As a result, most of the energy entering normal ears through the eardrum is transmitted into motion of the stapes and stimulation of the inner ear system.
The ossicles produce a lever action that further amplifies the pressure. The effective pressure (force per unit area) is increased by this amount. The area of the eardrum is about 17 times larger than the oval window (see inner ear). The middle ear enhances the transfer of this acoustical energy in two ways: The primary function of the middle ear is to transform the vibrating motion of the eardrum into motion of the stapes. The malleus (hammer), incus (anvil), and stapes (stirrup) make up the ossicles. The actual distance that the membrane moves is incredibly small (as little as one-billionth of a centimeter). The eardrum vibrates in response to sound pressure waves. It is somewhat cone-shaped in appearance, and is about 17.5 mm in diameter. The eardrum separates the outer ear from the middle ear, creating a barrier that protects the middle and inner areas from foreign objects. Sensitivity to sounds is greatest in this frequency region and noises in this range are the most hazardous to hearing. The net effect of the head, pinna, and ear canal is that sounds in the 2,000 to 4,000 Hz region are amplified by 10 to 15 dB. The ear canal protects the eardrum and acts as a resonator, providing about 10 decibels (dB) of gain to the eardrum at around 3,300 Hertz (Hz). This is an important factor to consider when fitting hearing protectors. The ear canal extends from the pinna to the eardrum and is about 26 millimeters (mm) in length and 7 mm in diameter. Each individual's pinna puts a distinctive imprint on the acoustic wave traveling into the auditory canal. The dimensions and folds of the pinna cause certain sound frequencies to be amplified and other frequencies to be weakened. Its function is to localize sound sources and direct sound into the ear. The pinna is the visible portion that is generally referred to as "the ear.". DECIBEL MEANING DOWNLOAD
The National Institute for Occupational Safety and Health (NIOSH) Sound Level Meter App is one tool available to the public to download on mobile iOS devices that measures sound levels in the workplace and provides noise exposure parameters to help reduce occupational noise-induced hearing loss.
Experience temporary hearing loss when leaving work. Have to shout to be heard by a coworker an arm's length away. Hear ringing or humming in your ears when you leave work. 
Noise may be a problem in your workplace if you: These include sound level meters, noise dosimeters, and octave band analyzers. Several sound-measuring instruments are available to measure the noise levels in a workspace. If you need to raise your voice to speak to someone 3 feet away, noise levels might be over 85 decibels. Whether you work at a sports venue, on a tarmac, or operate a jackhammer-hearing loss is preventable. The Center for Disease Control (CDC) estimates that 22 million workers are exposed to potentially damaging noise at work each year.
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