Environmental Engineering FOURTH EDITION

424 ENVIRONMENTALENGINEERING Figure 22-1. A piston creates pressure waves that are transmitted through air. to decrease the nois ...

Noise Pollution 425 Figure 22-2. Sound waves. All parts of the figure show the spatial variation along the wave at a particular ...

426 ENVIRONMENTAL ENGINEERING All other sounds are made up of a number of suitable sinusoidal waves, as demon- strated originall ...

Noise Pollution 427 where SPL (a) = sound pressure level (in dB), P = pressure of sound wave, and PEf = some reference pressure, ...

428 ENVIRONMENTAL ENGINEERING 80 70 40 30 Over-all 63 125 250 500 1000 2000 4000 8000 Octave band center frequency Figure 223. ' ...

Noise Pollution 429 3 2 1 0 3 4 5 6 7 8 9 1011121314 Decibels Numerical difference between total and smaller levels Figure 22-4. ...

430 ENVIRONMENTAL ENGINEERING EXAMPLE 22.2. A jet engine has a sound intensity level of 80dB, as heard from a distance of 50 ft. ...

Noise Pollution 43 1 120 20 v) a 0 20 100 1000 5000 10,000 Frequency in cycles per second Figure 22-5. Equal loudness contours. ...

432 ENVIRONMENTAL ENGINEERING ,))) Microphone fi/,T,Bq Filters G, Sound Sound level meter source * Figure 22-6. Schematic repres ...

Noise Pollution 433 “p Figure 22-8. A typical sound level meter. (Courtesy of General Radio.) ...

434 ENVIRONMENTAL ENGINEERING from people. A plethora of parameters have been devised to respond to this discrep- ancy in reacti ...

Noise Pollution 435 Table 22-2. Sample Traflic Noise Data and Calculations for Example 22.3 Rank % of time equal to Time (s) WA) ...

436 ENVIRONMENTAL ENGINEERING As defined earlier, the symbol L refers to the percentage of time the noise is equal to or greater ...

Noise Pollution 437 Table 22-3. OSHA Maximum Permissible Industrial Noise Levels Sound level Maximum duration during CWA) any wo ...

438 ENVIRONMENTAL ENGINEEFUNG micircular canal Auditory nerves -_,I--I-I Outerear I I Innerear I I I I Middle ear Figure 22-11. ...

Noise Pollution 439 -5 0 5 10 15 m 20 25 5 r3o I .- L 35 40 45 50 55 500 1000 2000 4000 8000 Frequency (Hz) Figure 22-13. Perm ...

440 ENVIRONMENTALENGINEERING 0 10 20 50 70 500Hz 1 OOOHz 2000Hz 3000Hz 4000Hz 6000Hz 8000Hz 12000Hz 20 30 40 50 60 70 Years age ...

Noise Pollution 441 Recent court cases have been won by workers seeking damages for hearing loss suffered on the job. The Vetera ...

442 ENVIRONMENTAL ENGINEERING areas and, whenever necessary, to have pilots use less than maximum power when the takeoff carries ...

Noise Pollution 443 ’Igble 22-4. Design Noise Levels Set by the Federal Highway Administration Land Design noise Description of ...