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  1. 1. Did you hear that SOUND? Sound is a form of energy that travels in waves.
  2. 2. The Facts Sound … 1. Is a form of energy produced & transmitted by vibrating matter 2. Travels in waves 3. Travels more quickly through solids than liquids or gases
  3. 3. The Ear • Sound is carried to our ears through vibrating air molecules. • Our ears take in sound waves & turn them into signals that go to our brains. • Sound waves move through 3 parts of the ear; outer ear, middle ear, & inner ear. Middle Ear
  4. 4. Vibration - Back and forth movement of molecules of matter - For example,
  5. 5. Compression - Where molecules are being pressed together as the sound waves move through matter - For example, - a wave travels through the springs just like sound waves travel through the air - the places where the springs are close together are like compressions in the air.
  6. 6. Sound Waves - Alternating areas of high & low pressure in the air - ALL sound is carried through matter as sound waves - Sound waves move out in ALL directions from a vibrating object
  7. 7. Sound Waves • Each Sound wave has unique pattern • Frequency • Wavelength • Amplitude
  8. 8. Sound mediums • A medium is a material that sound, a form of energy, need to transfer • Speed of sound – Solid : Fast speed – Liquid : Medium speed – Gas : Slow Speed • Standard Temperature and Pressure = 3.31 x 102 m/s – Vacuum : No Sound
  9. 9. Wavelength & Frequency - Wavelength is the distance between one part of a wave and the same part of the next wave - Frequency is the number of waves moving past a point in one second
  10. 10. Pitch • A measure of how high or low a sound is • Pitch depends on the frequency of a sound wave • For example, - Low pitch - Low frequency - Longer wavelength - High pitch - High frequency - Shorter wavelength
  11. 11. Sound and Instruments - Instruments can be played at different pitches by changing lengths of different parts. - For example, - Another way to make different pitches is to change the thickness of the material that vibrates. - For example, A trombone’s mute absorbs some of the sound waves produced, thus producing a softer note when played.
  12. 12. Ultrasound - sound waves with frequencies above the normal human range of hearing. Sounds in the range from 20-100kHz Infrasound - sounds with frequencies below the normal human range of hearing. Sounds in the 20-200 Hz range
  13. 13. Amplitude of Sound • Volume control • Loudness • Strength of the wave ( measured in db “decibels”) • Energy of the wave
  14. 14. Loudness of Sound in Decibels Sound Loudness (dbs) Hearing Damage Average Home 40-50 Loud Music 90-100 After long exposure Rock Concert 115-120 Progressive Jet Engine 120-170 Pain
  15. 15. Speed of Sound • Velocity(v) of a wave= Frequency (f) times the wavelength (λ) • V = f λ • The speed of sound depends on the physical properties of the medium and the temperature since the particle vibrate faster when hotter sound can travel faster.
  16. 16. Speed of Sound • Medium velocity m/sec air (20 C) 343 air (0 C) 331 water (25 C) 1493 sea water 1533 diamond 12000 iron 5130 copper 3560 glass 5640
  17. 17. Reflection and Refractions of Sound waves • Echo – Reflection of sound off a surface (Acoustics (Greek akouein,”to hear”),. It is more commonly used for the special branch of that PHYSICS that deals with the construction of enclosed areas so as to enhance the hearing of speech or music. • Reverb (Electronic echo) • Resonance – electronic envelope Helmholtz Resonator, spherical vessel of metal or glass with an opening and an earpiece on opposite sides. – The ear canal acts enhancing frequencies in the range from 1000 to 4000 Hz (hertz, or cycles per second).
  18. 18. Sonar - An instrument that uses reflected sound waves to find underwater objects - For example, Animals use sonar or echo location to find their prey; these sounds have such a high pitch or frequency that the human ear cannot hear Humans use sonar to locate or map objects
  19. 19. Doppler Effect •The frequency of the perceived wave is changed by the motion of the source –Increasing Frequency when the source approaches the sensor –Decreasing Frequency when the source increases the distance from the sensor
  20. 20. That’s all folks!