Chapter 21 Preview Section 1 What Is Sound? The Nature of Sound Preview Section 1 What Is Sound? Section 2 Properties of Sound Section 3 Interactions of Sound Waves Section 4 Sound Quality Concept Mapping

Chapter 21 Section 1 What Is Sound? Bellringer If you have ever been near a large fireworks display, you may have felt the sound of the explosions. Think of other times when you might feel sound and describe them in your science journal. Waves destroying a bridge http://www.archive.org/details/Pa2096Tacoma

Chapter 21 Sound and Vibrations Section 1 What Is Sound? Sound and Vibrations 1. All sounds are created by vibrations. A vibration is the complete back-and-forth motion of an object or material. The next slide shows how a stereo speaker produces sound.

Chapter 21 Section 1 What Is Sound? 2. compression 3. rarefaction

Sound and Vibrations, continued Chapter 21 Section 1 What Is Sound? Sound and Vibrations, continued 4. Sound Waves are longitudinal waves that are caused by vibrations, which are then carried through a substance and transfer energy. The particles of the substance vibrate back and forth along the path that the sound waves travel. Sound is transmitted through the vibrations and collisions of the particles.

Sound and Vibrations, continued Chapter 21 Section 1 What Is Sound? Sound and Vibrations, continued 5. Sound waves travel in all directions away from their source. However, the air or other matter through which the wave is traveling does not travel with the sound waves. The particles of air only vibrate back and forth. 6. We would all get blown away!

How Does Sound Reach the Ear?

Does Air travel with sound? No no no no no!!!!!! It does not

Sound and Vibrations, continued Chapter 21 Section 1 What Is Sound? Sound and Vibrations, continued Sound and Media All sound waves require a medium (plural, media). 7. A medium is a substance through which a wave can travel by vibrating particles in the material. Air is the most common medium of sound waves. There are no particles to vibrate in a vacuum chamber. So, no sound can be made in a vacuum chamber.

Discuss with class. 8 & 9 All sound waves require a medium (plural, media). Bell in Vacuum

Does sound travel through other material?

Chapter 21 How You Detect Sound Section 1 What Is Sound? How You Detect Sound Your ears are divided into three regions: the outer ear, the middle ear, and the inner ear. The outer ear collects sound waves. Then, organs in the middle ear increase the size of the sound wave’s vibrations. The inner ear changes the vibrations into electrical signals that your brain interprets as sound.

Chapter 21 Section 1 What Is Sound?

How You Detect Sound, continued Chapter 21 Section 1 What Is Sound? How You Detect Sound, continued Making Sound Versus Hearing Sound Making sound is separate from hearing sound. Sound can be made and not be heard. Suppose that a tree falls and and no one is around to hear it. When the tree falls, the tree and the ground vibrate. These vibrations create a sound wave. So, a sound was made—it just wasn’t heard.

The speed of sound

Chapter 21 Section 2 Properties of Sound Bellringer You are the commander of a space station located about halfway between Earth and the moon. You are in the Command Center, and your chief of security tells you that sensors have just detected an explosion 61.054 km from the station. How long will it be before you hear the sound of the explosion? Write your answer in your science journal.

Chapter 21 Objectives Compare the speed of sound in different media. Section 2 Properties of Sound Objectives Compare the speed of sound in different media. Explain how frequency and pitch are related. Describe the Doppler effect, and give examples. Explain how amplitude and loudness are related. Describe how amplitude and frequency can be “seen” on an oscilloscope.

