Tabela de Decibéis — Níveis de Som dB e Guia de Segurança Auditiva

Q: What is a decibel (dB) and why is it logarithmic?

A decibel (dB) is a dimensionless logarithmic unit expressing the ratio between an acoustic sound wave and the human threshold of hearing (20 micropascals). The logarithmic scale compresses a 10-million-fold span into an intuitive 0 to 140 dB scale.

Q: Why does a 10 dB increase sound twice as loud to human ears?

Human auditory perception is psychoacoustic. An increase of +10 dB is perceived by the brain as roughly twice as loud, even though the physical sound wave power has increased by 10 times!

Q: At what decibel level does hearing damage occur?

NIOSH and WHO establish that continuous noise at or above 85 dBA causes permanent hearing damage over time. Safe exposure at 85 dB is 8 hours, at 88 dB is 4 hours, and at 100 dB is just 15 minutes.

ACOUSTIC SAFETY SPECTRUM

Interactive Decibel Level Spectrum (0 to 140+ dB)

Click any acoustic zone below to inspect exposure thresholds, human ear sensitivity, and real-world examples.

0 dB30 dB60 dB85 dB (NIOSH)115 dB140+ dB

0 – 30 dBFaint

Faint / Barely Audible

Threshold of human hearing to whisper. Entirely harmless.

Safety Advice:Safe indefinitely. Promotes relaxation, concentration, and deep REM sleep.

30 – 60 dBModerate

Quiet to Moderate

Normal conversation, peaceful library, quiet office environment.

Safety Advice:Completely safe for continuous 24-hour daily exposure without any hearing fatigue.

60 – 80 dBLoud

Loud / Intrusive

City traffic, vacuum cleaners, noisy dining rooms, dishwasher cycles.

Safety Advice:Safe for normal daytime exposure, but prolonged exposure may cause stress or sleep interference.

80 – 90 dBHazardous

Very Loud / Hazardous (85 dB Limit)

Food blenders, lawn mowers, busy highways, milling machines.

Safety Advice:NIOSH 85 dBA threshold: Prolonged exposure beyond 8 hours begins permanent cochlear hair cell loss.

90 – 115 dBDangerous

Extremely Loud / High Damage Risk

Motorcycles, chainsaws, rock concerts, personal audio at max volume.

Safety Advice:Hearing damage can occur in under 15 minutes! Hearing protection (earplugs/muffs) is strongly advised.

115 – 140+ dBPainful

Pain Threshold / Immediate Acoustic Trauma

Siren at close range, jet takeoff (100 ft), gunshot, explosive fireworks.

Safety Advice:Human pain threshold is reached. Immediate permanent auditory damage or eardrum rupture without double ear protection.

COMPREHENSIVE DECIBEL DATABASE

Everyday Sound Levels & Decibel (dB) Comparison Table

Search, filter, and inspect verified decibel values, safe exposure time limits, and acoustic sound energy ratios.

