Is the whole concept of decibels (dB) foreign to you? Do you have a vague idea that more dB equals a louder sound, but no clue what a decibel is or how many you want out of your car’s sound system?

We’re here to help. In this article, we’ll explain exactly what a decibel is, and what levels of dB correspond to which real-world sounds.

What is a decibel?

The decibel is the standard international unit used to measure volume. One decibel (1 dB) isn’t equal to anything that’s easy to describe in the real world — it comes from a complex equation involving pressure that we don’t need to get into right now.

Instead, just remember that decibels are relative and logarithmic. Relative means that dB is only a useful measurement when compared to other dB values. Logarithmic means that, for every 10 dB, the corresponding real-world volume doubles. 40 dB is twice as loud as 30 dB, and half as loud as 50 dB.

Decibel Equivalent Tables

Inaudible Range (Less than 10 dB)

Since it’s logarithmic and relative, the decibel scale is also limitless in both directions and doesn’t stop at 0. Zero dB is theoretically the lowest limit of human perception, but in practice, a human will rarely be able to hear a sound below 10 dB.

Inaudible Range (Less than 10 dB) dB Rating Sound Exposure (hours per day) -9 World’s quietest room ♾ 0 Lowest audible sound to human ear ♾ 10 Average silent room ♾

Barely Audible Range (10 to 40 dB)

You’ll be able to hear these, but it will take a lot of effort, and there can’t be any distractions.

Barely Audible Range (10 to 40 dB) dB Rating Sound Exposure (hours per day) 13 Hum from a light bulb (switched on) ♾ 15 Pin drop on solid floor from 1 meter ♾ 30 Nighttime in rural area ♾ 35 Main hall of a library ♾ 40 Human whispering ♾ 45 Hum from a refrigerator ♾

Normal Range (40 to 85 dB)

Listening to these sounds poses little or no risk to the average person. 85 decibels is the highest volume that poses no health dangers.

Normal Range (40 to 85 dB) dB Rating Sound Exposure (hours per day) 50 Corporate office environment ♾ 55 Rainfall; light traffic (closed windows) ♾ 60 Average conversation between adults ♾ 65 Acoustic piano; moderate traffic ♾ 70 Busy restaurant ♾ 80 Vacuum cleaner; hairdryer ♾ 85 Garbage disposal; school cafeteria ♾

Dangerous Range (85 to 115 dB)

Sounds at this range can damage your hearing, either immediately or through prolonged exposure. Without ear protection, nobody should be exposed to 90 dB for more than 8 hours per day, 100 dB for 2 hours, 105 dB for 1 hour, or 110 dB for more than half an hour.

Dangerous Range (85 to 115 dB) dB Rating Sound Exposure (hours per day) 90 Tractor 8 95 Truck or motorcycle engine 4 100 Subway platform at rush hour; orchestra from the first row 2 105 Pneumatic drill; car stereo at max. volume 1 110 Rock concert from the gallery; car stereo with two 6×9 speakers and 100 watts 0.5 115 Power saw; backhoe; ambulance siren 0.3

Serious Injury Range (115 dB to 140 dB)

There is no safe amount of exposure to volumes in this range. Being near a sound above 115 dB for any length of time without protection can cause permanent hearing damage. At this level, you’ll also begin to feel the sounds in parts of your body other than your ears.

Serious Injury Range (115 dB to 140 dB) dB Rating Sound Exposure (hours per day) 120 Rock concert from the front row; thunderclap overhead Ø 125 Cymbal crash; loudest possible human scream Ø 130 Jet engine taking off; air raid siren Ø 135 Firecracker Ø 140 Shotgun blast directly beside ear Ø

Deadly Range (140 dB to 200 dB)

Forget hearing damage — these sounds will give you permanent everything damage. Below about 170 dB, ear protection can still save you, but store-bought earplugs and earmuffs won’t be enough. You’re also likely to start having other problems with whatever is creating the noise (here’s a hint: don’t stand next to a pound of TNT).

Deadly Range (140 dB to 200 dB) dB Rating Sound Exposure (hours per day) 150 Formula One car at full throttle Ø 160 Inside jet engine or rock concert speaker bin Ø 170 7,000-horsepower engine Ø 180 1 pound of TNT detonating 15 feet away Ø 190 Grenade blast epicenter Ø 200 Causes immediate death Ø

Extreme Range (more than 200 dB)

Since we’ve already established that being near sounds above 200 decibels will kill you instantly, these are just here as fun facts. Note that since it’s not possible to put a decibel meter near many of these events and have it survive, dB levels above 200 are mostly theoretical.

Extreme Range (more than 200 dB) dB Rating Sound Exposure (hours per day) 210.6 Epicenter of a magnitude 2.0 earthquake Ø 213 Sonic boom Ø 214 Space shuttle launch Ø 215 U.S.S. New Jersey firing all 9 of its 16-inch guns Ø 235.2 Epicenter of a magnitude 5.0 earthquake Ø 243 Volume of the largest non-nuclear explosion in history – the “British Bang” which in 1947 destroyed an entire island with 6,700 tons of ordnance Ø 248 Center of the atomic bomb blasts at Hiroshima and Nagasaki Ø 282 Center of the Tsar Bomba test conducted by the Soviet Union, believed to be the loudest sound ever created by humans Ø 286 Center of the Mount Saint Helens volcanic eruption Ø 310 Theoretical volume of nature’s loudest sound, the eruption of Indonesia’s Krakatoa volcano Ø

While no modern instruments recorded the event, barometers fluctuated at levels that suggest Krakatoa produced a 190-dB sound from 100 miles away. Remember, 190 DB is what you hear when a grenade explodes next to your face. Krakatoa was no joke.

Volume Effects on the Human Body

Above 140 dB, sounds cause humans physical distress: shortness of breath, nausea, nosebleeds, and other severe discomforts. Below that level, they can still cause permanent problems, including hearing loss and persistent tinnitus. Make sure you always have hearing protection, no matter how badass your car’s rig might be.