Because the ear handles an enormous range of pressures – the loudest bearable sound has about a million times the pressure of the faintest audible one – acoustics uses a logarithmic scale. 0 dB SPL is the threshold of hearing (20 micropascals). Every +10 dB is ten times more intensity and sounds roughly twice as loud.
Every 10 dB
0 dBBarely audible
Threshold of hearing, Normal breathing10 dBVery quiet
Threshold of hearing, Normal breathing, Rustling leaves20 dBVery quiet
Rustling leaves, Ticking watch, Cat purring30 dBQuiet
Rustling leaves, Cat purring, Whisper40 dBQuiet
Whisper, Quiet library, Refrigerator hum50 dBModerate
Moderate rainfall, Quiet office, Typing on a keyboard60 dBModerate
Air conditioner, Dishwasher, Normal conversation70 dBLoud
Snoring, Washing machine, Busy restaurant80 dBLoud
Airplane cabin, Alarm clock, Garbage disposal90 dBVery loud
Diesel truck, Dog barking, Jet hand dryer100 dBExtremely loud
Cicada chorus, Construction site, Garbage truck110 dBExtremely loud
Baby crying, Bagpipes, Car alarm120 dBPainful
Emergency siren, Thunder (close), Vuvuzela130 dBPainful
Emergency siren, White bellbird, Threshold of pain140 dBDangerous
.22 caliber rifle, Jet engine at takeoff, Loudest stadium crowd150 dBDangerous
Loudest stadium crowd, Firecracker, Fireworks160 dBDangerous
Fireworks, 9 mm handgun, 12-gauge shotgun170 dBDangerous
9 mm handgun, 12-gauge shotgun, Krakatoa eruption (1883)180 dBDangerous
Krakatoa eruption (1883)190 dBDangerous
Threshold of hearing, Normal breathing10 dBVery quiet
Threshold of hearing, Normal breathing, Rustling leaves20 dBVery quiet
Rustling leaves, Ticking watch, Cat purring30 dBQuiet
Rustling leaves, Cat purring, Whisper40 dBQuiet
Whisper, Quiet library, Refrigerator hum50 dBModerate
Moderate rainfall, Quiet office, Typing on a keyboard60 dBModerate
Air conditioner, Dishwasher, Normal conversation70 dBLoud
Snoring, Washing machine, Busy restaurant80 dBLoud
Airplane cabin, Alarm clock, Garbage disposal90 dBVery loud
Diesel truck, Dog barking, Jet hand dryer100 dBExtremely loud
Cicada chorus, Construction site, Garbage truck110 dBExtremely loud
Baby crying, Bagpipes, Car alarm120 dBPainful
Emergency siren, Thunder (close), Vuvuzela130 dBPainful
Emergency siren, White bellbird, Threshold of pain140 dBDangerous
.22 caliber rifle, Jet engine at takeoff, Loudest stadium crowd150 dBDangerous
Loudest stadium crowd, Firecracker, Fireworks160 dBDangerous
Fireworks, 9 mm handgun, 12-gauge shotgun170 dBDangerous
9 mm handgun, 12-gauge shotgun, Krakatoa eruption (1883)180 dBDangerous
Krakatoa eruption (1883)190 dBDangerous
All levels
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Frequently asked questions
What is 0 dB?
0 dB SPL is the reference pressure of 20 µPa – roughly the quietest 1 kHz sound a healthy young ear can detect. It does not mean silence.
What is the loudest possible sound?
In air at sea level, about 194 dB – where pressure troughs reach a vacuum. Louder events are shock waves.