Noise pollution is not just any sound—it’s sound at levels or durations high enough to cause physiological stress and hearing loss (EK STB-2.J.1). Practically that means loud, persistent, or chronic anthropogenic noise (measured in decibels, dB)—think traffic, aircraft, construction, industrial and domestic activity (EK STB-2.J.2). Regular sound can be short, low-level, or natural (birds, wind) and doesn’t harm hearing or cause chronic stress. Key differences: intensity (higher dB), duration/frequency (chronic exposure), and source (human-made vs natural). Ecologically, noise can mask animal communication or hunting, cause hearing damage, stress responses, and change migratory routes (EK STB-2.J.3). For AP review, connect this to STB-2.J learning objective and practice examples in the Topic 7 noise study guide (https://library.fiveable.me/ap-environmental-science/unit-7/noise-pollution/study-guide/55a1ghLYJsx9vOJFcYid). For broader Unit 7 review or more practice, see the unit page (https://library.fiveable.me/ap-environmental-science/unit-7) and practice problems (https://library.fiveable.me/practice/ap-environmental-science).

Noise damages hearing when loud sound waves physically stress and break hair cells in the inner ear; repeated damage causes a permanent auditory threshold shift (hearing loss). Loud noise also causes physiological stress and acoustic masking (you can’t hear communication or warning sounds), which affects people and wildlife (CED EK STB-2.J.1, EK STB-2.J.3). What’s “too loud”? Use decibels (dB): chronic exposure at or above about 85 dB (typical heavy traffic, city transit) for 8 hours increases risk of hearing loss (NIOSH/OSHA guidance used on the exam). Every ~3 dB increase halves safe exposure time (e.g., ~88 dB → ~4 hours). Sounds above ~120 dB are painfully loud; very intense impulses (≥140 dB) can cause immediate damage. For more AP-aligned review, see the Topic 7.8 study guide (https://library.fiveable.me/ap-environmental-science/unit-7/noise-pollution/study-guide/55a1ghLYJsx9vOJFcYid) and Unit 7 resources (https://library.fiveable.me/ap-environmental-science/unit-7). For extra practice, try Fiveable’s APES practice problems (https://library.fiveable.me/practice/ap-environmental-science).

Noise pollution harms animals in a few clear ways. Loud, chronic noise (think traffic, planes, construction) causes physiological stress and can produce permanent hearing loss when levels stay above ~85 dB. It also masks important sounds animals use to communicate, find mates, or detect predators/prey, so feeding, mating, and parenting success drops. Noise can change behavior and movement—animals shift territories, alter calling times, or avoid noisy migration routes—which fragments populations and reduces fitness. Over time chronic stress hormones weaken immune function and reproduction. On the APES exam this is Topic 7.8 (STB-2.J): know sources (transportation, construction, industry) and effects (stress, auditory threshold shift, acoustic masking, migratory disruption). For a focused review, see the Topic 7.8 study guide (https://library.fiveable.me/ap-environmental-science/unit-7/noise-pollution/study-guide/55a1ghLYJsx9vOJFcYid). For broader Unit 7 review and practice questions, check the unit page (https://library.fiveable.me/ap-environmental-science/unit-7) and practice problems (https://library.fiveable.me/practice/ap-environmental-science).

In cities the biggest sources of noise pollution are transportation (road traffic, buses, trains, and aircraft), construction (heavy machinery, jackhammers, demolition), and domestic/industrial activities (loud factories, HVAC systems, nightlife/entertainment, and noisy appliances). These anthropogenic sounds can reach decibel levels high enough to cause physiological stress and hearing loss (auditory threshold shift) and cause acoustic masking that interferes human communication and wildlife behaviors (stress, altered migration or hunting). For AP purposes remember EK STB-2.J.2: transportation, construction, and domestic/industrial activity are the primary urban sources, and EK STB-2.J.1 links high dB to health effects. If you want a quick Topic 7.8 review, check the Fiveable study guide (https://library.fiveable.me/ap-environmental-science/unit-7/noise-pollution/study-guide/55a1ghLYJsx9vOJFcYid) and Unit 7 overview (https://library.fiveable.me/ap-environmental-science/unit-7). Practice questions are at (https://library.fiveable.me/practice/ap-environmental-science).

