I purchased a set of small, foam ear plugs from our local drug store. The ear pl

Question

I purchased a set of small, foam ear plugs from our local drug store. The ear plugs had an advertised "Noise Reduction Rating" of 30 decibels. The sound level at the ear, when using the ear plugs is reduced by 30 dB. If I use the ear plugs and attend a rock concert, sitting near a loudspeaker which is powered by a 3000 watt amplifier (yes! Rock groups think bigger is better), what amplifier power level will give me the same sound level without the ear plugs as the 3000 watt amplifier gives me while wearing the ear plugs? Hint: The amplifier power without ear plugs is 30 dB less than the amplifier power with the ear plugs.


A. 3 watts B. 10 watts C. 2970 watts D. 30 watts E. 0.3 watts

Explanation / Answer

decibal = 10*log(I/Io) = 10*log(W/Wo) , base of log is 10 =>-30 = 10*log(I/3000) =>I = 3 watts.

Related Questions

Navigate

• Browse (All)
• Browse I
• Subjects

---