FEEL THE BASS N O I T C U D O R T N I It’s nice and quiet You’re about to write a paper for school But your brother has different plans He cranks up the stereo in his room The music radiates through closed doors and solid walls But the vocals are hard to hear You can’t quite make out what song it is 4
Then the bass kicks in You not only hear it but you can also feel the sound The windows rattle Hanging pictures jiggle a little Even your chest buzzes with the bass It makes it hard to concentrate on homework What you hear feel and see comes from vibrating sound waves These waves travel from the stereo through your house The high notes move in shorter waves They can’t travel as far However low bass notes have much longer waves These waves move through thick objects such as walls As sound waves pass through matter they make objects vibrate The louder the sound the more movement the waves create
W H AT I S SOUND A book makes no sound right This is true when it is lying still but open it up Turn the pages Listen as your fingers slide across the paper The sounds you hear start with energy provided by you All sounds require energy to occur This energy comes from a source that creates a vibration This source may be a clap or loud bark The created vibration moves in waves away from the source through a medium such as air The waves make the medium vibrate as well Sound is a form of energy transmitted in waves that are received by hearing Finally the vibrations reach your ears There the sound’s energy is changed into messages The messages are sent to the brain and you perceive them as sound 1 R E T P A H C 6
MEASURE IT MEASURING SOUND A sound’s loudness is measured in decibels dB A dB tells you how much force a sound wave carries This is the sound’s amplitude or intensity Quiet sounds are lower on the dB scale Louder sounds rank higher on the scale Here is a chart of the dB levels of some everyday sounds Sounds louder than 85 dB can damage human ears 85 dB BUSY CITY TRAFFIC WASHING MACHINE TYPICAL SPEECH RAINFALL WHISPER 75 65 55 45 35 25 15 5 0 dB SOFTEST SOUND HUMANS CAN HEAR 7