Decibels (dB) measure sound intensity on a logarithmic scale: every +10 dB ≈ 10× more sound energy. 0 dB is near human hearing threshold; normal conversation ≈ 60 dB; city traffic ≈ 70–85 dB. Sounds ≥85 dB can cause hearing damage with long or repeated exposure (OSHA uses 85 dB for an 8-hour exposure limit). Louder levels shorten safe exposure: ~100 dB becomes harmful in minutes to tens of minutes; ~120 dB is near the pain threshold and can cause immediate damage. Chronic exposure leads to auditory threshold shift, permanent hearing loss, stress, and acoustic masking—effects the AP CED highlights (EK STB-2.J.1 and EK STB-2.J.3). For examples of anthropogenic sources (traffic, aircraft, construction) and mitigation, check the Topic 7.8 study guide (https://library.fiveable.me/ap-environmental-science/unit-7/noise-pollution/study-guide/55a1ghLYJsx9vOJFcYid). For broader Unit 7 review and practice questions, see the unit page (https://library.fiveable.me/ap-environmental-science/unit-7) and Fiveable practice problems (https://library.fiveable.me/practice/ap-environmental-science).

Short answer: humans mainly suffer direct health effects (hearing loss and stress), while animals suffer those plus big ecological impacts that change behavior and population dynamics. Humans—at high dB levels noise causes auditory threshold shifts/hearing loss and physiological stress (sleep disruption, increased blood pressure, cardiovascular risk). Chronic urban sources: traffic, aircraft, construction (EK STB-2.J.1–2). On the AP exam, you should be able to link noise to hearing loss and chronic stress. Animals—all the human effects plus ecological consequences: acoustic masking that blocks mating, alarm, or hunting calls; damaged hearing that lowers survival; altered foraging, reproduction, and migratory routes; population declines or range shifts (EK STB-2.J.3). Noise can change community interactions and ecosystem function. For a quick review of Topic 7.8, see the Fiveable study guide (https://library.fiveable.me/ap-environmental-science/unit-7/noise-pollution/study-guide/55a1ghLYJsx9vOJFcYid). More unit resources (https://library.fiveable.me/ap-environmental-science/unit-7) and practice questions (https://library.fiveable.me/practice/ap-environmental-science) are great for exam prep.

Animals change migration routes because human noise interferes with the sounds they use to navigate, communicate, and sense their environment (EK STB-2.J.1, EK STB-2.J.3). Loud anthropogenic noise (ships, aircraft, traffic) can mask low-frequency cues or infrasound animals rely on to orient themselves, so they lose acoustic landmarks and alter routes. Chronic noise also causes physiological stress and can damage hearing, so animals avoid noisy areas to reduce stress and the risk of hearing loss. Over time, avoidance and masking push populations onto different paths or timings (e.g., whales shifting away from shipping lanes or birds changing stopover sites). These changes can reduce fitness by increasing energy costs, disrupting feeding or breeding, and fragmenting habitats. For a quick AP-aligned refresher on noise pollution and examples, check the Topic 7.8 study guide (https://library.fiveable.me/ap-environmental-science/unit-7/noise-pollution/study-guide/55a1ghLYJsx9vOJFcYid) and try practice questions (https://library.fiveable.me/practice/ap-environmental-science).

