Noise Meter
Measure real-time audio decibels (dB) using your microphone. Detect noise levels instantly with this free online sound meter tool. No download required.
Note: This is an estimation based on microphone input sensitivity.
About Noise Meter
How to Use This Tool
- 1.Grant microphone access when promptedâthe tool requires audio input to measure sound pressure levels.
- 2.Hold your device at arm's length (60-90cm) from the noise source for most accurate readings.
- 3.The meter displays real-time decibel levels (dBA) using your device microphone's frequency-weighted response.
- 4.Note peak and average readingsâsustained exposure matters more than brief spikes for hearing safety.
Decibel Measurement Methodology
Sound Pressure Level (SPL) Calculation
Decibels (dB) measure sound intensity on a logarithmic scale relative to the threshold of human hearing. The formula:
Where:
- P = Measured sound pressure (Pascals)
- Pâ = Reference pressure (20 micropascals, the quietest sound humans can hear)
- logââ = Logarithmic scale (every 10 dB increase = 10Ă louder, 20 dB = 100Ă louder)
A-Weighting: Why "dBA" Not Just "dB"
Human ears don't hear all frequencies equallyâwe're most sensitive to 1-5 kHz (speech range) and less sensitive to low/high frequencies. A-weighting (dBA) applies frequency filters matching human hearing response curves, reducing low-frequency contribution by 20-50 dB and high frequencies by 5-10 dB. This tool uses dBA because regulatory safety limits (OSHA, WHO) reference A-weighted measurements.
Smartphone Microphone Limitations
Consumer device microphones are calibrated for voice recording (40-85 dB range), not precision sound measurement. Accuracy limitations:
- ±5 dB error margin: Acceptable for general awareness, insufficient for legal/regulatory compliance
- Clipping above 90-100 dB: Loud environments (concerts, construction) may show artificially capped readings
- Poor low-frequency response: Bass-heavy noise (subwoofers, engines) underrepresented by 10-20 dB
- No calibration standard: Different phone models show 3-8 dB variance for identical sounds
For OSHA workplace compliance or legal documentation, use certified Class 1 or Class 2 sound level meters (±1-2 dB accuracy).
Decibel Scale Reference Chart
| dBA Level | Common Sound Example | Subjective Perception | Safe Exposure Time |
|---|---|---|---|
| 0-10 dBA | Threshold of hearing | Barely perceivable | No limit |
| 20-30 dBA | Whisper, rustling leaves | Very quiet | No limit |
| 40-50 dBA | Quiet office, library | Comfortable background | No limit |
| 60-70 dBA | Normal conversation, TV | Intrusive but safe | No limit |
| 80-85 dBA | Alarm clock, traffic | Annoying, tiring | 8 hours max (OSHA limit) |
| 90-95 dBA | Lawn mower, power tools | Very loud, uncomfortable | 2-4 hours max |
| 100-110 dBA | Chainsaw, nightclub | Extremely loud, painful | 15-30 minutes max |
| 120-130 dBA | Rock concert, ambulance siren | Pain threshold | Immediate damage risk |
| 140+ dBA | Jet engine, gunshot | Eardrum rupture risk | Instant hearing damage |
OSHA Permissible Exposure Limits (PEL): 85 dBA for 8 hours is the occupational safety threshold. For every 5 dB increase, safe exposure time is cut in half: 90 dBA = 4 hours, 95 dBA = 2 hours, 100 dBA = 1 hour, 105 dBA = 30 minutes, 110 dBA = 15 minutes.
