The Helmholtz resonator models confined air as a spring with an air-mass plug

Evidence

A simple but important type of resonator in acoustics is the Helmholtz resonator, which is shown in Figure 2.4. The air inside a closed volume V, due to its compressibility, acts as a mechanical spring, and the moving air in the tube or opening above behaves like a mass. Together they make a mass–spring system that works as an acoustic resonator. For instance, by properly blowing into the opening of an empty bottle, this effect can be easily demonstrated. — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 157

Another form of resonant absorber is based on the use of the resonance that occurs when air is trapped in a tube above an air space. This type of resonance is called a Helmholtz resonance and is the resonance that occurs in a beer bot­ tle when you blow across it. The cavity acts like a spring and the air in the tube above the cavity acts like the mass. — David Howard, Jamie Angus, coustics and Psychoacoustics, 2107

Categorization

• DEFINE: Helmholtz resonator mechanism clearly defined: compressible air volume is the spring, tube air is the mass.
• XREF: The bottle-blowing demo connects to everyday acoustic phenomena and to the blowing-across-bottle sound familiar in sound design.
• SHARE: Send to a musician friend — the empty-bottle Helmholtz demo is a tactile way to grasp how instrument air holes set lowest resonance frequency.
• corroborated: 2 independent passages support this claim — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 157; David Howard, Jamie Angus, coustics and Psychoacoustics, 2107