http://www.abc.net.au/pm/content/2007/s1964000.htm [1]
http://abc.net.au/news/stories/2007/06/28/1964944.htm [2]
Here is some research from NRDC that may help you.
http://www.nrdc.org/wildlife/marine/sonar.asp [3]

Each loudspeaker in the LFA system's wide array, for example, can generate 215 decibels' worth -- sound as intense as that produced by a twin-engine fighter jet at takeoff. Some mid-frequency sonar systems can put out over 235 decibels, as loud as a Saturn V rocket at launch. Even 100 miles from the LFA system, sound levels can approach 160 decibels, well beyond the Navy's own safety limits for humans.

Evidence of the harm such a barrage of sound can do began to surface in March 2000, when whales of four different species stranded themselves on beaches in the Bahamas after a U.S. Navy battle group used active sonar in the area. Investigators found that the whales were bleeding internally around their brains and ears. Although the Navy initially denied responsibility, the government's investigation established with virtual certainty that the strandings were caused by its use of active sonar

The Bahamas, it turned out, was only the tip of an iceberg. Additional mass strandings and deaths associated with military activities and active sonar have occurred in Madeira (2000), Greece (1996), the U.S. Virgin Islands (1998, 1999), the Canary Islands (1985, 1988, 1989, 2002, 2004), the northwest coast of the United States (2003) and coastal waters off North Carolina (2005). And in July 2004 researchers uncovered an extraordinary concentration of whale strandings near Yokosuka, a major U.S. Navy base off the Pacific coast of Japan. The Navy's active sonar program appears to be responsible for many more whale strandings than had previously been imagined.

During testing off the California coast, noise from a single LFA system was detected across the breadth of the North Pacific. By the Navy's own estimates, even 300 miles from the source these sonic waves can retain an intensity of 140 decibels -- still a hundred times more intense than the noise aversion threshold for gray whales. Many scientists believe that blanketing the oceans with such deafening sound could harm entire populations of whales, dolphins and fish.

Mid-frequency sonar can emit continuous sound well above 235 decibels, an intensity roughly comparable to a Saturn V rocket at blastoff. Marine mammals have extraordinarily sensitive hearing, and there is no scientific dispute that intense sonar blasts can disturb, injure, and even kill them. Whales exposed to high-intensity mid-frequency sonar have repeatedly stranded and died on beaches around the world; some bleeding from the eyes and ears, with severe lesions in their organ tissue. At lower intensities, sonar can interfere with the ability of marine mammals to navigate, avoid predators, find food, care for their young, and, ultimately, to survive.

"Military sonar needlessly threatens whole populations of whales and other marine animals," said Joel Reynolds, a senior attorney at NRDC. "In violation of our environmental laws, the Navy refuses to take basic precautions that could spare these majestic creatures. Now we're asking the courts to enforce those laws."

NOISE - AN NGO PERSPECTIVE.

Sue Arnold, Australians for Animals, PO Box 673, Byron Bay. Email:sarnold@byronit.com

In January 2003, Australians for Animals Inc. (AFA) filed a lawsuit against the US government to prevent a sonar experiment on thousands of Eastern Pacific gray whales, many of whom were heavily pregnant or accompanied by newborn calves.

The experiment, funded by the US Navy, was designed to broadcast mid, low and high frequency sonar at the whales for three weeks during their peak migration period. AFA won that lawsuit which was one of three critical legal challenges in the US on sonar issues. The National Resources and Defense Council (NRDC) was successful in significantly restraining the deployment of low frequency sonar by the US navy; the Center for Biological Resources succeeded in stopping an experiment by Columbia University and others using airgun arrays in the Gulf of California.

In January this year AFA filed a second lawsuit against the US government over a renewed attempt to experiment on Eastern Pacific Gray whales, this time broadcasting high frequency sonar.

We lost that legal challenge. However, as a result of these two major lawsuits, AFA has developed considerable expertise in the highly controversial complex issues surrounding noise in the ocean, particularly military sonar. Over the last three years, AFA has extensively lobbied the European Parliament and NATO on sonar issues.

As a result of many discussions with underwater acoustic specialists (who are as rare as the proverbial hens’ teeth) as well as many other highly qualified experts who have assisted our legal challenges by providing advice and/or affidavit evidence, AFA has identified major deficiencies in mitigation measures.

Many of these gaps have, of course, been identified by prestigious scientific organizations such as the National Academies of Science in the US and leading scientific organizations in Europe.

