HELMHOLTZ RESONATOR

Principle and Working:
Helmholtz resonator is described by a cavity of air with an opening which resonates at a natural frequency when the air is excited. The relationship of the resonate frequency to the volume of the cavity and size of the port is given by the following equation.

where f is the frequency of resonance, ν the velocity of sound in air, A the cross-sectional area of the port, V0 the static volume of the cavity, and Le the effective length of the port, which is L+1.5r, where L is the actual length and r the port radius (circular port). The resonance frequency varies linearly with the inverse square root of volume which can be investigated in the present setup.

Exp-1 To study acoustic cavity resonators and determine their characteristic frequency.
Exp-2 To study the dependence of characteristic frequency on the volume of cavity of the resonator.