[
 {
  "see": "A second leaf blower starts but it doesn't sound twice as loud",
  "is": "Two equal sources add only 3 dB; it takes about 10 dB to sound twice as loud",
  "section": "basics",
  "anchor": "Why don't decibels add up?",
  "tags": [
   "decibels",
   "add",
   "louder",
   "math"
  ],
  "c": "wht",
  "sid": "why-don-t-decibels-add-up"
 },
 {
  "see": "My meter shows different numbers in dBA and dBC",
  "is": "They are different filters; dBC keeps the bass that dBA turns down",
  "section": "basics",
  "anchor": "What is the difference between dB, dBA, dBC and dBZ?",
  "tags": [
   "dba",
   "dbc",
   "weighting",
   "meter",
   "bass"
  ],
  "c": "wht",
  "sid": "what-is-the-difference-between-db-dba-dbc-and-dbz"
 },
 {
  "see": "A report lists Leq, Lmax and L90 and I don't know which matters",
  "is": "Leq is the average, Lmax the loudest moment, L90 the background",
  "section": "basics",
  "anchor": "Which number is the \"real\" level? Leq, Lmax, L10, L90 and SEL",
  "tags": [
   "leq",
   "lmax",
   "l90",
   "metrics"
  ],
  "c": "wht",
  "sid": "which-number-is-the-real-level-leq-lmax-l10-l90-and-sel"
 },
 {
  "see": "The airport says my street is DNL 60",
  "is": "A 24-hour year average with a 10 dB night penalty; the FAA's standard metric",
  "section": "basics",
  "anchor": "What are DNL and Lden?",
  "tags": [
   "dnl",
   "airport",
   "aviation",
   "average"
  ],
  "c": "wht",
  "sid": "what-are-dnl-and-lden"
 },
 {
  "see": "A European noise map shows Lden and Lnight",
  "is": "EU 24-hour and night averages with evening and night penalties",
  "section": "basics",
  "anchor": "What are DNL and Lden?",
  "tags": [
   "lden",
   "lnight",
   "europe",
   "noise map"
  ],
  "c": "wht",
  "sid": "what-are-dnl-and-lden"
 },
 {
  "see": "Highway hum that carries for blocks",
  "is": "Roads act as line sources and lose only about 3 dB per doubling of distance",
  "section": "basics",
  "anchor": "How much quieter is it twice as far away?",
  "tags": [
   "highway",
   "distance",
   "traffic",
   "hum"
  ],
  "c": "wht",
  "sid": "how-much-quieter-is-it-twice-as-far-away"
 },
 {
  "see": "A jackhammer that fades quickly as I walk away",
  "is": "A point source loses about 6 dB each time you double the distance",
  "section": "basics",
  "anchor": "How much quieter is it twice as far away?",
  "tags": [
   "jackhammer",
   "distance",
   "construction"
  ],
  "c": "wht",
  "sid": "how-much-quieter-is-it-twice-as-far-away"
 },
 {
  "see": "Tall concrete walls along the highway",
  "is": "Noise barriers cut about 5-10 dB(A), up to about 20 dB(A)",
  "section": "basics",
  "anchor": "Do noise barriers work?",
  "tags": [
   "barrier",
   "highway",
   "wall"
  ],
  "c": "wht",
  "sid": "do-noise-barriers-work"
 },
 {
  "see": "Neighbor's bass thumps through the wall but no words",
  "is": "Walls block low frequencies far less, and bass travels through structure",
  "section": "basics",
  "anchor": "Why can I hear bass through my wall but not voices?",
  "tags": [
   "bass",
   "wall",
   "neighbor",
   "subwoofer",
   "thump"
  ],
  "c": "wht",
  "sid": "why-can-i-hear-bass-through-my-wall-but-not-voices"
 },
 {
  "see": "Sirens echo between tall buildings downtown",
  "is": "Hard parallel surfaces reflect sound back and add to the level",
  "section": "basics",
  "anchor": "What do hard walls and tall buildings do?",
  "tags": [
   "echo",
   "reflection",
   "buildings",
   "siren"
  ],
  "c": "wht",
  "sid": "what-do-hard-walls-and-tall-buildings-do"
 },
 {
  "see": "Is my phone's decibel app right?",
  "is": "Good iOS apps come within about 2 dBA; Android varies by device",
  "section": "basics",
  "anchor": "Is a phone decibel app accurate?",
  "tags": [
   "phone",
   "app",
   "niosh",
   "meter"
  ],
  "c": "wht",
  "sid": "is-a-phone-decibel-app-accurate"
 },
 {
  "see": "How loud is a whisper compared with a jet?",
  "is": "About 30 dB versus about 120 dB on the audiology chart",
  "section": "basics",
  "anchor": "How loud is loud? A rough decibel ruler",
  "tags": [
   "decibel chart",
   "whisper",
   "jet",
   "scale"
  ],
  "c": "wht",
  "sid": "how-loud-is-loud-a-rough-decibel-ruler"
 },
 {
  "see": "Do I have to shout to be heard here?",
  "is": "Shouting at 3 ft means likely 95 dBA or more, per NIOSH",
  "section": "basics",
  "anchor": "How loud is loud? A rough decibel ruler",
  "tags": [
   "shout",
   "loud",
   "bar",
   "hearing"
  ],
  "c": "wht",
  "sid": "how-loud-is-loud-a-rough-decibel-ruler"
 },
 {
  "see": "Where can I find a noise map for my street?",
  "is": "BTS publishes a modeled US national map; the EU requires maps by law",
  "section": "basics",
  "anchor": "What is a noise map?",
  "tags": [
   "noise map",
   "bts",
   "model"
  ],
  "c": "wht",
  "sid": "what-is-a-noise-map"
 },
 {
  "see": "Ringing in my ears after a concert",
  "is": "Tinnitus; NIDCD says noise-caused tinnitus may fade or, in some cases, last for life.",
  "section": "health",
  "anchor": "Does tinnitus from a concert go away?",
  "tags": [
   "tinnitus",
   "ringing",
   "concert",
   "ears"
  ],
  "c": "red",
  "sid": "does-tinnitus-from-a-concert-go-away"
 },
 {
  "see": "I have to shout to be heard at work",
  "is": "Likely 95 dBA or more, per NIOSH's arm's-length rule of thumb.",
  "section": "health",
  "anchor": "How loud is too loud for your ears?",
  "tags": [
   "workplace",
   "shouting",
   "dba",
   "niosh"
  ],
  "c": "red",
  "sid": "how-loud-is-too-loud-for-your-ears"
 },
 {
  "see": "Is my lawn mower or power tool loud enough to hurt my hearing",
  "is": "NIOSH puts these around 85-90 dBA, at or above its 8-hour limit.",
  "section": "health",
  "anchor": "How loud is too loud for your ears?",
  "tags": [
   "lawn mower",
   "power tools",
   "85 dba",
   "hearing"
  ],
  "c": "red",
  "sid": "how-loud-is-too-loud-for-your-ears"
 },
 {
  "see": "Headphones turned up all the way",
  "is": "Can reach 94-110 dBA per NIDCD; at 100 dBA NIOSH recommends no more than 15 minutes a day.",
  "section": "health",
  "anchor": "How long can I listen at 100 decibels?",
  "tags": [
   "headphones",
   "volume",
   "100 decibels",
   "safe time"
  ],
  "c": "red",
  "sid": "how-long-can-i-listen-at-100-decibels"
 },
 {
  "see": "A loud club or concert all night",
  "is": "Bars and clubs are often 95 dBA or more; WHO's venue standard caps 100 dB LAeq over 15 minutes.",
  "section": "health",
  "anchor": "How long can I listen at 100 decibels?",
  "tags": [
   "club",
   "concert",
   "venue",
   "exposure"
  ],
  "c": "red",
  "sid": "how-long-can-i-listen-at-100-decibels"
 },
 {
  "see": "Hearing seems fine but tests show a dip",
  "is": "An audiometric notch; CDC found one in 23.5% of adults who rated their hearing excellent or good.",
  "section": "health",
  "anchor": "How many people already have noise damage?",
  "tags": [
   "hearing test",
   "notch",
   "noise damage",
   "cdc"
  ],
  "c": "red",
  "sid": "how-many-people-already-have-noise-damage"
 },
 {
  "see": "Traffic outside all night keeping me up",
  "is": "WHO 2018 recommends road noise below 45 dB Lnight outside the home.",
  "section": "health",
  "anchor": "What are the WHO noise guidelines?",
  "tags": [
   "traffic",
   "road noise",
   "night",
   "who"
  ],
  "c": "red",
  "sid": "what-are-the-who-noise-guidelines"
 },
 {
  "see": "Planes overhead at night",
  "is": "WHO 2018 sets aircraft at below 40 dB Lnight and 45 dB Lden, its strictest values.",
  "section": "health",
  "anchor": "What are the WHO noise guidelines?",
  "tags": [
   "aircraft",
   "planes",
   "night noise",
   "who guidelines"
  ],
  "c": "red",
  "sid": "what-are-the-who-noise-guidelines"
 },
 {
  "see": "Noise wakes me up even when it is not that loud",
  "is": "WHO 2009 reported 42 dB Lnight outside as a threshold for waking.",
  "section": "health",
  "anchor": "What decibel level is safe for sleeping?",
