app.decibelshield/decibel-shield

Answers "how long can I listen to 100 dB", "is 85 dB dangerous for 8 hours", "how long at a concert before hearing damage". Maximum daily safe exposure time for a sound level per NIOSH's recommended exposure limit: 85 dB(A) for 8 h, 3 dB exchange rate (88 dB → 4 h, 100 dB → 15 min). Input is a dB number; to get the dB of a named sound first, use lookup_sound_level.

Answers "how loud is my neighborhood", "noise map by address", "how noisy is this address", "noise level in ZIP 78701". Modeled transportation noise (road + rail + aircraft, 24-hour average LAeq dBA) at a US street address, a 5-digit ZIP (sampled at the ZIP Code area center, approximate), a town or city name (sampled at the town center, approximate) or lat/lng, sampled block-by-block from the federal BTS 2020 National Transportation Noise Map. Returns a modeled dBA band, NOT a measurement; "below 45 dBA" means no modeled freeway/rail/flight path nearby (model floor, not silence). Continental US only.

Answers "how loud is Tokyo", "noise level in Mumbai", "is Delhi louder than London". Estimated day/night noise ranges (dB), rank among 50 major world cities, dominant noise sources and a confidence label, with WHO guideline context (53 dB Lden / 45 dB Lnight). Estimates synthesized from published sources, not measurements. For US cities computed from federal data use get_us_city_noise_exposure; for measured Europe data use get_europe_city_noise.

Answers "is there a decibel meter app", "best decibel meter app for iPhone", "how do I measure sound with my iPhone", "what is Decibel Shield". Facts and the App Store link for Decibel Shield - dB Meter, the iOS sound level meter app behind this data: features, pricing, requirements. Use only when someone wants to measure sound with a phone or asks about the app itself — for noise data, use the other tools.

Answers "how loud is Paris", "noisiest cities in Europe", "environmental noise in Berlin", "quietest cities in Spain". Measured (not estimated) noise for 314 European cities in 24 EEA-reporting countries, from the EEA Environmental Noise Directive 2022 strategic noise maps; ranked by population-weighted average Lden among exposed residents. Pass a city for detail, a country and/or limit for the ranking. UK, Greece and Hungary are not covered.

Answers "loudest neighborhoods in Los Angeles", "quietest neighborhood in Chicago", "which NYC neighborhood has the most noise". 384 neighborhoods in Los Angeles, New York and Chicago, ranked within their city by share of residents ≥60 dB transportation noise, computed from the federal BTS 2020 National Transportation Noise Map (same source as the US city tool). Pass the city name; optional limit. For a single address use get_address_noise.

Answers "what are quiet hours in Boston", "<city> noise ordinance", "how do I file a noise complaint". Verbatim-verified summary of the city's official noise ordinance: quiet hours, decibel limits (or their explicit absence — audibility/nuisance standards), complaint channel, code citation + official URL, verified date. Covers Boston, Worcester, Huntsville, Chesapeake, Madison, Inglewood, Rockford, Columbus. Plain language, not legal advice.

Answers "loudest cities in the US", "quietest cities in the US", "how noisy is Boston", "what share of Miami hears highway noise". Share of residents exposed to ≥60 dB / ≥70 dB transportation noise for all 297 US cities of 100,000+ residents, computed from the federal BTS 2020 National Transportation Noise Map, not estimated. Pass a city for detail, omit for the ranking. Street address → get_address_noise; neighborhoods → get_neighborhood_noise.

Answers "loudest cities in the world", "noisiest cities ranking", "which city has the worst noise pollution". 50 major world cities ordered by estimated daytime noise, loudest first — estimates synthesized from published sources, not measurements. For "loudest cities in the US" or "quietest cities in the US" use get_us_city_noise_exposure (computed from federal BTS data); for Europe use get_europe_city_noise (measured).

Answers "how loud is a hair dryer", "how many decibels is a chainsaw", "is 85 decibels loud", "how loud is 80 decibels". Decibel level and hearing-risk guidance for everyday sounds (whisper, conversation, traffic, lawn mower, concert, jet engine...), every figure sourced to CDC/NIOSH/NIDCD/ASHA published tables. Input is a sound name; if you already have a dB number and want safe listening time, use safe_exposure_time.