys will diversify resulting in more diverse applications and

requirements leading beyond sound pressure measurements, marine mammal detection,

identification and localisation towards multichannel devices integrating different acoustic

measurements including particle motion and sound pressure measurements at different depths and

sound frequency ranges.

5. Limitations and gaps of autonomous PAM systems

PAM systems, such as sonobuoys, are autonomous recording devices. Thus, power supply and space

is inherently limited, restricting processing power and data storage capacity (Zimmer 2011). These

limitations become especially crucial when data collection is required for high frequency sample

rates for periods of several months to exceeding a year.

In case real-time data processing is necessary, data transfer is only possible when the sending

element is located above the water surface. However, this will increase the vulnerability of the


17

system, for example, to overrunning ships or by hydrodynamic forces ripping the system apart

(Zimmer 2011).

Many stationary autonomous PAM devices do not allow for real-time monitoring of the recordings,

and this does not make available system control checks or adjustments of recording levels. In

addition, in case of monitoring presence/absence of marine mammal during pile driving or certain

ship movements, it is not possible to control human activity according to animal movements.

Some autonomous PAM devices offering real-time data monitoring do not allow for a two-way

communication, for example, PAM systems using radio transmission to transfer data. The possibility

for a two-way communication would allow for adjusting and controlling recording levels during

recordings to increase dynamic ranges, for example to adjust for very quiet ambient noise

interrupted by very loud ship passages.

As outlined in section 1, the increasing focus on non-marine mammals will lead to the necessity to

integrate particle motion in the future; however, none of the current systems offer this option. This

is partly the case because accelerometers have not yet been developed in a more widely available

commercial scope, possibly because the need is only becoming more widely recognised by policy

makers and regulators.

6. Potential of Ultra Electronics sonobuouys to meet requirements and to fill gaps

The Ultra Electronics sonobuoys are light-weight, and thus easy to transport and deploy. The system

is equipped with a surface floater allowing for real-time data transmission and monitoring. As the

sonobuoy is designed to drift freely with the water current, and the hydrophone is connected to the

sonobuoy by a coiled, low self-noise cable, the system allows for low self-noise recordings of low

level ambient noise at low depths. To increase the dynamic range, an additional filter is added to the

recording system (pre-whitening) reducing lower frequency sounds while boosting higher frequency

signals, as most sound energy in aquatic ambient noise is located in low frequency ranges, due to

water currents and anthropogenic noise, such as ship noise.

In addition to the above features, Ultra Electronics sonobuoys have a lot of potential to meet further

requirements by research and conservation by relatively simple modifications:

The increasing necessity of long-term ambient noise and anthropogenic noise assessments at

growing numbers of locations, the design of retrievable and reusable sonobuoys become


18

mandatory. Many researchers monitoring marine mammals switched to reusable solutions to avoid

littering the coast with one-way use sonobuoys containing lithium batteries, among other non-

biodegradable substances (Danielle Harris, personal communication). In order to facilitate sonobuoy

recollection, floaters could be designed to become more visible, as well as equipped with a GPS

locator. Information of current positions of the PAM device will become increasingly important as

with increasing floating time, the position will be substantially altered from the original deployment

site. Increasing floating time on the surface would also increase the probability to become overrun

by a ship. More visible floaters, possibly equipped with a flashing light or AIS signals, detectable from

approaching vessels, would also help to avoid collisions (Zimmer 2011), although environmental

effects of a flashing light need to be assessed thoroughly before integrating it in the system, as light

is reported to attract or disrupt the behaviour of many animals, including aquatic organisms (e.g.

Doherty 1987; Longcore & Rich 2004).

Retrievability and reusability would also provide the possibility to add a hard disc for back up data

storage in cases real-time transmission of data is impossible or interrupted. For extended use, solar

panels could be mounted on the floating part of the system to increase power supply, an inert

limitation of autonomous PAM systems.

Replacing radio transmission by wireless internet transmission would allow transferring higher data

loads, such as recordings of frequency levels higher than 15 kHz, the current limit for radio

transmitted signals. This will become necessary if adapting the system to monitoring marine

mammals or other animals emitting high frequency sounds. Harbour porpoises, for example, emit

sounds up to 140 kHz (Au 1993) and are abundant around the British coast (Northridge et al. 1995;

Shirihai 2006), where many marine renewable energy devices are planned. Transfer of high data

loads is also necessary when simultaneously transmitting signals of several hydrophones at different

depths or spatial locations, etc. Moreover, simultaneous multichannel data transmission will become

mandatory with the integration of particle motion measurements.