  "tags": [
   "sleep",
   "waking",
   "night noise",
   "lnight"
  ],
  "c": "red",
  "sid": "what-decibel-level-is-safe-for-sleeping"
 },
 {
  "see": "A restaurant getting louder as it fills up",
  "is": "The Lombard effect: people automatically raise their voices in noise.",
  "section": "health",
  "anchor": "Why do restaurants get so loud?",
  "tags": [
   "restaurant",
   "lombard effect",
   "voices",
   "crowd"
  ],
  "c": "red",
  "sid": "why-do-restaurants-get-so-loud"
 },
 {
  "see": "Living next to a busy road for years",
  "is": "WHO's 2018 review linked road noise to about 8% higher heart disease risk per 10 dB Lden.",
  "section": "health",
  "anchor": "Can traffic noise cause heart disease?",
  "tags": [
   "heart disease",
   "road traffic",
   "cardiovascular",
   "health"
  ],
  "c": "red",
  "sid": "can-traffic-noise-cause-heart-disease"
 },
 {
  "see": "School under a flight path",
  "is": "RANCH linked aircraft noise at schools to slower reading in children.",
  "section": "health",
  "anchor": "Do airplanes affect children's learning?",
  "tags": [
   "school",
   "children",
   "reading",
   "aircraft"
  ],
  "c": "red",
  "sid": "do-airplanes-affect-children-s-learning"
 },
 {
  "see": "Chewing sounds make me furious",
  "is": "Misophonia: decreased tolerance to specific sounds, per a 2022 consensus definition.",
  "section": "health",
  "anchor": "What is misophonia vs hyperacusis?",
  "tags": [
   "misophonia",
   "chewing",
   "sound sensitivity",
   "trigger"
  ],
  "c": "red",
  "sid": "what-is-misophonia-vs-hyperacusis"
 },
 {
  "see": "Everyday sounds feel painfully loud",
  "is": "Hyperacusis: a disproportionate increase in perceived loudness of normal-volume sounds (ICD-10 H93.23).",
  "section": "health",
  "anchor": "What is misophonia vs hyperacusis?",
  "tags": [
   "hyperacusis",
   "loudness",
   "pain",
   "sensitivity"
  ],
  "c": "red",
  "sid": "what-is-misophonia-vs-hyperacusis"
 },
 {
  "see": "My phone warned me about my weekly listening",
  "is": "WHO-ITU H.870 devices track a weekly sound allowance, 80 dB for 40 hours for adults.",
  "section": "health",
  "anchor": "Are there safe listening standards for headphones and venues?",
  "tags": [
   "headphone warning",
   "h.870",
   "weekly limit",
   "phone"
  ],
  "c": "red",
  "sid": "are-there-safe-listening-standards-for-headphones-and-venues"
 },
 {
  "see": "Earplugs that say NRR 33",
  "is": "Real protection is usually lower; OSHA and NIOSH derate the label.",
  "section": "health",
  "anchor": "What NRR earplugs do I need for a concert?",
  "tags": [
   "earplugs",
   "nrr",
   "concert",
   "protection"
  ],
  "c": "red",
  "sid": "what-nrr-earplugs-do-i-need-for-a-concert"
 },
 {
  "see": "How many Europeans are bothered by traffic noise",
  "is": "The EEA says more than 20% live at or above 55 dB Lden from transport noise.",
  "section": "health",
  "anchor": "How many people are affected in Europe?",
  "tags": [
   "europe",
   "eea",
   "exposure",
   "transport noise"
  ],
  "c": "red",
  "sid": "how-many-people-are-affected-in-europe"
 },
 {
  "see": "Is there a US federal noise law?",
  "is": "Yes, but EPA's noise office was defunded in 1981, so cities write most rules.",
  "section": "rules",
  "anchor": "Why is there no national noise law in the US?",
  "tags": [
   "federal",
   "epa",
   "noise control act",
   "onac"
  ],
  "c": "pnk",
  "sid": "why-is-there-no-national-noise-law-in-the-us"
 },
 {
  "see": "Can police ticket noise without a meter?",
  "is": "Many codes use a plainly audible test - if it can be clearly heard at a set distance, it violates.",
  "section": "rules",
  "anchor": "What does \"plainly audible\" mean?",
  "tags": [
   "plainly audible",
   "meter",
   "police",
   "ordinance"
  ],
  "c": "pnk",
  "sid": "what-does-plainly-audible-mean"
 },
 {
  "see": "Thumping bass from a bar next door",
  "is": "Some codes, like New York City's and Toronto's, set dBC or octave-band limits aimed at bass.",
  "section": "rules",
  "anchor": "Where is the noise measured?",
  "tags": [
   "bass",
   "bar",
   "dbc",
   "music"
  ],
  "c": "pnk",
  "sid": "where-is-the-noise-measured"
 },
 {
  "see": "Bar music coming through my apartment in New York",
  "is": "NYC caps commercial music at 42 dB(A) inside your home.",
  "section": "rules",
  "anchor": "What are New York City's noise rules?",
  "tags": [
   "nyc",
   "bar",
   "club",
   "music",
   "42 dba"
  ],
  "c": "pnk",
  "sid": "what-are-new-york-city-s-noise-rules"
 },
 {
  "see": "A neighbor's air conditioner humming all night",
  "is": "NYC limits air conditioners to 42 dB(A) inside a home; Toronto to 45 dB(A) outdoors at night.",
  "section": "rules",
  "anchor": "What are New York City's noise rules?",
  "tags": [
   "air conditioner",
   "hvac",
   "hum",
   "night"
  ],
  "c": "pnk",
  "sid": "what-are-new-york-city-s-noise-rules"
 },
 {
  "see": "A garbage truck crashing at 5 a.m.",
  "is": "NYC caps garbage trucks at 80 dBA at 35 ft and restricts them near homes 11 p.m. to 7 a.m.",
  "section": "rules",
  "anchor": "What are New York City's noise rules?",
  "tags": [
   "garbage truck",
   "trash",
   "early morning",
   "nyc"
  ],
  "c": "pnk",
  "sid": "what-are-new-york-city-s-noise-rules"
 },
 {
  "see": "A dog that won't stop barking",
  "is": "NYC bans unreasonable animal noise lasting 10 minutes by day or 5 minutes at night.",
  "section": "rules",
  "anchor": "What are New York City's noise rules?",
  "tags": [
   "dog",
   "barking",
   "animal",
   "nyc"
  ],
  "c": "pnk",
  "sid": "what-are-new-york-city-s-noise-rules"
 },
 {
  "see": "Construction noise after dark in San Francisco",
  "is": "Night work (8 p.m. to 7 a.m.) may not exceed ambient by 5 dBA without a permit.",
  "section": "rules",
  "anchor": "What about San Francisco?",
  "tags": [
   "construction",
   "san francisco",
   "night",
   "permit"
  ],
  "c": "pnk",
  "sid": "what-about-san-francisco"
 },
 {
  "see": "A gas leaf blower whining on a Saturday morning",
  "is": "Rules range from hours limits to outright gas bans (DC 2022, Cambridge 2025); California is phasing out sales.",
  "section": "rules",
  "anchor": "Who bans leaf blowers, and why is it contested?",
  "tags": [
   "leaf blower",
   "gas",
   "ban",
   "landscaping"
  ],
  "c": "pnk",
  "sid": "who-bans-leaf-blowers-and-why-is-it-contested"
 },
 {
  "see": "Loud neighbors in England",
  "is": "Councils must investigate statutory nuisance and can serve an abatement notice.",
  "section": "rules",
  "anchor": "How does the UK deal with noisy neighbors?",
  "tags": [
   "uk",
   "england",
   "neighbor",
   "statutory nuisance"
  ],
  "c": "pnk",
  "sid": "how-does-the-uk-deal-with-noisy-neighbors"
 },
 {
  "see": "Builders starting early in the UK",
  "is": "Councils set hours by section 60 notice or section 61 prior consent; 8 a.m. to 6 p.m. weekdays is common.",
  "section": "rules",
  "anchor": "What time can builders start in the UK?",
  "tags": [
   "uk",
   "construction",
   "builders",
   "section 61"
  ],
  "c": "pnk",
  "sid": "what-time-can-builders-start-in-the-uk"
 },
 {
  "see": "Party music in Toronto",
  "is": "Amplified sound is limited to 50 dB(A) outdoors and 42 dB(A) indoors at night.",
  "section": "rules",
  "anchor": "What are Toronto's noise limits?",
  "tags": [
   "toronto",
   "canada",
   "music",
   "bylaw"
  ],
  "c": "pnk",
  "sid": "what-are-toronto-s-noise-limits"
 },
 {
  "see": "Lawn mower at night in Sydney",
  "is": "NSW bars garden tools from being heard indoors next door 8 p.m. to 7 a.m. weekdays.",
  "section": "rules",
  "anchor": "What time can you mow the lawn in New South Wales?",
  "tags": [
   "nsw",
   "australia",
   "mower",
   "sydney"
  ],
  "c": "pnk",
  "sid": "what-time-can-you-mow-the-lawn-in-new-south-wales"
 },
 {
  "see": "Traffic noise standards in Japan",