Understanding the Logarithmic Scale
Why Logarithmic Matters: Human hearing perceives sound intensity logarithmically, not linearly. This means:
+3 dB = 2Ă Acoustic Power
Doubling speakers or sound sources adds 3 dB (e.g., two 80 dB sources together = 83 dB, not 160 dB)
+10 dB = 2Ă Perceived Loudness
Your ears perceive 80 dB as twice as loud as 70 dB, even though it's 10Ă more acoustic energy
+20 dB = 100Ă Acoustic Energy
A 90 dB environment has 100Ă more sound energy than 70 dB, explaining why hearing damage risk escalates rapidly
-10 dB = 50% Perceived Volume
Reducing noise by 10 dB makes it sound half as loud, requiring significant soundproofing or distance
Pro-Tips for Accurate Measurements
Distance Doubles = -6 dB (Inverse Square Law)
Sound intensity follows the inverse square law: doubling your distance from a noise source reduces the reading by 6 dB. A chainsaw measures 100 dB at 1 meter, 94 dB at 2 meters, 88 dB at 4 meters. For accurate readings, measure at consistent distances. WHO and OSHA standards specify measurement points (e.g., 1 meter from machinery, ear-level for worker exposure).
Remove Phone Case for +3-5 dB Accuracy Improvement
Phone cases, especially thick silicone or rugged cases, muffle microphones and reduce readings by 3-8 dB. For best accuracy, remove the case and position the microphone (usually bottom edge of phone) directly toward the sound source. Avoid covering the mic with your handâthis can attenuate readings by 10+ dB.
Wind Adds False +5-15 dBâUse Indoors When Possible
Outdoor measurements are compromised by wind noise hitting the microphone, creating artificial 5-15 dB spikes even in gentle breezes. Professional sound meters use foam windscreens; smartphones don't. For outdoor measurements, shield the microphone with your hand (without touching it) or take readings with your back to the wind. Indoor measurements are always more reliable.
Average Readings Over 60+ Seconds, Not Peak Spikes
Hearing damage correlates with sustained exposure, not momentary peaks. A construction site might spike to 105 dB when a drill starts but average 88 dB over 10 minutes. OSHA regulations reference time-weighted averages (TWA), not instantaneous maximums. Most smartphone meters show bothâfocus on the average reading for safety assessment. The exception: impulse noise (gunshots, fireworks) can cause instant damage above 140 dB.
Noise-Induced Hearing Loss (NIHL)
How Hearing Damage Occurs: Sound waves cause inner ear hair cells (stereocilia) to vibrate. At 85+ dBA sustained exposure, mechanical stress damages these cells. Unlike most body tissues, stereocilia cannot regenerateâhearing loss is permanent and cumulative.
Early Warning Signs of NIHL
- Temporary threshold shift: muffled hearing for 2-16 hours after noise exposure
- Tinnitus (ringing/buzzing) that persists beyond 24 hours
- Difficulty understanding speech in noisy environments (early high-frequency loss at 3-6 kHz)
- Needing to increase TV/music volume more than others
- Asking people to repeat themselves frequently
Prevalence Data: According to CDC and NIOSH studies, 22 million U.S. workers are exposed to hazardous noise annually. 24% of hearing loss in adults ages 20-69 is attributed to occupational noise exposure. Construction workers, musicians, military personnel, and manufacturing employees show 2-3Ă higher rates of hearing loss compared to general population.
Protection Guidelines: Use hearing protection (foam earplugs = 15-30 dB reduction, earmuffs = 20-35 dB reduction) when exposed to 85+ dBA for extended periods. Combine earplugs + earmuffs in 100+ dBA environments for maximum 40-50 dB reduction. WHO recommends limiting personal audio device volume to 60% maximum and taking 5-minute breaks every hour.
Medical & Legal Disclaimer: This decibel meter is an educational tool for general noise awareness, not a certified sound level meter for occupational safety, legal compliance, or medical diagnosis. Smartphone microphones have ±5-10 dB accuracy margins and are not calibrated to ANSI S1.4 or IEC 61672 standards required for OSHA workplace monitoring. Measurements should not be used for regulatory compliance, legal documentation, workers' compensation claims, or hearing damage assessment. For occupational noise assessment, use certified Class 1 or Class 2 sound level meters. If experiencing hearing loss symptoms (tinnitus, muffled hearing, difficulty understanding speech), consult an audiologist or ENT specialist. This tool provides estimates only and assumes no liability for hearing damage or regulatory violations.