[
 {
  "term": "310 CMR 7.10",
  "aka": "",
  "category": "Boston",
  "definition": "The Massachusetts regulation prohibiting unnecessary or excessive noise from man-made sources, treating noise as air pollution.",
  "section": "boston",
  "source_url": "https://www.bdlaw.com/publications/massdep-seeks-comment-on-revisions-to-longstanding-noise-policy/"
 },
 {
  "term": "65 DNL",
  "aka": "",
  "category": "Aircraft",
  "definition": "The FAA's long-standing threshold: homes, schools, hospitals and similar uses are considered incompatible with airport noise at or above it.",
  "section": "aircraft",
  "source_url": "https://www.portseattle.org/sites/default/files/2022-12/Part%20150%20Study%20Primer.pdf"
 },
 {
  "term": "A-weighting",
  "aka": "dBA, dB(A)",
  "category": "Sound basics",
  "definition": "A filter that turns down bass and extreme treble to mimic human hearing; the default for nearly all environmental and workplace noise rules.",
  "section": "basics",
  "source_url": "https://www.faa.gov/air_traffic/community_engagement/ataaps/ATAAPS_Appendix_F_Basics_of_Noise.pdf"
 },
 {
  "term": "AB 1346",
  "aka": "California small off-road engine law",
  "category": "Construction and tools",
  "definition": "A 2021 California law halting the sale of most new gas leaf blowers, mowers and other small off-road engines by 2024.",
  "section": "construction",
  "source_url": "https://sierraclub.org/sierra/california-bill-takes-aim-scourge-gas-powered-leaf-blowers"
 },
 {
  "term": "Abatement notice",
  "aka": "",
  "category": "Rules",
  "definition": "A UK council order requiring a statutory nuisance to stop or be limited; ignoring one is an offence.",
  "section": "rules",
  "source_url": "https://www.gov.uk/noise-nuisances-how-councils-deal-with-complaints"
 },
 {
  "term": "Accessible pedestrian signal",
  "aka": "APS",
  "category": "Designed sounds",
  "definition": "A crosswalk signal that gives walk information by sound and vibration as well as sight, for blind and low-vision pedestrians.",
  "section": "signals",
  "source_url": "https://sauerburger.org/signalAPS.html"
 },
 {
  "term": "Action level",
  "aka": "",
  "category": "Health",
  "definition": "Under OSHA, an 85 dBA 8-hour TWA (a 50% dose) at which employers must run a hearing conservation program.",
  "section": "health",
  "source_url": "https://www.ecfr.gov/current/title-29/subtitle-B/chapter-XVII/part-1910/subpart-G/section-1910.95"
 },
 {
  "term": "AEDT",
  "aka": "Aviation Environmental Design Tool",
  "category": "Aircraft",
  "definition": "The FAA model airports must use to produce noise contours for Part 150 studies.",
  "section": "aircraft",
  "source_url": "https://www.portseattle.org/sites/default/files/2022-12/Part%20150%20Study%20Primer.pdf"
 },
 {
  "term": "agent of change",
  "aka": "",
  "category": "Music and nightlife",
  "definition": "Planning principle that makes whoever arrives second - new homes beside a venue, or a new venue beside homes - pay to manage the noise between them.",
  "section": "nightlife",
  "source_url": "https://kellehers.com.au/latest-news/live-music-reforms-the-agent-of-change/"
 },
 {
  "term": "Ambient level",
  "aka": "background level",
  "category": "Rules",
  "definition": "The sound level present without the noise being complained about; some codes limit how far a source may rise above it.",
  "section": "rules",
  "source_url": "https://mail.sfpublicworks.org/sites/default/files/Noise_Control_Ordinance_0.pdf"
 },
 {
  "term": "Ambient-sensitive backup alarm",
  "aka": "",
  "category": "Boston",
  "definition": "A reversing alarm that adjusts its loudness to stay just above background; the Big Dig capped it at 5 dBA over background.",
  "section": "boston",
  "source_url": "https://nonoise.org/resource/construc/bigdig.htm"
 },
 {
  "term": "Annoyance",
  "aka": "long-term annoyance",
  "category": "Health",
  "definition": "A health outcome in noise research measured with standardized surveys; the EEA estimates almost 16.9 million Europeans are long-term annoyed by transport noise.",
  "section": "health",
  "source_url": "https://www.eea.europa.eu/en/analysis/publications/environmental-noise-in-europe-2025"
 },
 {
  "term": "anthropause",
  "aka": "",
  "category": "Nature",
  "definition": "The 2020 global slowdown in human activity during COVID-19 lockdowns, when human-made noise dropped sharply.",
  "section": "nature",
  "source_url": "https://www.usgs.gov/publications/global-quieting-high-frequency-seismic-noise-due-covid-19-pandemic-lockdown-measures"
 },
 {
  "term": "APCC",
  "aka": "Air Pollution Control Commission",
  "category": "Boston",
  "definition": "Boston's Air Pollution Control Commission, which writes the city's technical noise regulations, including zoning-district, octave-band and construction limits.",
  "section": "boston",
  "source_url": "https://www.cityofboston.gov/Images_Documents/noise_reg_tcm3-13127.pdf"
 },
 {
  "term": "Attention Alert Signal",
  "aka": "",
  "category": "Sirens and alarms",
  "definition": "Hawaii's one-minute steady outdoor siren tone, used in statewide siren tests.",
  "section": "sirens",
  "source_url": "https://spectrumlocalnews.com/hi/hawaii/news/2026/04/29/hawaii-siren-test-may-1-2026"
 },
 {
  "term": "Audiometric notch",
  "aka": "",
  "category": "Health",
  "definition": "A dip in a hearing test pattern that suggests noise damage; CDC found one in 24.4% of US adults aged 20 to 69.",
  "section": "health",
  "source_url": "https://www.cdc.gov/mmwr/volumes/66/wr/mm6605e3.htm"
 },
 {
  "term": "AVAS",
  "aka": "Acoustic Vehicle Alerting System",
  "category": "Designed sounds",
  "definition": "The artificial warning sound EU rules require on electric and hybrid vehicles up to about 20 km/h and in reverse.",
  "section": "signals",
  "source_url": "https://www.bvrla.co.uk/resource/new-rules-on-noise-warning-for-electric-and-hybrid-cars.html"
 },
 {
  "term": "Bosai musen",
  "aka": "goji no chaimu",
  "category": "Sirens and alarms",
  "definition": "Japan's municipal disaster-radio loudspeaker network, tested daily with an evening tune such as \"Yuyake Koyake.\"",
  "section": "sirens",
  "source_url": "https://japantimes.co.jp/news/2013/04/16/reference/bosai-musen"
 },
 {
  "term": "Broadband backup alarm",
  "aka": "white-noise alarm",
  "category": "Construction and tools",
  "definition": "A reverse alarm that hisses across many frequencies instead of beeping; OSHA said in 2004 it can comply with federal rules.",
  "section": "construction",
  "source_url": "https://www.osha.gov/laws-regs/standardinterpretations/2004-05-27-0"
 },
 {
  "term": "Bypass ratio",
  "aka": "",
  "category": "Aircraft",
  "definition": "How much air a turbofan's fan pushes around the engine core compared with through it; higher ratios mean slower, cooler, quieter exhaust.",
  "section": "aircraft",
  "source_url": "https://ntrs.nasa.gov/citations/20050198876"
 },
 {
  "term": "C-weighting",
  "aka": "dBC, dB(C)",
  "category": "Sound basics",
  "definition": "A much flatter filter that keeps the bass; commonly used for peak measurements and bass-heavy sources.",
  "section": "basics",
  "source_url": "https://www.sonitussystems.com/insights/glossary-of-common-acoustic-definitions/"