  "is": "Japan targets 55 dB by day and 45 dB at night in residential areas, higher beside main roads.",
  "section": "rules",
  "anchor": "What are Japan's noise standards?",
  "tags": [
   "japan",
   "standards",
   "traffic",
   "residential"
  ],
  "c": "pnk",
  "sid": "what-are-japan-s-noise-standards"
 },
 {
  "see": "Delivery wagons kept ancient Romans awake",
  "is": "Caesar's 44 BCE rule pushed wagons into the night",
  "section": "history",
  "anchor": "Did ancient Rome have noise laws?",
  "tags": [
   "rome",
   "ancient",
   "wagons",
   "history"
  ],
  "c": "yel",
  "sid": "did-ancient-rome-have-noise-laws"
 },
 {
  "see": "Who fought street musicians in Victorian London?",
  "is": "Charles Babbage, who counted 165 interruptions in 80 days",
  "section": "history",
  "anchor": "Babbage against the organ grinders (London, 1860s)",
  "tags": [
   "babbage",
   "organ grinder",
   "london",
   "street music"
  ],
  "c": "yel",
  "sid": "babbage-against-the-organ-grinders-london-1860s"
 },
 {
  "see": "Why are tugboat whistles regulated?",
  "is": "Julia Barnett Rice's 1906 campaign led to the 1907 Bennett Act",
  "section": "history",
  "anchor": "Julia Barnett Rice and the tugboat whistles (New York, 1906)",
  "tags": [
   "tugboat",
   "whistle",
   "new york",
   "rice"
  ],
  "c": "yel",
  "sid": "julia-barnett-rice-and-the-tugboat-whistles-new-york-1906"
 },
 {
  "see": "When did a city first measure its noise in decibels?",
  "is": "New York's Noise Abatement Commission, from 1929",
  "section": "history",
  "anchor": "New York measures its noise (1929-1936)",
  "tags": [
   "new york",
   "1929",
   "commission",
   "decibel"
  ],
  "c": "yel",
  "sid": "new-york-measures-its-noise-1929-1936"
 },
 {
  "see": "Why doesn't the EPA regulate noise anymore?",
  "is": "Its noise office lost funding in 1981; the 1972 Act is still law",
  "section": "history",
  "anchor": "The US Noise Control Act of 1972 and the office that vanished",
  "tags": [
   "epa",
   "onac",
   "noise control act",
   "federal"
  ],
  "c": "yel",
  "sid": "the-us-noise-control-act-of-1972-and-the-office-that-vanished"
 },
 {
  "see": "Why does Europe have noise maps and the US mostly doesn't?",
  "is": "The 2002 EU Directive requires them every five years",
  "section": "history",
  "anchor": "Europe maps its noise: the 2002 Directive",
  "tags": [
   "eu",
   "directive",
   "noise map",
   "europe"
  ],
  "c": "yel",
  "sid": "europe-maps-its-noise-the-2002-directive"
 },
 {
  "see": "What does 'soundscape' mean?",
  "is": "The sound environment as people perceive it, in context (ISO 12913-1)",
  "section": "history",
  "anchor": "From noise to soundscape: Schafer and ISO 12913",
  "tags": [
   "soundscape",
   "schafer",
   "iso 12913",
   "acoustic ecology"
  ],
  "c": "yel",
  "sid": "from-noise-to-soundscape-schafer-and-iso-12913"
 },
 {
  "see": "A siren that rises and falls slowly",
  "is": "The wail tone.",
  "section": "sirens",
  "anchor": "What are the different siren sounds?",
  "tags": [
   "siren",
   "wail",
   "ambulance",
   "police"
  ],
  "c": "red",
  "sid": "what-are-the-different-siren-sounds"
 },
 {
  "see": "A siren that warbles fast near an intersection",
  "is": "The yelp or phaser tone.",
  "section": "sirens",
  "anchor": "What are the different siren sounds?",
  "tags": [
   "siren",
   "yelp",
   "phaser",
   "intersection"
  ],
  "c": "red",
  "sid": "what-are-the-different-siren-sounds"
 },
 {
  "see": "A siren with two alternating notes",
  "is": "Hi-lo or two-tone siren.",
  "section": "sirens",
  "anchor": "What are the different siren sounds?",
  "tags": [
   "siren",
   "hi-lo",
   "two-tone"
  ],
  "c": "red",
  "sid": "what-are-the-different-siren-sounds"
 },
 {
  "see": "A deep throbbing I feel in my car when police pass",
  "is": "A low-frequency Rumbler siren.",
  "section": "sirens",
  "anchor": "What is the police siren that makes my car shake?",
  "tags": [
   "rumbler",
   "police",
   "vibration",
   "low frequency"
  ],
  "c": "red",
  "sid": "what-is-the-police-siren-that-makes-my-car-shake"
 },
 {
  "see": "European sirens that go 'ta-tu-ta-ta'",
  "is": "Germany's legally required two-tone Martinshorn.",
  "section": "sirens",
  "anchor": "Why do sirens sound different in Europe?",
  "tags": [
   "germany",
   "europe",
   "two-tone",
   "martinshorn"
  ],
  "c": "red",
  "sid": "why-do-sirens-sound-different-in-europe"
 },
 {
  "see": "An ambulance siren that hurts my ears at the curb",
  "is": "About 122 dBA at 10 ft, per NIOSH.",
  "section": "sirens",
  "anchor": "How loud is an ambulance siren?",
  "tags": [
   "ambulance",
   "loud",
   "decibels",
   "hearing"
  ],
  "c": "red",
  "sid": "how-loud-is-an-ambulance-siren"
 },
 {
  "see": "I can't tell which street the siren is on",
  "is": "Pure-tone sirens and building reflections confuse direction cues.",
  "section": "sirens",
  "anchor": "Why can't I tell which direction a siren is coming from?",
  "tags": [
   "direction",
   "localization",
   "siren",
   "echo"
  ],
  "c": "red",
  "sid": "why-can-t-i-tell-which-direction-a-siren-is-coming-from"
 },
 {
  "see": "A long steady siren at the same time every month",
  "is": "An outdoor warning siren test.",
  "section": "sirens",
  "anchor": "What are outdoor warning sirens, and why do they test them?",
  "tags": [
   "warning siren",
   "test",
   "civil defense",
   "hawaii"
  ],
  "c": "red",
  "sid": "what-are-outdoor-warning-sirens-and-why-do-they-test-them"
 },
 {
  "see": "Music from loudspeakers at 5 pm in a Japanese town",
  "is": "A daily test of the bosai musen disaster speakers.",
  "section": "sirens",
  "anchor": "What are outdoor warning sirens, and why do they test them?",
  "tags": [
   "japan",
   "5 pm",
   "chime",
   "bosai musen"
  ],
  "c": "red",
  "sid": "what-are-outdoor-warning-sirens-and-why-do-they-test-them"
 },
 {
  "see": "A parked car cycling through honks and whoops",
  "is": "A car alarm, usually false.",
  "section": "sirens",
  "anchor": "Do car alarms actually stop theft?",
  "tags": [
   "car alarm",
   "false alarm",
   "theft"
  ],
  "c": "red",
  "sid": "do-car-alarms-actually-stop-theft"
 },
 {
  "see": "A constant roar from the highway that never stops",
  "is": "Mostly tire-pavement noise; road traffic is the most widespread noise source.",
  "section": "traffic",
  "anchor": "Is traffic really the biggest source of city noise?",
  "tags": [
   "highway",
   "roar",
   "traffic",
   "road"
  ],
  "c": "org",
  "sid": "is-traffic-really-the-biggest-source-of-city-noise"
 },
 {
  "see": "Half the cars but it barely sounds quieter",
  "is": "Halving traffic only lowers the level about 3 dBA.",
  "section": "traffic",
  "anchor": "Why doesn't cutting traffic in half make it twice as quiet?",
  "tags": [
   "traffic volume",
   "decibels",
   "loudness"
  ],
  "c": "org",
  "sid": "why-doesn-t-cutting-traffic-in-half-make-it-twice-as-quiet"
 },
 {
  "see": "A whine or hum from cars on the highway",
  "is": "Tire noise, which dominates above about 20 mph (32 km/h).",
  "section": "traffic",
  "anchor": "Are tires or engines louder?",
  "tags": [
   "tires",
   "highway",
   "whine",
   "speed"
  ],
  "c": "org",
  "sid": "are-tires-or-engines-louder"
 },
 {
  "see": "The road suddenly gets quieter on a new stretch of pavement",
  "is": "A quieter surface such as porous asphalt or tined concrete.",
  "section": "traffic",
  "anchor": "What is quiet pavement, and does it last?",
  "tags": [
   "pavement",
   "asphalt",
   "road surface",
   "quiet"
  ],
  "c": "org",
  "sid": "what-is-quiet-pavement-and-does-it-last"
 },
 {
  "see": "A tall wall along the highway behind houses",
  "is": "A noise barrier, built under the FHWA Noise Abatement Criteria.",
  "section": "traffic",
  "anchor": "When does a highway get a noise wall?",
  "tags": [
   "noise wall",
   "barrier",
   "highway",
