Two loudspeakers are about 10 m apart in the front of a large classroom. if either

Two loudspeakers are about 10 m apart in the front of a large classroom. if either speaker plays a pure tone at a single frequency of 400 hz, the loudness seems pretty even as you wander around the room, and gradually decreases in volume as you move farther from the speaker. if both speakers then play the same tone together, what do you hear as you wander around the room?