Two identical sources of sound, both emitting waves of equal amplitude and a frequency of 2000Hz, are 80cm apart.

Sound (speed = 343 m/s) exits a diffraction horn loudspeaker through a rectangular opening like a small doorway. A person is sitting at an angle a off to the side of a diffraction horn that has a width D of 0.068 m. This individual does not hear a sound wave that has a frequency of 8400 Hz. When she is sitting at an angle of a/2, the frequency that she does not hear is different. What is this frequency? Number i Units

Two loudspeakers, 1.7 m apart, emit sound waves with the same frequency along the positive x-axis. Victor, standing on the axis to the right of the speakers, hears no sound. As the frequency is slowly tripled, Victor hears the sound go through the sequence loud-soft-loud-soft-loud before becoming quiet again. What was the original sound frequency? Assume room temperature of 20∘C.

Sound with a 29 cm wavelength travels rightward from a source and through a tube that consists of a straight portion and a half-circle.  Part of the soundwave travels through the circle and rejoins the the rest of the wave which goes directly through the straight portion.  This rejoining results in interference.  What is the smallest radius r  (in cm) that results in an intensity minimum at the detector.  The maximum destructive interference will occur when the difference in the distance travelled by the two waves is 1/2 of a wavelength.  To solve this problem express the difference in the distance travelled by the two waves as a function of r and set this amount equal to 1/2 of a wavelength.