Showing 21 of 21 standard acoustic references

Sound Level	Scale Visual	Sound Source & Real-World Examples	Safe Exposure Limit	Perceived Loudness
0dB	0 – 5 dB	Threshold of Human HearingAuditory threshold for a healthy young ear (20 µPa)	Indefinite / Safe	1/64x (Imperceptible)Power: 1x (Reference Base)
10dB	5 – 15 dB	Normal Breathing & Rustling LeavesCalm human breathing at 1 meter, gentle leaves rustling	Indefinite / Safe	1/32xPower: 10x
20dB	15 – 25 dB	Soft Whisper & Ticking WatchQuiet whisper at 2 meters, mechanical wristwatch ticking	Indefinite / Safe	1/16xPower: 100x
30dB	25 – 35 dB	Quiet Bedroom & Rural NightSuburban bedroom late at night, quiet public library	Indefinite / Safe	1/8xPower: 1,000x
40dB	35 – 45 dB	Refrigerator Hum & Gentle RainModern kitchen refrigerator cooling, light rainfall outdoors	Indefinite / Safe	1/4xPower: 10,000x
50dB	45 – 55 dB	Quiet Office & Moderate RainfallModern air-conditioned office, computer cooling fans, calm conversation	Indefinite / Safe	1/2xPower: 100,000x
60dB	55 – 65 dB	Normal Human ConversationSpoken dialogue at 1 meter, background background music, dishwasher	Indefinite / Safe	1x (Baseline)Power: 1,000,000x
70dB	65 – 75 dB	Vacuum Cleaner & Busy Street TrafficDomestic vacuum cleaner at 2m, curbside traffic on busy arterial road	Indefinite (May cause fatigue)	2x as loud as speechPower: 10,000,000x
75dB	70 – 80 dB	Noisy Restaurant & Highway CommuteBustling dining hall, interior of passenger car at 65 mph on highway	Safe for 24 hours (Fatiguing)	2.8x as loud as speechPower: 31,600,000x
80dB	78 – 85 dB	Garbage Disposal & Alarm ClockUnder-sink waste disposal, electric alarm buzzer at 1m, freight train at 15m	Up to 24 hours	4x as loud as speechPower: 100,000,000x
85dB	82 – 88 dB	Kitchen Blender & Heavy Diesel TruckHigh-speed food blender at 1m, diesel city bus passing at 10m	8 Hours (NIOSH Threshold Limit)	5.6x as loud as speechPower: 316,000,000x
90dB	85 – 95 dB	Gasoline Lawn Mower & Power ToolsWalk-behind lawn mower operator ear level, circular hand saw, milling tool	2 Hours (NIOSH) / 8 Hours (OSHA PEL)	8x as loud as speechPower: 1,000,000,000x
95dB	90 – 100 dB	Subway Train Platform & MotorcycleSubway train braking into underground station, passing motorcycle at 5m	47 Minutes (NIOSH) / 4 Hours (OSHA)	11.3x as loud as speechPower: 3,160,000,000x
98dB	95 – 102 dB	Impact Hand Drill & Belt SanderPneumatic or electric impact driver drilling concrete or hardwood	23 Minutes (NIOSH)	13.9x as loud as speechPower: 6,300,000,000x
105dB	100 – 110 dB	Chainsaw & Pneumatic JackhammerGas-powered chainsaw at operator ear, street jackhammer at 2m	4.7 Minutes (NIOSH) / 1 Hour (OSHA)	22.6x as loud as speechPower: 31,600,000,000x
108dB	105 – 112 dB	Earbuds at Maximum VolumeSmartphone headphones or in-ear monitors driven to 100% digital gain	2.3 Minutes (NIOSH)	27.8x as loud as speechPower: 63,000,000,000x
112dB	110 – 120 dB	Live Rock Concert & Stadium PAStanding 10–15 meters from arena line-array speaker stacks	Under 1 Minute (NIOSH)	36.8x as loud as speechPower: 158,000,000,000x
120dB	115 – 125 dB	Emergency Siren & ThunderclapAmbulance or police siren at 3 meters, nearby lightning strike crack	Under 9 Seconds (NIOSH) / Instant Risk	64x as loud as speechPower: 1,000,000,000,000x
130dB	125 – 135 dB	Commercial Jet Takeoff (100 ft)Jet airliner engine spooling to maximum thrust at 30 meters distance	Under 1 Second / Immediate Permanent Harm	128x as loud as speechPower: 10,000,000,000,000x
140dB	135 – 150 dB	12-Gauge Shotgun Blast & Fireworks12-gauge shotgun discharged at shooter’s ear without hearing protection	Immediate Permanent Damage (0 Seconds)	256x as loud as speechPower: 100,000,000,000,000x
165dB	160 – 190 dB	Orbital Rocket Launch (Saturn V / Falcon)Saturn V or Falcon Heavy rocket launch pad sound suppression zone	Physical Trauma / Structural Destruction	1,400x+ as loud as speechPower: 31,600,000,000,000,000x

FERRAMENTA INTERATIVA

Comparador de Decibéis e Energia Sonora

Selecione duas fontes para comparar a diferença em decibéis e a energia física da onda sonora.