Chapter 21 The Speed of Sound Section 2 Properties of Sound 10. The differences between sounds depends on the properties of the sound waves 11. The speed of sound depends only on the medium in which the sound is traveling. How the Speed of Sound Can Change Sound travels quickly through air, but it travels even faster in liquids and even faster in solids. 12. Temperature also affects the speed of sound. The cooler the medium, the slower the speed of sound. 13. As particles slow down, energy is transmitted more slowly The Speed of Sound

14. Chuck Yeager was a hero because everyone else was afraid that the plane would blow up. He broke the sound barrier. When an object travels the speed of sound, it creates a sonic boom 1500 mph 2200 mph 760 mph

Chapter 21 Pitch and Frequency 15. Pitch is Section 2 Properties of Sound Pitch and Frequency 15. Pitch is -how low or high a sound seems to be -related to the frequency of the sound wave 16. D. Pitch is not related to how far away the sound is from your ear. 17. Frequency and Hearing The frequencies of some sounds are out of the range of human hearing. Sounds that have a frequency too high for people to hear are called ultrasonic. Sound waves frequency shown with salt- http://media.photobucket.com/video/sound%20waves/shuga9buga/salt-sound-waves.flv?o=2&call=1

What is pitch?

Tuning Fork Experiment Tuning forks are U-shaped metal objects with a handle. They can be made of steel or aluminum. A tuning fork can give you a standard tone or pitch. Musicians use them to tune their instruments. The frequency is stamped on the handle. A mark of 256 gives off 256 vibrations per second which is equal to “C” on the music scale. You are going to experiment with tuning forks. Here are some rules to protect both you and the tuning forks. Keep the U-shaped end away from glass, your eyes and teeth. Use the stem to hold the tuning fork at all times. Never strike the tuning fork against wood or metal, only use the rubber hammer provided. Click below for a demonstration of how a tuning fork works. Then complete instructions on handout.

  Step 5-Conclusion-Write at least 3-5 sentences -restate the purpose -write what you did to test your hypothesis, use nouns, tell what you “see and hear” -tell if observations support the hypothesis -tell other ways to test or other investigations that could be created using this information

A sound wave is a longitudinal wave which travels in all directions away from the source.

128Hz 20 20,000 67 45,000 dogs humans 20,000 45,000

18. The Doppler Effect is the apparent change in the frequency of a sound caused by the motion of either the listener or the source of the sound. Check WS “it works for bats”

Doppler Effect and Sound Chapter 21 Section 2 Properties of Sound Doppler Effect and Sound 19. The compressions and rarefactions are closer together and you hear a higher pitch 20. The pitch seems higher Visual Concept 21. The pitch seems lower. 22. The driver always hears the same pitch because he is moving with the car.

Doppler effect

Sheldon as Doppler effect http://www.youtube.com/watch?v=Tn35SB1_NYI

23-25 Loudness and Amplitude Chapter 21 Section 2 Properties of Sound 23-25 Loudness and Amplitude Loudness is a measure of how well a sound can be heard. Energy and Vibration The harder you strike a drum, the louder the sound. As you strike the drum harder, you transfer more energy to the drum. The drum moves with a larger vibration and transfers more energy to the air around it.

Loudness and Amplitude, continued Chapter 21 Section 2 Properties of Sound Loudness and Amplitude, continued Increasing Amplitude The amplitude of a wave is the largest distance the particles in a wave vibrate from their rest positions. The larger the amplitude, the louder the sound. Measuring Loudness The most common unit to express loudness is the decibel (dB). The softest sounds a human can hear are at a level of 0 dB. Can your voice shatter glass? See Bill Nye on Dr. Oz http://www.doctoroz.com/videos/myth-busting-bill-nye-pt-2 http://www.sharecare.com/question/can-human-voice-shatter-glass

Science behind glass shattering 2 minutes http://www.youtube.com/watch?v=JiM6AtNLXX4

Decibels- click here for cool info. on decibels! http://www.nidcd.nih.gov/health/education/decibel/decibel.asp There is a sound level meter in classroom cabinet

wavelength and wave speed volume Warm-up: Make a 3 column chart and show the differences between Pitch and Loudness. Use these words: amplitude, frequency, Hertz, decibels, sounds high or low, sounds loud or soft, volume, wave speed, wave length Characteristics pitch loudness How do you perceive it? Shown on a wave diagram Measured in Changes shown by sounds high or low sounds loud or soft frequency amplitude Hertz (Hz) decibels (dB) wavelength and wave speed volume Lower volume Higher volume

increases increases

“Seeing” Amplitude and Frequency Chapter 21 Section 2 Properties of Sound “Seeing” Amplitude and Frequency 26. From Sound to Electrical Signal A microphone attached to an oscilloscope changes a sound wave into an electrical signal. The electrical signal is graphed on the screen in the form of a transverse wave. A device called an oscilloscope can graph representations of sound waves, as shown below. Notice that the graphs look like transverse waves rather than longitudinal waves.

