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“Blindness separates us from things, but deafness separates us from people.”

“Blindness separates us from things, but deafness separates us from people.”. Helen Keller. BCIS 3615 The Visual Display of Business Information. Sound. Wave Basics. Wave. … a periodic disturbance of the medium that is traveled through. Longitudinal Waves. Wikipedia. Compression.

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“Blindness separates us from things, but deafness separates us from people.”

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  1. “Blindness separates us from things, but deafness separates us from people.” Helen Keller

  2. BCIS 3615The Visual Display of Business Information Sound

  3. Wave Basics

  4. Wave … a periodic disturbance of the medium that is traveled through

  5. Longitudinal Waves Wikipedia Compression Rarefaction

  6. Transverse Waves Wikipedia

  7. Waveforms Analog Digital Wikipedia

  8. Waveform Components F = λ/t A λ Amplitude = Loudness (dB) Frequency = Pitch (kHz) Wavelength = Period (t)

  9. Frequency High frequency Low frequency

  10. Sound Basics

  11. Sound Wikipedia …vibration transmitted through a solid, liquid, or gas; particularly, sound means those vibrations composed of frequencies capable of being detected by ears.

  12. Limits of Human Hearing 20,000 Hz 300-16,000 Hz 300-8,000 Hz 300-3,000 Hz 20 Hz

  13. Hearing Physiology Inner ear Outer ear Eardrum Middle ear

  14. Perception of High and Low Pitch Inner ear Sound Eardrum Cochlea

  15. Doppler Effect

  16. Noise Cannot Be Removed from Analog Signals • (unwanted electrical / • electromagnetic energy) Analog signal Distorted Signal Noise

  17. Noise is Easily Removed from Digital Signals 1 1 1 0 0 0 Noise Digital Signal Distorted Signal Threshold Detector Processor Regenerated Digital Signal

  18. Phonograph Record (78 RPM) UNT, D. Peak

  19. Phonograph Record With Scratched Surface Grooves Scratches Scratches Grooves

  20. Removing Noise with Software Scratches Scratches 1920s lacquer recording with noise Recording after processing with Adobe Audition

  21. Sound Recording History

  22. World’s Oldest Playable Instrument (China, 7000 BC) Brookhaven National Laboratory

  23. Ancient Musical Notation (Egypt, 70 AD) Yale University

  24. Thomas Edison (1877) Used tin foil strips Recorded “Mary Has a Little Lamb” by shouting (i.e., acoustic recording) Intended for dictated messages

  25. Wax Cylinder Format (1885) • Perfected by Edison (invented by others) • Stored 2 min. (1908: 4 min.) of music • Intended for home use (1907: Enrico Caruso 1st million-copy singer)

  26. Sound Recording Studio, Circa 1885

  27. Samples of Early Recordings British Museum Frank Lambert’s Clock(1878, lead cylinder; earliest playable voice) Handel: Israel in Egypt (June 29, 1888; Crystal Palace London; oldest known playable recorded music) Sousa: Liberty Bell March (1897)

  28. Evolution of Sound Recording Formats 1887: Flat-disk (initially of hard rubber) 1906: Triode amplifier invented by DeForest 1928: 33 1/3 (LP, but not sold until 1948) 1963: Audio cassette 1982: CD (outsells vinyl records 1988; outsells cassettes 1992) 1997: MP3 2001: Apple iPod; CD sales start decline 2004: Apple iTunes

  29. Recall Forms of Signal Information Analog: A differentiable time-continuous signal Digital: A non-differentiable time-discontinuous signal with discrete levels (0 and 1 in binary)

  30. Recording and Playing Analog Sound Electrical Waves Sound Waves Sound Waves Analog Amplifier Assymetrix

  31. Recording and Playing Digital Sound Digital Sound Card .WAV and .MID A/D Converter D/A Converter Assymetrix

  32. Sound Engineering at Pixar Studios Animation - Sound engineering - Monsters Inc (2003).mpg

  33. Sound Digitization by Sampling

  34. Two "Frequencies" in Digital Sound Sound frequency = analog Pitch (high / low) for conversion and playback Sampling frequency = N samples (of the analog pitch) per second for digitization

  35. Two "Hertz" in Digital Sound Sound frequency Hz = 440Hz is 440 sound vibrations per second analog Sampling frequency Hz = 44,100Hz is 44,100 samples taken per second digital 1,000Hz = 1kHz

  36. Digitizing Analog Waves Analog sound frequency x 4 Analog sound frequency

  37. Digitizing Analog Waves: Nyquist Sampling Analog sound frequency x 4 Analog sound frequency Sample frequency

  38. Sampling Frequencies (X Axis) 11.025 kHz(poor AM radio quality) 22.050 kHz (near FM radio quality) 44.100 kHz(audio CD quality) 48.000 kHz(DVD quality) Note: Human hearing limits = 300Hz to 20.000 kHz analog

  39. Amplitude Bit Depth (Y Axis) 8-bit = 256 measurement intervals 16-bit = 65,536 intervals 24-bit = professional use

  40. Sampling Analog Sound to Digitize It Amplitude Bits per sample Amplitude Bits per sample Samples per second Samples per second

  41. Use Monaural or Stereo? Monaural– 1 sound channel (only format commercially available until 1950’s) Stereo– 2 sound channels; 2x monaural storage requirement Dolby Surround – 5x monaural Monaural unless authenticity vital

  42. Some Waveform File Formats .WAV(uncompressed; Windows) .MP3 (Windows, Mac) .AIF, .SOU (Apple Mac) .AU, .PCM, .SND (UNIX) .ACC (Advanced Audio Coding; iTunes) .WMA (Windows Media Audio)

  43. End of Section Sound

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