 },
 {
  "term": "CA/T specification 721.560",
  "aka": "Big Dig noise spec",
  "category": "Construction and tools",
  "definition": "The Central Artery/Tunnel project's construction noise specification, the source of the FHWA's equipment spec limits.",
  "section": "construction",
  "source_url": "https://www.fhwa.dot.gov/Environment/noise/construction_noise/handbook/handbook09.cfm"
 },
 {
  "term": "Change ringing",
  "aka": "",
  "category": "Boston",
  "definition": "Ringing a set of tuned bells in mathematical sequences rather than melodies, as at Old North Church.",
  "section": "boston",
  "source_url": "https://oldnorth.com/blog/the-bells-at-old-north/"
 },
 {
  "term": "City Code Section 16-26",
  "aka": "",
  "category": "Boston",
  "definition": "The Boston ordinance setting 50 dBA from 11 p.m. to 7 a.m. and 70 dBA at other times; nuisance citations do not require scientific measurement.",
  "section": "boston",
  "source_url": "https://www.boston.gov/sites/default/files/file/2026/09/Noise%20Control%20Hearing%20Order.pdf"
 },
 {
  "term": "Class 1 / Class 2 meter",
  "aka": "Type 1 / Type 2",
  "category": "Measuring and quiet",
  "definition": "IEC 61672 grades for precision and general-purpose sound level meters; the older US terms are Type 1 and Type 2.",
  "section": "quiet",
  "source_url": "https://cirrusresearch.com/?p=60011"
 },
 {
  "term": "Community Advisory Committee",
  "aka": "CAC, Massport CAC",
  "category": "Boston",
  "definition": "A body created by the state legislature to advise Massport, representing 35 communities.",
  "section": "boston",
  "source_url": "http://winthroptranscript.com/2022/09/15/noise-insulation-to-come-to-winthrop/"
 },
 {
  "term": "compensation zone",
  "aka": "quiet zone, rest zone",
  "category": "Music and nightlife",
  "definition": "Lower-level area at an event where audiences can rest their ears; Switzerland requires 85 dB(A) or less for long loud events, and AAO-HNS recommends 70 dB LAeq,15min or less.",
  "section": "nightlife",
  "source_url": "https://zg.ch/en/gesundheit/gesund-bleiben/informationen-fuer-veranstaltende/schall-und-laser"
 },
 {
  "term": "Cooling tower",
  "aka": "",
  "category": "Hums and machines",
  "definition": "Equipment that sheds heat by evaporating water; at data centers, up to 70 dBA within 400 feet according to EESI.",
  "section": "hums",
  "source_url": "https://www.eesi.org/articles/view/communities-are-raising-noise-pollution-concernsabout-data-centers"
 },
 {
  "term": "Corona",
  "aka": "corona discharge",
  "category": "Hums and machines",
  "definition": "Electrical discharge into the air around high-voltage conductors, which can make power lines hum.",
  "section": "hums",
  "source_url": "https://graphsearch.epfl.ch/concept/2227992"
 },
 {
  "term": "Crossover speed",
  "aka": "",
  "category": "Traffic",
  "definition": "The speed above which tire-on-pavement noise becomes louder than engine noise; about 20 mph (32 km/h) for cars, higher for trucks.",
  "section": "traffic",
  "source_url": "https://www.cptechcenter.org/wp-content/uploads/2020/04/Noise_101_tech_brief.pdf"
 },
 {
  "term": "Curfew",
  "aka": "",
  "category": "Aircraft",
  "definition": "Hours when an airport is closed to most flights, such as Sydney's 11 pm-6 am curfew.",
  "section": "aircraft",
  "source_url": "https://avlaw.com.au/sydney-airport-operational-efficiency/"
 },
 {
  "term": "dawn chorus",
  "aka": "",
  "category": "Nature",
  "definition": "Burst of birdsong around first light; a Leiden study found urban birds start it 22 minutes earlier on average than rural birds.",
  "section": "nature",
  "source_url": "https://scholarlypublications.universiteitleiden.nl/access/item%3A3134959/download"
 },
 {
  "term": "Day-evening-night level",
  "aka": "Lden",
  "category": "Sound basics",
  "definition": "The EU 24-hour average with +5 dB added in the evening (19:00-23:00) and +10 dB at night (23:00-07:00) by default.",
  "section": "basics",
  "source_url": "https://en.wikipedia.org/wiki/Day%E2%80%93evening%E2%80%93night_noise_level"
 },
 {
  "term": "Day-night average sound level",
  "aka": "DNL, Ldn",
  "category": "Sound basics",
  "definition": "A US 24-hour, A-weighted average that counts sound from 10 p.m. to 7 a.m. as 10 dB louder; the FAA's standard aviation metric.",
  "section": "basics",
  "source_url": "https://www.faa.gov/air_traffic/community_engagement/ataaps/ATAAPS_Appendix_F_Basics_of_Noise.pdf"
 },
 {
  "term": "dB(C)",
  "aka": "LCeq, C-weighting",
  "category": "Music and nightlife",
  "definition": "Sound level with C-weighting, which counts bass more fully than A-weighting; used to cap low-frequency sound at shows, such as France's 118 dB(C) limit.",
  "section": "nightlife",
  "source_url": "https://www.banquedesterritoires.fr/les-lieux-de-musiques-amplifiees-et-les-festivals-vont-devoir-baisser-dun-ton"
 },
 {
  "term": "dBA",
  "aka": "A-weighted decibels",
  "category": "Health",
  "definition": "Decibels adjusted to roughly match human hearing, de-emphasizing low bass; the unit used in US workplace noise limits.",
  "section": "health",
  "source_url": "https://www.cdc.gov/niosh/noise/prevent/understand.html"
 },
 {
  "term": "dBC",
  "aka": "C-weighting",
  "category": "Measuring and quiet",
  "definition": "Decibels measured with a flatter filter that keeps bass; some codes use it to limit thumping music.",
  "section": "quiet",
  "source_url": "https://nonoise.org/regulation/ordinance/New York, New York.pdf"
 },
 {
  "term": "Decibel",
  "aka": "dB",
  "category": "Sound basics",
  "definition": "A logarithmic unit comparing a sound's pressure with a reference of 20 micropascals; +3 dB doubles the energy and about +10 dB sounds twice as loud.",
  "section": "basics",
  "source_url": "https://www.fhwa.dot.gov/environMent/noise/regulations_and_guidance/polguide/polguide02.cfm"
 },
 {
  "term": "Derating",
  "aka": "",
  "category": "Health",
  "definition": "Reducing a protector's labeled NRR to estimate real protection, such as OSHA's subtract-7 method or NIOSH's 50% for foam plugs.",
  "section": "health",
  "source_url": "https://canadianaudiologist.ca/hearing-protection-attenuation-feature/"
 },
 {
  "term": "DIN 14610",
  "aka": "",
  "category": "Sirens and alarms",
  "definition": "German standard for sound warning devices on authorized emergency vehicles; current edition March 2022.",
  "section": "sirens",
  "source_url": "https://www.din.de/en/wdc-beuth:din21:349179751"
 },
 {
  "term": "DNL",
  "aka": "day-night average sound level",
  "category": "Boston",
  "definition": "The FAA's annual airport noise metric, with a 65 dB significance threshold that the FAA's Noise Policy Review examined.",
  "section": "boston",
  "source_url": "https://www.cambridgema.gov/CDD/Transportation/regionalplanning/logannoisestudy"
 },
 {
  "term": "dual brood",
  "aka": "",
  "category": "Nature",
  "definition": "Two periodical cicada broods emerging in the same year, as Broods XIII and XIX did in 2024 for the first time in 221 years.",
  "section": "nature",
  "source_url": "https://audiology.org/?p=94377"
 },
 {
  "term": "Engine compression brake",
