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Musical Sounds

Musical Sounds. Physical Science101. Chapter twenty. Amanda Hyer. Noise. Music. Pitch. High. Low. Intensity Loudness. Soft. Loud. Sound Intensity. Decibel Sound Level. Decibel Sound Level. Exercise.

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Musical Sounds

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  1. Musical Sounds Physical Science101 Chapter twenty Amanda Hyer

  2. Noise

  3. Music

  4. Pitch High Low

  5. Intensity Loudness Soft Loud

  6. Sound Intensity

  7. Decibel Sound Level

  8. Decibel Sound Level

  9. Exercise • What is decibel level of a sound that is 1000 times louder than the threshold of human hearing? • Given: Intensity/10-12=1000=103 • Wanted: decibel level • Solution: dB=10log(Intensity/10-12) • dB=10log(103) = 30 dB

  10. Exercise • What is decibel level of a sound that is 10,000 times louder than a sound of 50 dB? • Given: 50 dB=dB1 and • Int2 =10,000 Int1 • Wanted: dB2 • Solution: Int1=100,000 (10-12) • Int2=10,000*100,000 (10-12)= 109(10-12) • dB2=10log(109) = 90 dB

  11. it’s actually easy • intensity 10 (101) louder 10 dB higher • intensity 100 (102) louder 20 dB higher • intensity 1000 (103) louder 30 dB higher • intensity 10,000 (104) louder 40 dB higher • intensity 1,000,000 (106) louder 60 dB higher

  12. Exercise • What is decibel level of a sound that is 1000 times louder than a sound of 70 dB? • Given: 70 dB=dB1 and • Int2 =1000 Int1 • Wanted: dB2 • Solution: dB2 is 30 dB higher • dB2=70+30 dB=100 dB

  13. Quality • The quality of sound from a musical instrument depends on the number of higher harmonics included with the fundamental frequency.

  14. Quality (a pure tone)

  15. Quality (1, .4, 0, .2)

  16. Quality (1, 0, 0, .3, 0, 0, .5)

  17. Fourier Any periodic signal can be made up from a sum of harmonic waves (sine waves).

  18. Fourier (1, 0, -(1/9)) Any periodic signal can be made up from a sum of harmonic waves (sine waves).

  19. Fourier (1, 0, -(1/9), 0, +(1/25)) Any periodic signal can be made up from a sum of harmonic waves (sine waves).

  20. Fourier (1, 0, -(1/9), 0, 1/25,0,-(1/49),0)

  21. Fourier (1,0) Any periodic signal can be made up from a sum of harmonic waves (sine waves).

  22. Fourier (1,0, (1/3)) Any periodic signal can be made up from a sum of harmonic waves (sine waves).

  23. Fourier (1,0,1/3,0,1/5) Any periodic signal can be made up from a sum of harmonic waves (sine waves).

  24. Fourier (1,0,1/3,0,1/5,0,1/7) Any periodic signal can be made up from a sum of harmonic waves (sine waves).

  25. Compact Discs binary numbers 00 0 01 1 10 2 11 3 100 4=22 101 5 10000 16=24 11111111 255

  26. Compact Discs Sample rate of 44,100 bytes per second This gives 0 to 10,000 Hz frequencies

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