Glossary - C
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C

C-weighting
a frequency weighting function that was originally designed to predict the human ear’s sensitivity to tones at high noise levels; however, nearly all noise measurements for hearing conservation are measured with A-weighting; units dB(C) or dBC.
caldera
depression formed at the summit of a volcano
California mantis shrimp
Hemisquilla californiensis
California sea lion
Zalophus californianus
callosities
thick, white patches of hardened skin, called chitin, that are covered with tiny crustaceans, called "whale lice." These patches are found on the heads, over the eyes, and around the mouths of whales, particularly right whales and bowhead whales. The patterns created by the patches are used by marine mammal researchers to identify individual whales.
calve
the sudden release and breaking away of a mass of ice from a glacier, iceberg, ice front, or ice shelf.
canine teeth
sharp, fang-like teeth adapted for capturing and penetrating prey
Cape fur seal
Arctocephalus pusillus
capillaries
the smallest of the network of blood vessels throughout an organism
carapace
hard, protective outer case or shell that covers the back or part of the back of an animal (as in a turtle or a lobster).
cardioid
a heart-shaped curve generated by a point on a circle that rolls without slipping on another fixed circle of the same diameter.
Caribbean spiny lobster
Panulirus argus
caudal peduncle
The narrow part of the body to which the caudal fin (or tail) attaches to the body.
cavitation
formation of gas-filled cavities in liquids in motion when the pressure is reduced to a critical value. Low pressure regions are often created by rotating ship propellers. As the propellers rotate, bubbles form in the water. A loud acoustic sound is created when these bubbles collapse.
central nervous system
the complex of nerve tissues that controls the activities of the body. In vertebrates it comprises the brain and spinal cord.
cephalopod
class of soft-bodied invertebrates that includes octopuses, squids, nautiluses and cuttlefishes. These animals have many arms and well-developed eyes.
cetacean
order of mammals that includes whales, dolphins and porpoises
characteristic impedance
a material property of a medium, defined as the density of the medium times the sound speed through the medium.
cheliped
the first two claws of a crab. A male fiddler crab has an enlarged claw or cheliped.
chordotonal organs
for Crustaceans, they are located at the joint segments and they serve as mechanoreceptors (sensory organs).
cichlids
family (Cichlidae) of freshwater fishes found throughout tropical and subtropical waters of the Americas, Africa and parts of Asia
cilia
hair cells of the neuromast
cleaner shrimp
Periclimenes longicarpus
click
a short pulse of sound, often used to describe pulses produced by toothed whales for echolocation.
click train
rapid sequence of clicks, produced by whales and dolphins, that are associated with echolocation. The clicks are emitted from the melon of the whale.
climatologist
a scientist who studies climate
clupeids
fish belonging to the herring family
coalesced
fused or grown together
cochlea
the spiral-shaped chamber within the inner ear that transforms sound waves into nerve impulses. The cochlea is a fluid-filled organ that houses many structures related to hearing, including the basilar membrane and the organ of Corti. It is considered "the organ of hearing."
cod
Gadus morhua
coda
patterned set of clicks produced by sperm whales. Each sperm whale may have its own individually distinct coda pattern.
common carp
Cyprinus carpio carpio
common dolphin
Delphinus capensis (long-beaked common dolphin), Delphinus delphis (short-beaked common dolphin)
common octopus
Octopus vulgaris
common prawn
Palaemon serratus
communication space
the area over which one individual can detect the signal of another.
Comprehensive Nuclear-Test-Ban Treaty
The Comprehensive Nuclear-Test-Ban Treaty (CTBT) bans all nuclear explosions on Earth whether for military or for peaceful purposes. It was adopted by the United NAtions General Assembly in 1996. The treaty contains provisions for monitoring which include acoustic monitoring. The treaty is not yet in force because it has not been ratified by some nations.
compression wave
a wave propagated by compressing the medium; longitudinal wave
Computerized Tomography (CT)
method of constructing a three-dimensional image of an object from narrow x-ray beams that are passed through the object from several angles
conductive hearing loss
transmission of sound to the inner ear is impaired
conductivity-temperature-depth (CTD)
Oceanographic tool used to determine the essential physical properties of sea water: conductivity (salinity), temperature, and depth. Depth measurements are derived from measurement of hydrostatic pressure and salinity is measured from electrical conductivity. The CTD may be incorporated into an array of sampling bottles referred to as a "carousel" or "rosette". The sampling bottles close at predefined depths, triggered either manually or by a computer, and the water samples may subsequently be analyzed further for biological and chemical parameters.
conspecific
animals (or plants) belonging to the same species
controlled experiments
tests or experiments used to demonstrate a cause and effect relationship. Results from tests performed on an experimental sample (which receives a particular treatment) are compared to those from a control sample (which does not receive the treatment) with all other aspects of the experiment remaining the same between the two groups.
convergence zone
a region of high intensity created by the refraction of sound waves in the SOFAR channel transmitted by a source near the sea surface. Convergence zones occur at about the same depth as the source approximately every 50-60 km away from it.
coronet
a star-shaped ossified crest mounted in a socket-like base
correlation
a relationship between two variables during a period of time, especially when there is a close match between the variables' movements. Correlation may indicate association between the variables; however, it does not mean that there is a cause and effect relationship.
corticosteroid
a type of hormone produced by the adrenal glands. Corticosteroids levels may be elevated as a response to stress.
courtship
behaviors in animals, that are used to initiate mating
critical habitat
specific geographic area(s) that contains features essential for the conservation of a threatened or endangered species and that may require special management and protection.
crustaceans
a class of mainly aquatic, gill-breathing arthropods such as crabs, lobsters, shrimp, and barnacles. They usually have a hard exoskeleton and two pairs of antennae.
cupula
gel-like cover of cilia in the neuromast
Cuvier's beaked whale
Ziphius cavirostris
cylindrical spreading
energy spreading out from a sound source in the shape of a cylinder; no energy radiates above the top or below the bottom of the cylinder