Wireless data transmission would also allow for a two-way communication, and thus increase

controllability of sonobuoy recordings. Dynamic ranges could thus be further increased by additional

adjustability of recording levels, etc.

To increase flexibility of sonobuoys, modifying its case would allow inclusion of multiple connectors

for the recording system to include hydrophones sensitive to high frequency and hydrophones

sensitive to low frequency signals at the same time, as well as hydrophones at different depths, or

directional hydrophones. Collection of additional data, such as data loggers recording non-acoustic


19

data to allow for a more holistic approach of acoustic monitoring projects (see above), and particle

motion in addition to sound pressure measurements will become mandatory with the development

of new accelerometers and the increasing interest in non marine mammal species and with it, the

integration of three additional, simultaneous recording channels.

Part II: Detection and classification of marine mammals

We tested two well-developed marine mammal detection programs, PAMGUARD v1.12.05 BETA

(Gillespie et al. 2009) and Marine Mammal Acoustic Detector (MMAD; trial version 3-2 WAV; Kaon

Ltd. , Guildford, UK) using audio files of:

(1) Humpback whale songs (Megaptera novaeangliae) recorded in Madagascar by Federica Pace in

July 2011, using a SSQ 906G LOFAR Sonobuoy (Ultra Electronics, Greenford, UK). Acoustic signals

were radio transmitted using WiNRADiO G 305 v2.22 (20013 WiNRADiO Communications, RADIXON

UK Ltd, Chesterfield, UK) and recorded to a laptop computer (Dell Latitude (Dell Corporation Limited,

Bracknell, UK) using Audacity v1.3.13 (1999-2011 Audacity Team; SourceForge.net)

(2) Bottlenose dolphin whistles (Tursiops truncatus) and clicks recorded in Onslow Bay, North

Carolina (33°46.081'N, 76°27.598'W) by Lynne Williams Hodge and Andy Read in January 2008

during a project funded by Naval Facilities Engineering Command Atlantic (Williams Hodge 2011).

Unfiltered recordings were made using a towed 4-element hydrophone array with 300 m tow cables

(Seiche Measurements Ltd, Bradworthy, UK) with a flat frequency response (+/- 3 dB) between 2 and

100 kHz, sensitivity -165 dB re 1 V/µPA), connected to a MOTU Traveler audio interface (Mark of the

Unicorn, Cambridge,MA, USA), and a laptop using Ishmael (Mellinger 2001). The hydrophone array

was towed 150 m behind the vessel at an approximate speed of 16.7 km/h.

(3) Ambient noise recorded by the author in Blyth in July 2013 (55°11.322'N / 1°27.799'W), in an

area for which an offshore wind farm is planned for 2014/2015. Recordings were made using a SSQ

906G LOFAR Sonobuoy (Ultra Electronics, Greenford, UK). Acoustic signals were radio transmitted

using WiNRADiO G 305 v2.22 (20013 WiNRADiO Communications, RADIXON UK Ltd, Chesterfield,

UK) and recorded to a laptop computer (Toshiba Tecra M11-17V (Toshiba Information Systems UK

Limited, Weybridge, UK) using Audacity v2.0.3 (1999-2013 Audacity Team; SourceForge.net).

Recordings made by sonobuoys were pre-filtered decreasing low frequency sound levels and

enhancing high frequency sound levels to increase dynamic range (see above). Thus, for sound files

recorded by sonobuoys (the humpback recordings and the ambient noise recordings from Blyth),


20

detection performance of the two detection programs was compared using untreated files and files

after restoring original sound levels at the test sites using a inverse filter in Adobe Audition 1.5 (©

1992-2004 Adobe Systems Incorporated).

The development of PAMGUARD by experienced PAM users and marine mammal researchers in the

UK and the USA (coordinated by Douglas Gillespie) has been funded by the oil and gas industry since

2004 (www.pamguard.org). PAMGUARD is an open access software. The purpose of the software

was to provide a worldwide standard detection, localisation and classification program to improve

acoustic monitoring techniques of marine mammals for research, regulation and mitigation

procedures. The software is organised in modules which can be combined and further developed for

specific needs. For testing the software, I used a moan detector to detect low frequency calls of

baleen whales, combined with a sperm whale and dolphin detector to detect dolphin whistles and a

click detector to detect clicks (see Appendix 3 for exact parameter settings). All three detectors were

run simultaneously for all test files to use it as a universal detection program for baleen whales and

odontocetes.

