Underwater Acoustics for Biologists and Conservation Managers: A comprehensive tutorial designed for environmental professionals. This three-day course is designed for biologists, and conservation managers, who wish to enhance their understanding of the underlying principles of underwater and engineering acoustics needed to evaluate the impact of anthropogenic noise on marine life. This course provides a framework for making objective assessments of the impact of various types of sound sources. Critical topics are introduced through clear and readily understandable heuristic models and graphics.

1. Professional Development Short Course On:
Underwater Acoustics for Biologists and Conservation Managers
Instructors:
Dr. William T. Ellison
Dr. Orest Diachok
ATI Course Schedule: http://www.ATIcourses.com/schedule.htm
ATI's Underwater Acoustics for Biologists: http://www.aticourses.comunderwater_acoustics_for_biologists_and_conservation_managers.htm

2. Underwater Acoustics for Biologists and Conservation Managers
A comprehensive tutorial designed for environmental professionals
NEW!
Summary
This three-day course is designed for biologists, and
conservation managers, who wish to enhance their
understanding of the underlying principles of June 15-17, 2010
underwater and engineering acoustics needed to Silver Spring, Maryland
evaluate the impact of anthropogenic noise on marine
life. This course provides a framework for making $1590 (8:30am - 4:30pm)
objective assessments of the impact of various types of
sound sources. Critical topics are introduced through "Register 3 or More & Receive $10000 each
clear and readily understandable heuristic models and Off The Course Tuition."
graphics.
Course Outline
Instructors 1. Introduction. Review of the ocean
Dr. William T. Ellison is president of Marine Acoustics, anthropogenic noise issue (public opinion, legal
Inc., Middletown, RI. Dr. Ellison has over findings and regulatory approach), current state
45 years of field and laboratory experience of knowledge, and key references summarizing
in underwater acoustics spanning sonar scientific findings to date.
design, ASW tactics, software models and
biological field studies. He is a graduate of 2. Acoustics of the Ocean Environment.
the Naval Academy and holds the degrees Sound Propagation, Ambient Noise
of MSME and Ph.D. from MIT. He has Characteristics.
published numerous papers in the field of acoustics and is
a co-author of the 2007 monograph Marine Mammal
3. Characteristics of Anthropogenic Sound
Noise Exposure Criteria: Initial Scientific Sources. Impulsive (airguns, pile drivers,
Recommendations, as well as a member of the ASA explosives), Coherent (sonars, acoustic modems,
Technical Working Group on the impact of noise on Fish depth sounder. profilers), Continuous (shipping,
and Turtles. He is a Fellow of the Acoustical Society of offshore industrial activities).
America and a Fellow of the Explorers Club.
4. Overview of Issues Related to Impact of
Dr. Orest Diachok is a Marine Biophysicist at the Johns
Hopkins University, Applied Physics Laboratory. Dr.
Sound on Marine Wildlife. Marine Wildlife of
Diachok has over 40 years experience in acoustical Interest (mammals, turtles and fish), Behavioral
oceanography, and has published Disturbance and Potential for Injury, Acoustic
numerous scientific papers. His career has Masking, Biological Significance, and Cumulative
included tours with the Naval Effects. Seasonal Distribution and Behavioral
Oceanographic Office, Naval Research Databases for Marine Wildlife.
Laboratory and NATO Undersea Research
Centre, where he served as Chief 5. Assessment of the Impact of
Scientist. During the past 16 years his work Anthropogenic Sound. Source characteristics
has focused on estimation of biological parameters from (spectrum, level, movement, duty cycle),
acoustic measurements in the ocean. During this period Propagation characteristics (site specific
he also wrote the required Environmental Assessments for character of water column and bathymetry
his experiments. Dr. Diachok is a Fellow of the Acoustical
Society of America. measurements and database), Ambient Noise,
Determining sound as received by the wildlife,
absolute level and signal to noise, multipath
What You Will Learn propagation and spectral spread. Appropriate
• What are the key characteristics of man-made metrics and how to model, measure and
sound sources and usage of correct metrics. evaluate. Issues for laboratory studies.
• How to evaluate the resultant sound field from 6. Bioacoustics of Marine Wildlife. Hearing
impulsive, coherent and continuous sources.
Threshold, TTS and PTS, Vocalizations and
• How are system characteristics measured and
calibrated.
Masking, Target Strength, Volume Scattering and
Clutter.
• What animal characteristics are important for
assessing both impact and requirements for 7. Monitoring and Mitigation Requirements.
monitoring/and mitigation. Passive Devices (fixed and towed systems),
• Capabilities of passive and active monitoring and Active Devices, Matching Device Capabilities to
mitigation systems. Environmental Requirements (examples of
From this course you will obtain the knowledge to passive and active localization, long term
perform basic assessments of the impact of monitoring, fish exposure testing).
anthropogenic sources on marine life in specific ocean
environments, and to understand the uncertainties in 8. Outstanding Research Issues in Marine
your assessments. Acoustics.
Register online at www.ATIcourses.com or call ATI at 888.501.2100 or 410.956.8805 Vol. 102 – 11