  "aka": "Jake brake",
  "category": "Traffic",
  "definition": "A truck engine mode that changes exhaust valve timing so the engine absorbs power to slow the truck; loud with poor or straight-pipe mufflers.",
  "section": "traffic",
  "source_url": "https://www.maine.gov/mdot/mlrc/docs/technical/JakeBrakeIssues.pdf"
 },
 {
  "term": "Environmental Noise Directive",
  "aka": "END, 2002/49/EC",
  "category": "History",
  "definition": "The 2002 EU law requiring strategic noise maps and action plans on a five-year cycle, without EU-wide limits.",
  "section": "history",
  "source_url": "https://ieep.eu/wp-content/uploads/2022/12/10.2_Assessment_and_management_of_noise_-_final.pdf"
 },
 {
  "term": "Exchange rate",
  "aka": "",
  "category": "Health",
  "definition": "How many decibels of increase halves the allowed exposure time: 3 dB for NIOSH, 5 dB for OSHA.",
  "section": "health",
  "source_url": "https://www.cdc.gov/niosh/noise/prevent/understand.html"
 },
 {
  "term": "Exhaust label match-up",
  "aka": "",
  "category": "Traffic",
  "definition": "US rule that motorcycles built after 1982 carry chassis and muffler labels with matching codes; a mismatch on a regulated bike violates the Noise Control Act.",
  "section": "traffic",
  "source_url": "https://www.noiseoff.org/publications/loud-motorcycles/the-label-match-up-program"
 },
 {
  "term": "Flange lubrication",
  "aka": "Greaser",
  "category": "Trains and transit",
  "definition": "Greasing the wheel flange or rail to reduce squeal; cut levels by 8 to 11 dB in a French trial.",
  "section": "transit",
  "source_url": "https://uic.org/IMG/pdf/uic_soa_combatting_curve_squeal_p2.pdf"
 },
 {
  "term": "Flanking",
  "aka": "flanking path",
  "category": "Sound basics",
  "definition": "Sound traveling around a wall through floors, slabs or stud cavities instead of through it.",
  "section": "basics",
  "source_url": "https://commercial-acoustics.com/sound-advice/why-bass-is-hard-to-block/"
 },
 {
  "term": "FMVSS 141",
  "aka": "",
  "category": "Designed sounds",
  "definition": "US federal safety standard requiring hybrid and electric vehicles to make sound when stopped in gear, in reverse and up to 30 km/h.",
  "section": "signals",
  "source_url": "https://www.govinfo.gov/content/pkg/FR-2018-02-26/html/2018-03721.htm"
 },
 {
  "term": "Frequency",
  "aka": "Hz, hertz",
  "category": "Sound basics",
  "definition": "How many pressure cycles pass per second, heard as pitch; human hearing runs from about 20 Hz to 10,000-20,000 Hz.",
  "section": "basics",
  "source_url": "https://www.faa.gov/air_traffic/community_engagement/ataaps/ATAAPS_Appendix_F_Basics_of_Noise.pdf"
 },
 {
  "term": "Friction modifier",
  "aka": "Top-of-rail friction modifier",
  "category": "Trains and transit",
  "definition": "A product applied to the top of the rail to control wheel-rail friction and reduce squeal; results vary by site.",
  "section": "transit",
  "source_url": "https://uic.org/IMG/pdf/uic_soa_combatting_curve_squeal_p2.pdf"
 },
 {
  "term": "Global standard for safe listening venues and events",
  "aka": "WHO safe listening standard",
  "category": "Music and nightlife",
  "definition": "Voluntary 2022 WHO standard with six features, led by a 100 dB LAeq,15min audience limit, plus monitoring, better acoustics, hearing protection, quiet zones and staff training.",
  "section": "nightlife",
  "source_url": "https://www.who.int/news-room/feature-stories/detail/who-hearing-guidelines-implemented-at-major-arts-festival"
 },
 {
  "term": "Grid frequency",
  "aka": "line frequency, mains frequency",
  "category": "Hums and machines",
  "definition": "How many times per second alternating current reverses: 60 Hz in North America, 50 Hz in much of the world.",
  "section": "hums",
  "source_url": "https://graphsearch.epfl.ch/concept/2227992"
 },
 {
  "term": "Ground loop hum",
  "aka": "",
  "category": "Hums and machines",
  "definition": "Hum in audio equipment at the line frequency itself (50 or 60 Hz), rather than at double it.",
  "section": "hums",
  "source_url": "https://graphsearch.epfl.ch/concept/2227992"
 },
 {
  "term": "Harmonics",
  "aka": "overtones",
  "category": "Hums and machines",
  "definition": "Tones at multiples of a fundamental frequency; mains hum has strong harmonics that make it sound buzzy.",
  "section": "hums",
  "source_url": "https://graphsearch.epfl.ch/concept/2227992"
 },
 {
  "term": "Hassha melody",
  "aka": "departure melody",
  "category": "Designed sounds",
  "definition": "A short tune, about seven seconds, played at Japanese stations before a train departs.",
  "section": "signals",
  "source_url": "https://en.wikipedia.org/wiki/Train_melody"
 },
 {
  "term": "Head-related transfer function",
  "aka": "HRTF",
  "category": "Sirens and alarms",
  "definition": "The direction-dependent filtering of sound by the outer ear and head, one of the cues the brain uses to locate a sound.",
  "section": "sirens",
  "source_url": "https://en.wikipedia.org/wiki/Siren_(alarm)"
 },
 {
  "term": "Healthy life years lost",
  "aka": "DALYs",
  "category": "Health",
  "definition": "Years of healthy life lost to illness, disability or early death; the EEA estimates 1.5 million a year from transport noise in Europe.",
  "section": "health",
  "source_url": "https://www.eea.europa.eu/en/analysis/publications/environmental-noise-in-europe-2025"
 },
 {
  "term": "Hi-lo",
  "aka": "two-tone",
  "category": "Sirens and alarms",
  "definition": "Siren tone that alternates between two fixed pitches.",
  "section": "sirens",
  "source_url": "https://en.wikipedia.org/wiki/Siren_(alarm)"
 },
 {
  "term": "Highly annoyed",
  "aka": "",
  "category": "Aircraft",
  "definition": "Survey category for people choosing the top of an annoyance scale; used to link noise levels to community reaction.",
  "section": "aircraft",
  "source_url": "https://www.faa.gov/regulations_policies/policy_guidance/noise/survey"
 },
 {
  "term": "Hoe ram",
  "aka": "mounted impact hammer",
  "category": "Construction and tools",
  "definition": "A hydraulic breaking hammer mounted on an excavator arm; measured at 90 dBA Lmax at 50 feet in the FHWA table.",
  "section": "construction",
  "source_url": "https://www.fhwa.dot.gov/Environment/noise/construction_noise/handbook/handbook09.cfm"
 },
 {
  "term": "Hush City",
  "aka": "",
  "category": "Nature",
  "definition": "Citizen-science app developed by Antonella Radicchi at TU Berlin for mapping peaceful places; used in Berlin and Limerick quiet-area planning.",
  "section": "nature",
  "source_url": "https://euronews.com/green/2020/08/19/the-invisible-threat-of-noise-pollution-how-do-we-protect-quiet"
 },
 {
  "term": "Hyperacusis",
  "aka": "",
  "category": "Health",
  "definition": "Per ICD-10 H93.23, an abnormally disproportionate increase in the sensation of loudness in response to sounds of normal volume.",
  "section": "health",
  "source_url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC10076672"
 },
 {
  "term": "Insertion loss",
  "aka": "",
  "category": "Traffic",
  "definition": "How many decibels a noise wall removes compared with no wall; about 5 to 10 dBA for homes directly behind one.",
  "section": "traffic",