Chapter 21 Section 2 Properties of Sound The graph shows the sound as if it were a transverse wave. So, the sound’s amplitude and frequency are easier to see. 29. the crests represent compressions and the troughs represent rarefactions.

Chapter 21 Section 4 Sound Quality Music or Noise? Most of the sounds you hear are noises. Noise is any sound that is of a random mix of frequencies. The difference between a musical sound and noise is shown in the images below.

Chapter 21 Section 3 Interactions of Sound Waves Objectives Explain how echoes are made, and describe their use in locating objects. List examples of constructive and destructive interference of sound waves. Explain what resonance is.

30. Reflections of Sound Waves Chapter 21 Section 3 Interactions of Sound Waves 30. Reflections of Sound Waves Reflection is the bouncing back of a wave after it strikes a barrier. An echo is a reflected sound wave. The strength of a reflected sound wave depends on the reflecting surface. Sound waves reflect best off smooth, hard surfaces.

Reflections of Sound Waves, continued Chapter 21 Section 3 Interactions of Sound Waves Reflections of Sound Waves, continued The images below explain why you are more likely to hear an echo in a gymnasium than you would in an auditorium.

31. Reflections of Sound Waves, continued Chapter 21 Section 3 Interactions of Sound Waves 31. Reflections of Sound Waves, continued Echolocation is the use of reflected sound waves to find objects. Animals, such as bats, use echolocation to hunt food and find objects in their path. Animals that use echolocation can tell how far away something is based on how long it takes sound waves to echo back to their ears. Mrs. Guillory also has a 15 minute video on a blind teen who uses echolocation http://www.cbsnews.com/stories/2006/07/19/earlyshow/main1817689.shtml?tag=currentVideoInfo;videoMetaInfo

Echolocation

More on Ben Underwood and the science behind it 10min. http://www.youtube.com/watch?v=G1QaCeosUmw

Chapter 21 Section 3 Interactions of Sound Waves

Farther apart and lower pitch Tim’s E A E B Farther apart and lower pitch H Higher to lower to pitch D C higher pitch to lower pitch

Reflections of Sound Waves, continued Chapter 21 Section 3 Interactions of Sound Waves Reflections of Sound Waves, continued Echolocation Technology People use echoes to locate objects underwater by using sonar. Sonar is a type of electronic echolocation. Sonar can also help navigators on ships avoid icebergs and can help oceanographers map the ocean floor.

Chapter 21 Section 3 Interactions of Sound Waves

Watch the Crazy Science Project below

The following slides are for enrichment

Reflections of Sound Waves, continued Chapter 21 Section 3 Interactions of Sound Waves Reflections of Sound Waves, continued Ultrasonography is a medical procedure that uses echoes to “see” inside a patient’s body without doing surgery. Ultrasonography is used to examine kidneys, gallbladders, and other organs. It is also used to check the development of an unborn baby in a mother’s body.

Interference of Sound Waves Chapter 21 Section 3 Interactions of Sound Waves Interference of Sound Waves Interference happens when two or more waves overlap. Two types of interference are shown below.

Interference of Sound Waves, continued Chapter 21 Section 3 Interactions of Sound Waves Interference of Sound Waves, continued Interference and the Sound Barrier As the source of a sound—such as a jet plane—gets close to the speed of sound, the sound waves in front of it combine by constructive interference. The result of this interference is a high-density compression called the sound barrier.