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4. Introduction
• Student Introduction
• Identify key Interests of Students
• Course Objectives
– Introduction to Marine Mammals from an Acoustic Viewpoint
• their sounds & hearing and
• how they are affected by and respond to anthropogenic sounds
– Methods and Tools for Bioacoustic Issues
• Metrics
• Examples of past/present research (may do last!)
– Bowhead Whales in the Arctic (1980’s)
– SOCAL SRP Tagged Fin Whale (1990’s)
– Stellwagen Bank NOPP (Today) W
– Tools and Concepts for Evaluating Impacts on the Marine
Environment
• Life Cycle Approach to Environmental Compliance (EC)
• The Utility of Modeling as an EC Tool
• Assessment Techniques

5. Key Reference Material
• Southall, et al. 2007, Marine Mammal Noise Exposure Criteria: Initial
Scientific Recommendations
• Richardson, et al.1995, Marine Mammals and Noise
• Urick, (any ed.) Principles of Underwater Sound for Engineers
• Harris (ASA Reprint) Handbook of Acoustical Measurements and
Noise Control
• Crocker (ASA Pub), Encyclopedia of Acoustics
• Kryter (any ed.) The Effects of Noise on Man
• Bregman, Acoustic Scene Analysis, MIT Press
• ANSI STD’s
– ANSI S12.7 – Methods for measurement of impulse noise
– ANSI S1.1 – Acoustical Terminology
– ANSI S1.42 – Acoustic Weighting Networks
• NRC Reports
– 2000 Marine Mammals and Low Frequency sound
– 2003 Ocean Noise and Marine Mammals
– 2005 Marine Mammal Populations and Ocean Noise: Determining when
Noise causes Biologically Significant Effects

6. Part I - Introduction to Marine
Mammals from an Acoustic
Viewpoint*
*Primary Reference is Southall, et al. 2007
*Primary Reference is Southall, et al. 2007

7. Mystery Sound

8. Whale Sounds
&
Videos
{Separate Media}

9. Marine Mammal Hearing
o One of the major accomplishments in [Southall, 2007] was the derivation
of recommended frequency-weighting functions for use in assessing the
effects of relatively intense sounds on hearing in some marine mammal
groups. It is abundantly clear from:
o measurements of hearing in the laboratory,
o sound output characteristics made in the field and in the laboratory,
and
o auditory morphology
o that there are major differences in auditory capabilities across marine
mammal species (e.g., Wartzok & Ketten, 1999).
o Most previous assessments of acoustic effects failed to account for
differences in functional hearing bandwidth among marine mammal
groups and did not recognize that the ‘nominal’ audiogram might be a
relatively poor predictor of how the auditory system responds to relatively
strong exposures.