  "source_url": "https://www.cptechcenter.org/wp-content/uploads/2020/04/Noise_101_tech_brief.pdf"
 },
 {
  "term": "ITU-T H.870",
  "aka": "WHO-ITU safe listening standard",
  "category": "Health",
  "definition": "A 2019 voluntary standard for phones and headphones that tracks a weekly sound allowance (80 dB for 40 hours a week for adults).",
  "section": "health",
  "source_url": "https://cdn.who.int/media/docs/default-source/documents/health-topics/deafness-and-hearing-loss/standard-summary-make-listening-safe.pdf?sfvrsn=fc114686_14"
 },
 {
  "term": "L10",
  "aka": "",
  "category": "Boston",
  "definition": "The sound level exceeded 10 percent of the time during a measurement - a measure of the louder moments. Boston's construction limits use it.",
  "section": "boston",
  "source_url": "https://www.cityofboston.gov/Images_Documents/noise_reg_tcm3-13127.pdf"
 },
 {
  "term": "L10 / L90",
  "aka": "statistical levels",
  "category": "Sound basics",
  "definition": "The levels exceeded 10% and 90% of the time; L10 is used for traffic, L90 for background sound.",
  "section": "basics",
  "source_url": "https://www.sonitussystems.com/insights/glossary-of-common-acoustic-definitions/"
 },
 {
  "term": "L90",
  "aka": "",
  "category": "Measuring and quiet",
  "definition": "The level exceeded 90% of the time during a measurement; a common measure of background noise.",
  "section": "quiet",
  "source_url": "https://www.sonitussystems.com/insights/glossary-of-common-acoustic-definitions/"
 },
 {
  "term": "LAeq",
  "aka": "equivalent continuous level",
  "category": "Health",
  "definition": "The steady A-weighted level with the same sound energy as a fluctuating sound over a set time, such as 15 minutes or 24 hours.",
  "section": "health",
  "source_url": "https://cdn.who.int/media/docs/default-source/documents/health-topics/deafness-and-hearing-loss/mls_whd_infographic.pdf?sfvrsn=93a7a1ef_5"
 },
 {
  "term": "LAeq,15min",
  "aka": "",
  "category": "Music and nightlife",
  "definition": "A-weighted equivalent (average) sound level over 15 minutes; the measure used by the WHO venue standard and France's legal cap.",
  "section": "nightlife",
  "source_url": "https://www.who.int/news-room/feature-stories/detail/who-hearing-guidelines-implemented-at-major-arts-festival"
 },
 {
  "term": "LAFmax",
  "aka": "",
  "category": "Aircraft",
  "definition": "The maximum A-weighted sound level, with fast time weighting, during a single event such as a drone pass.",
  "section": "aircraft",
  "source_url": "https://www.frontiersin.org/journals/acoustics/articles/10.3389/facou.2025.1624669/pdf"
 },
 {
  "term": "LAmax",
  "aka": "",
  "category": "Traffic",
  "definition": "The highest A-weighted sound level during an event; the UK proposed 95 dB LAmax at 7.5 m for noise cameras.",
  "section": "traffic",
  "source_url": "https://www.ioa.org.uk/news/Results-of-noise-camera-trials-for-roads-published"
 },
 {
  "term": "LAmax,fast",
  "aka": "LAFmax",
  "category": "Music and nightlife",
  "definition": "The highest A-weighted level measured with the meter's fast time response; AAO-HNS uses it for peak caps of 140 dB (adults) and 120 dB (children).",
  "section": "nightlife",
  "source_url": "https://www.entnet.org/resource/mitigation-of-noise-induced-hearing-loss-at-music-venues/"
 },
 {
  "term": "Lateral creep",
  "aka": "",
  "category": "Trains and transit",
  "definition": "Sideways slip of a wheel across the railhead on a curve; the most important cause of curve squeal.",
  "section": "transit",
  "source_url": "https://uic.org/IMG/pdf/uic_soa_combatting_curve_squeal_p2.pdf"
 },
 {
  "term": "Lden",
  "aka": "Day-evening-night level",
  "category": "Traffic",
  "definition": "A 24-hour average sound level with penalties for evening and night noise; the EU uses it to map road, rail and aircraft noise.",
  "section": "traffic",
  "source_url": "https://eea.europa.eu/publications/managing-exposure-to-noise-in-europe/noise-in-europe-updated-population-exposure/action-download-pdf"
 },
 {
  "term": "Leq",
  "aka": "equivalent continuous level",
  "category": "Measuring and quiet",
  "definition": "The steady level that would carry the same total sound energy as a fluctuating sound over the same period.",
  "section": "quiet",
  "source_url": "https://www.faa.gov/noise/aviation_noise/fundamentals_of_noise"
 },
 {
  "term": "Leq(h)",
  "aka": "Hourly equivalent level",
  "category": "Traffic",
  "definition": "The steady sound level carrying the same energy as the actual fluctuating sound over one hour; used in US federal highway noise rules.",
  "section": "traffic",
  "source_url": "https://mm.nh.gov/files/uploads/dot/remote-docs/2016-noise-policy.pdf"
 },
 {
  "term": "Lmax",
  "aka": "maximum sound level",
  "category": "Construction and tools",
  "definition": "The highest sound level reached during a measurement - the peak moment, not an average.",
  "section": "construction",
  "source_url": "https://www.fhwa.dot.gov/Environment/noise/construction_noise/handbook/handbook09.cfm"
 },
 {
  "term": "Lnight",
  "aka": "",
  "category": "Measuring and quiet",
  "definition": "The average sound level over the night period, used in EU noise maps to estimate sleep disturbance.",
  "section": "quiet",
  "source_url": "https://dlrcoco.ie/environmental-health/environmental-noise"
 },
 {
  "term": "Locator tone",
  "aka": "",
  "category": "Designed sounds",
  "definition": "A quiet tone repeating once per second during \"don't walk\" that helps pedestrians find the APS push button.",
  "section": "signals",
  "source_url": "https://sauerburger.org/signalAPS.html"
 },
 {
  "term": "Lombard effect",
  "aka": "",
  "category": "Health",
  "definition": "The automatic tendency to speak louder, and change pitch and pace, in noise.",
  "section": "health",
  "source_url": "https://vufind.lboro.ac.uk/PrimoRecord/cdi_proquest_miscellaneous_918050849"
 },
 {
  "term": "Low-frequency sound component",
  "aka": "",
  "category": "Construction and tools",
  "definition": "The low-pitched part of a sound; a 2018 Arup study found gas blowers have much more of it than electric ones, which helps them carry.",
  "section": "construction",
  "source_url": "https://scarsdale.gov/DocumentCenter/View/6644/Gas-Leaf-Report-to-Village-Board---Dec-2020"
 },
 {
  "term": "Lpeak",
  "aka": "peak",
  "category": "Sound basics",
  "definition": "The highest instantaneous sound pressure, measured with no time averaging.",
  "section": "basics",
  "source_url": "https://www.sonitussystems.com/insights/glossary-of-common-acoustic-definitions/"
 },
 {
  "term": "Mach cutoff",
  "aka": "",
  "category": "Aircraft",
  "definition": "Flying supersonic at a speed and altitude where the boom bends upward before reaching the ground.",
  "section": "aircraft",
  "source_url": "https://www.faa.gov/newsroom/ARM-260115-001_Supersonic_NPRM_06-10-26.pdf"
 },
 {
  "term": "Magnetostriction",
  "aka": "",
  "category": "Hums and machines",
  "definition": "The slight change in shape of iron or steel in a magnetic field; it makes transformer cores vibrate and hum.",
  "section": "hums",
  "source_url": "https://graphsearch.epfl.ch/concept/2227992"
 },
 {
