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SOUND

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SOUND

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    1. SOUND

    2. CHAPTER 10 – WAVES Sections 1 and 2 only CHAPTER 11 - SOUND AND LIGHT

    3. vocabulary Wave – crest, trough, amplitude, wavelength Medium Vacuum Pitch/frequency Doppler effect Amplitude/loudness/decibel Echo/reflection sonar

    4. A Typical Wave

    5. One Wavelength One wavelength is from crest to crest or trough to trough.

    6. SOUND A form of energy produced by a vibrating object. The vibrating object pushes and pulls the surrounding air, producing alternating compressed and expanded layers of air particles called SOUND WAVES. Sound waves spread outward in all directions from their source.

    7. QUESTION? Why can Abby hear Tessa calling her if they are in different rooms and around the corner from each other?

    8. Sound waves travel in all directions - even around corners. Sound waves travel through a medium so it travels also through the wall separating you from your friend.

    9. Objects that can produce sound are bells, radio speakers, guitar strings, violin strings or anything else that vibrates.

    10. To ‘hear’ a sound, it must be transmitted to your ear through a substance. MEDIUM - the substance that sound travels through - like air or water. A medium can be a liquid, gas or solid. (Native Americans would put their ear to the ground to feel the vibrations of someone coming.)

    11. RULE - THE DENSER THE MEDIUM THE FASTER THE SOUND TRAVELS!!!

    12. The Speed of Sound: Density Density and speed - the denser the medium, the faster the sound waves can travel through it. Is sound going to travel the fastest through a solid, liquid or gas?

    13. SOLID!! Generally, sound travels the fastest through solids and slowest through gases.

    14. Speed of sound through different substances Medium State Speed(m/s) Iron solid 5200 Glass solid 4540 Water liquid 1497 Air gas 346

    15. VACUUM Vacuum - a space with no atoms or molecules SOUND CANNOT TRAVEL THROUGH A VACUUM BECAUSE THERE ARE NO PARTICLES OF MATTER. Light waves can travel in space.

    16. Sound waves are different than light waves Light and radio waves are electromagnetic waves. They are completely different than sound, which is vibration of matter. Electromagnetic waves are related to electrical and magnetic fields and readily travel through space.

    17. Sound is mechanical energy - why? You may ask.

    18. Sound waves start particles ‘moving’ or vibrating therefore it is a form of mechanical energy. The mechanical energy is transformed into electrical energy in your ear. The electrical impulses are sent to your brain.

    20. See overhead of ear. The outer ear acts as a funnel for sound waves and collects the waves. The middle ear contains three bones which act as levers to increase the size of the vibrations. The inner ear is where vibrations are changed into electrical signals for the brain to interpret.

    21. Your vocal cords vibrate in your throat which produces sound - place your hand on your throat and talk. Feel the vibration!

    22. COMPRESSION WAVE Sound is a longitudinal, compression wave - LIKE THE SLINKY.

    23. The back-and-forth vibration of an object creates the compression waves of sound. The motions of a loudspeaker cone, drumhead and guitar string are good examples of vibration that cause compression waves. This is different than the up and down or transverse motion of a water wave.

    24. SOUND IS COMPRESSION WAVES

    25. COMPRESSION OR LONGITUDINAL WAVE

    26. Fill in Diagram of Sound wave http://www.glenbrook.k12.il.us/gbssci/Phys/mmedia/waves/lw.html

    27. AMPLITUDE = LOUDNESS The amplitude of a sound wave is the same thing as its loudness. A sound wave will spread out after it leaves its source, decreasing its amplitude or loudness. The more dense the particles the louder the sound.

    28. LOUDNESS Loudness is measured in decibals (dB). The threshold of the human ear before it causes pain is about 120 dB. Rock concerts are at 115 dB. Continued exposure to sounds above 85 dB can cause gradual hearing loss by permanently damaging the hair cells in your inner ear.

    29. Blue man group Notice the pitch changing as the tube is extended! Why does the pitch change? We’ll answer this question in a few slides.

    30. FREQUENCY = PITCH The frequency of sound is the rate at which the waves pass a given point. Frequency = # of vibrations per second It is also the rate at which a guitar string or a loud speaker vibrates. Frequency is also called the pitch of a sound. It is called the note in musical sounds.

    31. Pitch and Frequency High pitch = high-frequency sound (more vibrations per second). A violin produces a high-pitched sound. Low pitch = low-frequency sound (fewer vibrations per second). A bass drum produces a low-pitched sound.

    32. Blue Man Group As the tube is extended the frequency of the waves picked up by the microphone will be less because they the sound waves have a longer distance to travel.

    33. DRAW THIS!!

    34. FREQUENCY AND AMPLITUDE http://www.teachersdomain.org/resources/hew06/sci/phys/energy/sound/index.html

    35. What is a Hertz - not the car company! What is frequency? What is amplitude? What is the difference between sound and light? What type of wave is a sound wave?