10. Marine Mammal Hearing
• [Southall, 2007] delineated five groups of functional
hearing in marine mammals and developed a
generalized frequency-weighting (called “M-
weighting”) function for each.
• The five groups and the associated designators are:
– (1) mysticetes (baleen whales), designated as “low-
frequency” cetaceans (Mlf);
– (2) some odontocetes (toothed whales) designated as “mid-
frequency” cetaceans (Mmf);
– (3) odontocetes specialized for using high frequencies, i.e.,
porpoises, river dolphins, Kogia, and the genus
Cephalorhynchus (Mhf);
– (4) pinnipeds, (seals, sea lions and walruses) listening in
water (Mpw); and
– (5) pinnipeds listening in air (Mpa).

11. Frequency Weighting
“In assessing the effects of noise on humans, either an A- or C-weighted curve is applied to correct the sound level
measurement for the frequency-dependent hearing function of humans. Early on, the panel recognized that
similar, frequency-weighted hearing curves were needed for marine mammals; otherwise, extremely low- and
high-frequency sound sources that are detected poorly, if at all, might be subject to unrealistic criteria.” Southall et
al. (2007).
Figure 3.1a below illustrates the A-, B- and C-weighting curves for human hearing (Harris, 1998, Figure 5.17).
Weighting Curves
Weighting Curves
for Human Hearing
for Human Hearing
Metrics.
Metrics.
C-Filter is used as
C-Filter is used as
Functional Basis for
Functional Basis for
the M-Weighting
the M-Weighting
Filter for Marine
Filter for Marine
Mammals
Mammals

12. M-Weighting Southall, 2007 - -For injury
Southall, 2007 For injury
assessment, behavior not
assessment, behavior not
addressed. Issue!
addressed. Issue!
For Marine Mammal
For Marine Mammal
Hearing Metrics: same
Hearing Metrics: same
mathematical structure
mathematical structure
as the C-weighting
as the C-weighting
used in human hearing,
used in human hearing,
Odontocetes
Mysticetes

13. M-Weighting
The M-weighting Southall, 2007 developed for the five functional marine
mammal hearing groups has the same mathematical structure as the C-weighting used
in human hearing, which reflects the fact that sounds must be more intense at high and
low frequencies for them to be perceived by a listener as equally loud. This weighting is
most appropriate determining the effects of intense sounds, i.e., those with equal
loudness to a tone 100 dB above threshold at 1000 Hz. The M-weighting was designed
to do much the same for the different marine mammal groups with the only difference
being the low- and high-frequency cutoffs. The M-weighting for marine mammals, like
the C-weighting used in humans, rolls off at a rate of 12-dB per octave.
The general expression for M-weighting [M(f)], using estimated frequency cut-
offs for each functional marine mammal hearing group, is given as:
R( f )
M ( f )  20 log10 (7) eq.
max{ R( f ) }
2 2
f high f
R( f ) 
( f 2  f high )( f 2  f low )
2 2 (8) eq.
The estimated lower and upper “functional” hearing limits are designated (flow and
fhigh) for each of the five functional marine mammal hearing groups

14. M-Weighting (Application)
The application of M-
-9dB Weighting is most
easily conceived of as a
simple filter. For
example, if a Hi-Freq
Cetacean was exposed
to a sound at 100Hz,
the effective level for
assessment purposes
could be reduced by
9dB.
100 Hz

15. Part II - Methods and Tools for
Bioacoustic Issues
& Analysis

16. Bioacoustic metrics and field work
Sound source characterization
– Sound Types
• Pulsed
• Non-Pulsed
• Continuous
– Issues include:
• Effective SL as most are not point sources
(SL=RL+TL)
• Energy (Time integration), Peak, RMS???
• Band measurements (M-Filter, 1/3 Octave….)