  "term": "Mains hum",
  "aka": "line hum, electrical hum",
  "category": "Hums and machines",
  "definition": "The drone from electrical equipment tied to grid frequency, centered on 120 Hz on 60 Hz grids and 100 Hz on 50 Hz grids.",
  "section": "hums",
  "source_url": "https://graphsearch.epfl.ch/concept/2227992"
 },
 {
  "term": "Martinshorn",
  "aka": "Folgetonhorn, Einsatzhorn",
  "category": "Sirens and alarms",
  "definition": "The German two-tone emergency horn, defined by DIN 14610 and the only warning tone German priority vehicles may use.",
  "section": "sirens",
  "source_url": "https://epetitionen.bundestag.de/petitionen/_2022/_02/_21/Petition_131006.abschlussbegruendungpdf.pdf"
 },
 {
  "term": "Mass law",
  "aka": "",
  "category": "Sound basics",
  "definition": "The rule that a wall blocks about 6 dB more for each doubling of its mass or of the sound's frequency, so bass gets through more easily.",
  "section": "basics",
  "source_url": "https://commercial-acoustics.com/sound-advice/why-bass-is-hard-to-block/"
 },
 {
  "term": "MassDEP Noise Policy",
  "aka": "10 dBA rule",
  "category": "Boston",
  "definition": "MassDEP's 1990 guidance: a source violates 310 CMR 7.10 if it raises sound 10 dBA above ambient L90, or creates a pure tone, at the property line and nearest receptor.",
  "section": "boston",
  "source_url": "https://www.bdlaw.com/publications/massdep-seeks-comment-on-revisions-to-longstanding-noise-policy/"
 },
 {
  "term": "MEND",
  "aka": "Mediating Establishment and Neighborhood Disputes",
  "category": "Music and nightlife",
  "definition": "New York City Office of Nightlife program that uses mediation instead of enforcement for venue-neighbor disputes; reports an 80% resolution rate.",
  "section": "nightlife",
  "source_url": "https://csmonitor.com/USA/Society/2023/0810/They-like-the-nightlife-Night-mayors-revive-cities-after-dusk"
 },
 {
  "term": "Misophonia",
  "aka": "",
  "category": "Health",
  "definition": "Per a 2022 consensus definition, a disorder of decreased tolerance to specific sounds or their associated stimuli.",
  "section": "health",
  "source_url": "https://www.frontiersin.org/articles/10.3389/fnins.2022.841816/text"
 },
 {
  "term": "Music Noise Level",
  "aka": "MNL",
  "category": "Music and nightlife",
  "definition": "UK Pop Code measure of concert noise at neighbors: a 15-minute LAeq taken 1 m from the facade of noise-sensitive homes.",
  "section": "nightlife",
  "source_url": "https://WWW.GOV.JE/SiteCollectionDocuments/Leisure%20and%20entertainment/ID%20Code%20of%20Practice%20on%20Environmental%20Noise%2020110517%20RWJ.pdf"
 },
 {
  "term": "Neighborhood Environmental Survey",
  "aka": "NES",
  "category": "Aircraft",
  "definition": "FAA national survey (mailed from October 2015 around 20 airports) whose 2021 results showed far more annoyance than the Schultz Curve.",
  "section": "aircraft",
  "source_url": "https://www.faa.gov/regulations_policies/policy_guidance/noise/survey"
 },
 {
  "term": "night mayor",
  "aka": "night czar",
  "category": "Music and nightlife",
  "definition": "City official or appointee who works between nightlife businesses, residents and city government.",
  "section": "nightlife",
  "source_url": "https://csmonitor.com/USA/Society/2023/0810/They-like-the-nightlife-Night-mayors-revive-cities-after-dusk"
 },
 {
  "term": "NIOSH Sound Level Meter app",
  "aka": "NIOSH SLM",
  "category": "Measuring and quiet",
  "definition": "A free iOS app from the US National Institute for Occupational Safety and Health, accurate to about 2 dBA with the built-in mic in lab tests.",
  "section": "quiet",
  "source_url": "https://stacks.cdc.gov/view/cdc/227833/cdc_227833_DS1.pdf"
 },
 {
  "term": "Noise Abatement Criteria",
  "aka": "NAC",
  "category": "Traffic",
  "definition": "US federal highway noise levels in 23 CFR 772 (67 dBA Leq(h) outside homes) that trigger consideration of noise walls.",
  "section": "traffic",
  "source_url": "https://mm.nh.gov/files/uploads/dot/remote-docs/2016-noise-policy.pdf"
 },
 {
  "term": "Noise camera",
  "aka": "Noise radar, sound-activated enforcement device",
  "category": "Traffic",
  "definition": "A roadside sound meter linked to a license plate camera that records vehicles above a set level.",
  "section": "traffic",
  "source_url": "https://www.chp.ca.gov/siteassets/forms/programs--services/sb-1079-2025-report-on-sound-activated-enforcement-devices.pdf"
 },
 {
  "term": "Noise certification Stage",
  "aka": "ICAO Chapter",
  "category": "Aircraft",
  "definition": "US class of the maximum noise a new aircraft type may make, set in 14 CFR Part 36; ICAO groups equivalent limits into Chapters.",
  "section": "aircraft",
  "source_url": "https://www.faa.gov/about/office_org/headquarters_offices/apl/noise_emissions/airport_aircraft_noise_issues/levels"
 },
 {
  "term": "Noise contour",
  "aka": "",
  "category": "Measuring and quiet",
  "definition": "A line on an airport noise map joining points of equal sound level, like a topographic line.",
  "section": "quiet",
  "source_url": "https://www.faa.gov/noise/aviation_noise/fundamentals_of_noise"
 },
 {
  "term": "Noise map",
  "aka": "strategic noise map",
  "category": "Sound basics",
  "definition": "A computer model of long-term average sound levels from roads, rail and aircraft, not a direct measurement.",
  "section": "basics",
  "source_url": "https://www.bts.gov/newsroom/bts-releases-national-transportation-noise-map"
 },
 {
  "term": "Noise mitigation plan",
  "aka": "",
  "category": "Rules",
  "definition": "A New York City-required plan for how a construction site will reduce noise, needed for every after-hours authorization.",
  "section": "rules",
  "source_url": "https://nonoise.org/regulation/ordinance/New York, New York.pdf"
 },
 {
  "term": "Noise ordinance",
  "aka": "bylaw",
  "category": "Rules",
  "definition": "A local law setting when and how loud sounds may be; in Canada usually called a bylaw.",
  "section": "rules",
  "source_url": "https://www.toronto.ca/legdocs/municode/1184_591.pdf"
 },
 {
  "term": "Noise Policy Review",
  "aka": "",
  "category": "Aircraft",
  "definition": "FAA review opened May 2023 of whether to keep DNL and the 65 DNL threshold; awaiting an advisory committee report as of October 2026.",
  "section": "aircraft",
  "source_url": "https://www.faa.gov/noisepolicyreview"
 },
 {
  "term": "Noise Reduction Rating",
  "aka": "NRR",
  "category": "Health",
  "definition": "The EPA-required lab rating on US hearing protectors, on labels since 1979; real-world protection is usually lower.",
  "section": "health",
  "source_url": "https://canadianaudiologist.ca/hearing-protection-attenuation-feature/"
 },
 {
  "term": "Noise-induced hearing loss",
  "aka": "NIHL",
  "category": "Health",
  "definition": "Hearing loss caused by loud sound; NIDCD calls it the only completely preventable type of hearing loss.",
  "section": "health",
  "source_url": "https://www.nidcd.nih.gov/health/noise-induced-hearing-loss"
 },
 {
  "term": "NoiseScore",
  "aka": "",
  "category": "Boston",
  "definition": "An app from BU's Community Noise Lab that pairs sound readings with how a sound makes people feel on a live map.",