   "fhwa"
  ],
  "c": "org",
  "sid": "when-does-a-highway-get-a-noise-wall"
 },
 {
  "see": "Drivers honking for no reason",
  "is": "Unnecessary horn use is barred by state law in places like North Carolina.",
  "section": "traffic",
  "anchor": "Is it illegal to honk for no reason?",
  "tags": [
   "horn",
   "honking",
   "car",
   "law"
  ],
  "c": "org",
  "sid": "is-it-illegal-to-honk-for-no-reason"
 },
 {
  "see": "Endless honking at every intersection abroad",
  "is": "Horn culture in India; Mumbai tried a signal that punishes honking.",
  "section": "traffic",
  "anchor": "Elsewhere in the world: horns in India",
  "tags": [
   "horn",
   "india",
   "mumbai",
   "honking"
  ],
  "c": "org",
  "sid": "elsewhere-in-the-world-horns-in-india"
 },
 {
  "see": "A crackling, popping exhaust or a very loud motorcycle",
  "is": "Likely a modified exhaust; EPA caps new street motorcycles at 80 dBA.",
  "section": "traffic",
  "anchor": "What are the rules on loud motorcycles and exhausts?",
  "tags": [
   "exhaust",
   "motorcycle",
   "muffler",
   "loud car"
  ],
  "c": "org",
  "sid": "what-are-the-rules-on-loud-motorcycles-and-exhausts"
 },
 {
  "see": "A box with a microphone and camera on a pole by the road",
  "is": "A noise camera, used or trialed in New York City, France and the UK.",
  "section": "traffic",
  "anchor": "How do noise cameras work, and do they hold up?",
  "tags": [
   "noise camera",
   "radar",
   "enforcement",
   "ticket"
  ],
  "c": "org",
  "sid": "how-do-noise-cameras-work-and-do-they-hold-up"
 },
 {
  "see": "A machine-gun rattle from a truck slowing down",
  "is": "An engine compression brake (Jake brake), loudest with a poor muffler.",
  "section": "traffic",
  "anchor": "What does a \"no engine brake\" sign mean?",
  "tags": [
   "jake brake",
   "truck",
   "engine brake",
   "rattle"
  ],
  "c": "org",
  "sid": "what-does-a-no-engine-brake-sign-mean"
 },
 {
  "see": "Garbage truck noise early in the morning",
  "is": "Diesel engine and compactor noise; electric trucks cut the engine part.",
  "section": "traffic",
  "anchor": "Are electric garbage trucks quieter?",
  "tags": [
   "garbage truck",
   "trash",
   "refuse",
   "electric"
  ],
  "c": "org",
  "sid": "are-electric-garbage-trucks-quieter"
 },
 {
  "see": "A train blasting its horn at night: long, long, short, long",
  "is": "The federally required crossing horn, 96 to 110 dB(A).",
  "section": "transit",
  "anchor": "How loud is a train horn, and why do trains honk at night?",
  "tags": [
   "train horn",
   "crossing",
   "night",
   "railroad"
  ],
  "c": "blu",
  "sid": "how-loud-is-a-train-horn-and-why-do-trains-honk-at-night"
 },
 {
  "see": "Trains go through crossings without honking",
  "is": "A quiet zone created by the local authority.",
  "section": "transit",
  "anchor": "How does a town get a train quiet zone?",
  "tags": [
   "quiet zone",
   "train",
   "crossing",
   "horn"
  ],
  "c": "blu",
  "sid": "how-does-a-town-get-a-train-quiet-zone"
 },
 {
  "see": "Steady rumble from a rail line near home",
  "is": "Railway noise, the second most widespread source in Europe.",
  "section": "transit",
  "anchor": "How many people hear rail noise?",
  "tags": [
   "rail",
   "train",
   "rumble",
   "exposure"
  ],
  "c": "blu",
  "sid": "how-many-people-hear-rail-noise"
 },
 {
  "see": "The subway is so loud I cover my ears",
  "is": "NYC platform peaks have reached 102 to 106 dBA.",
  "section": "transit",
  "anchor": "How loud is the subway?",
  "tags": [
   "subway",
   "platform",
   "hearing",
   "loud"
  ],
  "c": "blu",
  "sid": "how-loud-is-the-subway"
 },
 {
  "see": "A piercing screech when a train goes around a bend",
  "is": "Wheel squeal from wheels slipping sideways on a tight curve.",
  "section": "transit",
  "anchor": "Why do trains screech on curves?",
  "tags": [
   "screech",
   "squeal",
   "curve",
   "subway"
  ],
  "c": "blu",
  "sid": "why-do-trains-screech-on-curves"
 },
 {
  "see": "A curve that used to screech is quieter now",
  "is": "Likely lubrication, friction modifier or water spray on the rail.",
  "section": "transit",
  "anchor": "What fixes wheel squeal?",
  "tags": [
   "lubrication",
   "squeal",
   "fix",
   "rail"
  ],
  "c": "blu",
  "sid": "what-fixes-wheel-squeal"
 },
 {
  "see": "The Green Line shrieking at Boylston",
  "is": "One of the sharpest subway curves in North America.",
  "section": "transit",
  "anchor": "In Boston: the Green Line at Boylston",
  "tags": [
   "green line",
   "boylston",
   "mbta",
   "boston"
  ],
  "c": "blu",
  "sid": "in-boston-the-green-line-at-boylston"
 },
 {
  "see": "Planes now pass over the same few blocks one after another",
  "is": "Satellite-guided RNAV routes concentrate flights on one precise track",
  "section": "aircraft",
  "anchor": "Why are planes suddenly flying over my house?",
  "tags": [
   "flight path",
   "rnav",
   "nextgen",
   "planes",
   "new route"
  ],
  "c": "blu",
  "sid": "why-are-planes-suddenly-flying-over-my-house"
 },
 {
  "see": "The airport says my house isn't in the noise zone",
  "is": "Official US noise zones are yearly-average 65 DNL contours, not single flights",
  "section": "aircraft",
  "anchor": "How is airport noise measured in the US?",
  "tags": [
   "dnl",
   "65 dnl",
   "noise map",
   "contour"
  ],
  "c": "blu",
  "sid": "how-is-airport-noise-measured-in-the-us"
 },
 {
  "see": "Can the airport pay to soundproof my windows?",
  "is": "Possibly, through an FAA Part 150 noise program",
  "section": "aircraft",
  "anchor": "How is airport noise measured in the US?",
  "tags": [
   "soundproofing",
   "sound insulation",
   "part 150",
   "windows"
  ],
  "c": "blu",
  "sid": "how-is-airport-noise-measured-in-the-us"
 },
 {
  "see": "Older jets sounded like a crackling roar, new ones whine",
  "is": "High-bypass turbofans cut jet roar; the big fan adds a tonal whine",
  "section": "aircraft",
  "anchor": "Why are newer jets quieter?",
  "tags": [
   "jet engine",
   "turbofan",
   "quieter planes",
   "whine"
  ],
  "c": "blu",
  "sid": "why-are-newer-jets-quieter"
 },
 {
  "see": "A loud old plane still flying - isn't that banned?",
  "is": "Types are certified to a noise Stage; the oldest Stages are banned from US operation",
  "section": "aircraft",
  "anchor": "What are aircraft noise \"Stages\" and ICAO \"Chapters\"?",
  "tags": [
   "stage 3",
   "stage 5",
   "certification",
   "old jets"
  ],
  "c": "blu",
  "sid": "what-are-aircraft-noise-stages-and-icao-chapters"
 },
 {
  "see": "Is anyone going to change how airport noise is judged?",
  "is": "The FAA is reviewing 65 DNL; no change as of October 2026",
  "section": "aircraft",
  "anchor": "What did the FAA's 2021 noise survey find, and is 65 DNL changing?",
  "tags": [
   "faa",
   "noise policy review",
   "65 dnl",
   "survey"
  ],
  "c": "blu",
  "sid": "what-did-the-faa-s-2021-noise-survey-find-and-is-65-dnl-changing"
 },
 {
  "see": "Planes landing before dawn near Heathrow",
  "is": "About 80% of Heathrow night flights land 04:30-06:00 under a quota system",
  "section": "aircraft",
  "anchor": "Does the airport have a curfew? (Elsewhere in the world)",
  "tags": [
   "heathrow",
   "night flights",
   "quota",
   "london"
  ],
  "c": "blu",
  "sid": "does-the-airport-have-a-curfew-elsewhere-in-the-world"
 },
 {
  "see": "Does this airport close at night?",
  "is": "Sydney, Frankfurt and Narita have night bans; rules vary by airport",
  "section": "aircraft",
  "anchor": "Does the airport have a curfew? (Elsewhere in the world)",
  "tags": [
   "curfew",
   "night flights",
   "sydney",
   "frankfurt",
   "narita"
  ],
  "c": "blu",
  "sid": "does-the-airport-have-a-curfew-elsewhere-in-the-world"
 },
 {
  "see": "A sharp double bang from the sky",
  "is": "A sonic boom from an aircraft flying faster than sound",
  "section": "aircraft",
  "anchor": "Is supersonic flight over land legal now?",
