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II. Properties of sound 1. loudness - your perception of the energy if sound A. what you hear B. depends on 2 factors I. Amount of energy it takes to make the sound ii. distance from the source of sound 2. energy of a sound source A. greater the energy used to make a sound, louder the sound B. larger the amplitude of the sound wave, the more energy it has and louder it sounds 3. distance from a sound source C. closer the wave is to source,= more energy it has in a given area D. intensity - amount of energy a sound wave carries per sound thru a unit area I. greater intensity sounds louder 4. measuring loudness A. decibel(dB) loudness of different sounds is compared using this unit B. pitch- how high or low the sound seems to a person 1. pitch depends on the frequency of the sound wave 2. high frequency=high pitch 3. low frequency - low pitch 4. measured in hertz 5. hear sounds 20-20,000 Hz 6. ultrasound - sound waves with frequencies above the normal human range of hearing 7. infrasound - sound with frequencies below the human range of hearing 8. important property of music - I. uses specific pitches called notes ii. singing - changing pitch using vocal cords a.) larynx- vocal cords are in your voice box, larynx b.) vibrate more than 1000x/second C. Doppler effect 1. the change in frequency of a wave as its source moves in relation to an observer I. Austrian scientist ii. Christian droppler 2. when a sound source moves, the frequency of the waves changes because the motion of the source adss to the motion of the waves 3. shock waves form as waves overlap I. release huge amount of energy ii. sonic boom - breaking sound barrier Quiz 1. loudness 2.frequency 3.pitch 4.ultrasound 5.decibles 6.doppler effect 7.infrasound 8.intensity 9.laynx Study guide 1. laynx 2.infrasound 4.is the amount of energy the waves carries per second thru the unit area 12.ultrasound waves 21. pitch of trains whistle will become higher from girls perspective. as sound source moves closer to listen reach higher frequency makes pitch higher 22. Doppler effect 29. speed of sound is lower in dry air at lower temp. exceeding sound barrier is easier under these conditions 30. string should be loosened. tight strings make higher pitches thean loose strings. if pitch is high- the string is too tight.