Noise Dose 噪音计量Duration per Day - OHLearning.PPT

BASIC PRINCIPLES IN OCCUPATIONAL HYGIENE职业卫生基本原则 Day 3 第3天 13 – NOISE13-噪音 NOISE噪音 Noise is unwanted sound. 噪音是有害的。 Known for many years as a cause of hearing loss in industry. 多年前就已确定，噪音是工业听力损失的原因之一。 Sound is the sensation that is perceived by the human or animal brain as a result of longitudinal vibrations of molecules of the air impinging on the ear. 声音是空气分子的纵向振动撞击耳朵，导致人类或动物大脑有感知的能量。 Sounds are actually pressure waves caused by a vibrating body, which radiate from the source. 声音是声源振动产生的压力波。 Cochlea耳蜗 External Ear外耳 Middle Ear鼓室 Source: Wikimedia Commons 资料来源：维基共享资源 The Ear 耳朵 Audible Sound可听音 Two key features of sound are frequency and intensity. 声音的两个主要特征是频率和强度。 The number of pressure waves/vibrations per second is known as the frequency, and is expressed in the unit Hertz (Hz) 频率系指每秒压力波/振动的次数，单位是赫兹（Hz）。 The more fluctuations per second the higher the pitch of the sound 每秒波动次数越多，音高越高。 By intensity (I) we mean the amplitude (size) of the pressure waves and is defined as the average amount of energy passing through a unit area in unit time (Wm2). 强度（I）系指压力波的振幅（大小），是单位时间通过单位面积的平均能量（ Wm2 ）。 Decibels, Pascals Watts/metre2 分贝、帕斯卡、瓦特/平方米 Source: Canadian Centre for Occupational Health and Safety 资料来源：加拿大职业健康与安全中心 声压和声压级对比 声压，Pa 摇滚乐队 动力草坪割草机（操作员耳朵的声压） 铣床（4英尺位置） 垃圾处理（3英尺位置） 吸尘器 窗式空调机（25英尺位置） 声压级，dB 气錾 （5英尺位置） 纺织机 报版轮转机 40 时速的柴油卡车（50英尺位置） 50时速的客车（50英尺位置） 会话（3英尺位置） 净室 Health Effects of Excessive Noise过量噪音对健康的影响 Noise Induced Hearing Loss (NIHL), a cumulative effect from repeated exposure and it is due to damage to the hair cells of the cochlea in the inner ear. 噪声导致听力损失（NIHL）是反复接触的累积效果，因内耳的耳蜗毛细胞受损所致。 Tinnitus - Noise heard in the ear without external cause, frequently accompanies deafness. 耳鸣——外部无声音，但听到声音，通常伴随耳聋。 Temporary Threshold Shift (TTS) - Damage to the hair cells of the inner ear which can impair hearing temporarily, resulting from exposure to high noise levels. 一时性听力障碍（TTS）——因接触较高噪音，导致内耳毛细胞受损，可能会暂时出现听力受损。 Physical damage