17. Sound source characterization
• Sound Types need to be broken down in categories:
– Pulsed
– Non-Pulsed
– Continuous
• Why?
– Experience has shown that these sound types result in different
effects for both injury and behavior
– Need different metrics like:
• SEL,
• Peak Pressure or RMS,
• Freq. Weighting,
• Barotrauma (Acoustic impulse Pa-Sec)

18. Pulse vs. Non-Pulse*
•The term PULSE is used here to describe brief, broadband,
atonal, transients (ANSI 12.7, 1986; Harris, Ch. 12, 1998),
which are characterized by a relatively rapid rise time to
maximum pressure followed by a decay that may include a
period of diminishing and oscillating maximal and minimal
pressures. Examples of pulses are explosions, gunshots,
sonic booms, seismic airgun pulses, and pile driving strikes.
•NON-PULSE (intermittent or continuous) sounds can be tonal,
broadband, or both. They may be of short duration, but without
the essential properties of pulses (e.g., rapid rise-time).
Examples of anthropogenic, oceanic sources producing such
sounds include vessels, aircraft, machinery operations such as
drilling or wind turbines, and many active sonar systems. As a
result of propagation, sounds with the characteristics of a pulse
at the source may lose pulse-like characteristics at some
(variable) distance and can be characterized as a non-pulse by
certain receivers. (This last is a key issue to be analyzed)
*As defined in Southall, 2007 Criteria Paper

19. Metrics
Peak sound pressure is the maximum absolute value of the instantaneous sound
pressure during a specified time interval and is denoted as Pmax in units of
Pascals (Pa). It is not an averaged pressure. Peak pressure is a useful metric for
either pulses or non-pulse sounds, but it is particularly important for characterizing
pulses (ANSI 12.7, 1986; Harris, Ch. 12, 1998). Because of the rapid rise-time of
such sounds, it is imperative to use an adequate sampling rate, especially when
measuring peak pressure levels (Harris, Ch. 18, 1998).
mean-squared pressure (rms) is the average of the squared pressure over some
duration. For non-pulse sounds, the averaging time is any convenient period
sufficiently long to permit averaging the variability inherent in the type of sound. To
be applied with care to pulse sounds
SPL - Sound pressure levels are given as the decibel (dB) measures of the
pressure metrics defined above. The root-mean-square (rms) sound pressure
level (SPL) is given as dB re: 1 µPa for underwater sound and dB re: 20 µPa for
aerial sound. Peak sound pressure levels (hereafter “peak”) are given as dBpeak
re: 1 µPa in water and dBpeak re: 20 µPa in air. Peak-to-peak sound pressure
levels (hereafter “peak-peak”) are dBp-p re: 1 µPa in water and dBp-p re: 20 µPa
in air.

20. Metrics
Sound exposure level (SEL) is the decibel level of the cumulative
sum-of-square pressures over the duration of a sound (e.g., dB re: 1
μPa2-s) for sustained non-pulse sounds where the exposure is of a
constant nature (i.e., source and animal positions are held roughly
constant), .
For pulses and transient non-pulse sounds, it is extremely useful
because it enables sounds of differing duration to be related in terms of
total energy for purposes of assessing exposure risk.
The SEL metric also enables integrating sound energy across multiple
exposures from sources such as seismic airguns and most sonar
signals.
 N T 2 
   pn (t ) dt 
 n 1 0 
SEL  10 log10  2 
 p ref 

 


21. Source Characterization (SL)
• Distributed sources (arrays) require
special consideration
– Major issue in understanding near field
exposure for large aperture arrays such as
LFA and seismic (early point of contention!)
– Modeling requires near/far field analysis
– Particle velocity considerations (seismic
example)
A Tool that engineers
A Tool that engineers
can bring to the table!
can bring to the table!

22. SL in the Near field/Far field Regions
[RN-RC ]< /4 SL=SLE+20Log(NFF)
where:
RN = [RC2+HN2]1/2
NFF = # of elements in the
HN Far Field
RC
Far Field Criteria for a
Vertical Line Array of Sources:
RFF = RC
SLE = SL of when [RN-RC ]< /4
ea element