  "tags": [
   "sonic boom",
   "supersonic",
   "bang"
  ],
  "c": "blu",
  "sid": "is-supersonic-flight-over-land-legal-now"
 },
 {
  "see": "A soft thump from a NASA test plane",
  "is": "NASA's X-59 is designed to make a quiet supersonic thump",
  "section": "aircraft",
  "anchor": "Is supersonic flight over land legal now?",
  "tags": [
   "x-59",
   "nasa",
   "thump",
   "supersonic"
  ],
  "c": "blu",
  "sid": "is-supersonic-flight-over-land-legal-now"
 },
 {
  "see": "A rhythmic thwop over the river all afternoon",
  "is": "Helicopter rotor noise, often tourist flights in New York",
  "section": "aircraft",
  "anchor": "Why are helicopters so loud in New York?",
  "tags": [
   "helicopter",
   "thwop",
   "tourist flights",
   "new york"
  ],
  "c": "blu",
  "sid": "why-are-helicopters-so-loud-in-new-york"
 },
 {
  "see": "A high buzzing whine overhead in a quiet area",
  "is": "A small drone; studies find drones annoying out of proportion to their level",
  "section": "aircraft",
  "anchor": "Are delivery drones loud?",
  "tags": [
   "drone",
   "buzz",
   "whine",
   "delivery"
  ],
  "c": "blu",
  "sid": "are-delivery-drones-loud"
 },
 {
  "see": "What plane just flew over my house?",
  "is": "Check the airport's WebTrak map or a flight tracker",
  "section": "aircraft",
  "anchor": "What plane just flew over, and how do I complain?",
  "tags": [
   "webtrak",
   "flight tracker",
   "what plane",
   "complaint"
  ],
  "c": "blu",
  "sid": "what-plane-just-flew-over-and-how-do-i-complain"
 },
 {
  "see": "How do I complain about Logan Airport noise?",
  "is": "Call Massport's noise line or use its online form",
  "section": "aircraft",
  "anchor": "In Boston",
  "tags": [
   "logan",
   "massport",
   "complaint",
   "boston"
  ],
  "c": "blu",
  "sid": "in-boston"
 },
 {
  "see": "Departures over Cambridge since 2014",
  "is": "Logan Runway 33L RNAV departures concentrated over north and west Cambridge",
  "section": "aircraft",
  "anchor": "Why are planes suddenly flying over my house?",
  "tags": [
   "logan",
   "33l",
   "cambridge",
   "rnav"
  ],
  "c": "blu",
  "sid": "why-are-planes-suddenly-flying-over-my-house"
 },
 {
  "see": "A helicopter over Boston that Massport can't identify",
  "is": "Massport's system has limited data on non-Logan helicopters and small planes",
  "section": "aircraft",
  "anchor": "Why are helicopters so loud in New York?",
  "tags": [
   "helicopter",
   "boston",
   "massport",
   "small planes"
  ],
  "c": "blu",
  "sid": "why-are-helicopters-so-loud-in-new-york"
 },
 {
  "see": "Jackhammering on the street that rattles the windows",
  "is": "Jackhammers measure about 89 dBA Lmax at 50 feet in the FHWA table.",
  "section": "construction",
  "anchor": "How loud is a jackhammer?",
  "tags": [
   "jackhammer",
   "construction",
   "drilling",
   "loud"
  ],
  "c": "yel",
  "sid": "how-loud-is-a-jackhammer"
 },
 {
  "see": "A deep pounding thud from a building site, over and over",
  "is": "An impact pile driver, the loudest item in the FHWA table at 101 dBA Lmax at 50 feet.",
  "section": "construction",
  "anchor": "How loud is a jackhammer?",
  "tags": [
   "pile driver",
   "pounding",
   "construction",
   "thud"
  ],
  "c": "yel",
  "sid": "how-loud-is-a-jackhammer"
 },
 {
  "see": "A screaming grinding sound cutting through pavement",
  "is": "A concrete saw, about 90 dBA Lmax at 50 feet.",
  "section": "construction",
  "anchor": "How loud is a jackhammer?",
  "tags": [
   "concrete saw",
   "grinding",
   "cutting",
   "construction"
  ],
  "c": "yel",
  "sid": "how-loud-is-a-jackhammer"
 },
 {
  "see": "Beep beep beep from a truck backing up at dawn",
  "is": "A tonal reverse signal alarm, required by OSHA on vehicles with an obstructed rear view unless a spotter is used.",
  "section": "construction",
  "anchor": "Why do trucks beep when they back up?",
  "tags": [
   "backup beeper",
   "reverse alarm",
   "truck",
   "beeping"
  ],
  "c": "yel",
  "sid": "why-do-trucks-beep-when-they-back-up"
 },
 {
  "see": "A truck that hisses like static instead of beeping when it reverses",
  "is": "A broadband (white-noise) backup alarm, which OSHA says can comply with its rules.",
  "section": "construction",
  "anchor": "Why do some backup alarms sound like static instead of beeping?",
  "tags": [
   "white noise",
   "backup alarm",
   "static",
   "hiss"
  ],
  "c": "yel",
  "sid": "why-do-some-backup-alarms-sound-like-static-instead-of-beeping"
 },
 {
  "see": "Why is every construction noise number 'at 50 feet'?",
  "is": "The FHWA table fixes distance so machines can be compared; levels drop as you move away.",
  "section": "construction",
  "anchor": "Why are construction numbers always \"at 50 feet\"?",
  "tags": [
   "decibels",
   "distance",
   "lmax",
   "construction"
  ],
  "c": "yel",
  "sid": "why-are-construction-numbers-always-at-50-feet"
 },
 {
  "see": "Where did the standard construction noise numbers come from?",
  "is": "From the Big Dig's specification 721.560, via the FHWA's RCNM table.",
  "section": "construction",
  "anchor": "Why does every US construction noise table look the same?",
  "tags": [
   "big dig",
   "rcnm",
   "fhwa",
   "boston"
  ],
  "c": "yel",
  "sid": "why-does-every-us-construction-noise-table-look-the-same"
 },
 {
  "see": "Construction starting early in the morning",
  "is": "Hours are set by local noise codes; the rules section covers specifics.",
  "section": "construction",
  "anchor": "What time can construction start?",
  "tags": [
   "construction hours",
   "early",
   "permit",
   "morning"
  ],
  "c": "yel",
  "sid": "what-time-can-construction-start"
 },
 {
  "see": "A whining drone from a yard down the street",
  "is": "A gas leaf blower, typically 65-80 dBA at 50 feet.",
  "section": "construction",
  "anchor": "How loud is a leaf blower?",
  "tags": [
   "leaf blower",
   "whine",
   "yard",
   "gas"
  ],
  "c": "yel",
  "sid": "how-loud-is-a-leaf-blower"
 },
 {
  "see": "A leaf blower I can hear through closed windows from blocks away",
  "is": "Gas blowers carry low-frequency sound; one study heard them at 800 feet.",
  "section": "construction",
  "anchor": "Why can you hear a leaf blower from blocks away?",
  "tags": [
   "leaf blower",
   "low frequency",
   "distance",
   "windows"
  ],
  "c": "yel",
  "sid": "why-can-you-hear-a-leaf-blower-from-blocks-away"
 },
 {
  "see": "Is an electric leaf blower really quieter?",
  "is": "In one 2018 study, about 10 dB quieter at 50 feet than gas models.",
  "section": "construction",
  "anchor": "Are electric leaf blowers quieter?",
  "tags": [
   "electric",
   "battery",
   "leaf blower",
   "quieter"
  ],
  "c": "yel",
  "sid": "are-electric-leaf-blowers-quieter"
 },
 {
  "see": "Are gas leaf blowers banned where I live?",
  "is": "Depends on the town or state; DC, California sales rules and many towns restrict them, while Georgia and Texas limit local bans.",
  "section": "construction",
  "anchor": "Who bans leaf blowers, and why is it a fight?",
  "tags": [
   "ban",
   "gas leaf blower",
   "law",
   "california"
  ],
  "c": "yel",
  "sid": "who-bans-leaf-blowers-and-why-is-it-a-fight"
 },
 {
  "see": "A steady engine drone from lawn mowing",
  "is": "Gas mowers are covered by many of the same rules as blowers, including California's AB 1346.",
  "section": "construction",
  "anchor": "What about lawn mowers?",
  "tags": [
   "lawn mower",
   "mowing",
   "engine",
   "garden"
  ],
  "c": "yel",
  "sid": "what-about-lawn-mowers"
 },
 {
  "see": "A low hum from a green box on the sidewalk",
  "is": "A pad-mounted transformer, humming at about 120 Hz in North America because of magnetostriction.",
  "section": "hums",
  "anchor": "Why does electrical equipment hum?",
  "tags": [
   "transformer",
   "hum",
   "electrical",
   "120 hz"
  ],
  "c": "pur",
