Sound and hearing
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Sound and hearing

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Sound and hearing Presentation Transcript

  • 1. Sound and Hearing
  • 2. Properties of Sound Waves • What type of waves are sound waves?
  • 3. Properties Sounds behave in certain ways because of the properties of sound waves. Some properties are: • Speed • Intensity & Loudness • Frequency & Pitch • Timber or quality
  • 4. Speed • Speed of sound = 331 m/s • Sound speed varies, depending on medium – Travel fastest in solids, slowest in gases – Travel fastest in the most dense media – Speed of Sound animation
  • 5. Speed of sound in different materials Materials Air (0 ͦ C) He (0 ͦ C) H (20 ͦ C) Water Seawater Iron and Steel Aluminum Hard wood Speed of Sound (m/s) • 331 • 1005 • 1300 • 1440 • 1560 • 5000 • 5100 • 4000
  • 6. Intensity • Intensity: the rate at which a wave’s energy flows through an area • Sound intensity depends on – Amplitude – Distance from source • Measured in decibels (dB)
  • 7. Source of sound Level (dB) Jet engine, 30 m away 140 Threshold of pain 120 Amplified rock music 115 Old subway train 100 Average factory 90 Busy street traffic 70 Normal conversation 60 Library 40 Close whisper 20 Normal breathing 10 Threshold of hearing 0
  • 8. Loudness • Subjective! (This means it depends on the person who is hearing it.) • Loudness is a personal, physical response to the intensity of sound. • As intensity increases, so does loudness, but loudness also depends on the listener’s ears and brain.
  • 9. Frequency & Pitch • Frequency of a sound wave depends on how fast the source of the sound is vibrating. • Pitch is how we hear frequency of sound waves • Pitch depends on frequency…high frequency sounds are high pitched, and low frequency sounds are low pitched. • Pitch also depends on age and health
  • 10. Frequency and Pitch animation
  • 11. Timber color or tone quality-used to distinguished between two different sounds that have the same pitch and loudness
  • 12. The Doppler Effect • Where have you heard of the term “Doppler”? • Doppler Effect: a change in sound frequency (pitch) caused by the motion of the sound source, the listener, or both • Why do we observe this? • Doppler Effect animation
  • 13. • Refraction of sound-change in direction, as the wave moves from one medium to another- It bends or refracts as they move through air. • Sound waves refract.
  • 14. • Reflection of sound • Echo- reflected sound - it is what you heard shortly after the original • Diffraction of Sound- Sound waves bend or diffract around corners or barriers like doors and walls.
  • 15. • waves overlapping are the result of two or more sound INTERFERENCE. 2 types • Constructive interference-the sound waves arrive at the same time and phase • Destructive interference-waves arrive at interval and are out of phase
  • 16. • Resonance - the inducing of vibrations of a natural rate by a vibrating source having the same frequency.
  • 17. Hearing and the Ear • Your ear has a membrane that vibrates when sound waves hit it…what is this membrane?
  • 18. Hearing & the Ear Ear consists of 3 main parts • Outer Ear – gathers and focuses sound • Middle Ear – receives and amplifies vibrations • Inner Ear – uses nerve endings to sense vibrations and send signals to the brain
  • 19. • Most people hear sounds between 20 and 20,000 Hz. – Infrasound – sound at frequencies lower than people usually hear – Ultrasound – sound at frequencies higher than people usually hear • Used in technologies such as sonar and ultrasound imaging
  • 20. • Sonar – a technique used to determine the distance to an object under water. • Ultrasound – medical technique used to take pictures of different organs (or a fetus!)
  • 21. I HOPE YOU LIKE !!! <3