Two identical loudspeakers are placed a distance d apart. They emit sound of wavelength λ in phase. At what angles θ relative to the perpendicular bisector of the line joining the speakers will constructive interference occur?
Correct: A
For constructive interference, the path difference d sin(θ) must equal an integer multiple of the wavelength, nλ. Therefore, d sin(θ) = nλ, so sin(θ) = nλ/d, and θ = sin⁻¹(nλ/d).