Name :Chobits (羅莉) 生日 :07年12月 2日 (中年 11歲)
體: 3014/3038 法: 139/139 攻擊力:512 敏捷 :456 知識 :1388
快樂 :14575 滿意 :20708 疲勞 :5130 氣質 :103 體重 :31.33
病氣 :1 乾淨 :30 食物 :11 大補丸:0 藥品 :4
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生病了...累得昏迷了...很快樂..很滿足..
The ruling out of nonindustrial cause of hearing loss.It has been estimate
that 1.7 million workers in the United States between 50 and 59 years of
age have compensable noise-induced hearing loss. Assuming that only 10
percent of these workers file for compensation and that the average claim
amounts to$3,000, the pontential cost to industry could exceed $500 million.
The generation and propagation of sound are easily visualized by means of
a sample model. Consider a plate vibrate rapidly back and forth. As travels
in either direction, it compresses the air, causing a slight increase in it's
pressure. When the ??????? reverses direction, it leaves a partial vacuum, or
rarefaction, of the air. These alternate compression and rarefactions cause
small but repeated fluctuations in the atmopheric pressure that extend
outward from the plate. When these pressure variations strike an eardrum,
they cause it to vibrate in response to the slight changes in atmospheric
pressure. The disturbance of the eardrum is translated into a neural sensation
in the inner ear and is carried to the brain, where it is interpreted as
sound.
Sound waves are particular from of a general class od waves know as elastic
waves. Sound waves can occur in any elastic medium such as air, water, or
steel. One sound waves may have three times the frequency and one-third the
intensity(amplitude) of another sound wave. However, if both the waves cross
their respective zero positions in the same direction at the same time, they
are said to be in phase.
Frequency is preceived as pitch, The audible range of frequencies for human
with good hearing is between 20Hz and 20,000 Hz. Most everday sounds contain
a mixture od frequencies generaterd by a variety of sources. A sound's
frequency composition is called its spectrum. The frequency spectrum can be
a determining factor in the level of annonying cause by noise; high-frequency
noise. Also nareeow frequency bands or pure tones (sigle frequencies) ans be
somewhat more harmful to hearing than boardband noise.
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