MMAD (Marine Mammal Acoustic Detector) is a commercially available software package developed

by KAON (www.kaon.co.uk/mmad.asp) to provide easy to use software for industrial purposes,

which does not require specific expertise to operate. The software is developed to raise alarms

when marine mammal sounds are detected that human activities can be modified accordingly, for

example, to interrupt pile driving when marine mammals are present.

1. Humpback whales in Madagaskar

PAMGUARD

In general, PAMGUARD algorithms detected the majority of humpback calls (over 70% in both files,

table 8). Undetected calls were either relatively short, thus shorter than specified in the moan

detector (Appendix 3), or they consisted of none or very few harmonic structures, thus sound was

not connected as much as specified. The number of missed detections could be minimised by

modifying parameter specifications to enable detection of shorter and less harmonic calls, however,

false positive detection rates would increase as a consequence, especially in the presence of ship

noise with signatures containing harmonic elements. Since all undetected calls were emitted as

elements within songs lasting for several minutes, missed calls did not result in a failure to detect

humpback presence. False positive detection rates were very low for files containing humpback


21

songs (table 8), but could be as high as 4 detections/minute in file 2, a recording lacking humpback

calls. False positive detections were recorded by both, the moan and whistle detectors (Appendix 3).

There was no difference between original recordings and inverse-filtered audio files.

The click detector recorded a very high number of clicks (up to 2590/minute, table 8), even though

the audio files tested did not contain any marine mammal clicks. The click detector mainly identifies

sudden occurrence of sound, which can easily resemble random ambient noise, even though a high

pass filter was used to exclude click detections outside dolphin click frequency ranges (Appendix 3).

Thus, a visual inspection of the spectrogram is mandatory to verify any indicated click detections.

There was no qualitative difference in the numbers of click detections between untreated, original

recordings and inverse-filtered recordings (table 8).

Table 8. Detection results in PAMGUARD.

Sound files File

duration

Total calls Correctly

detected

Missed calls False positive

detections (calls)

Clicks

detected

File 1

original 3:17.093 147 128 (87.1%)

19 (12.9%)

2 (1.4%)

7905

filtered 3:17.093 147 128 (87.1%)

19 (12.9%)

1 (0.7%)

7329

File 2 original 22:46.841

0 n/A n/A 68

24164

filtered 22:46.841

0 n/A n/A 80

24151

File 3 original 20:00.000

940 674 (71.7%)

266 (28.3%)

2 (0.2%)

51772

filtered 20:00.000

940 674 (71.7%)

266 (28.3%)

1 (0.1%)

51799

MMAD

MMAD classified some of the detected humpback moans as calls of Minke whales. Minke whale call

features can resemble humpback calls, especially because of the high variability and diversity of

humpback calls. In our case, using less specific species classifications may be preferable, such as “low

frequency mysticete/baleen whale calls”. If species identification is necessary in a given project, the

program may need to be updated with humpback song samples and other marine mammal sounds

recorded at the project sites will be conducted prior to using it as an identification tool.


22

Warning lag times could be less than a minute, however, in one test file, lag time duration was

longer than two minutes in the original audio file, but a warning message already occurred within

the first minutes in the reverse filtered test file. In file 1, in contrast, lag times were lower in the

original audio file (table 9). Thus, more files need to be tested to determine whether inverse-filtering

the audio files prior to running it through the MMAD detection and classification program would

improve or negatively affect results. Similar to PAMGUARD, MMAD also produced false positive

detections for file 2, in which no marine mammal songs and clicks occurred (table 9). For audio file 2,

more false detections were reported by the program for the inverse filtered file than for the

untreated original file (table 9).