Short answer: not dramatic—construction noise can cause real physiological stress and even hearing damage. The CED’s EK STB-2.J.1 defines noise pollution as sound loud enough to cause physiological stress and hearing loss. Typical construction equipment runs ~80–110 dB (heavy jackhammers and pile drivers are near the top); repeated or chronic exposure above ~85 dB risks permanent hearing loss (auditory threshold shift) and can trigger a chronic stress response (increased blood pressure, elevated cortisol, sleep disruption). Noise also causes acoustic masking and behavioral stress in wildlife (EK STB-2.J.3). For AP review, study how sources (transportation, construction, industrial) link to health and ecosystem effects in Topic 7.8 (see the Topic 7 study guide: https://library.fiveable.me/ap-environmental-science/unit-7/noise-pollution/study-guide/55a1ghLYJsx9vOJFcYid). Want practice Qs on this unit? Check the Unit 7 overview (https://library.fiveable.me/ap-environmental-science/unit-7) and many practice problems (https://library.fiveable.me/practice/ap-environmental-science).

Noise pollution masks animal communication and hunting sounds through acoustic masking: loud, persistent anthropogenic noise (traffic, aircraft, construction) raises background sound levels so key signals fall below an animal’s auditory threshold. That means mating calls, alarm calls, territory signals, or prey/echolocation clicks get drowned out or must be made louder and longer. Consequences include less successful mating, missed predator warnings, reduced hunting efficiency (e.g., bats and owls can’t detect prey as well), and chronic stress that can change behavior or migration. At high decibel levels repeated exposure also causes auditory threshold shifts (hearing loss) so animals permanently lose sensitivity to important frequencies. For AP exam connections, use terms like acoustic masking, auditory threshold shift, chronic stress response, and list common urban sources (transportation, industrial, construction) as per the CED (Topic 7.8). For a quick review, see the Topic 7.8 study guide (https://library.fiveable.me/ap-environmental-science/unit-7/noise-pollution/study-guide/55a1ghLYJsx9vOJFcYid) and Unit 7 overview (https://library.fiveable.me/ap-environmental-science/unit-7). For practice questions, check Fiveable’s practice bank (https://library.fiveable.me/practice/ap-environmental-science).

The biggest human sources of noise pollution are transportation (road traffic, trains, and especially aircraft), construction (jackhammers, heavy equipment), and industrial activity (factories, power plants). Recreational and domestic sources (loud concerts, nightlife, lawn equipment) and military operations also produce high dB levels. Typical ranges: busy traffic ~70–85 dB (chronic exposure can cause stress), jet takeoff ~120 dB (risk of immediate hearing damage). These activities cause physiological stress and auditory threshold shift (hearing loss) in people and acoustic masking, disrupted communication, altered behavior, and changed migratory routes in wildlife—exactly what the CED’s EK STB-2.J notes. For AP exam prep, be ready to name sources, give decibel examples, and explain effects like masking and chronic stress. For a quick topic review, see Fiveable’s Topic 7.8 study guide (https://library.fiveable.me/ap-environmental-science/unit-7/noise-pollution/study-guide/55a1ghLYJsx9vOJFcYid) and try related practice problems (https://library.fiveable.me/practice/ap-environmental-science).

Sound damages hearing by physically harming the tiny sensory cells in your inner ear. Sound waves travel through the outer and middle ear and make the fluid in the cochlea vibrate. These vibrations bend bundles of hair-like stereocilia on hair cells. At moderate levels this creates a nerve signal you perceive as sound, but very loud or prolonged noise (high decibel levels) overstretches and shears those stereocilia, or causes metabolic stress that kills the hair cells. Dead hair cells don’t regenerate, so you get a permanent auditory threshold shift (hearing loss). Sudden very loud sounds can cause acoustic trauma (immediate loss); chronic exposure causes gradual hearing loss and acoustic masking (difficulty hearing signals over background noise). This is exactly what EK STB-2.J.1 describes. For AP review, check the Topic 7.8 study guide (https://library.fiveable.me/ap-environmental-science/unit-7/noise-pollution/study-guide/55a1ghLYJsx9vOJFcYid) and practice questions (https://library.fiveable.me/practice/ap-environmental-science).

