The velocity of sound in air of density rho=1.29 kg/m^3 may be taken to be 330m/s. Show that the acoustic pressure for the painfull sound of 10 W/m^2 ~ 6.5x10^-4 of an atm. (atm~10^5 N/m^2) What is acoustic pressure. This question is easy I am sure, but I dont really know what it is asking for. I have read and re-read the chapter on sound waves, but I dont see any term defined as acoustic pressure. I am guessing it is the "overpressure", but I dont know of a relationship between overpressure and Intensity.