An open car window creates a living Helmholtz resonator with strong low-frequency pressure fluctuations

Evidence

The principle of Helmholtz resonance takes different shapes. The body of the violin or the guitar is a good example where the air hole(s) and the body result in the lowest resonance frequency of the instrument. A bass-reflex type of loudspeaker enclosure adds a desired boost to the low-frequency response of the loudspeaker (see Section 4.1.1). The interior of a car cabin, when a window is slightly opened while driving fast, may strongly amplify turbulent noise at low or very low (infrasound) frequencies. — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 160 (#exemplifies, via linked claim)

Categorization

• XREF: connects to: Helmholtz resonators serve as transducers, amplifiers, and sound controllers.; Trapped compressible air and moving air form a mass-spring acoustic resonator; Helmholtz resonance is the trapped-air cavity resonance exploited in perforated-panel absorbers (+6 more)

Broader Connections

• Trapped compressible air and moving air form a mass-spring acoustic resonator #expands (0.95)
• Helmholtz resonance is the trapped-air cavity resonance exploited in perforated-panel absorbers #expands (0.85)
• Helmholtz resonance shapes violin bodies, speaker designs, and car cabin noise #exemplifies (0.85) — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 160
• A vocal tract constriction at the mouth forms a Helmholtz resonator #expands (0.85)
• Resonator pitch scales with gas speed, volume, neck geometry #expands (0.85)
• Blowing across a bottle mouth produces a Helmholtz resonance #exemplifies (0.80)
• An open mouth amplifies faint sounds by serving as a resonant chamber #exemplifies (0.75) — Gordon Hempton, John Grossmann, One Square Inch of Silence- One Man’s…, 191