Interference of Sound Waves, continued Chapter 21 Section 3 Interactions of Sound Waves Interference of Sound Waves, continued When a jet reaches speeds faster than the speed of sound, the sound waves trail off behind the jet. At their outer edges, the sound waves combine by constructive interference to form a shock wave. A sonic boom is the explosive sound hear when a shock wave reaches your ears.

Chapter 21 Sonic Boom Click below to watch the Visual Concept. Section 3 Interactions of Sound Waves Sonic Boom Click below to watch the Visual Concept. Visual Concept

Interference of Sound Waves, continued Chapter 21 Section 3 Interactions of Sound Waves Interference of Sound Waves, continued Interference and Standing Waves A pattern of vibration that looks like a wave that is standing still is called a standing wave. Standing waves form because of interference. Where you see maximum amplitude, waves are interfering constructively. Where the wave seems to be standing still, waves are interfering destructively.

Interference of Sound Waves, continued Chapter 21 Section 3 Interactions of Sound Waves Interference of Sound Waves, continued The frequencies as which standing waves are made are called resonant frequencies. The lowest resonant frequency is called the fundamental. Higher resonant frequencies are called overtones.

Chapter 21 Section 3 Interactions of Sound Waves Resonance Resonance happens when an object vibrating at or near a resonant frequency of a second object cause the second object to vibrate. Resonance in Musical Instruments Musical instruments use resonance to make sound. Vibrations are amplified when resonance causes standing waves to form inside instruments.

Chapter 21 Section 4 Sound Quality Bellringer Answer the following questions in your science journal. Which strings on a piano have lower pitch? Why does a tuba have a lower pitch than a trumpet? Why are some sounds pleasing to hear and some sounds not? Explain your answer.

Chapter 21 Section 4 Sound Quality Objectives Explain why different instruments have different sound qualities. Describe how each family of musical instruments produces sound. Explain how noise is different from music.

Chapter 21 What Is Sound Quality? Section 4 Sound Quality What Is Sound Quality? Imagine that the same note is played on a piano and on a violin. You could probably tell the instruments apart because they make different sounds. The notes sound different because a single note on an instrument actually comes form several different pitches: the fundamental and several overtones, as shown at right.

What Is Sound Quality?, continued Chapter 21 Section 4 Sound Quality What Is Sound Quality?, continued The result of several pitches mixing together through interference is sound quality. Instruments sound different because each has a unique sound quality, as shown below.

Sound Quality of Instruments Chapter 21 Section 4 Sound Quality Sound Quality of Instruments The difference in sound quality among different instruments come from their structural differences. All instruments produce sound by vibrating. But instruments vary in the part that vibrates and the way the vibrations are made. Three families of instruments are string instruments, wind instruments, and percussion instruments.

Sound Quality of Instruments, continued Chapter 21 Section 4 Sound Quality Sound Quality of Instruments, continued String Instruments Violins, guitars, and banjos are examples of string instruments. String instruments make sound when their strings vibrate after being plucked or bowed. The pitch of a string can be changed by changing the string’s length. Shorter strings vibrate at higher frequencies, and thus have higher pitches.

Sound Quality of Instruments, continued Chapter 21 Section 4 Sound Quality Sound Quality of Instruments, continued Wind Instruments Saxophones, flutes, French horns, and tubas are examples of wind instruments. Wind instruments make sound when a vibration is created at one end of its air column. Pitch is changed by changing the length of the air column. The longer the air column is, the lower the pitch is.

Sound Quality of Instruments, continued Chapter 21 Section 4 Sound Quality Sound Quality of Instruments, continued Percussion Instruments Drums, bells, and cymbals are examples of percussion instruments. Percussion instruments make sound when struck. Instruments of different sizes are used to get different pitches. Usually, the larger the instrument is, the lower the pitch is.

Chapter 21 Concept Mapping The Nature of Sound Concept Mapping Use the terms below to complete the Concept Mapping on the next slide. loudness oscilloscope frequency sound interference pitch medium

Chapter 21 The Nature of Sound

Chapter 21 The Nature of Sound

Ok Go Needing/Getting Making of the video