Measure sound levels, protect your hearing, and understand noise in our world
Current sound level is safe for extended exposure without hearing protection.
Noise pollution affects millions of people worldwide and is linked to health problems including hearing loss, stress, sleep disruption, and cardiovascular disease.
Day: <55 dB average
Night: <40 dB average
Goal: Prevent health effects
Daytime: 70-80 dB
Traffic Areas: 80-85 dB
Status: Above WHO limits
Near Runway: 130+ dB
Residential: 65-75 dB
Impact: Sleep disruption
Heavy Equipment: 85-95 dB
Legal Limits: 55-65 dB (residential)
Duration: Limited hours
Sound is a mechanical wave that travels through air (or other media) as pressure variations. When objects vibrate, they create compressions and rarefactions in the air molecules around them. Our ears detect these pressure changes and our brain interprets them as sound.
Sound has three main characteristics: amplitude (which we perceive as loudness), frequency (which we perceive as pitch), and timbre (which gives sounds their unique character).
The decibel (dB) is a logarithmic unit used to measure sound intensity. The scale is based on the ratio between measured sound pressure and a reference pressure level (20 micropascals, the threshold of human hearing).
Because the decibel scale is logarithmic, small changes in dB represent large changes in actual sound pressure or intensity:
Human hearing is not equally sensitive to all frequencies. We hear mid-range frequencies (1-4 kHz) most clearly, while very low and very high frequencies seem quieter at the same sound pressure level.
A-weighting (dBA) adjusts measurements to match human hearing sensitivity. It reduces the contribution of low frequencies (below 1 kHz) and very high frequencies (above 6 kHz) in the measurement. Most environmental and occupational noise standards use dBA measurements.
C-weighting (dBC) has a flatter response and is used for peak sound measurements and very loud sounds where A-weighting might underestimate the risk.
Human Hearing Range: 20 Hz to 20,000 Hz (20 kHz)
Most Sensitive: 2,000 Hz to 5,000 Hz
Speech Range: 250 Hz to 8,000 Hz
Age-related Loss: High frequencies decline first (presbycusis)
Prolonged exposure to loud sounds can cause permanent hearing damage through several mechanisms:
Temporary Threshold Shift (TTS): Short-term hearing reduction after noise exposure. Usually recovers within hours to days, but repeated TTS can lead to permanent damage.
Permanent Threshold Shift (PTS): Irreversible hearing loss from damage to hair cells in the inner ear. These cells do not regenerate in humans.
Tinnitus: Ringing, buzzing, or other phantom sounds often associated with noise-induced hearing loss. Affects about 15% of adults.
Workplace noise exposure is regulated by organizations worldwide to prevent hearing loss:
The exchange rate determines how exposure time changes with sound level. A 3 dB exchange rate means each 3 dB increase halves the safe exposure time, while a 5 dB rate is less protective.
Based on NIOSH recommendations (3 dB exchange rate):
Foam Earplugs: 25-33 dB reduction. Inexpensive and effective for most situations. Must be properly inserted (roll, insert, hold).
Silicone/Wax Earplugs: 20-25 dB reduction. Comfortable for sleeping, less effective for very loud environments.
Earmuffs: 20-30 dB reduction. Good for intermittent exposure, easier to use correctly than earplugs.
Custom-molded Earplugs: 25-35 dB reduction. Most comfortable for regular use, expensive but durable.
Electronic/Active Protection: Variable reduction. Allows normal conversation while protecting against loud impulse sounds.
Understanding sound levels in context helps assess risk and make informed decisions about hearing protection:
Quiet Environments (0-40 dB): Rural nighttime, anechoic chambers, libraries. These levels support rest, concentration, and recovery from noise exposure.
Comfortable Levels (40-70 dB): Normal conversation, background music, residential areas. No hearing risk, optimal for communication and productivity.
Moderate Noise (70-85 dB): Busy restaurants, traffic, vacuum cleaners. Safe for 8+ hours but may cause stress and interfere with communication.
Loud Environments (85-100 dB): Power tools, lawn mowers, shouting. Hearing protection recommended for extended exposure. OSHA action levels begin here.
Very Loud (100-120 dB): Concerts, sporting events, motorcycles. Hearing protection essential. Damage possible within minutes to hours.
Extremely Loud (120+ dB): Jet engines, gunshots, explosions. Immediate hearing damage possible. Always requires hearing protection.
Beyond hearing loss, chronic noise exposure affects overall health and quality of life:
Sleep Disruption: Noise above 40 dB can interfere with sleep quality. Traffic noise above 55 dB increases insomnia and daytime fatigue.
Cardiovascular Effects: Chronic exposure to noise above 65 dB is linked to increased blood pressure, heart disease, and stroke risk.
Cognitive Impact: Classroom noise above 35 dB impairs learning and reading comprehension in children. Office noise above 50 dB reduces productivity and increases stress.
Mental Health: Persistent environmental noise is associated with increased anxiety, depression, and aggression.
Modern cities often exceed WHO noise guidelines, creating widespread health impacts:
Traffic Noise: The dominant source of urban noise pollution. Major highways can produce 70-80 dB at 100 meters, well above WHO recommendations for residential areas.
Aircraft Noise: Affects millions living near airports. Peak levels can exceed 130 dB, with average levels of 65-75 dB in nearby residential areas.
Construction Noise: Temporary but intense, often exceeding 85-95 dB. Regulated by time restrictions and local ordinances, but enforcement varies.
Industrial Noise: Factories, power plants, and processing facilities can produce continuous noise pollution affecting surrounding communities.
Effective noise control follows the hierarchy of controls:
Elimination: Remove the noise source entirely (electric vehicles vs. gasoline engines).
Engineering Controls: Reduce noise at the source (mufflers, sound barriers, building design).
Administrative Controls: Limit exposure time, restrict noisy activities to certain hours.
Personal Protection: Individual hearing protection devices when other methods are insufficient.
Active Noise Control: Technology that uses destructive interference to cancel unwanted sounds. Already common in headphones, expanding to architectural applications.
Smart City Planning: Urban design that considers acoustic environments, using sound mapping and modeling to reduce noise pollution.
Electric Transportation: The shift to electric vehicles could dramatically reduce urban noise pollution, though it also creates new challenges for pedestrian safety.
Building Standards: Evolving acoustic building codes that prioritize occupant health and comfort over minimum requirements.
Protecting your hearing and managing noise exposure: