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Unformatted text preview: Homework Assignment #6 answer guidelines Total: 40 points 1. (5 pts) Is going to an amplified rock concert really that bad for my ears?... a. 115 dB – 15 minutes/day or less b. How loud is the average (indoor) rock concert? 120-150 dB (e.g.: http://www.asha.org/public/hearing/disorders/noise.htm) c. Clearly long term exposure would be bad for your hearing. 2. (14 pts) I have built a simple auditorium for chamber concerts which is little more than a big, ugly box, 50 feet wide x 50 feet long x 40 feet tall. a. (2 pts) V =100,000 ft 3 . Any answer from 1.0 – 1.5 seconds for T R is fine. b. (2 pts) A wall = 2000 ft 2 ; A ceiling = A floor = 2500 ft 2 c. T R = (55.2 * V ) / ( S * A ) means that [ T ] = [ V ]/[ S * A ] = ft 3 /(ft/s * ft 2 ) = seconds; note that the coefficients “ a ” are unitless and don't enter into this part of the problem. d. Carpet on the floor: a floor =0.3 at 500 Hz and 0.2 at 250 Hz Acoustical board on the ceiling: a acou =0.8 at 500 Hz and 0.45 at 250 Hz Plywood on the walls:...
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- Fall '08
- Hz Acoustical, Hz Acoustical board