Table 9. Detection results in MMAD

Sound files HF

Mysticete

Minke

whale

Delphinid

clicking

Delphinid

whistles

Odontocete

Sperm /

Bottlenose

Whale

unclassified Warning

lagtime

File 1 original 1 2 1 0 0 0 0:00

filtered 1 2 2 0 0 0 0:21

File 2 original 1 16 14 0 0 0 n/A

filtered 1 32 30 0 1 0 n/A

File 3 original 1 13 13 0 0 0 2:21

filtered 1 13 14 2 0 0 0:21

2. Dolphin clicks and whistles North Carolina

PAMGUARD

For dolphin whistles, detection rates are similar to the ones for humpback calls. The lowest

detection rate was 66.7% (table 10), which was lower than detection rates of humpback calls (71.7%;

table 8). In all files, presence of whistling dolphins could be detected, however, some call sequences

were completely missed, as dolphins emit whistles in short sequences only. This is unlike song

sequences in humpback whales, which can last for up to 30 min (Payne & McVay 1971). All files

showed a relatively low signal to noise ratio. Moreover, signals were more distorted than humpback

calls, resulting in interrupted signals more difficult to detect. Signals were most likely more distorted

not only by the generally high ambient noise levels, and potentially longer recording distances, but


23

also by the fact that higher frequencies degrade more quickly with distance than lower frequencies

(Au & Hastings 2008). Detection rate could only be improved by shortening the duration; acoustic

signals need to be correlated between spectrogram windows, in contrast to moan detector settings

(Appendix 3). Consequently, frequency ranges were restricted to 3 kHz to 20 kHz to minimise false

positive detections caused by passing ships, which can contain harmonic low frequency elements in

their noise signature. In spite of these restrictions in the dolphin whistle detector settings, they still

resulted in relatively high numbers of false positive detections in test files recorded in Blyth, which

did not contain any marine mammals (see below, table 12).

PAMGUARD click detector algorithms also detected a high rate of Dolphin clicks. However, unlike

moan and whistle detections, determining numbers of false positive and missed detections is not as

straightforward, as click detections are not indicated in the spectrogram by the program, and log

files record detection times according to the time clicks were detected by the computer, which do

not correspond to the actual file duration.

Table 10: detection results in PAMGUARD

Sound files File

duration

Total calls Correctly

detected

Missed

calls

False

positive

detections

Clicks

detected

PeterUSWTR-070923-

115637 (3)

3:22.280 105

77 (73.3%)

28 (26.7%)

0

1743

PeterUSWTR-070923-

120000 (3)

10:00.000 127

108 (85.0%)

19 (15.0%)

1 (0.8%)

7473

PeterUSWTR-071017-

132000 (2)

2:21.168 48 32 (66.7%)

16 (33.3%)

1 (2.1%)

1417

PeterUSWTR-071112-

113000 (4)

10:00.000 206

181 (87.9%)

25 (12.1%)

2 (1.0%)

9636

MMAD

In three of four files, dolphin whistles and clicks were correctly detected (table 11). In one file, no

dolphin whistles and clicks were detected (table 11). Most likely, signal to noise ratio was too low

and the test file too short to allow the program to detect whistles and clicks at a confidence level of


24

50%, which is the set threshold for the MMAD program to log it as a detection, as single detections

are not reported. Thus, potential single detections could not be verified and evaluated.

Similar to the test files of humpback songs, classification seems a bit vague and misleading, as there

were no sperm whales (Physeter macrocephalus) and bottlenose whales (Hyperoodon sp.) present.

For these recordings as well, it would be preferable to report “odontocetes detected” instead.

Table 11. Detection results in MMAD

Sound files HF

Mysticete

Minke

whale

Delphinid

whistles

Delphinid

clicking

Odontocete

Sperm /

Bottlenose

Whale

unclassified Warning

lagtime

PeterUSWTR-

070923-115637 (3)

0 0 2 2 0 0 0:00

PeterUSWTR-

070923-120000 (3)

0 0 5 4 3 2 0:20

PeterUSWTR-

071017-132000 (2)

0 0 0 0 0 0 n/A

PeterUSWTR-

071112-113000 (4)

0 0 3 1 2 0 4:18

3. Ambient noise in Blyth

In test files 1 and 2, recordings have been tested in areas with marine mammals present in most of

the files. However, we also intended to test false positive detection rates in recordings of areas and

during times in which no vocalising marine mammals have been recorded. Thus, ambient noise files

recorded in Blyth were included in our analyses.

