1. The problem statement, all variables and given/known data One wheel goes at 850 rpm and the other at 780 rpm, and obviously they make a noise. Standing in an enclosed room, you hear the sound intensity increase and then decrease periodically due to wave interference. How long does it take between successive times for the sound intensity to reach a peak? f1= 850 f2= 780 Vs =343 m/s 2. Relevant equations λ=Vs/f 3. The attempt at a solution 343/850=0.40 343/780=0.44 So how do I find a peak? Does it have something to do with constructive interference?