The level of anthropogenic noise in the sea has increased by a factor of ten in the last 40 years. Expansion in marine telemetry, marine exploration and increasing military exploitation of the sea threatens to exponentially increase the noise level again in the next five years.

At a Law of the Sea Conference convened by the University of Sydney Law School two years ago, some of the presentations related to present and proposed seismic exploration of the deep biosphere – a juggernaut in terms of current and potential seismic activity and future noise trauma.

Ascertaining the effects and ramifications of noise in the marine environment are issues beyond the lay person. It’s no exaggeration to say that the many of these complexities are beyond the average scientist. As a result , decisions on highly technical, deeply convoluted matters are taken against a background of far too many unknown factors by politicians and others who are unaware of the potential ramifications.

Questions raised by noise issues require a multi disciplinary approach by experts. AFA believes it is simply not possible to evaluate the effects of noise on marine mammals and the ocean environment without years of dedicated study and the establishment of global data bases which allow governments, scientists, researchers and NGO’s to evaluate the true extent of noise pollution.

At a time when there are currently no quick fix solutions for sick oceans, overfishing, pollution, global warming, pesticides, increased seawater temperature and a raft of major marine problems world wide , governments need to exercise the Precautionary Principle when it comes to dealing with noise issues. The focus needs to be on diminishing ocean noise rather than attempting to increase the sonic pollution currently inflicted on cetaceans and the marine environment.

Permitting experiments which allow benchmarks on noise level and frequency acceptability using animal avoidance behavior as a trigger factor is reckless. The current ‘flavor of the month’ mitigation measures – observers or slow ramp up procedures do absolutely nothing in terms of evaluating whether short or long term damage to cetacean populations has occurred. These measures are ‘feel good’ responses which cannot be supported logically or biologically.

Interpreting avoidance behavior as an indication that animals are protecting their hearing is an anthropomorphic interpretation. We have no idea whether whales know what is damaging to their hearing or not or how they would behave.

The most basic point surely is the fact that there is no means of establishing a controlled noise experiment. Noise is broadcast at whales without any human ability to test their individual hearing sensitivities pre experiment and post experiment.

Less than one year after the US Navy funded low frequency sonar experiments on Eastern Pacific gray whales during l997/98 massive die-offs occurred which continued for another three years. The population has dropped by 9,000 animals, nearly 40% of the species. We have no way of knowing whether these whales were impacted by sonar or climate change, lack of food or a combination of all factors.

Key Issues.

• Do we have the right to subject whales to noise trauma ?
• Every particle of factual evidence supports the contention that the higher mammalian vertebrates experience pain sensations at least as acute as our own.
• Cetaceans are sentient beings with the capacity to suffer. They cannot lose consciousness.
• Of some 80 species of extant cetaceans, audiograms are available for fewer than l0 species.
• Marine mammals as a group have functional hearing ranges of l0 Hz to 200 kHz..
• The impact of an acoustic source can be either on the hearing of a marine animal )( if the source is in the frequency band of efficient hearing for that animal) or ( at higher received levels) outside the hearing band ( by direct trauma due to acceleration/displacement of tissues due to acoustic pressure fluctuations as an acoustic wave passes by or perhaps enhanced by resonance of cavities in the lungs, intestines or sinus cavities and the vestibular system.

• Any reduction in hearing ability – whether by physical damage or masking of sounds – is likely to seriously compromise the viability of individuals and, potentially, populations..

• According to the experts, there is a very limited understanding of the use of sound by marine mammals and similarly limited understanding of the complexity of ecosystems on which whales depend; their migratory routes;
Breeding grounds;population dynamics; population numbers; status of prey; status of habitat.

• No attempts have been made to model the effects of noise on the habitat and ecosystem of marine mammals. Fish and other marine organisms respond to noise in both experimental systems and marine environment.

• No studies have been undertaken to ascertain whether noise effects prey species in a way that will increase or decrease their availability to predators

• Current mitigation measures do not take into account physiological and psychological stress. Nor is there provision for comparing the birth or breeding successes or even the intermediate term health of whales subjected to noise. These are basic issues.

• Being cognizant of a smorgasbord of sonar experiments targeting millions of cetaceans over the next five years, the lack of any global data base which indicates current status , numbers and frequency of sonar experiments, deployment of military sonar; seismic activities etc, there can be no accurate assessment of the amount of noise being visited on the ocean environment.

