Unless indicated otherwise, assume the speed of sound in air to be v = 344 m/s. The intensity due to a number of independent sound sources is the sum of the individual intensities. (a) When four quadruplets cry simultaneously, how many decibels greater is the sound intensity level than when a single one cries? (b) To increase the sound intensity level again by the same number of decibels as in part (a), how many more crying babies are required?

Solution 20E (a).The sound level intensity as function of intensity of source is given as = 10 dB log (I/I )0 Where I = intensity of source I = intensity of sound(10 12W/m )2 0 Sound intensity level of sound if four quadruplets cry simultaneously = 10 dB log (I /I ) 0 = 10 dB log (4I/I )0 From above two equation calculate difference in sound intensity level - = 10 dB log( I /I)0 10 dB log( I/I ) 0 = 10 dB log (4I/I )010 dB log( I/I ) 0 =10 dB log(4 I/I I/I ) 0 0 = 10 dB log(4 ) =6.02...