Two loudspeakers are positioned close together and are directed in the same direction. A microphone linked to an oscilloscope is then moved along a line at some distance from the loudspeakers, as illustrated. Which statement about the waves produced by the loudspeakers is not a necessary condition for the microphone to find a fixed point on the line where no sound is heard?
- AThe waves must be emitted in phase.
- BThe waves must be emitted with a similar amplitude.
- CThe waves must have the same frequency.
- DThe waves must have the same wavelength.