  "section": "boston",
  "source_url": "https://dailyfreepress.com/blog/2019/11/20/community-noise-lab-launches-to-research-noise-pollution/"
 },
 {
  "term": "OBSI",
  "aka": "On-board sound intensity",
  "category": "Traffic",
  "definition": "The usual US method for measuring tire noise, using microphones mounted a few inches from a rolling test tire.",
  "section": "traffic",
  "source_url": "https://www.cptechcenter.org/wp-content/uploads/2020/04/Noise_101_tech_brief.pdf"
 },
 {
  "term": "Octave band",
  "aka": "",
  "category": "Boston",
  "definition": "A slice of the frequency spectrum, such as 63 Hz or 1,000 Hz; Boston's APCC rules set a separate limit for each band from 31.5 Hz to 8,000 Hz.",
  "section": "boston",
  "source_url": "https://www.cityofboston.gov/Images_Documents/noise_reg_tcm3-13127.pdf"
 },
 {
  "term": "Office of Noise Abatement and Control",
  "aka": "ONAC",
  "category": "Rules",
  "definition": "The EPA office created to carry out the Noise Control Act of 1972; Congress stopped funding it in 1981.",
  "section": "rules",
  "source_url": "https://www.acus.gov:443/sites/default/files/documents/92-6.pdf"
 },
 {
  "term": "Open-graded friction course",
  "aka": "OGFC, porous asphalt",
  "category": "Traffic",
  "definition": "An asphalt with connected air voids that absorb some tire noise; benefits vary widely and can fade within a few years.",
  "section": "traffic",
  "source_url": "https://dot.ca.gov/-/media/dot-media/programs/research-innovation-system-information/documents/preliminary-investigations/caltrans-pi-quieter-pavement-a11y.pdf"
 },
 {
  "term": "Part 150",
  "aka": "14 CFR Part 150",
  "category": "Aircraft",
  "definition": "Voluntary FAA program in which an airport maps its 65 DNL contour and proposes noise fixes that can qualify for federal grants.",
  "section": "aircraft",
  "source_url": "https://www.portseattle.org/sites/default/files/2022-12/Part%20150%20Study%20Primer.pdf"
 },
 {
  "term": "PB/5",
  "aka": "",
  "category": "Designed sounds",
  "definition": "Australian pedestrian push button designed in 1984 with a slow locator chirp, a rapid tick-tock to cross and a \"kapow\" on change.",
  "section": "signals",
  "source_url": "https://en.wikipedia.org/wiki/PB/5_pedestrian_crossing_button"
 },
 {
  "term": "periodical cicada",
  "aka": "",
  "category": "Nature",
  "definition": "Cicadas that emerge in huge numbers on 13- or 17-year cycles; choruses have been reported at 90-100 dB.",
  "section": "nature",
  "source_url": "https://nbcchicago.com/news/local/cicadas-are-among-the-loudest-insects-in-the-world-just-how-loud-will-the-illinois-broods-be/3407343"
 },
 {
  "term": "Permissible Exposure Limit",
  "aka": "PEL",
  "category": "Health",
  "definition": "OSHA's enforceable US workplace noise limit, 90 dBA over 8 hours with a 5 dB exchange rate.",
  "section": "health",
  "source_url": "https://www.osha.gov/noise"
 },
 {
  "term": "Phaser",
  "aka": "pierce, priority",
  "category": "Sirens and alarms",
  "definition": "A very rapid electronic siren sweep, one of the standard tones on electronic sirens.",
  "section": "sirens",
  "source_url": "https://en.wikipedia.org/wiki/Siren_(alarm)"
 },
 {
  "term": "Plainly audible standard",
  "aka": "clearly audible",
  "category": "Rules",
  "definition": "A rule broken if a sound can be clearly heard at a set distance or place, with no meter needed.",
  "section": "rules",
  "source_url": "https://www.nyc.gov/assets/dep/downloads/pdf/environment/education/nyc-noise-code-fact-sheet.pdf"
 },
 {
  "term": "PLdB",
  "aka": "perceived level in decibels",
  "category": "Aircraft",
  "definition": "A loudness measure for booms based on human hearing; NASA's X-59 targets under 75 PLdB on the ground.",
  "section": "aircraft",
  "source_url": "https://theaviationist.com/2026/06/08/nasas-x-59-quesst-goes-supersonic/"
 },
 {
  "term": "Point of reception",
  "aka": "",
  "category": "Rules",
  "definition": "Where a noise is measured for enforcement, usually the complainant's property line or inside their home.",
  "section": "rules",
  "source_url": "https://www.toronto.ca/legdocs/municode/1184_591.pdf"
 },
 {
  "term": "Point source / line source",
  "aka": "",
  "category": "Sound basics",
  "definition": "A single spot that loses about 6 dB per doubling of distance, versus a long stream like a highway that loses about 3 dB.",
  "section": "basics",
  "source_url": "https://www.fhwa.dot.gov/Environment/noise/noise_barriers/design_construction/design/design03.cfm"
 },
 {
  "term": "Pop Code",
  "aka": "Code of Practice on Environmental Noise Control at Concerts",
  "category": "Music and nightlife",
  "definition": "The UK Noise Council's 1995 code for outdoor concert noise at nearby homes, with limits from 09:00 to 23:00 and inaudibility indoors after 23:00.",
  "section": "nightlife",
  "source_url": "https://WWW.GOV.JE/SiteCollectionDocuments/Leisure%20and%20entertainment/ID%20Code%20of%20Practice%20on%20Environmental%20Noise%2020110517%20RWJ.pdf"
 },
 {
  "term": "Pre-construction acoustics baseline",
  "aka": "",
  "category": "Hums and machines",
  "definition": "A measurement of neighborhood sound before a facility is built; Chandler, Arizona requires one for data centers.",
  "section": "hums",
  "source_url": "https://www.princewilliamtimes.com/news/some-cities-suffering-from-data-center-noise-turn-to-tough-limits/article_2aa7fb8c-b6aa-11ed-8626-5738aae2f76c.html"
 },
 {
  "term": "Preemption",
  "aka": "",
  "category": "Rules",
  "definition": "When a higher level of government's rule blocks a lower one from setting a different rule; federal EPA product noise standards preempt different local product standards.",
  "section": "rules",
  "source_url": "https://www.acus.gov:443/sites/default/files/documents/92-6.pdf"
 },
 {
  "term": "psf",
  "aka": "pounds per square foot",
  "category": "Aircraft",
  "definition": "Unit of sonic boom overpressure; the FAA's 2026 proposal would cap booms at the surface at 0.11 psf.",
  "section": "aircraft",
  "source_url": "https://www.faa.gov/newsroom/ARM-260115-001_Supersonic_NPRM_06-10-26.pdf"
 },
 {
  "term": "Pure tone",
  "aka": "",
  "category": "Boston",
  "definition": "A noise dominated by one pitch, such as a whine or hum, which the MassDEP Noise Policy treats as a violation condition in itself.",
  "section": "boston",
  "source_url": "https://www.bdlaw.com/publications/massdep-seeks-comment-on-revisions-to-longstanding-noise-policy/"
 },
 {
  "term": "quiet area",
  "aka": "",
  "category": "Nature",
  "definition": "Area a city can designate and protect from noise under the EU Environmental Noise Directive.",
  "section": "nature",
  "source_url": "https://urbact.eu/articles/escape-city-noise-limericks-hush-city-approach"
 },
 {
  "term": "Quiet hours",
  "aka": "night hours",
  "category": "Rules",
  "definition": "Times, usually overnight, when stricter noise limits apply, such as 11 p.m. to 7 a.m. in Boston.",
  "section": "rules",
  "source_url": "https://nonoise.org/regulation/ordinance/Boston, Massachusetts.pdf"
 },
 {
  "term": "Quiet zone",
  "aka": "",
  "category": "Trains and transit",