Because transportation (cars, trucks, trains, planes) is constant, loud, and widespread, it dominates urban noise pollution. Engines, tires on pavement, and jet engines produce high sound levels measured in decibels (dB) that can be above thresholds causing physiological stress and hearing loss (EK STB-2.J.1). Transportation noise is continuous along roads, rails, and flight paths, so it chronically exposes people and wildlife—unlike one-off construction or isolated industrial sources. That continuous sound also causes acoustic masking (blocking communication and hunting calls) and can change animal behavior or migration (EK STB-2.J.3). On the AP exam, expect questions linking sources (traffic, aircraft) to effects like chronic stress, auditory threshold shift, and masking (EK STB-2.J.2–3). For a focused review, see the Topic 7.8 study guide on Fiveable (https://library.fiveable.me/ap-environmental-science/unit-7/noise-pollution/study-guide/55a1ghLYJsx9vOJFcYid) and practice questions at (https://library.fiveable.me/practice/ap-environmental-science).

Noise pollution has real impacts on wildlife through acoustic masking, hearing damage, stress, and changed movements (CED EK STB-2.J). Examples: - Marine: Navy sonar and seismic airgun surveys (for oil/gas) mask whale and dolphin communication, causing strandings, lost foraging, and altered migration routes. Large commercial ships produce chronic low-frequency noise that forces whales to shift habitats. - Birds: Urban traffic and airport noise force birds to sing at higher pitches or louder volumes, which can reduce mating success and increase stress. - Mammals: Bats avoid noisy areas and may miss insect prey; terrestrial mammals (e.g., deer) show elevated cortisol and altered movement near highways. - Amphibians: Construction and road noise mask frog calls, reducing mate attraction and breeding success. These are good examples to cite for STB-2.J on the exam. For a concise topic review, see Fiveable’s Topic 7.8 study guide (https://library.fiveable.me/ap-environmental-science/unit-7/noise-pollution/study-guide/55a1ghLYJsx9vOJFcYid). For broader Unit 7 review and extra practice, check the unit page (https://library.fiveable.me/ap-environmental-science/unit-7) and practice problems (https://library.fiveable.me/practice/ap-environmental-science).

Scientists measure noise pollution using instruments and standard metrics. They use sound level meters to record decibel (dB) levels and apply A-weighting (dBA) to match human hearing sensitivity. Key metrics include instantaneous levels (dB), Leq (equivalent continuous level over a period), and peak levels; long-term exposure is assessed with dosimeters worn by people or animals to estimate auditory threshold shift and risk of hearing loss. Frequency analysis (octave or 1/3-octave bands) shows which pitches cause acoustic masking for wildlife. Data are often logged over time (rush hour vs. night) to find chronic stressors and sources like traffic, aircraft, or construction. For AP relevance, know decibels, hearing loss, masking, and typical urban sources (CED EK STB-2.J.1–3). For quick review, see the Topic 7.8 study guide (https://library.fiveable.me/ap-environmental-science/unit-7/noise-pollution/study-guide/55a1ghLYJsx9vOJFcYid) and more unit resources (https://library.fiveable.me/ap-environmental-science/unit-7) or practice questions (https://library.fiveable.me/practice/ap-environmental-science).

Short answer: noise pollution can affect whole ecosystems long-term, not just individual animals. Why: chronic anthropogenic noise (traffic, aircraft, construction) at high dB causes physiological stress and hearing loss (auditory threshold shifts) in many individuals. That leads to behavioral changes—masked communication and hunting, altered mating calls, and shifted migratory routes—which lower reproductive success, change survival rates, and push species away from noisy habitats. Over time those population changes can alter community composition and food-web interactions (trophic cascades), reducing biodiversity and changing ecosystem function. Numbers to remember for the exam: think “chronic” exposure and acoustic masking, not only single loud events; even moderate continuous noise can cause long-term stress. For more AP-aligned review on sources, effects, and mitigation, check the Topic 7.8 study guide (https://library.fiveable.me/ap-environmental-science/unit-7/noise-pollution/study-guide/55a1ghLYJsx9vOJFcYid). For extra practice, Fiveable has unit reviews and practice problems (https://library.fiveable.me/ap-environmental-science/unit-7 and https://library.fiveable.me/practice/ap-environmental-science).