How Fish Hear

2017-02-08T16:40:49+00:00

How Fish Hear Not all fish have the same morphology. Fish can have as many as 3 systems for hearing. The lateral line is a line of nerves (neuromasts) that extend out of the side of the body of a fish. These nerves sense “particle motion” or the physical movement of the water. The swim [...]

Brief Intro to the Hearing Systems of Fish

2017-02-08T16:40:49+00:00

Brief into to the Hearing Systems of Fish You can determine a lot about a fish’s hearing from their environment.  Fish in turbid, dark environments can have very developed hearing systems.  Fish that are more sedentary and rely on disguise may have only rudimentary hearing systems because they don’t need to hear. (Instead their sense [...]

Intro to Odontocetes & Mysticetes

2017-02-08T16:40:49+00:00

Odontocetes & Mysticetes Cetaceans are animals that were amphibious who came back into the water. There are two families of whales the Mysticetes (mustache whales) and the Odontocetes, the toothed whales.   Main Points: There are 2 “sub-orders” of cetaceans: odontocetes and mysticetes. Odontocetes: There are two families of odontocetes distinguished by the shape of [...]

Skull Morphology

2017-02-08T16:40:49+00:00

Skull Morphology All vertebrates have a middle ear and inner ear systems in an auditory bulla or otic capsule that is variously fused, embedded, or attached to their skulls. The morphology, or variations in how these attachments evolved tells us much about the particular animal’s adaptations to their environment. While we are still learning about [...]

How Hearing Works

2017-02-08T16:40:49+00:00

How Hearing Works Hearing has evolved in animals based on the acoustical information they need to determine their dynamic relationships with their surroundings. Hearing adaptations reflect predator/prey relationships, community settings, and the strength or suitability of other perceptions. For example: you are likely to find more complex hearing adaptations in habitats that are less conducive [...]

Acoustic Harassment Devices

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2016-06-14T17:45:24+00:00

Audiograph: Acoustic Harassment Device Marine aquaculture is a rapidly developing field. The protein conversion inefficiencies notwithstanding, the sea-pens and enclosures are also targets for marine life – mostly seals and sea lions, that don’t miss the fact that if they can broach the barriers they could be on “easy street.” In order to [...]

Offshore Energy: Wind and Tidal Swings

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2016-05-24T21:19:04+00:00

Audiograph: Wind Turbine Audiograph Increasingly energy is being converted from natural sources such as wind and tidal swings. While these sources are marked improvement over fossil fuels in terms of global impacts, offshore energy comes with its own set of problems; noise being one. From installation through operation we can anticipate various noises [...]

Underwater Communication Signals

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2017-02-08T16:40:49+00:00

Audiograph: HLF 5 Active Sonar: Frequency Shift Key communication sonar Audiograph: M-sequence communication sonar The ocean is largely opaque to radio frequency energy so underwater communication either needs to be transmitted by wire, or by sound. Increasingly as military and industrial processes take place in the ocean they will use various [...]

Mid-Frequency Sonar

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2016-05-24T21:06:11+00:00

Audiograph: Haro Straight, USS Shoup sonar test event Audiograph: C-53 Sonar from Haro Straight Mid-Frequency military sonar has proven one of the most troubling acoustical assaults on marine life, particularly associated with catastrophic strandings of marine mammals. The most common victims have been odontocetes – toothed whales and dolphins, but Minke [...]

Low-Frequency Sonar

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2016-05-24T21:04:30+00:00

Audiograph: Airguns and Echosounders Audiograph: Low-Frequency Active Sonar simulation Low-Frequency Sonar came out of the work of the brilliant physical oceanographer Walter Munk. He had been working on the transmission of ‘phase coherent’ long wavelength signals since 1978. Taking advantage of the efficiency with which water transmits acoustical energy, and the [...]