Lesson 4 — Decibel scale

• Sound
• Middelbare school
• havo, vwo
• Leerjaar 2

This lesson

• The research assignment
• The decibel scale
• Doing calculation using the decibel scale

Learning goals

• Name the unit of sound intensity.
  

• Explain which two factors influence the number of decibels measured.

• Explain how the deicbel scale works and be able to apply it in simple calculations.

•  Name three ways of reducing the risk of hearing damage.

The decibel

• the unit of sound intensity
• Symbol — dB.
• Invented in 1920 by New York telephone engineers.

Decibel meter

The Decibel research assignment

The amount of decibels you measure depends on two factors:

•  The loudness of the sound source.
• The distance between you and the sound source.

The Decibel research assignment

The decibel is a relative unit

Can you find the pattern?

Can you find a pattern?

• Conversation – city traffic — 10 times louder

• Conversation – Vacuum cleaner — 100 times louder

• Conversation – Tractor — 1000 times louder

• Refrigerator hum – Air conditioning unit —... times louder?

Can you find a pattern?

• Conversation – city traffic — 10 times louder

• Conversation – Vacuum cleaner — 100 times louder

• Conversation – Tractor — 1000 times louder

• Refrigerator hum – Air conditioning unit —100 times louder?

Exercise.

Two students are video calling. They both have a decibel meter on their phone. 

One of them is sitting at home while someone is vacuum cleaning in the same room. The other one is measuring a sound that is 100 times louder. 

A) How many decibels is the second student measuring?

B) What could be happening around the second one?

Reducing the risks of hearing loss.

Learning goals

• Name the unit of sound intensity.
  

• Explain which two factors influence the amount of decibel measured.

• Explain how the deicbel scale works and be able to do simple calcualtions with it.

•  Name three ways of reducing the risk of loud noises.