Who Heard That?

If you honk your horn right now, how many people will hear it? Anywhere on Earth, semi-rigorously.

…or click anywhere on the map to park your car there.

Is this real? (methodology)

Sort of. The physics is real; the inputs are educated guesses.

  • Loudness: a car horn is roughly 107 dB at one metre. Sound drops 6 dB every time distance doubles, plus an extra ~4 dB per 100 m for urban clutter, plus a small boost for street-canyon reflections. Buildings block about 60% of the circle.
  • "Heard": a horn is tonal, so it cuts through and is detectable a bit below the background level. Background is estimated from how busy the area is and drops by up to 12 dB overnight. "Bothered" means it was clearly louder than the background.
  • Indoors: closed windows knock off ~27 dB, open ones ~10 dB. How many are open depends on the season. Offices never open theirs.
  • People: anywhere on Earth comes from the European Commission's Global Human Settlement Layer: residents per 1 km cell (GHS-POP 2025) plus non-residential building volume (GHS-BUILT-V) as a proxy for the daytime crowd of workers and shoppers, calibrated on Midtown Manhattan. We blur about 500 m around your car. The time of day blends residents and daytime crowd, and decides how many are asleep or outdoors.
  • Waking up: sleepers start waking around 42 dB indoors. Longer honks wake more of them.
  • Annoyance: everyone within earshot has a fuse. People close enough that the horn is clearly louder than the background are annoyed instantly; the rest get there after a few seconds of sustained honking. Keep holding.
  • Dogs, babies, video calls: NYC has about 1 dog per 14 people; we assume the world does too. The rest is vibes.

Accuracy: within an order of magnitude, probably. The $350 fine for unnecessary honking is real in New York City (Admin. Code §24-221); enforcement is not. Population data © European Union, 2023, GHSL R2023A, CC BY 4.0. Search and place names by Photon and OpenStreetMap.