Multiple-Concept Example 3 reviews the concepts that are important in this problem. The entrance to a large lecture roomconsists of two side-by-side doors, one hinged on the left and theother hinged on the right. Each door is 0.640 m wide. Sound offrequency 624 Hz is coming through the entrance from within theroom. Take the speed of sound to be 345 m/s. What is the diffraction angle of the sound after it passes through the doorway when (a)one door is open and (b) both doors are open?