PAMGUARD

PAMGUARD algorithms detected relatively high numbers of moans and whistles, and very high

numbers of clicks (table 12). Moans were more often detected in the presence of ship noise, as

some harmonic elements of the ship noise signatures meet the criteria of correlated spectrogram

https://www.google.ch/search?rlz=1C1LENP_enCH517CH517&es_sm=93&q=entenwale+hyperoodon+ampullatus&stick=H4sIAAAAAAAAAGOovnz8BQMDQygHnxCXfq6-gVGBYWFxihKYnZSXU5VspGWZnWyln5SZn5OfXqmfX5SemJdZnBufnJNYXJyZlpmcWJKZn2eVk1-eWqSAKljs9OT4tj9Tb3JHHi_-vj90pbK-nUsUABexRMRyAAAA&sa=X&ei=XyxCUoftI8TQtQaEp4CQAw&ved=0CL0BEJsTKAIwEg


25

windows as specified by the moan detector. Thus, verifications by trained staff will be mandatory

before human activities are shut down or modified in case of using the device as a warning tool for

marine mammal presence. In case of using PAM devices for research purposes, parameters can be

adjusted to meet specific detection requirements, or additional detectors can be built in to be used

for specific audio file sequences. Most false positive detections were clicks. Clicks were most likely

detected because of regular occurrence of short mechanical noise of water banging against the

research vessel’s hull, noises emitted by invertebrates and/or escaping gas bubbles from the seabed,

and other sudden and short noise outbursts of ambient noises. This was still the case after filtering

out low frequency noises (Appendix 3), as most of these sounds were broadband, as well. As in

audio files recorded in Madagascar, reverse-filtering original recordings resulted in slightly lower,

but not qualitatively different detection rates.

Table 12. Detection results in PAMGUARD

Sound files File

duration

moan and

whistle

detector

Sperm wales

and dolphins

detector

Total detections

(without clicks)

Click

detector

3 July 14:20

original 29:26.073 101 0 101 23049

filtered 29:26.073 97 0 97 23055

3 July 14:46 original 23:55.078 75 2 77 11907

filtered 23:55.078 69 2 71 11905

3 July 15:10 original 22:56.561 42 25 67 9830

filtered 22:56.561 33 26 59 9815

3 July 15:43 original 32:12.447 7 0 7 6247

filtered 32:12.447 5 0 5 6248

3 July 16:10 original 25:47.709 2 29 31 11267

filtered 25:47.709 3 29 32 11268

3 July 16:40 original 22:00.000 0 13 13 5403

filtered 22:00.000 0 13 13 5397

MMAD

MMAD did correctly detect no marine mammal sounds in three of six audio files tested in Blyth

(table 13). In the three remaining test files, however, different types of marine mammal sounds

were still detected, ranging from moans to clicks. This is especially apparent in the first two test files,

corresponding to the first 30 minutes of recordings in Blyth, during which the research vessel


26

remained stationary with motors switched off and moved away from the sonobuoy during the

following 30 minutes. Thus, ship noise artefacts of waves hitting the ship’s hull, as well as the ship

motor driving away from the sonobuoy more closely matched detection parameters than the

naturally occurring ambient noise dominating recordings made after the first hour the sonobuoy was

deployed from the boat. This pattern is also replicated by PAMGUARD detections declining with time

after sonobuoy deployment.

Filtering sonobuoy recordings to get original frequency distributions did not minimise false positive

detection substantially in the three files marine mammal sounds were detected (table 13).

Table 13. Detection results in MMAD. Green cells indicate files for which correctly no marine

mammal calls were detected.

Sound files

and duration

Minke detected Delphinid clicking Odontocete Sperm /

Bottlenose Whale

unclassified

3 July 14:20

29:26.073

original 1 5 2 1

filtered 2 5 5 2

3 July 14:46

23:55.078

original 3 2 0 1

filtered 3 2 0 1

3 July 15:10

22:56.561

original 0 0 0 0

filtered 0 0 0 0

3 July 15:43

32:12.447

original 0 0 0 0

filtered 0 0 0 0

3 July 16:10

25:47.709

original 0 0 0 0

filtered 0 0 0 0

3 July 16:40

22:00.000

original 0 0 3 0

filtered 0 0 2 0

4. Conclusions

In general, both detection programs fulfilled their purpose to detect different types of marine

mammal calls, ranging from long, harmonic low frequency moans to higher frequency whistles and

short, sudden noise pulses in clicks. In all files, except for one file of a duration of 2:21 minutes by

MMAD, the programs correctly detected the presence of marine mammal sounds. Thus, it is

important to allow for enough assessment time before human activities in question are executed.


