Physical Science - Chapter 18 

Sound

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18A Sound Waves

• Acoustic Energy
  • ==Sound Energy==: a type of mechanical wave energy that can be detected by the human ear
• Characteristics of Sound Waves
  • ==Acoustic Spectrum==: the continuum of all possible sound waves
  • ==Pitch==: how high or low an audible tone sounds to the human ear; related to the concept of wave frequency
  • ==Loudness==: human perception of the intensity of a sound value
  • ==Intensity==: a measure of the power contained in a wave; often refers to sound or electromagnetic waves
  • ==Decibel==: the unit for measuring relative sound intensity
  • ==Timbre==: the distinctive sound of an instrument; also called quality

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18B Hearing and Music

• Producing Sound

1. ==Larynx==: the box-like structure located at the top of the trachea that supports the vocal cords
2. ==Vocal Cords==: folds of tissue in the throat that when vibrated produce the sound waves that humans use to communicate
3. throat and sinus passages
4. tongue, teeth, and lips
5. diaphragm

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The Human Ear

• Outer ear

1. auditory canal
2. ==Tympanic Mmembrane==: the thin, flexible membrane that separates the outer ear from the middle ear and converts acoustic energy to kinetic energy

Middle ear

1. ==Hammer==: one of the three bones, along with the anvil and stirrup, of the middle ear that transmit energy from the outer ear to the inner ear
2. ==Anvil==: one of the three bones, along with the hammer and stirrup, of the middle ear that transmit energy from the outer ear to the inner ear
3. ==Stirrup==: one of the three bones, along with the anvil and hammer, of the middle ear that transmit energy from the outer ear to the inner ear
4. ==Eustachian Tube==: the canal that connects the middle-ear cavity with the throat to allow the equalization of pressure on both sides of the ear drum

• Inner ear

1. ==Cochlea==: the inner-ear organ that converts kinetic energy to electrical impulses
2. auditory nerve
3. semicircular canals

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• Tones

==Fundamental Tone==: the longest ( lowest frequency) standing wave produced by a vibration of a structure

==Overtone==: a shorter, faster vibration (higher pitch) in addition to the fundamental tone produced by a vibrating structure

==Harmonics==: the fundamental tone and its overtones

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18C Using Sound Waves

• Sound Technologies

  • ==Acoustic Amplification==: the process of making a sound louder
  • ==Echolocation==: the process that uses the time interval and direction of an echo to determine the position of an object
  • ==Passive Sonar==: a system of underwater microphones that can only receive, not produce, underwater sounds in order to detect a submerged object

  ==Active Sonar==: an underwater device that produces short pulses of sound that echo back to the sending object; used to find the bearing and range of submerged objects

• Infrasonic and Ultrasonic

  • ==Infrasonic Sound==: sound having frequencies below the range of human hearing
  • ==Ultrasonic Sound==: sound having frequencies above the range of human hearing
  • ==Sonography==: technology that uses ultrasound to create images of objects found inside other objects

• Putting Ultrasound to Work

  • Sonograms
  • Nondestructive testing
  • Veterinary medicine

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