Explain in simple words that decibels (dB) are a ratio scale: every +10 dB is 10 times more sound energy, which the ear hears as roughly twice as loud
Compare everyday sounds on a dB ruler and work out how many "ten-steps" separate two levels
Read a relative level from a microphone meter and say why it is not an exact dB value
Name actions that reduce noise exposure: move away, turn the volume down, rest the ears
KEY CONCEPTS
sound level in decibels; reference examples: whisper 30, library 40, normal conversation 60, doorbell 80, heavy traffic inside a car 85, shouted conversation 90, hair dryer 100, siren nearby 120 (example values from a public health-organisation table)
weekly listening-time guide in that table: 80 dB → 40 h, 85 dB → 12 h 30 min, 90 dB → 4 h, 100 dB → 20 min, 120 dB → 12 s; the WHO-ITU standard for personal audio devices uses 80 dB / 40 h per week for adults and 75 dB / 40 h per week for children
keep headphone volume at no more than 60% of maximum (WHO safe-listening Q&A)
10 dB ≈ doubling of perceived loudness (rule of thumb, roughly valid above about 40 phon; not exact)
a browser microphone meter gives a relative level (0–100 here, from RMS in dBFS), not calibrated dB SPL; echo cancellation, noise suppression and auto gain are asked to be off
history hook: in 1928 the Bell System renamed its "transmission unit" the decibel, one tenth of a bel, after Alexander Graham Bell
human inner-ear hair cells do not grow back, so protecting hearing matters
STRUCTURE
goal → 1 Remember (3 warm-up questions) → 2 Story (decibel and Bell, 60–90 s) → 3 Worked example (60 dB vs 100 dB) → 4 Try it (Predict "+10 dB = ? times" → Run: dB ruler, no sound played → Change: optional microphone meter with a no-microphone slider fallback) → 5 Unplugged ("Noise map" of the home, nothing measured) → 6 Make your own (family quiet-listening card) → 7 What I learned (3-question check + skill badge, no points, no streaks) → 8 I have a question (form: the child writes ≤280 chars, the parent enters an e-mail and consents; double opt-in; plus "Was it useful?" / "We did the lesson" buttons — aggregate counts only)
ANSWERS
predict: +10 dB = 10 times more sound energy (2× is roughly how loud it sounds; 100× is +20 dB)
worked example: 100 − 60 = 40 dB = four ten-steps = 10 × 10 × 10 × 10 = 10,000 times more energy; perceived roughly 2⁴ = 16 times louder
check: q1 +20 dB = 100 times (b) · q2 the page shows a relative level, not exact dB (a) · q3 move away, turn it down, rest the ears (c)
SAFETY
the microphone starts only after a click and the browser's permission; audio is processed locally in memory, never recorded, stored or sent; tracks stop on the Stop button, when the tab is hidden and when the page closes
fallback: a slider works without any microphone
the page never plays sound; the unplugged task never asks to make loud noise; no shouting, no ears next to speakers
educational numbers only: not an official noise measurement, not medical advice; no "safe/unsafe" verdict is drawn from a child's measurement
no personal data is entered or stored; the page works offline
NEXT
Previous: DB-IS-06 · Dust in the Air (PM2.5) · Next: DB-IS-08 · Water: Temperature, Clarity, Conductivity
SOURCES · LICENCE
original content of the Children's Library (East Accelerator Foundation), 2026
You cannot see or touch sound. But it can become a number — and the number can tell you when to turn it down, step away or let your ears rest.
⏱ 10–15 minTinkererMeasuring My World · 7grades 5–6
You will be able to explain what decibels are, compare two sounds with numbers and say what you do when it is too noisy around you.
For parents: a one-page guide — dinner questions and a game without a screen.
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01Remember
Think first, then open the answer.
What does a sensor do?
It turns something from the world — light, heat, sound — into a number that a computer can read.
How does a sound become a number?
A microphone catches how the air vibrates and turns it into a weak electric signal. The computer measures it many times every second and so it gets numbers.
What should happen after the number?
Understanding and action. A number that does not make you decide something is only a number.
02Story
At the start of the last century, the engineers of telephone lines in America had a problem. A signal gets weaker along a long cable — but by how much? They needed a unit.
In 1928, the Bell telephone company named the new unit the decibel(dB). It is one tenth of a “bel” — a name in honour of Alexander Graham Bell, one of the pioneers of the telephone.
Today decibels are used for sound too. And sound matters for our ears: deep in the inner ear there are tiny cells with little hairs that catch sound. If very loud noise damages them, human ones do not grow back. That is why we protect our ears.