27

Missed detections of humpback calls in PAMGUARD mainly concerned shorter calls or less harmonic

calls, which were elements embedded in a song sequence. Thus, not detecting the presence of

humpback whales by missed detections of shorter and less harmonic calls is unlikely. However, if

dolphin whistles are missed, which was the case when distorted and occurring in low signal to noise

ratio, dolphin presence will more likely remain undetected, as dolphin whistles are emitted in much

shorter sequences with longer silent periods in between sequences (see above). Thus, especially in

high levels of ambient noise and if calls are highly distorted, the probability to miss dolphin presence

will increase. PAMGUARD detections seemed more sensitive than MMAD, as none of the files

containing marine mammal calls were undetected. However, KAON’s MMAD has been developed as

a warning tool, informing workers and shipping staff of the presence of marine mammals to adjust

human activities. Thus, detections are only reported in log files after reaching a predefined threshold

of certainty, which has been set at 50%, and has to reach 70% certainty to elicit a warning signal on

the screen. Thus, an assessment time of 2:21 minutes may not have been enough to allow the

program to detect sufficient numbers of recurring whistles to elicit a warning. Thus, optimal

certainty levels and minimum monitoring time before starting pile driving or drilling have to be

assessed prior to use it as a warning or detection system. However, as the program does not record

single detections in the log file and does not indicate detections in spectrograms, it is difficult to

determine causes for false positive or negative detections and thus evaluate optimal detection

settings.

The high number of click detections in PAMGUARD can be reduced by adding a click train identifier

and spatial information by using sonobuoy arrays with GPS localisers attached. This additional

information allows discrimination between random sudden noises, invertebrate clicks and moving

marine mammals. MMAD also detected marine mammal clicks in files which did not contain any,

however, algorithms and parameters for click detections are not declared, and thus, it is not clear

whether additional temporal or spatial information would increase detection precision. Evaluation of

false negative and false positive detection in MMAD is less straightforward to conduct than in

PAMGUARD, as the software does not log individual detections and does not indicate detections in

spectrograms by colouring detected elements.

In general, the many false negative and false positive detections show that it is difficult to find

generally applicable detection parameters to achieve low numbers of both. Thus, trained staff will

be needed to supervise at least the initial phase of using detection programs for monitoring marine

mammal presence and abundance. For PAMGUARD, it is recommendable that trained staff initially

adjusts and optimises detection parameters and possibly add more detectors to optimise detection


28

of specific marine mammal vocalisations, such as relatively short or less harmonic humpback moans.

For MMAD, it is recommendable that set detection parameters are adjusted by KAON using

recordings of the specific sites the program will be used. For both programs, it is important to verify

detections by checking the spectrograms before taking action or analysing data.

In general, MMAD comes with an easier to use interface, however, it leaves less flexibility to adjust

detection parameters or add specific detectors for specific user needs, as well as it is not possible to

assess detection precision as detailed as in PAMGUARD. However, as PAMGUARD is an open source

software and no full-time support staff is available, support may not be provided to a level and

extent KAON is able to offer. Developers of MMAD are highly flexible and approachable, and the

software can be modified to specific user needs. Thus, it will depend on the end user’s needs,

budget and expertise whether PAMGUARD or MMAD will be the preferable choice. For applications

with Ultra Electronics sonobuoys, a practicable solution may be to offer sonobuoys with the option

to integrate MMAD for end users not extensively trained on the use of marine mammal detection

programs. Another solution would involve investing more work in the development of an easier to

use user interface with detection algorithms and a module-like structure based on PAMGUARD, thus

allowing a higher level of user control over parameter settings and algorithms to integrate.

NERC MRE knowledge exchange internship as a tool to use knowledge acquired by

academic research for commercial interests

This internship gave me the unique opportunity to get an insight into a section of a commercial

organisation specialised in active and passive sonar. It also allowed me to view my research area of

effects of anthropogenic noise on aquatic organisms from a different angle and taught me the

different stages involved in developing and modifying a device for wider commercial use. The

internship also integrated me into the BARC consortium, a group of researchers and physicists of

commercial and academic background monitoring anthropogenic noise emission and investigating

its effect on marine ecosystems in a more holistic and integrative approach at an area, in which

construction and operation of an offshore windfarm is planned for 2014/2015.

