446 ENVIRONMENTAL,ENGINEERZNG
22.22 A noise is found to give the following responses on a sound level meter:
82 &(A), 83 cB(B), and 84 dB(C). Is the noise of a high or low frequency?
22.23 A machine produces 80 &(A) at 100 Hz (almost pure sound).a. Would a person who has suffered a noise-induced threshold shift of 40 dB at
that frequency be able to hear this sound? Explain.
b. What would this noise measure on the B(C) scale?
22.24 What reduction in sound intensity would have been necessary to reduce the
takeoff noise of the American SST from 120 to 105 dB?