• A global data base on the number of super tankers and other noise creating ships etc. and their routes should be developed.

• International conventions such as the UN Law of the Sea and the International Whaling Convention need to be altered to reflect and deal with the serious nature of noise and its effects on cetaceans.

Other Considerations include:

• The timing of deliberate exposure whether it be military or seismic relative to important stages of annual cycles of affected animals; consideration of the proportion of total or local population affected, the amount of a particular part of a season should be considered.
• What other noise activities are taking place or have taken place in the region/area.
Internal factors
• Individual hearing sensitivity, activity pattern, motivational and behavioral state at time of exposure, past exposure which may have led to habituation or sensitization, individual noise tolerance, demographic factors
• External factors. Nonacoustic characteristics of sound source. Location as proximity to shoreline.

Geoacoustic Factors.

• Morphology of sea floor and any adjacent coast which might restrict the ability of animals to avoid high source levels.
• Predicting radius of impact. Whether there is spherical spreading transmission or cylindrical spreading transmission.
• What kind of beam source. Omni directional or wide beam sources will affect a much larger area than focused beam equipment with the same source level.

Issues raised by Professor John Potter, internationally recognized expert.

Professor Potter is an underwater acoustician who has published extensively. He set out some major concerns in discussions with AFA pre the January 2004 lawsuit.

a) Ambient noise in the marine environment is characterized by an extreme geographical and temporal variability, an enormously complex area.
b) The use of sound by marine mammals and the hearing sensitivity of many species is poorly understood or even completely unknown.
c) In practice, many different types of impacts may arise from long term and short term exposure.
d) There can also be indirect effects, mediated by the effects of noise on prey species.
e) The more subtle effects associated with long term exposure to low level noise are much more difficult to observe and quantify than the more obvious trauma associated with high level noise which causes direct tissue damage.
f) The potential for extremely long range propagation in the ocean and the long life span and slow reproductive rate of whales suggests a potential for effects on temporal and spatial scales far beyond those normally considered.

High Frequency Sonar.

High Frequency sonar is generally regarded by many experts as harmless to cetaceans because it quickly dissipates. However, as a result of our January 2004 lawsuit, AFA believes that high frequency sonar can be damaging to whales. Expert evidence indicated that Eastern Pacific Gray Whales may have hearing up to 300 kHz or are capable of feeling the vibrations or resonance of high frequency broadcasts, reacting adversely to this exposure.

Some experts informed AFA that high frequency sonar can travel much further than anticipated depending on several factors.

These factors are generally known as geoacoustic parameters.

The efficiency of the sound path can be affected by :-

*water temperature profiles;
*salinity;
*organisms in the water
*air bubbles of particulate matter in suspension
*background noise generated by wind and wave motion
*soniferous animals, pounding surf, grinding sea ice, ships, aircraft.

The National Academies report entitled Ocean Noise & Marine Mammals indicates that data on the physical properties of the ocean waters and the near sea floor sediments exist in detail in some places and are non-existent in others. Yet it is crucial to know details of the seafloor topography, water column, sound speed and absorption properties, seismic velocities, densities and absorption properties of the strata below the sea floor. According to the report there are few studies to relate specific dosage of sound to effects likely to be of biological significance.

In continental shelf waters, geoacoustic parameters such as compressional sound speed, attenuation and sediment density can significantly affect the acoustic propagation. Variability introduced in these parameters can substantially affect model predictions, propagation loss can be incorrect by as much as 20dB as a result of inaccurate geoacoustic parameters.

SUMMARY.

Noise in the marine environment and its impact on marine mammals and their ecosystems is one of the most important environmental issues of our time. It is therefore incumbent on governments to protect the health of the world’s oceans, our very survival depends on that health.

The Australian Navy does not use low frequency sonar and has adopted modest mitigation measures. Seismic industry activities operating within Australian waters appear to be largely self regulating although bound by the provisions of the EPBC Act and certain guidelines. AFA believes that current mitigation measures adopted by the Navy and the seismic industry are ineffective and need to be significantly strengthened.

Australia is regarded as a world leader in whale conservation. The federal government needs to develop a comprehensive data base of all noise activities in Australian waters and to promote benign research into the effects of noise on cetaceans.

Above all, Australia could make a stand internationally for diminishing noise in the world’s oceans at the same time supporting the global adoption of the Precautionary Principle in relation to noise in the marine environment.