The internship revealed that the majority of PAM users, as well as regulators and engineers, still

focus on anthropogenic impacts on marine mammals, ignoring effects on other animals, such as fish

and invertebrates, even though marine mammals heavily depend on them as their main food source.

Clearly, more work is needed to increase awareness and knowledge about impacts of anthropogenic


29

noise on other aquatic organisms than marine mammals. This will also be necessary in order to

move technical developments forward to integrate particle motion quantifications and other

measurements relevant to other organisms and to increase research projects with a more holistic

approach.

This internship showed that combining commercial work with research work can be difficult, as

careers in academia differ from careers in industry. For instance, proceeding in a research career

requires publication of original work in peer-reviewed journals driving the research field forward so

that research funding can be secured for specific projects of fixed time-scales of a few months to a

few years. Thus, researchers are moving from project to project, while business partners of some

companies tend to be employed with fixed contracts, determining the role of the employee within

the company rather than goals to be achieved by a specific project. Thus, work focus and timescales

can differ substantially between research and business partners potentially leading to conflicts of

interests.

Future projects will need to take this aspect into account when linking researchers with business

partners, to favour projects enabling researchers to feed their research results into applications of

everyday life (for example by using a device under development to generate new data), rather than

evaluating potentials of products for wider commercial use. This is especially important in more

applied research fields, such as conservation, in which researchers are already facing conflicts of

interest between the requirement of high quality research to deliver ground breaking findings and

applied research requiring systematic data on different aspects of an already known effect to map

species differences, the role of specific environmental contexts, and related topics to increase

specific knowledge needed for effective regulation of human activities.

Acknowledgements

I thank especially my internship supervisor Peter Dobbins for giving me the opportunity for this

project and his supervision, Steve Goodwin and the management of Ultra electronics for having me,

Lynne and Federica for providing marine mammal acoustic recordings, Michael Ainslie, Paul Lepper,

Dick Hazelwood, Nathan Merchant, and Joanne Garrett for acoustic discussions. I also thank Per

Berggren, Simon Laing, Silvana Neves, Danielle Harris and Doug Gillespie for discussions on marine

mammal detection, and Marc Armstrong for letting us have an adapted copy of the MMAD

computer program for evaluation.


30

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Appendix 1: Sonobuoy description

Original description of Ultra Electronics SSQ 906G LOFAR sonobuoys:


33


34

Appendix 2: SurveyMonkey questionnaire

Questionnaire published in SurveyMonkey

PAGE 1

Background Information

Thank you for joining in.

This survey is being conducted as part of an ongoing study to investigate the state of the art in

PAM systems and to find out where users consider the gaps in the available capability lie and

where further research and development should be aimed to meet their requirements.

In particular we would like to explore the ways in which military sonobuoys might be modified to

make them more useable for marine mammal monitoring and ambient noise measurement.

If you are a user of PAM equipment, we should be extremely grateful if you would complete this

survey. It shouldn’t take more than a few minutes and the information will be used for statistical

purposes only. Your name and contact details will not be associated with the results and will

certainly not be passed on to any third parties.

The survey begins here:

Question 1

1. Are you/your organisation

An academic institution?

A government research organisation?

A commercial research organisation?

An oil and gas exploration and production organisation?

A PAM service provider to the oil and gas industry?

A renewable energy organisation?

A PAM service provider to the renewable energy sector?

A regulatory organisation?

https://www.surveymonkey.com/MySurvey_EditPage.aspx?sm=4wr6TcEnnjKrp8%2fHeWuOacNsN7RijaW8MJGua0MzX%2fZ%2biv4jhvo8HrnBHgwoVTf%2b&TB_iframe=true&height=450&width=650


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A branch of the military?

An outreach or leisure organisation?

Other (please specify)

Question 2

2. How many PAM systems do you currently operate?

1

2-5

6-10

More than 10

Please give a brief description of these systems

Question 3

3. What, approximately, is the total use of these systems in a period of one year?

Less than a week?

A week to a month?

One to three months?

Three to six months?


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Six to nine months?

Nine months to a year?

More than a year?

PAGE 2

Your Application

With questions 4 and 5 we would like to learn precisely what sounds you want to monitor to assess your requirements for parameters such as bandwidth, sampling rate, and dynamic range.

