Helicopter ear

{
  "id": "MLC-T-IND-007032",
  "term": "Helicopter ear",
  "field": "Industrial and trades",
  "definition": "A low-frequency pulsing, throbbing sound heard in a moving vehicle when one window is open, caused by Helmholtz resonance of the air in the cabin. The cabin acts as a resonator and the open window as its opening, so air flowing past the window drives the air inside at the cabin's natural frequency. Opening a second window usually reduces the effect.",
  "subject": "Shop talk and trade slang",
  "translations": {
    "de": "Hubschrauberohr",
    "es": "oreja de helicóptero",
    "fr": "oreille d'hélicoptère"
  },
  "url": "https://mlchart.com/terminology/industrial/helicopter-ear/"
}