Som A (Base)

60 dB

Normal Human ConversationSpoken dialogue at 1 meter, background background music, dishwasher

Limit: Indefinite / Safe

VS

Som B (Comparação)

90 dB

Gasoline Lawn Mower & Power ToolsWalk-behind lawn mower operator ear level, circular hand saw, milling tool

Limit: 2 Hours (NIOSH) / 8 Hours (OSHA PEL)

Por que tanta diferença? Os decibéis são logarítmicos. 30 dB soam 8 vezes mais altos, mas têm 1.000 vezes mais energia!

OSHA vs. NIOSH Permissible Noise Exposure Limits

Understand occupational safety standards, daily noise dose limits, and why NIOSH recommends stricter thresholds.

Decibel Level	NIOSH Limit (3 dB Rule)	OSHA PEL (5 dB Rule)	Real-World Risk & Sound Context	Hearing Protection
85 dBA	8 hours	16 hours	Baseline hazardous noise threshold. Continuous daily exposure requires hearing conservation programs.	PPE Advised
88 dBA	4 hours	10.6 hours	Doubling of acoustic sound energy under the NIOSH 3 dB rule.	PPE Required
90 dBA	2 hours 30 min	8 hours (OSHA PEL)	OSHA Permissible Exposure Limit (PEL) for workplace shifts without hearing PPE.	PPE Required
91 dBA	2 hours	6 hours 55 min	Heavy power tools, commercial lawn maintenance equipment.	PPE Required
94 dBA	1 hour	4 hours 36 min	Motorcycles, subway trains passing in enclosed stations.	PPE Required
97 dBA	30 minutes	3 hours	Gas-powered leaf blowers, wood router saws at close proximity.	PPE Required
100 dBA	15 minutes	2 hours	Hand drills on concrete, night clubs, sports arenas.	PPE Required
103 dBA	7.5 minutes	1 hour 18 min	Chainsaws, pneumatic rivet guns, table saws.	PPE Required
106 dBA	3.75 minutes	52 minutes	Commercial car audio at high volume, snowmobiles.	PPE Required
109 dBA	1.87 minutes (~112 sec)	34 minutes	Helicopter hover at 30m, power press stamping.	PPE Required
112 dBA	~56 seconds	22 minutes	Live concert speaker stacks, stock car racing pit lanes.	PPE Required
115 dBA	~28 seconds	15 minutes (OSHA Ceiling)	OSHA maximum permissible exposure ceiling for steady-state noise.	PPE Required
120 dBA	Immediate risk (< 9 sec)	Not permitted without PPE	Emergency vehicle sirens, thunderclaps, painful sound levels.	PPE Required
140 dBA	0 seconds (Instant damage)	Unprotected exposure prohibited	Gunfire, fireworks, jet takeoff. Instantaneous mechanical cochlear trauma.	PPE Required

Scientific consensus: NIOSH standards are significantly more protective against permanent occupational hearing loss than minimum legal OSHA limits.

Understanding the Logarithmic Decibel (dB) Scale

Why decibels aren’t linear numbers, how sound pressure works, and the rule of 10 dB doubling.

Formula 01

Sound Pressure Level (SPL)

L_p = 20 · log₁₀(P / P₀)

Sound Pressure Level is calculated in decibels relative to reference pressure 20 µPa. Each 20 dB step represents a 10× multiplication of acoustic sound pressure.

Formula 02

The 80 dB + 80 dB = 83 dB Rule

L_total = 10 · log₁₀(10^(L₁/10) + 10^(L₂/10))

If two separate lawn mowers each produce 80 dB, their combined noise is 83 dB, not 160 dB! Doubling identical sound sources adds exactly +3 dB.

Formula 03

dBA vs. dBC Weighting Filters

dBA (Human Ear) vs dBC (Flat / Low Bass)

dBA cuts low bass and high treble, matching the human ear at moderate volumes. dBC provides a flatter response, essential for concert subwoofers and industrial machinery.

Frequently Asked Questions About Decibels & Noise Levels

Key acoustic questions about the decibel scale, hearing loss prevention, and sound measurement.

What is a decibel (dB) and why is it logarithmic?