The Helmholtz resonator and its mechanical correlate.
In the ``low-frequency limit'', an open tube is a direct acoustic correlate to the mechanical mass.
In the ``low-frequency limit'', a cavity is a direct acoustic correlate to the mechanical spring.
Using Newton's Second Law to model the air mass in the tube and Hooke's Law for fluids to model the compressibility of the air cavity, a sinusoidal solution can be found with natural frequency
, where c is the speed of sound in air, A is the cross-sectional area of the tube, L is the length of the tube, and V is the volume of the cavity.