1. 100,000 10,000 1,000 100 10 1 0 human dog elephant bat mouse dolphin Which animals hear the lowest and the highest frequencies? frequency (Hz) Comparing hearing ranges

2. Loud Sounds Where might you come across very loud sounds? Write some places or situation down in the back of your book. What are sounds measured in?

3. Sound Levels

4. Damaging your ears? Loud sounds (above 85dB) can damage the hairs inside your ears. This damage can be reversed unless caused by a sudden very loud noise However if you continue to expose your ears over and over again the damage becomes permanent. If you go to parties or gigs where they play loud music you could experience temporary deafness Tinnitus is a side effect of noise-induced hearing problems – hearing a ringing or buzzing even when there is no sound! High frequency (pitch) sounds get lost first. Listening to sounds at over 110 to 120 dB can damage your hearing in less than 1 ½ hours

5. Using a decibel meter How loud is it in this classroom? Can you get the meter to read 0? How loud is it when you’re all talking? What about in other parts of the school?