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Section 5 <br />Effects of Noise <br />Physical carnage to human hearing begins at prolonged exposure to noise Revels <br />higher than 85 dBA. Extended periods of noise exposure above 90 dBA could <br />result in permanent hearing damage. When the noise level reaches 120 dBA' a <br />ticking sensation occurs in the human ear even with short-term exposure. This <br />level of noise is called the threshold of feeling. As the sound reaches 140 dBA, <br />the tickling sensation is replaced by the feeling of pain in the ear. This is called <br />the threshold of pain. A sound level of 190 dBA will rupture the eardrum and <br />permanently the inner ear. Table 32 summarizes typical noise sources, levels, <br />and responses. <br />Table 32'. Noise Levels and Human Response <br />Nolte Sourte <br />Noise Level d6A <br />Response <br />Library <br />30 <br />Very gulet <br />Refriqerator humming <br />40 <br />Quiet <br />Quiet office <br />50 <br />Wet <br />Normal oonversation <br />60 <br />Vntrusive <br />Vacuum cleaner <br />70 <br />Telephone use difficult <br />'Frey ht train at 50 feet <br />80 <br />Interferes with conversation <br />Heavy-duty truck at 50 feet <br />90 <br />Annoying <br />Jet takeoff at 2,000 feet <br />100 <br />Very annoyhg; hearing damage at <br />sustained exposure levels <br />Unmuffled motorcycle <br />110 <br />Maximum vocal effect, physical <br />discomfort <br />Jet takeoff at 200 feet <br />120 <br />Regular exposure over one minute <br />risks permanent hearing loss <br />Shotgun firm Q <br />130 <br />Pain threshold <br />I Carrier let operation <br />140 <br />Harmfully loud ........ . <br />ISMrce MOville C WvtOl and R. bale Beland, <br />Existing Noise Environment <br />The project site is located at Centennial Park and at the Heritage Museum, <br />• The nearest sensitive receptor to MBI-2 would be Godinez High School <br />located approximately 450 feet southeast of the proposed construction <br />activities. <br />Mid Basin Centennial Park �tej 6Project Final EIR 5-145 <br />4 <br />