  "sid": "why-does-electrical-equipment-hum"
 },
 {
  "see": "A hum that sounds slightly different in Europe",
  "is": "Transformer hum is about 100 Hz on 50 Hz grids versus 120 Hz on 60 Hz grids.",
  "section": "hums",
  "anchor": "Why is the hum 120 Hz in North America and 100 Hz in Europe?",
  "tags": [
   "100 hz",
   "120 hz",
   "europe",
   "grid"
  ],
  "c": "pur",
  "sid": "why-is-the-hum-120-hz-in-north-america-and-100-hz-in-europe"
 },
 {
  "see": "A buzz in my speakers or amp that changes when I plug things in",
  "is": "Audio hum, often a ground loop, at the line frequency itself (60 or 50 Hz).",
  "section": "hums",
  "anchor": "What is the 60 Hz buzz in my speakers?",
  "tags": [
   "ground loop",
   "speaker",
   "buzz",
   "60 hz"
  ],
  "c": "pur",
  "sid": "what-is-the-60-hz-buzz-in-my-speakers"
 },
 {
  "see": "A crackle or sizzle from overhead high-voltage lines",
  "is": "Corona discharge around the conductors.",
  "section": "hums",
  "anchor": "Why do transformers and power lines hum?",
  "tags": [
   "power lines",
   "corona",
   "crackle",
   "high voltage"
  ],
  "c": "pur",
  "sid": "why-do-transformers-and-power-lines-hum"
 },
 {
  "see": "A fan roar from a roof that cycles on and off",
  "is": "HVAC equipment such as rooftop units, condensers or cooling towers.",
  "section": "hums",
  "anchor": "What about rooftop units, chillers and generators?",
  "tags": [
   "hvac",
   "rooftop unit",
   "fan",
   "air conditioning"
  ],
  "c": "pur",
  "sid": "what-about-rooftop-units-chillers-and-generators"
 },
 {
  "see": "A diesel engine that runs for a while on a schedule, then stops",
  "is": "Likely a backup generator test; data center generators are tested at least monthly.",
  "section": "hums",
  "anchor": "What about rooftop units, chillers and generators?",
  "tags": [
   "generator",
   "diesel",
   "test",
   "engine"
  ],
  "c": "pur",
  "sid": "what-about-rooftop-units-chillers-and-generators"
 },
 {
  "see": "A constant whooshing drone at night near an industrial building",
  "is": "Possibly data center cooling, much of it low-frequency.",
  "section": "hums",
  "anchor": "Why are data centers so loud?",
  "tags": [
   "data center",
   "cooling",
   "drone",
   "night"
  ],
  "c": "pur",
  "sid": "why-are-data-centers-so-loud"
 },
 {
  "see": "What noise limits apply to a data center near me?",
  "is": "Local rules vary; examples include Prince William County, Niagara Falls and Chandler.",
  "section": "hums",
  "anchor": "Who sets data center noise limits?",
  "tags": [
   "data center",
   "noise limit",
   "ordinance",
   "zoning"
  ],
  "c": "pur",
  "sid": "who-sets-data-center-noise-limits"
 },
 {
  "see": "A low throbbing hum at night that nobody else can hear",
  "is": "Reports like this are called 'the Hum'; most cases are unexplained.",
  "section": "hums",
  "anchor": "What is \"the Hum\"?",
  "tags": [
   "the hum",
   "low frequency",
   "night",
   "mystery"
  ],
  "c": "pur",
  "sid": "what-is-the-hum"
 },
 {
  "see": "The Windsor Hum",
  "is": "A Canadian-funded study linked it to Zug Island blast furnaces in Michigan; reports faded in 2020.",
  "section": "hums",
  "anchor": "The Windsor Hum",
  "tags": [
   "windsor",
   "zug island",
   "ontario",
   "hum"
  ],
  "c": "pur",
  "sid": "the-windsor-hum"
 },
 {
  "see": "How do I find out what is making a hum?",
  "is": "Note its pattern and pitch, walk toward likely sources, ask neighbors, and do not rely on a dBA reading alone.",
  "section": "hums",
  "anchor": "How to track down a hum",
  "tags": [
   "hum",
   "find source",
   "pitch",
   "measure"
  ],
  "c": "pur",
  "sid": "how-to-track-down-a-hum"
 },
 {
  "see": "Fast clicking like a machine gun at a crosswalk",
  "is": "The rapid tick: walk now.",
  "section": "signals",
  "anchor": "Why do crosswalks make a machine gun sound?",
  "tags": [
   "crosswalk",
   "rapid tick",
   "walk",
   "aps"
  ],
  "c": "grn",
  "sid": "why-do-crosswalks-make-a-machine-gun-sound"
 },
 {
  "see": "A slow beep from the crosswalk button when nobody is crossing",
  "is": "The locator tone that helps people find the button.",
  "section": "signals",
  "anchor": "What does the beeping at a crosswalk mean?",
  "tags": [
   "crosswalk",
   "locator tone",
   "beep",
   "push button"
  ],
  "c": "grn",
  "sid": "what-does-the-beeping-at-a-crosswalk-mean"
 },
 {
  "see": "A voice saying the walk sign is on",
  "is": "An accessible pedestrian signal's speech walk message.",
  "section": "signals",
  "anchor": "Why do crosswalks make a machine gun sound?",
  "tags": [
   "crosswalk",
   "speech",
   "walk sign",
   "blind"
  ],
  "c": "grn",
  "sid": "why-do-crosswalks-make-a-machine-gun-sound"
 },
 {
  "see": "Bird chirps or a song at a crossing in Japan",
  "is": "Japan's accessible signals use melodies and birds.",
  "section": "signals",
  "anchor": "Why do crossings in Japan play bird songs and music?",
  "tags": [
   "japan",
   "crossing",
   "bird",
   "toryanse"
  ],
  "c": "grn",
  "sid": "why-do-crossings-in-japan-play-bird-songs-and-music"
 },
 {
  "see": "A tick-tock and a 'kapow' at an Australian crossing",
  "is": "The PB/5 pedestrian push button.",
  "section": "signals",
  "anchor": "What is the \"tick-tock\" and \"kapow\" at Australian crossings?",
  "tags": [
   "australia",
   "pb/5",
   "kapow",
   "crossing"
  ],
  "c": "grn",
  "sid": "what-is-the-tick-tock-and-kapow-at-australian-crossings"
 },
 {
  "see": "A soft whir from an electric car pulling out",
  "is": "The required low-speed warning sound (FMVSS 141 or AVAS).",
  "section": "signals",
  "anchor": "Why do electric cars make a sound at low speed?",
  "tags": [
   "electric car",
   "ev",
   "avas",
   "whir"
  ],
  "c": "grn",
  "sid": "why-do-electric-cars-make-a-sound-at-low-speed"
 },
 {
  "see": "The EV hum goes quiet once the car speeds up",
  "is": "Above about 20-30 km/h tire noise takes over and the sound may switch off.",
  "section": "signals",
  "anchor": "At what speed does an electric car's warning sound turn off?",
  "tags": [
   "ev",
   "speed",
   "crossover",
   "tire noise"
  ],
  "c": "grn",
  "sid": "at-what-speed-does-an-electric-car-s-warning-sound-turn-off"
 },
 {
  "see": "A short tune before the train doors close in Japan",
  "is": "A hassha departure melody.",
  "section": "signals",
  "anchor": "What is the little tune before a train leaves in Japan?",
  "tags": [
   "japan",
   "train",
   "melody",
   "station"
  ],
  "c": "grn",
  "sid": "what-is-the-little-tune-before-a-train-leaves-in-japan"
 },
 {
  "see": "Bird sounds near exits in a Tokyo station",
  "is": "Guidance sounds for visually impaired riders.",
  "section": "signals",
  "anchor": "What is the little tune before a train leaves in Japan?",
  "tags": [
   "tokyo",
   "station",
   "bird",
   "accessibility"
  ],
  "c": "grn",
  "sid": "what-is-the-little-tune-before-a-train-leaves-in-japan"
 },
 {
  "see": "Music so loud I can feel it in my chest at the front row",
  "is": "Ground-stacked subwoofers; front-row peaks have topped 140 dBC in research at real shows",
  "section": "nightlife",
  "anchor": "How loud does a concert or club actually get?",
  "tags": [
   "concert",
   "bass",
   "subwoofer",
   "front row",
   "loud"
  ],
  "c": "pnk",
  "sid": "how-loud-does-a-concert-or-club-actually-get"
 },
 {
  "see": "My ears are ringing after a club night",
  "is": "Venue sound commonly exceeds 100 dB; WHO says 40% of young people face damaging levels at venues",
  "section": "nightlife",
  "anchor": "How loud does a concert or club actually get?",
  "tags": [
   "club",
   "ringing",
   "ears",
   "hearing",
   "nightclub"
  ],
  "c": "pnk",
  "sid": "how-loud-does-a-concert-or-club-actually-get"
 },
 {
  "see": "Is 100 dB at a concert safe?",
  "is": "WHO's voluntary venue limit is 100 dB LAeq averaged over 15 minutes",
  "section": "nightlife",
