You are standing 2.5 m directly in front of one of the two loudspeakers shown in FIGURE

Question:

You are standing 2.5 m directly in front of one of the two loudspeakers shown in FIGURE P17.68. They are 3.0 m apart and both are playing a 686 Hz tone in phase. As you begin to walk directly away from the speaker, at what distances from the speaker do you hear a minimum sound intensity?
The room temperature is 20°C.

Walk 2.5 m 3.0 m FIGURE P17.68