Interference of Sound

Setup http://robynsrevison.weebly.com/double-slit-interference.html

Central Maximum Same distance to each speaker Start in phase Constructive interference

First Order Maxima S S θ d } ΔS

In Phase l

If L>>d then the waves are almost parallel Approximation If L>>d then the waves are almost parallel θ d }

First Order Maxima S S θ d } ΔS

Equation for Maxima m is the order of the maxima, so if m = 1 then they are called the first order maxima, m = 3 then they are the third order maxima, etc.

180º Out of Phase

First Order Minima S X θ θ S d } ΔS X

Second Order Minima X S X S θ θ d } ΔS X X

Equation for Minima If m = 0 then they are called the first order minima, m = 2 then they are called the third order minima, etc.

Beats

Definition Periodic and repeating fluctuations heard in the intensity of a sound when two sound waves of very similar frequencies interfere with one another http://www.physicsclassroom.com/Class/sound/U11L3a.html

Animation http://www.kettering.edu/~drussell/Demos.html

Simulation https://faraday.physics.utoronto.ca/PVB/Harrison/Flash/ClassMechanics/Beats/Beats.html

Calculating The number of beats heard per second is simply the difference between the two frequencies.