03Worked example
A normal conversation is about 60 dB, and a hair dryer is about 100 dB. How many times is the hair dryer “more sound”? Not 40 times. Here is how to work it out:
The rule
Every 10 dB up means 10 times more sound energy.
Count the steps
From 60 to 100 is 40 dB. That is 4 steps of 10.
Multiply
10 × 10 × 10 × 10 = 10,000 times more sound energy.
What does the ear hear?
The ear is more “modest”: for every 10 dB it hears roughly twice as loud. Four steps are about 2 × 2 × 2 × 2 = 16 times as loud. This is a rough rule, not exact science.
SOUNDwhat happens
MICROPHONEsensor
NUMBERlevel
ACTIONwhat you do
04Try it now
1 · Predict
One sound is 10 dB louder than another. How many times more sound energy does it have? Choose before you check.
2 · Run: the decibel ruler
Slide to choose a sound. There is no sound at all here — only numbers and examples.
quieterlouder
The examples and times come from a table by health experts (see Sources) and are for information. They are not a verdict on your own measurements.
3 · Change: listen to the noise around you (optional)
You can turn your device's microphone into a noise sensor. Do it only if you want to, and with an adult next to you.
🔒
What the page does with the microphone
It switches it on only after you press the button and the browser asks you for permission. The sound is worked out only inside your device and shown as a bar. It is not recorded, not sent and not kept. “Stop” switches it off at once.
quieterlouder
relative level: 0 of 100
Important: this is a relative level, not exact decibels. Every microphone and every device hears differently, so the number is only for comparing here and now.
Try: 1) sit quietly; 2) speak calmly; 3) clap gently; 4) step one pace away and repeat. What does the bar do when you move away? Do not shout and do not play loud music — there is no need.
✋
Look after your ears
Do not make loud noise on purpose and do not put your ear next to a speaker. If something hurts or rings in your ear — tell an adult.
05No screen: “Noise map”
You need: a sheet of paper, coloured pencils and an adult who walks with you. Nothing is measured with a device — you only listen.
Draw a simple plan of your home: kitchen, hall, your room, bathroom, balcony.
Go into one room, stay quiet and listen. Which sounds do you hear? A fridge, the street, a TV, running water…
Colour the room and give it 1 to 5 little ears: 1 = very quiet, 5 = the noisiest place in your home. Write down the loudest sound.
Pick the noisiest place. Think together: what could make it quieter? (A closed window, a lower TV, a rug, moving away.)
06Make your own
Make a “quiet listening card” for your family or class.
Pick three sounds from your day (for example headphones, the street, the school bell).
Next to each one write how many little ears you give it and what you do when it is loud.
Add one family rule for headphones. Experts advise keeping their volume at no more than 60% of the device's maximum.
07What I learned
Decibels are a scale: every 10 dB up is 10 times more sound energy, and the ear hears about twice as loud.
The louder and the longer you listen, the more your ears are at risk. So we turn it down, move away and rest.
The microphone on this page gives a relative level, not exact decibels.
A microphone only counts sound — it does not hear like you. How do you know when it is too noisy for you?
Check yourself
1. One sound is 20 dB louder than another. How many times more sound energy does it have?
2. What does the microphone bar in the lesson show?
3. It is very loud around you. Which is a good action?
🎧
Skill badge: “I understand decibels” It is yours when you can explain to someone why 20 dB more is a lot more sound and what you do when it is loud. No points and no rankings — just a skill.
08I have a question
Do you still have a question? Write it here. It goes to your parent, not to strangers. Your parent confirms their e-mail first.
The form is loading… If it does not appear, write your question on paper and show it to a parent or teacher.
·Sources
Title: Noise: How Loud Is It? (DB-IS-07) · Author: Children's Library, East Accelerator Foundation · Source: original content, 2026 · Rights: CC BY-SA 4.0.
Example sounds, the “listening time per week” table and the 60% volume advice: World Health Organization (WHO), “Deafness and hearing loss: Safe listening”, checked 01.10.2026. Numbers selected for this lesson.
The story and the rule “10 dB ≈ twice as loud”: facts from the articles “Decibel” and “Sone” (Wikipedia, CC BY-SA 4.0) — retold in our own words. The rule is approximate.
This lesson is for learning: it is not an official noise measurement and not medical advice.
Licence:CC BY-SA 4.0 · Children's Library, East Accelerator Foundation, 2026. You may share and adapt this lesson if you credit the author and keep the same licence. Learning is free forever.