Question 4

4. Are you interested in (choose all that apply)

Marine mammal vocalisations and clicks?

Non-marine mammal sound production?

Seismic noise?

Other natural abiotic noise?

Anthropogenic noise?

Acoustic environment characterisation?

Sound propagation model evaluation?


Question 5

5. If you are monitoring marine mammals, please tick the species of most interest (all that apply)

Porpoises


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Oceanic Dolphins

River Dolphins

Orcas

Sperm Whales

Beaked Whales

Belugas and Narwhals

Right and Bowhead Whales

Rorquals

Gray Whales

Harbour Seals

Grey Seals

California Sea Lions

Steller Sea Lions


PAGE 3

Proposed Specification

In questions 6 and 7, we list potential specifications for our proposed PAM buoy and the software

package that accompanies it. We would like to know how essential these features will be for your

purposes, along with suggestions for other features. All comments and suggestions will be

gratefully received.

Question 6

6. Here are potential outline specifications for the hardware in a new sonobuoy PAM system.

Please select "yes" if the respective feature will be essential to you, "no", if it is irrelevant to you,


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and "not essential", if it will be helpful for additional or future data collection, but not essential for

your project at the moment.

yes no not essential

Small, lightweight, hand deployed by one person

from small boat

Recoverable, reusable buoy with rechargeable

battery

GPS/compass positioning

Data logger recording temperature, salinity, pH

Directional hydrophones

Hydrophone depth selectable 15/30/60 m



Drogue and compliant hydrophone suspension to

minimise flow noise and surface motion

interference

HiFi quality signal 10Hz – 20kHz

Compressed signal 10kHz – 150kHz

FM radio telemetry – line of sight range 5km or

more for boat mounted receiver

Up to 100 selectable independent transmission

channels

On-board full bandwidth backup recording

Please comment on these suggestions or list any other hardware features you would consider

important


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Question 7

7. Here are potential outline specifications for the receiver/software in a new sonobuoy PAM

system. Please select "yes" if the respective feature will be essential to you, "no", if it is irrelevant to

you, and "not essential", if it will be helpful for additional or future data collection, but not essential

for your project at the moment.

yes no not essential

Choice of single or multi-channel (up to 8) FM receiver

Receiver output transferred directly to computer and

recorded on hard disk

Dedicated software package displays signal waveforms

and spectra for all channels or waveform, spectrum and

spectrogram for single selected channel

In-built detection algorithms of marine mammal

vocalisations

In-built species identification algorithms based on

clicks, whistles and other vocalisations in addition to

detection

Bearing localisation with single buoy

Localisation in range and bearing with three or more

buoys and range, bearing and depth with four or more

buoys

Plan and waterfall displays for detections


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Programmable alerts for presence of selected species

or any cetacean within selected range

Amendable settings during recording

sessions/interactive device control

Adjustable recording levels

Please comment on these suggestions or list any other features you would consider important

PAGE 4

Conclusion

Finally, we would like to hear any comments you have on passive acoustic monitoring in general

and the equipment currently available. Could you comment in particular on whether there are

specific features missing in the system you are currently using you would like to incorporate in

your future projects?

Question 8

8. Your comments please

Thank you, that is the end of the survey. If you are happy with your answers, please click the

“done” button to submit them.


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Appendix 3: Marine mammal detector settings

PAMGUARD settings:

Spectrogram engine settings underlying detection parameters:

Spectrogram settings Click removal filter settings

Spectral noise filter settings


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Settings for moan detector:

Detection parameter settings Filter and detection threshold settings

Settings for whistle detector

Detection parameter settings Filter and detection threshold settings

Click detector settings:


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Click high pass filter settings:

Click detection parameter settings (left to default settings):


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Spectrogram view

Click detector view:


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Settings for KAON MMAD

Settings were left at default:

odontoceteWhistleSensitivity = 1.0

odontoceteClickSensitivity = 1.0

spermClickSensitivity = 1.0

hfMysticeteWhistleSensitivity = 1.0

lfMysticeteWhistleSensitivity = 1.0

alarmThreshold = 70.0

warningThreshold = 50.0

odontoceteDisplayDecimation = 4

hfMysticeteDisplayDecimation = 2

lfMysticeteDisplayDecimation = 1

Documents

Automation and standardisation of a passive acoustic