  "definition": "A stretch of rail line, generally at least half a mile long, where trains do not routinely sound horns at crossings after added safety measures.",
  "section": "transit",
  "source_url": "https://railroads.dot.gov/sites/fra.dot.gov/files/fra_net/1226/finalrulesummary042605.pdf"
 },
 {
  "term": "Quota count",
  "aka": "night quota",
  "category": "Aircraft",
  "definition": "A points budget for night flights in which noisier aircraft cost more points; used at Heathrow since 1993.",
  "section": "aircraft",
  "source_url": "https://www.heathrow.com/company/local-community/noise/operations/night-flights"
 },
 {
  "term": "Rapid tick",
  "aka": "machine gun sound",
  "category": "Designed sounds",
  "definition": "The fast percussive walk indication on US accessible pedestrian signals, 10 repetitions per second.",
  "section": "signals",
  "source_url": "https://www.kqed.org/news/11795009/why-do-some-crosswalks-make-a-machine-gun-sound"
 },
 {
  "term": "RCNM",
  "aka": "Roadway Construction Noise Model",
  "category": "Construction and tools",
  "definition": "The Federal Highway Administration's model for predicting construction noise, built on a table of equipment noise levels at 50 feet.",
  "section": "construction",
  "source_url": "https://www.fhwa.dot.gov/Environment/noise/construction_noise/handbook/handbook09.cfm"
 },
 {
  "term": "Recommended Exposure Limit",
  "aka": "REL",
  "category": "Health",
  "definition": "NIOSH's health-based workplace noise limit, 85 dBA over 8 hours with a 3 dB exchange rate; advice, not law.",
  "section": "health",
  "source_url": "https://www.cdc.gov/niosh/noise/prevent/understand.html"
 },
 {
  "term": "Resilient wheel",
  "aka": "",
  "category": "Trains and transit",
  "definition": "A train wheel with rubber layers between hub and rim to damp vibration; does not guarantee an end to squeal.",
  "section": "transit",
  "source_url": "https://uic.org/IMG/pdf/uic_soa_combatting_curve_squeal_p2.pdf"
 },
 {
  "term": "Reverse signal alarm",
  "aka": "backup alarm, backup beeper",
  "category": "Construction and tools",
  "definition": "The alarm OSHA requires on construction vehicles with an obstructed rear view unless a spotter signals the vehicle back.",
  "section": "construction",
  "source_url": "https://jjkellercompliancenetwork.com/regsense/equipment-reverse-signal-alarms-must-be-audible-above-surrounding-noise-level"
 },
 {
  "term": "RNAV",
  "aka": "area navigation",
  "category": "Boston",
  "definition": "Satellite-based navigation that lets aircraft fly precise paths; at Logan since 2014 it concentrated Runway 33L departures over the same neighborhoods.",
  "section": "boston",
  "source_url": "https://www.cambridgema.gov/CDD/Transportation/regionalplanning/logannoisestudy"
 },
 {
  "term": "RNP",
  "aka": "Required Navigation Performance",
  "category": "Boston",
  "definition": "A precision navigation procedure that allows curved approaches; Logan's curved Runway 33L RNP approach was implemented in 2021.",
  "section": "boston",
  "source_url": "https://alumcommunity.mit.edu/news/877862"
 },
 {
  "term": "Rumbler",
  "aka": "",
  "category": "Sirens and alarms",
  "definition": "Federal Signal add-on that plays a low-frequency (182-400 Hz) copy of the siren through extra speakers so it can be felt inside cars; runs in eight-second bursts.",
  "section": "sirens",
  "source_url": "https://en.wikipedia.org/wiki/Rumbler_siren"
 },
 {
  "term": "SAE J1849",
  "aka": "",
  "category": "Sirens and alarms",
  "definition": "SAE recommended practice for laboratory testing of single-speaker electronic and electromechanical emergency vehicle sirens.",
  "section": "sirens",
  "source_url": "https://saemobilus.sae.org/content/J1849_201210"
 },
 {
  "term": "Schultz Curve",
  "aka": "",
  "category": "Aircraft",
  "definition": "Older dose-response curve linking noise level to percent highly annoyed, based on data behind the 65 DNL policy; showed 12.3% highly annoyed at DNL 65.",
  "section": "aircraft",
  "source_url": "https://kaplankirsch.com/resources-and-news/faa-releases-long-awaited-study-on-noise-annoyance"
 },
 {
  "term": "Section 60 notice",
  "aka": "s.60",
  "category": "Rules",
  "definition": "A UK council notice setting hours and conditions on a construction site after a substantiated complaint.",
  "section": "rules",
  "source_url": "https://www.arun.gov.uk/section-61-of-the-control-of-pollution-act-1974"
 },
 {
  "term": "Section 61 prior consent",
  "aka": "s.61",
  "category": "Rules",
  "definition": "A UK agreement on construction noise methods and hours made with the council before work starts, applied for at least 28 days ahead.",
  "section": "rules",
  "source_url": "https://www.arun.gov.uk/section-61-of-the-control-of-pollution-act-1974"
 },
 {
  "term": "Section 721.560",
  "aka": "Big Dig construction noise spec",
  "category": "Boston",
  "definition": "The Central Artery/Tunnel Project's construction noise specification, with background-based lot-line limits and per-machine emission limits at 50 ft.",
  "section": "boston",
  "source_url": "https://nonoise.org/resource/construc/bigdig.htm"
 },
 {
  "term": "seismic noise",
  "aka": "",
  "category": "Nature",
  "definition": "Ground vibration picked up by seismometers, much of it from traffic, industry and people moving around; fell up to 50% at high frequencies during 2020 lockdowns.",
  "section": "nature",
  "source_url": "https://www.usgs.gov/publications/global-quieting-high-frequency-seismic-noise-due-covid-19-pandemic-lockdown-measures"
 },
 {
  "term": "Society for the Suppression of Unnecessary Noise",
  "aka": "",
  "category": "History",
  "definition": "The New York group founded by Julia Barnett Rice in 1906, which began with tugboat whistles near hospitals.",
  "section": "history",
  "source_url": "https://www.noiseoff.org/library/timeline"
 },
 {
  "term": "Sonic boom",
  "aka": "",
  "category": "Aircraft",
  "definition": "Shock wave from flying faster than sound, heard on the ground as a bang or thump.",
  "section": "aircraft",
  "source_url": "https://www.faa.gov/newsroom/ARM-260115-001_Supersonic_NPRM_06-10-26.pdf"
 },
 {
  "term": "Sound exposure level",
  "aka": "SEL",
  "category": "Sound basics",
  "definition": "One event's total sound energy expressed as if it had happened within one second.",
  "section": "basics",
  "source_url": "https://www.faa.gov/noise/aviation_noise/fundamentals_of_noise"
 },
 {
  "term": "Sound Transmission Class",
  "aka": "STC",
  "category": "Sound basics",
  "definition": "A single-number wall rating averaged over 125-4,000 Hz, which can miss weak spots at lower bass frequencies.",
  "section": "basics",
  "source_url": "https://commercial-acoustics.com/sound-advice/why-bass-is-hard-to-block/"
 },
 {
  "term": "Soundscape",
  "aka": "",
  "category": "Measuring and quiet",
  "definition": "The acoustic environment as people perceive or experience it, in context, as defined in ISO 12913-1 (2014).",
  "section": "quiet",
  "source_url": "https://www.frontiersin.org/journals/psychology/articles/10.3389/fpsyg.2019.02514/full"
 },
 {
  "term": "Spotter",
  "aka": "observer",
  "category": "Construction and tools",