23. 2. Near Field Receive Level Analysis - The analysis required to evaluate the near field of a VLA source can be easily
accomplished by replacing each nth element of the N element array with an equivalent point source,1
Pn[R] = {PE/|R-Rn|}{cos(k|R-Rn|) + i sin(k|R-Rn|)} (3)
where,
PE = 10exp[SLE/20] (4)
The resultant pressure, P[R] at the field point R is given by:
P[R] =  Pn[R], n=1,N (5)
Note that this is a complex term, and the resultant receive level value, RL in dB, can be arrived at by taking:
RL=20Log(|P[R]|) (6)
The difference, RL, between that value and that approximated by simple spherical spreading from the center of the
array using the far field SL is given by:
RL= RL-[SL-20Log(|R|)] (7)
The geometry used to evaluate the VLA and relevant coordinate system is shown in Figure 1 along with an example
for an array of 4 elements.
R = xiX + yiY + ziZ (8)
1
M.C. Junger, D.L. Feit, Sound, Structures, and Their Interaction, MIT Press, Cambridge, 1972,
Section 3, Applications of the Elementary Acoustic Solutions, et seq.

24. nth Z
element
R-R Y Fig 1: Cartesian
n Coordinate System
With example showing an N
element VLA with spacing=d
zn  R
z
iY
d iZ
r 
X
iX
R=xiX+yiY+ziZ
R= zniZ
x=rcos()
y=rsin()
z=Rcos(
r=Rsin(

25. Subaperture Shortcut to Array Near-Field Effects
The near field value can also be evaluated in an approximate way by determining the far field range
of each of the embedded subapertures in the array. For example, the far field range for array subapertures
from 4 elements to 18 is shown in Table 2-1:
Table 2-1 Subaperture Far Field Effects
No. Elements Rff 20Log(N/Rff)
4 6 -4
6 18 -10
8 35 -13
10 58 -15
12 87 -17
14 122 -19
16 162 -20
18 208 -21
20 260 -22
In Table 2-1, RFF was calculated from Eqn 1 for a typical LFAA VLA. The third column in Table 2-1
demonstrates the difference between the element source level and the on-axis receive level calculated by
using the subaperture method:
RL[RFF(NS)] = SLE + 20Log(NS) - 20Log(RFF) [Column 3 of Table 2-1]

26. Effective SL in the Near field & Fairfield Regions
Near field Region
•Diffuse unfocused beam
Farfield Region
•Receive Level near HLA = SLE
•Focused beam
•Cannot Measure Effective SL of
•RL=SLE+20Log(NE)-TL
the array
•Can Measure ‘Effective SL’ of
•RL not equal to Far-Field SL-TL
the array
•Velocity component 3 dimensional
•RL equals SL-TL
& computed by dP/dx, dP/dy, dP/dz
RFF
Horizontal Line
Array (HLA)
Source, Example
shows 4 elements
Range

27. Transmitted Near Field Pressure Sound Levels from a
lateral Distance in meters
Low Frequency Multi-Element HLA
150
100
50
Array Main Response Axis
Horizontal
Axis
0
0 100 200 300
Vertical Range in meters
Receive Level relative to the SL of an individual element, SLE
0 -20 -40 -60 -80

28. Fig 2-2: Comparing Actual Coherent Array Levels on Axis with
the Far Field Approximation & a SubAperture Approximation
(Element SL=0dB, 20 Elements, Narrowband Signal)
30
20*log(|Coherent sum|)
20
20log(N)-20Log(R)
10
Sub Aperture Approx
Receive Level in dB
0
-10
-20
-30
-40
-50
-60
1.0 10.0 100.0 1000.0
Range in meters

29. Particle velocity considerations
(single element seismic example)
Particle velocity in the radial Particle velocity normal to the radial
direction for the 50Hz source at 7m direction for the 50Hz source at 7m
depth, log scale in cm/sec, i.e. @ depth, log scale in cm/sec, i.e. @
color scale = -1, uR = 1x10-1 cm/sec color scale = -1, Ut = 1x10-1 cm/sec
Based on same analytical technique used for line array with MATLAB Graphics
Based on same analytical technique used for line array with MATLAB Graphics

30. Examples of
Bioacoustic Research
(Past & Present)
–Bowhead Whales in the Arctic
(1980’s)
–SOCAL SRP Tagged Fin Whale
–Stellwagen Bank NOPP (Today)

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Underwater Acoustics for Biologists and Conservation Managers
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