The health experts say many persons develop permanent hearing damage because of increasing levels of noise in the environment.

健康专家们表示许多人由于环境中噪声级数的增加而使听力受到了永久性的伤害。

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While physical hearing protection can reduce sound pressure levels, they do not adequately prevent NIHL in very noisy environments.

对听力的物理防护可以降低声压水平，但若噪声过强，这种物理防护并不能完全保证听力不受损害。

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Methods: 11 subjects abilities to detect near threshold pure tone levels were measured in different noise free from hearing disorder.

方法：测试在不同的噪声水平时听力正常的11名受试者感知听阈附近纯音的能力。

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One provides natural hearing when sound levels are safe and either 9- or 15-dB sound reduction when sounds exceed safe levels.

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Several weeks later, although hearing sensitivity had recovered to normal levels, activity in the auditory nerve connecting the inner ear to the brain remained impaired.

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Now though, with the discount having shrunk back to more normal levels, Connelly is hearing more questions about how big a deal can get done, rather than the feasibility of completing a deal.

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