  "definition": "A worker who signals that it is safe for a vehicle to reverse; OSHA's alternative to a reverse alarm.",
  "section": "construction",
  "source_url": "https://jjkellercompliancenetwork.com/regsense/equipment-reverse-signal-alarms-must-be-audible-above-surrounding-noise-level"
 },
 {
  "term": "Statutory nuisance",
  "aka": "",
  "category": "Rules",
  "definition": "In England and Wales, noise that unreasonably and substantially interferes with the use or enjoyment of a home or injures health; councils must act on it.",
  "section": "rules",
  "source_url": "https://www.gov.uk/noise-nuisances-how-councils-deal-with-complaints"
 },
 {
  "term": "Strategic noise map",
  "aka": "",
  "category": "Measuring and quiet",
  "definition": "An EU-required, modeled map of long-term noise exposure from major roads, railways, airports and large cities, redone every five years.",
  "section": "quiet",
  "source_url": "https://noiseportaleionet.eea.europa.eu/noise-policy"
 },
 {
  "term": "The Hum",
  "aka": "",
  "category": "Hums and machines",
  "definition": "A persistent low-frequency sound reported by some people in a place that others there cannot hear; most cases are unexplained.",
  "section": "hums",
  "source_url": "https://www.cbc.ca/1.3548758"
 },
 {
  "term": "Time-weighted average",
  "aka": "TWA",
  "category": "Health",
  "definition": "Noise exposure averaged over a work shift, usually 8 hours.",
  "section": "health",
  "source_url": "https://www.osha.gov/noise"
 },
 {
  "term": "Tinnitus",
  "aka": "",
  "category": "Health",
  "definition": "Hearing ringing, buzzing or roaring with no outside source; a 2022 meta-analysis put adult prevalence at 14.4%.",
  "section": "health",
  "source_url": "https://cris.maastrichtuniversity.nl/en/publications/global-prevalence-and-incidence-of-tinnitus-a-systematic-review-a"
 },
 {
  "term": "Tire-pavement noise",
  "aka": "",
  "category": "Traffic",
  "definition": "Sound made where the tire tread meets the road surface; the main source of car noise at highway speeds.",
  "section": "traffic",
  "source_url": "https://www.cptechcenter.org/wp-content/uploads/2020/04/Noise_101_tech_brief.pdf"
 },
 {
  "term": "Train Horn Rule",
  "aka": "49 CFR Part 222",
  "category": "Trains and transit",
  "definition": "FRA rule requiring locomotive horns 15-20 seconds before public grade crossings, at 96 to 110 dB(A), in a long-long-short-long pattern.",
  "section": "transit",
  "source_url": "https://railroads.dot.gov/railroad-safety/divisions/crossing-safety-and-trespass-prevention/train-horn-rulequiet-zones"
 },
 {
  "term": "Turbofan",
  "aka": "",
  "category": "Aircraft",
  "definition": "Jet engine with a large front fan that moves extra air around the core, reducing exhaust speed and jet noise.",
  "section": "aircraft",
  "source_url": "https://ntrs.nasa.gov/citations/20050198876"
 },
 {
  "term": "UN Regulation 138",
  "aka": "UN R138",
  "category": "Designed sounds",
  "definition": "UN test rule for quiet road transport vehicles: maximum 75 dBA at 10 and 20 km/h measured 2 m from center line, with pitch rising over 0.8% per km/h.",
  "section": "signals",
  "source_url": "https://blogs.sw.siemens.com/simcenter/avas-electric-vehicle-warning-sounds/"
 },
 {
  "term": "Urban Quiet Park",
  "aka": "",
  "category": "Nature",
  "definition": "Quiet Parks International certification; the first went to Yangmingshan National Park, Taipei, in June 2020.",
  "section": "nature",
  "source_url": "https://euronews.com/green/2020/08/19/the-invisible-threat-of-noise-pollution-how-do-we-protect-quiet"
 },
 {
  "term": "V-NISSG",
  "aka": "",
  "category": "Music and nightlife",
  "definition": "Swiss ordinance in force since June 2019 that regulates sound and laser exposure at events in tiers up to 100 dB(A) LAeq1h; replaced the 1996 Sound and Laser Ordinance.",
  "section": "nightlife",
  "source_url": "https://zg.ch/en/gesundheit/gesund-bleiben/informationen-fuer-veranstaltende/schall-und-laser"
 },
 {
  "term": "Vibratory pile driver",
  "aka": "",
  "category": "Construction and tools",
  "definition": "A machine that drives piles by shaking them into the ground rather than hammering; measured at 101 dBA Lmax at 50 feet in the FHWA table.",
  "section": "construction",
  "source_url": "https://www.fhwa.dot.gov/Environment/noise/construction_noise/handbook/handbook09.cfm"
 },
 {
  "term": "Wail",
  "aka": "",
  "category": "Sirens and alarms",
  "definition": "Siren tone that rises and falls slowly in pitch; on a mechanical siren it comes from the rotor speeding up and slowing down.",
  "section": "sirens",
  "source_url": "https://en.wikipedia.org/wiki/Siren_(alarm)"
 },
 {
  "term": "Wavelength",
  "aka": "",
  "category": "Sound basics",
  "definition": "The physical length of one sound cycle: the speed of sound divided by frequency, about 17 m at 20 Hz and 34 cm at 1 kHz.",
  "section": "basics",
  "source_url": "https://commercial-acoustics.com/sound-advice/why-bass-is-hard-to-block/"
 },
 {
  "term": "Wayside horn",
  "aka": "Automated wayside horn",
  "category": "Trains and transit",
  "definition": "A horn mounted at a gated crossing and aimed down the road, which may substitute for the train horn.",
  "section": "transit",
  "source_url": "https://railroads.dot.gov/sites/fra.dot.gov/files/fra_net/1226/finalrulesummary042605.pdf"
 },
 {
  "term": "WebTrak",
  "aka": "",
  "category": "Aircraft",
  "definition": "Public airport flight-tracking tool showing tracks, altitude, aircraft type and noise monitor readings, with a complaint button.",
  "section": "aircraft",
  "source_url": "https://aircraftnoise.panynj.gov/webtrak/"
 },
 {
  "term": "Wheel squeal",
  "aka": "Curve squeal",
  "category": "Trains and transit",
  "definition": "High-pitched noise from steel wheels slipping sideways on the rail in tight curves; up to about 100 dB(A) at 10 m.",
  "section": "transit",
  "source_url": "https://uic.org/IMG/pdf/uic_soa_combatting_curve_squeal_p2.pdf"
 },
 {
  "term": "Windsor Hum",
  "aka": "",
  "category": "Hums and machines",
  "definition": "A low rumble reported in Windsor, Ontario from about 2011, which a Canadian-funded study linked to blast furnaces on Zug Island, Michigan.",
  "section": "hums",
  "source_url": "https://www.rcinet.ca/en/2014/05/23/windsor-hum-discovered-cross-border-cooperation-needed-now"
 },
 {
  "term": "Yelp",
  "aka": "",
  "category": "Sirens and alarms",
  "definition": "Siren tone that sweeps up and down much faster than the wail.",
  "section": "sirens",
  "source_url": "https://en.wikipedia.org/wiki/Siren_(alarm)"
 },
 {
  "term": "Z-weighting",
  "aka": "dBZ",
  "category": "Sound basics",
  "definition": "No weighting: a flat, unadjusted response between 10 Hz and 20 kHz.",
  "section": "basics",
  "source_url": "https://www.sonitussystems.com/insights/glossary-of-common-acoustic-definitions/"
 },
 {
  "term": "Zug Island",
  "aka": "",
  "category": "Hums and machines",
  "definition": "An industrial island in River Rouge, Michigan, home to U.S. Steel blast furnaces identified as the likely source of the Windsor Hum.",
  "section": "hums",
  "source_url": "https://www.rcinet.ca/en/2014/05/23/windsor-hum-discovered-cross-border-cooperation-needed-now"
 }
]