    36. HERTZ HERTZ = unit of measurement for frequency. A wave that occurs every second has a frequency of 1 Hz. If two waves pass you every second, then the frequency of the wave is 2 per second, or 2 Hz.

    37. FORMULA FOR FREQUENCY FOR ANY WAVE: Frequency = Speed/wavelength

    38. Problem: The speed of a wave on a rope is 50 cm/s and its wavelength is 10 cm. What is the wave’s frequency? Use formula and set up the problem:

    39. Frequency - speed /wavelength ??? = 50 (cm/s) / 10 cm Frequency = 5 Hz 5 crests will pass a point every second.

    40. Did you ever notice when an ambulance is driving away from you that the pitch of the siren falls? DOPPLER EFFECT - is the change in frequency and wavelength of a wave as perceived by an observer moving relative to the source of the waves. Towards you = higher pitch Away from you = lower pitch

    41. When a blaring ambulance siren is moving toward you, the sound waves are crowded together producing a higher frequency and a higher pitch. When the siren is moving away from you, the sound waves spread out, producing a lower frequency and a lower pitch.

    42. DRAW:

    45. Sound speed and Temperature The higher the temperature, the faster the sound waves.

    46. Sound waves vs. light waves - which travel faster? Think thunderstorm - which travels faster - sound or light?

    47. Light! A lightning bolt produces a flash of light and a clap of thunder at the same time. The speed of light is so fast that the light reaches us almost instantly. The speed of the thunder travels much more slowly, so we usually hear the thunder a few seconds after we see the lightning.

    48. Echo An echo is when sound waves reflect off a surface. Echolation is the process of using reflected sound waves to find objects. Bats and beluga whales use echolation to find food.

    50. SONAR SONAR (sound navigation and ranging) - a type of electronic echolocation. Ultrasonic waves are used because their short wavelengths provide more details about the objects they reflect. Fish finders are sonar devices. Sonar is used to determine the depth of water, map the ocean floor, locate sunken ships, etc.

    51. Planet earth - cave dvd on bats and birds in caves

    55. Sonogram Doctors use ultrasound imaging to look inside the human body. The picture that is produced from the reflected ultrasound waves is called a sonogram. Used to look at babies in the uterus, kidney stones, gall stones and tumors.

    57. Sonic boom A sonic boom is produced when a jet goes faster than the speed of sound. The sound waves trail off behind the jet to form a shock wave. A sonic boom is so loud it can hurt your ears and break windows.

    60. bellwork What is the Doppler effect? What is pitch? What is the measurement of pitch? What is amplitude? What is the measurement of amplitude?

    61. Review for Quiz Speed of sound waves can be influenced or is dependent on ____________ and ______________ . The Doppler effect is…. If the fire engine is moving away from you the Doppler effect will cause the siren to sound _____________________.

    62. 4. The sound wave: a. __________________ - the section of the sound wave where the air particles are pushed closer together. This is an area of higher density and pressure. b. __________________ - the section of the wave where the air particles are spread out. This is an area of lesser density and pressure

    63. 5. Name the part of the ear - a. the “funnel” b. vibrations are converted to electrical signals for the brain to interpret. c. where the three bones are located that act as levers to increase the size of the vibrations.

    64. 6. The difference between sound and light - a. which is faster? b. which one needs particles of matter to travel by?

    65. 7. Units in sound: a. what is the unit for amplitude? b. what is the unit for frequency?

    66. 8. Match the words that go together: Pitch Amplitude Frequency Loudness

    67. 9. DENSITY AND MEDIUMS: List the order of mediums (gas, solid, liquid) that sound travels through FROM FASTEST TO SLOWEST: 1. 2. 3.

    68. 10. Echolation is …….. 11. Name two animals that use echolation.

    69. 12. SPEED OF SOUND AND TEMPERATURE: As temperature increases, the speed of sound increases or decreases? As temperature decreases, the speed of sound will increase or decrease?

    70. 13. Sound waves travel like the slinky or like the rope that goes up and down? 14. What type of wave is this? 15. What’s another name for this wave?

    71. 16. Here is a deep philosophical question: If a tree falls in a forest and no one is around to hear it - does it make a sound? Why or why not?

    72. 17. Another deep philosophical question: If a tree on a planet with no atmosphere falls and no one is around to it - will it make a sound? Why or why not?

    73. 18. Name two sonar devices and what they are used for.

    74. 19. Air travels about 340 meters/second in air. Lillian yelled ‘Hey, Vicky!’ across a canyon and it returned to her as an echo. It took the echo 4 seconds to return to her. a. What is the distance the sound traveled? b. What is the distance across the canyon?

    75. answers 1360 meters - across the canyon and back in 4 sec. 680 meters - one way across the canyon

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