1. What we will do today: State how me measure sound levels. State the unit of sound. Carry out experiments to find the sound levels of everyday occurrences.

2. Measuring Sound Level We measure sound levels with a sound meter. Sound levels are measured in a unit called decibels. Decibels have the symbol dB.

3. Now measure some different sounds and record them in the table below: ObjectSound Level (dB) Liam’s voice84 Door slamming70 Tap running71 Phone ringing87 Liam screaming98

4. Typical Noise levels Noise sourceLevel, dB Minimum sound0 Normal conversation60 Heavy lorry95 Pneumatic drill100 Pop group at 1m110 Jet engine130 Pain threshold140

5. Danger!!! Regular exposure to noise above 90dB can cause damage to hearing. For this reason, noises above 90dB are described as ‘noise pollution’. We must know least two examples. We can prevent hearing damage by wearing ear muffs or using sound insulation. These absorb the loud sounds and protect the ears.