  "anchor": "What is the WHO safe listening standard for venues?",
  "tags": [
   "safe",
   "100 db",
   "who",
   "limit",
   "concert"
  ],
  "c": "pnk",
  "sid": "what-is-the-who-safe-listening-standard-for-venues"
 },
 {
  "see": "A quieter room at a festival with free earplugs",
  "is": "A quiet zone, one of six features of the WHO safe listening standard",
  "section": "nightlife",
  "anchor": "What is the WHO safe listening standard for venues?",
  "tags": [
   "quiet zone",
   "earplugs",
   "festival",
   "rest"
  ],
  "c": "pnk",
  "sid": "what-is-the-who-safe-listening-standard-for-venues"
 },
 {
  "see": "A decibel meter display at the mixing desk in France",
  "is": "French law requires continuous dB(A) and dB(C) recording and display at venues over 300 people",
  "section": "nightlife",
  "anchor": "Which countries cap concert volume by law?",
  "tags": [
   "france",
   "decibel",
   "law",
   "mixing desk"
  ],
  "c": "pnk",
  "sid": "which-countries-cap-concert-volume-by-law"
 },
 {
  "see": "An outdoor concert I can hear from home",
  "is": "UK Pop Code limits music noise at nearby homes; in the US it is set by local permits",
  "section": "nightlife",
  "anchor": "When do outdoor concerts have to stop?",
  "tags": [
   "outdoor concert",
   "festival",
   "neighbors",
   "curfew"
  ],
  "c": "pnk",
  "sid": "when-do-outdoor-concerts-have-to-stop"
 },
 {
  "see": "Music stopped at exactly 11pm",
  "is": "The UK Pop Code's 23:00 cutoff for audible music inside nearby homes",
  "section": "nightlife",
  "anchor": "When do outdoor concerts have to stop?",
  "tags": [
   "11pm",
   "curfew",
   "concert",
   "uk"
  ],
  "c": "pnk",
  "sid": "when-do-outdoor-concerts-have-to-stop"
 },
 {
  "see": "New condos next to a club and noise complaints",
  "is": "The agent of change principle decides who pays for soundproofing",
  "section": "nightlife",
  "anchor": "What is the agent of change principle?",
  "tags": [
   "agent of change",
   "condo",
   "club",
   "soundproofing",
   "developer"
  ],
  "c": "pnk",
  "sid": "what-is-the-agent-of-change-principle"
 },
 {
  "see": "Who do I call about a noisy bar instead of the police?",
  "is": "Night mayors and mediation programs like NYC's MEND",
  "section": "nightlife",
  "anchor": "What does a night mayor do?",
  "tags": [
   "night mayor",
   "mediation",
   "bar",
   "complaint"
  ],
  "c": "pnk",
  "sid": "what-does-a-night-mayor-do"
 },
 {
  "see": "A stadium crowd roar that shakes the seats",
  "is": "The Guinness record is 142.2 dBA, set at Arrowhead Stadium in 2014",
  "section": "nightlife",
  "anchor": "How loud is the loudest stadium crowd?",
  "tags": [
   "stadium",
   "crowd",
   "record",
   "roar"
  ],
  "c": "pnk",
  "sid": "how-loud-is-the-loudest-stadium-crowd"
 },
 {
  "see": "Call to prayer over a loudspeaker",
  "is": "Local noise codes set hours for amplified religious sound; Minneapolis allowed all five calls in 2023",
  "section": "nightlife",
  "anchor": "Are church bells and calls to prayer exempt from noise rules?",
  "tags": [
   "call to prayer",
   "adhan",
   "mosque",
   "religious"
  ],
  "c": "pnk",
  "sid": "are-church-bells-and-calls-to-prayer-exempt-from-noise-rules"
 },
 {
  "see": "Church bells ringing on the hour",
  "is": "Religious sound is usually handled through hours or exemptions in local noise codes",
  "section": "nightlife",
  "anchor": "Are church bells and calls to prayer exempt from noise rules?",
  "tags": [
   "church bells",
   "bells",
   "religious",
   "noise code"
  ],
  "c": "pnk",
  "sid": "are-church-bells-and-calls-to-prayer-exempt-from-noise-rules"
 },
 {
  "see": "What is the nighttime noise limit in Boston?",
  "is": "As reported in 2019, 50 decibels from 11 p.m. to 7 a.m. (weighting not stated)",
  "section": "nightlife",
  "anchor": "In Boston",
  "tags": [
   "boston",
   "night",
   "limit",
   "ordinance"
  ],
  "c": "pnk",
  "sid": "in-boston"
 },
 {
  "see": "Birds singing loudly before sunrise",
  "is": "The dawn chorus, which starts earlier in cities",
  "section": "nature",
  "anchor": "Why do birds start singing so early in the city?",
  "tags": [
   "dawn chorus",
   "birds",
   "sunrise",
   "morning"
  ],
  "c": "grn",
  "sid": "why-do-birds-start-singing-so-early-in-the-city"
 },
 {
  "see": "A bird singing at 3am near a streetlight",
  "is": "Urban robins sing at night where daytime noise is high",
  "section": "nature",
  "anchor": "Why is a bird singing at 3 a.m.?",
  "tags": [
   "robin",
   "night",
   "bird",
   "3am",
   "streetlight"
  ],
  "c": "grn",
  "sid": "why-is-a-bird-singing-at-3-a-m"
 },
 {
  "see": "Birds sound higher-pitched on busy streets",
  "is": "Great tits raise the lowest notes of their songs to get above traffic noise",
  "section": "nature",
  "anchor": "Do birds sing higher in cities?",
  "tags": [
   "great tit",
   "pitch",
   "traffic",
   "birdsong"
  ],
  "c": "grn",
  "sid": "do-birds-sing-higher-in-cities"
 },
 {
  "see": "A bird that seems to be shouting over traffic",
  "is": "Nightingales in noisier Berlin territories sang louder, by about 14 dB",
  "section": "nature",
  "anchor": "Do birds sing louder in noisy places?",
  "tags": [
   "nightingale",
   "loud",
   "traffic",
   "berlin"
  ],
  "c": "grn",
  "sid": "do-birds-sing-louder-in-noisy-places"
 },
 {
  "see": "A deafening electric buzz from the trees in summer",
  "is": "Periodical cicadas; choruses reported at 90-100 dB, distance not given",
  "section": "nature",
  "anchor": "How loud are cicadas?",
  "tags": [
   "cicada",
   "buzz",
   "insects",
   "summer",
   "drone"
  ],
  "c": "grn",
  "sid": "how-loud-are-cicadas"
 },
 {
  "see": "Where can I go in the city to hear nothing but nature?",
  "is": "Quiet areas, Hush City maps and certified quiet parks",
  "section": "nature",
  "anchor": "Where can you find quiet in a city?",
  "tags": [
   "quiet park",
   "quiet area",
   "peace",
   "hush city"
  ],
  "c": "grn",
  "sid": "where-can-you-find-quiet-in-a-city"
 },
 {
  "see": "The city sounded so quiet in spring 2020",
  "is": "Lockdowns cut high-frequency seismic noise up to 50% and London street sound by 5.4 dB LAeq on average",
  "section": "nature",
  "anchor": "Did cities really get quieter during the 2020 lockdowns?",
  "tags": [
   "lockdown",
   "covid",
   "quiet",
   "2020",
   "anthropause"
  ],
  "c": "grn",
  "sid": "did-cities-really-get-quieter-during-the-2020-lockdowns"
 },
 {
  "see": "Can my phone measure how loud it is?",
  "is": "A good iPhone app is within about 2 dB of a pro meter; Android varies by device.",
  "section": "quiet",
  "anchor": "Can I measure noise with my phone?",
  "tags": [
   "phone",
   "app",
   "decibel",
   "niosh"
  ],
  "c": "wht",
  "sid": "can-i-measure-noise-with-my-phone"
 },
 {
  "see": "What sound meter do the professionals use?",
  "is": "Class 1 or Class 2 meters under IEC 61672 (Type 1 or 2 in older US terms).",
  "section": "quiet",
  "anchor": "What is a real sound level meter?",
  "tags": [
   "sound level meter",
   "class 1",
   "type 2",
   "calibration"
  ],
  "c": "wht",
  "sid": "what-is-a-real-sound-level-meter"
 },
 {
  "see": "Should I set my meter to dBA or dBC?",
  "is": "dBA for most limits; dBC if the problem is bass and your code has a dBC limit.",
  "section": "quiet",
  "anchor": "How do I take a reading that means something?",
  "tags": [
   "dba",
   "dbc",
   "weighting",
   "settings"
  ],
  "c": "wht",
  "sid": "how-do-i-take-a-reading-that-means-something"
 },
 {
  "see": "A noise map shows my street in red",
  "is": "Maps model long-term averages; check the metric (Lden or LAeq) before comparing.",
  "section": "quiet",
  "anchor": "How do I read a noise map?",
  "tags": [
   "noise map",
   "lden",
   "bts",
   "eu"
  ],
  "c": "wht",
  "sid": "how-do-i-read-a-noise-map"
 },
 {
  "see": "How do I report a noisy neighbor?",
