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Human Sound Waves. How do Humans Produce Sound?. Vocal cords 2 skin-covered flaps of muscle that open and close across the passage to our lungs Vocal cords oscillate with a wave motion as air is exhaled Started out as an evolutionary trend (attract mates, warning calls)
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Human Sound Waves
How do Humans Produce Sound? • Vocal cords • 2 skin-covered flaps of muscle that open and close across the passage to our lungs • Vocal cords oscillate with a wave motion as air is exhaled • Started out as an evolutionary trend (attract mates, warning calls) • Males have slightly larger vocal cords
How Vocal Cords Work Vocal cord muscles vibrate Air passes through vocal cords Produces a pressure wave Air escapes through lungs
How Vocal Cords Work • Beth's First Laryngoscopy - Vocal Cords in Action • http://www.youtube.com/watch?v=iYpDwhpILkQ
Blowing Out Candles • Using the sound wave created by your voice, try to blow out a candle • Alter the sound of your voice and try to determine if lower sounds or higher sounds cause the flame to move more/less • Does your voice create enough pressure to blow out a candle? Do you think a speaker would? • http://www.youtube.com/watch?v=tPno3yZRt7U
How do we produce different sounds? • Coordination between lips, mouth, tongue, throat, and respiratory system • Tongue is able to move freely and help create variety of sounds • Humans can alter tone by raising and lowering larynx • Trained singers are able to relax and contract muscles in the larynx to produce different sounds
Human Sound Production • David MeShow - Extreme Beatbox (No Instrument) • http://www.youtube.com/watch?v=gNS8vBq5bWE&feature=fvwrel • Inuit Throat Singing Demonstration • http://www.youtube.com/watch?v=8IqOegVCNKI&feature=related
How do humans alter pitch? How do humans alter pitch? • In sound science, the term pitch refers to the frequency of a wave • What is the formula for determining frequency? • Cycles/second (Hz) • More cycles = higher frequency
How do humans alter pitch? • Pitch depends on number of times per second vocal cords collide (frequency) • Low A = 55 cycles/second (55 Hz) • High C = 1047 cycles/second (1047 Hz) • Universal Wave Equation