Physics of Sound 1.) If you attend a rock concert wearing earplugs that provide
ID: 1978048 • Letter: P
Question
Physics of Sound1.) If you attend a rock concert wearing earplugs that provide a reduction of 13 dB, what percentage of the incoming sound density is being blocked out?
Doppler Effect
2.)A train passes the station with its horn blaring at a frequency of 522 Hz. If a stationary observer at the station hears a frequency of 529 Hz,
A.) Is the train moving towards the station or away from it?
B.)How fast is the train moving? Assume that the air temperature is T=15 degrees, and therefore the speed of sound is c(s)=340 m/s.
Explanation / Answer
similar question If you attend a rock concert wearing earplugs that provide a reduction of 20 dB, what is the ratio of the sound intensity reaching your eardrums to that just outside the plugs? What percentage of the sound energy is getting through? What percentage is being blocked out? In order to achieve 30 dB reduction, what percentage would have to be blocked out? Please explain Power in dB = 10 log (Power in / Power out) 20 = 10 * log ( Pi/Po) 20 / 10 = 2 = log ( ) 10^2 = ( Pi/Po) = 100 so for 20 dB , only 1 % of the energy outside gets to the ear. for 30 dB 10^3 = 1000 => 0.1% of emergy