  "is": "Talk first, keep a dated log, use 311 or the council, and consider mediation.",
  "section": "quiet",
  "anchor": "How do I complain about noise effectively?",
  "tags": [
   "complaint",
   "311",
   "neighbor",
   "mediation"
  ],
  "c": "wht",
  "sid": "how-do-i-complain-about-noise-effectively"
 },
 {
  "see": "Where do I report noise in Boston?",
  "is": "Different offices handle parties, construction, aircraft and HVAC; see the Boston section.",
  "section": "quiet",
  "anchor": "In Boston",
  "tags": [
   "boston",
   "311",
   "report",
   "police"
  ],
  "c": "wht",
  "sid": "in-boston"
 },
 {
  "see": "Highway roar that carries for blocks",
  "is": "Line sources like highways fall only about 3 dB per doubling of distance.",
  "section": "quiet",
  "anchor": "How do people find or make quiet?",
  "tags": [
   "highway",
   "traffic",
   "distance",
   "roar"
  ],
  "c": "wht",
  "sid": "how-do-people-find-or-make-quiet"
 },
 {
  "see": "I can hear the bass but not the voices through my wall",
  "is": "Walls block low frequencies far less than high ones, and door seals don't help bass.",
  "section": "quiet",
  "anchor": "How do people find or make quiet?",
  "tags": [
   "bass",
   "wall",
   "soundproofing",
   "neighbor"
  ],
  "c": "wht",
  "sid": "how-do-people-find-or-make-quiet"
 },
 {
  "see": "A party next door going past 11 p.m.",
  "is": "Boston's night limit is 50 dBA from 11 p.m. to 7 a.m.; call 911 or the BPD Party Line.",
  "section": "boston",
  "anchor": "Who do I call about noise in Boston?",
  "tags": [
   "party",
   "night",
   "police",
   "boston",
   "311"
  ],
  "c": "blu",
  "sid": "who-do-i-call-about-noise-in-boston"
 },
 {
  "see": "An air conditioner or building fan humming all night",
  "is": "HVAC noise goes to the Boston Public Health Commission; APCC octave-band limits can catch low hum.",
  "section": "boston",
  "anchor": "What are Boston's noise limits?",
  "tags": [
   "hvac",
   "hum",
   "low frequency",
   "boston"
  ],
  "c": "blu",
  "sid": "what-are-boston-s-noise-limits"
 },
 {
  "see": "Construction starting before 7 a.m.",
  "is": "Boston's regular construction hours are 7 a.m.-6 p.m. weekdays; check the after-hours permit database.",
  "section": "boston",
  "anchor": "What time can construction start in Boston?",
  "tags": [
   "construction",
   "early",
   "permit",
   "isd"
  ],
  "c": "blu",
  "sid": "what-time-can-construction-start-in-boston"
 },
 {
  "see": "Garbage trucks at 6 a.m.",
  "is": "Residential pickup starts at 6 a.m.; state law limits the city on commercial pickup hours.",
  "section": "boston",
  "anchor": "What time can construction start in Boston?",
  "tags": [
   "trash",
   "garbage truck",
   "early",
   "morning"
  ],
  "c": "blu",
  "sid": "what-time-can-construction-start-in-boston"
 },
 {
  "see": "A new fan or compressor in a quiet town",
  "is": "Massachusetts flags sources more than 10 dBA over background or with a pure tone.",
  "section": "boston",
  "anchor": "What is the Massachusetts 10 dBA rule?",
  "tags": [
   "massdep",
   "10 dba",
   "compressor",
   "tone"
  ],
  "c": "blu",
  "sid": "what-is-the-massachusetts-10-dba-rule"
 },
 {
  "see": "Gas leaf blowers on a weekend morning",
  "is": "Brookline, Cambridge, Arlington and others restrict seasons, hours or gas models.",
  "section": "boston",
  "anchor": "Who regulates leaf blowers around Boston?",
  "tags": [
   "leaf blower",
   "brookline",
   "cambridge",
   "gas"
  ],
  "c": "blu",
  "sid": "who-regulates-leaf-blowers-around-boston"
 },
 {
  "see": "Jets over Cambridge or Somerville on the same line every few minutes",
  "is": "RNAV paths since 2014 concentrate Logan Runway 33L departures.",
  "section": "boston",
  "anchor": "Why are there so many planes over Cambridge and Somerville?",
  "tags": [
   "airplane",
   "logan",
   "33l",
   "rnav",
   "overflights"
  ],
  "c": "blu",
  "sid": "why-are-there-so-many-planes-over-cambridge-and-somerville"
 },
 {
  "see": "A plane woke me up and I want to complain",
  "is": "Massport Noise Complaint Line 617-561-3333 or its online portal.",
  "section": "boston",
  "anchor": "How do I complain about Logan Airport noise?",
  "tags": [
   "massport",
   "complaint",
   "airplane",
   "logan"
  ],
  "c": "blu",
  "sid": "how-do-i-complain-about-logan-airport-noise"
 },
 {
  "see": "Living near Logan and wondering about soundproofing",
  "is": "Massport has insulated more than 11,000 homes since 1985.",
  "section": "boston",
  "anchor": "Does Massport soundproof homes?",
  "tags": [
   "insulation",
   "soundproofing",
   "massport",
   "homes"
  ],
  "c": "blu",
  "sid": "does-massport-soundproof-homes"
 },
 {
  "see": "A loud screech from a trolley turning underground",
  "is": "Green Line wheel squeal on tight 1897-era curves such as Boylston.",
  "section": "boston",
  "anchor": "Why does the Green Line screech?",
  "tags": [
   "green line",
   "squeal",
   "mbta",
   "subway",
   "screech"
  ],
  "c": "blu",
  "sid": "why-does-the-green-line-screech"
 },
 {
  "see": "Train horns blowing long-long-short-long",
  "is": "Federal rule: 96-110 dB, 15-20 seconds before public crossings.",
  "section": "boston",
  "anchor": "Why do commuter rail trains honk so much?",
  "tags": [
   "train horn",
   "commuter rail",
   "crossing",
   "quiet zone"
  ],
  "c": "blu",
  "sid": "why-do-commuter-rail-trains-honk-so-much"
 },
 {
  "see": "A backup beeper that seems quieter than usual",
  "is": "Ambient-sensitive backup alarms adjust to background; the Big Dig required them.",
  "section": "boston",
  "anchor": "What did the Big Dig teach about construction noise?",
  "tags": [
   "backup alarm",
   "beeper",
   "construction",
   "big dig"
  ],
  "c": "blu",
  "sid": "what-did-the-big-dig-teach-about-construction-noise"
 },
 {
  "see": "Bells tumbling with no tune on Sunday late morning",
  "is": "Change ringing at Old North Church after the 11 a.m. service.",
  "section": "boston",
  "anchor": "When do Boston's church bells ring?",
  "tags": [
   "bells",
   "church",
   "old north",
   "sunday"
  ],
  "c": "blu",
  "sid": "when-do-boston-s-church-bells-ring"
 },
 {
  "see": "Westminster chimes on the quarter hour",
  "is": "Park Street Church's bells chime Westminster quarters.",
  "section": "boston",
  "anchor": "When do Boston's church bells ring?",
  "tags": [
   "chimes",
   "bells",
   "clock",
   "park street"
  ],
  "c": "blu",
  "sid": "when-do-boston-s-church-bells-ring"
 },
 {
  "see": "Booms at the end of the July 4 concert",
  "is": "National Guard howitzers fired during the 1812 Overture.",
  "section": "boston",
  "anchor": "Are the July 4 cannons real?",
  "tags": [
   "cannons",
   "july 4",
   "fireworks",
   "pops"
  ],
  "c": "blu",
  "sid": "are-the-july-4-cannons-real"
 },
 {
  "see": "A horn blast out on the harbor in fog",
  "is": "Automated fog signals at Boston Harbor lighthouses such as Boston Light.",
  "section": "boston",
  "anchor": "Does Boston Harbor still have foghorns?",
  "tags": [
   "foghorn",
   "harbor",
   "lighthouse",
   "fog"
  ],
  "c": "blu",
  "sid": "does-boston-harbor-still-have-foghorns"
 },
 {
  "see": "Which part of Boston is loudest",
  "is": "Walker's 2015 sampling found East Boston and Savin Hill tied for loudest daytime.",
  "section": "boston",
  "anchor": "What is the loudest neighborhood in Boston?",
  "tags": [
   "loudest",
   "neighborhood",
   "sound map",
   "research"
  ],
  "c": "blu",
  "sid": "what-is-the-loudest-neighborhood-in-boston"
 },
 {
  "see": "Calls about noise seem to go nowhere",
  "is": "The City Council filed a July 2026 hearing order on noise enforcement.",
  "section": "boston",
  "anchor": "What happened at the July 2026 City Council noise hearing?",
  "tags": [
   "enforcement",
   "city council",
   "complaints",
   "hearing"
  ],
  "c": "blu",
  "sid": "what-happened-at-the-july-2026-city-council-noise-hearing"
 }
]