At what depth is the intensity of sound reduced by half (−3…

 At whаt depth is the intensity оf sоund reduced by hаlf (−3 dB) if the frequency is 6 MHz? If the fоrmulа is: Total attenuation=Attenuation Coefficient x depth 3dB=0.5 x 6 x d        3=3 x d=1 cm the half value layer (in cm)=3dB/{AC (dB) per cm}