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Audiogram. An audiogram is a graph that shows the audible threshold for standardized frequencies as measured by an audiometer. The Y axis represents intensity measured in decibels (dB) and the X axis represents frequency measured in hertz (Hz). [1] The threshold of hearing is plotted relative to a standardised curve that represents 'normal ...
Headphones are also known as earphones[1] or, colloquially, cans. [2] Circumaural (around the ear) and supra-aural (over the ear) headphones use a band over the top of the head to hold the drivers in place. Another type, known as earbuds or earpieces, [1] consists of individual units that plug into the user's ear canal.
See also: Plug (jewellery) Pre-molded earplugs (left), formable earplugs (center), and roll-down foam earplugs (right) An earplug is a device that is inserted in the ear canal to protect the user's ears from loud noises, intrusion of water, foreign bodies, dust or excessive wind. Since they reduce the sound volume, earplugs may prevent hearing ...
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The TV Parental Guidelines are a television content rating system in the United States that was first proposed on December 19, 1996, by the United States Congress, the American television industry, and the Federal Communications Commission (FCC). The guidelines went into effect by January 1, 1997, on most major broadcast and cable networks in ...
TL. v. t. e. Sound pressure or acoustic pressure is the local pressure deviation from the ambient (average or equilibrium) atmospheric pressure, caused by a sound wave. In air, sound pressure can be measured using a microphone, and in water with a hydrophone. The SI unit of sound pressure is the pascal (Pa).
The decibel originates from methods used to quantify signal loss in telegraph and telephone circuits. Until the mid-1920s, the unit for loss was miles of standard cable (MSC). 1 MSC corresponded to the loss of power over one mile (approximately 1.6 km) of standard telephone cable at a frequency of 5000 radians per second (795.8 Hz), and matched closely the smallest attenuation detectable to a ...
Equal-loudness contour. An equal-loudness contour is a measure of sound pressure level, over the frequency spectrum, for which a listener perceives a constant loudness when presented with pure steady tones. [1] The unit of measurement for loudness levels is the phon and is arrived at by reference to equal-loudness contours.