Interference and Diffraction of Sound Concept

Demonstrations in Interference and Diffraction of Sound

Agilent 33120A function generator on the lecture hall AV island, with BNC cable connected to the front panel output and RCA audio inputs visible on the AV system below
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Two Source Sound Interference

Two speakers driven by a single function generator create an interference pattern that students explore by moving through the room. Students experience constructive and destructive interference directly, connecting path length …
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Two Source Sound Interference, Oscillating

Two speakers driven in phase on a rotating bar create a spatial interference pattern that sweeps across the room. Students hear alternating loud and quiet regions, directly experiencing constructive and …
Wooden-framed box with glass panel containing two sinusoidal wire shapes, offset so peaks of one align with troughs of the other. Sliding handle visible on left.

Interference Lantern Slide

Visually demonstrates constructive and destructive interference using two overlapping wire sinusoids on a sliding mechanism. Moving the handle shifts one wave relative to the other, showing in-phase reinforcement and out-of-phase …
Large plywood baffle board with circular hole in center; small speaker on ring stand at left, function generator on bench below

Speaker and Baffle

An oscillating speaker cone emits sound from both front and back surfaces, 180° out of phase. Without a baffle, these waves interfere destructively ("acoustic short-circuiting"). Inserting the speaker into a …