Sound Now hear this!

What is sound? Sound is a form of energy. Other types of energy we will learn about are heat and light.

What you will learn? (Utah curriculum) Science Benchmark Heat, light, and sound are all forms of energy... Sound is created by vibration and cannot travel through a vacuum. Pitch is determined by the vibration rate of the sound source Standard 6 Students will understand properties and behavior of heat, light, and sound.

More of what you will learn… Objective 3 Describe the production of sound in terms of vibration of objects that create vibrations in other materials. Describe how sound is made from vibration and moves in all directions from the source in waves. Explain the relationship of the size and shape of a vibrating object to the pitch of the sound produced. Relate the volume of a sound to the amount of energy used to create the vibration of the object producing the sound. Make a musical instrument and report on how it produces sound.

Musical Instrument Go over musical instrument rubric. Answer questions.

Sound …is a disturbance that travels through a medium as a longitudinal wave (definition). …is made by vibrations. …travels in waves. …can travel through solids, liquids, and gases. …is absent from outer space. …travels in all directions. …when the disturbance reaches our ears, we call it sound.

How sound travels Sound travels through the air by spreading out in a series of ripples, like ripples in a pond when you throw a stone. The ripples that disturb the air are called sound waves. Energy from vibrations stirs up surrounding air molecules, allowing the sound wave to spread out away from the source of the vibration.

One example of how sound waves work (gasses) You beat the drum Surface begins to vibrate Air molecules are disturbed When the drum moves, it pushes molecules together, creating compressions When the molecules are pushed farther apart, rarefactions are created. http://www.dosits.org/science/sound/howismade/

Another example pluck guitar string Causes vibrations Vibrations create rarefactions & compressions Waves travel through air to your ears

Examples of sound waves in solids When you knock on a door, the particles of the door vibrate Vibration causes sound waves that travel through the door Sound waves reach other side of door Waves in door travel to air outside door

More solids Have you ever seen someone in a movie put his or her ear on the ground to tell if a train is coming? The sound of a train travels through the tracks You might be able to hear distant traffic if you put your ear on the ground (be careful— don’t do this in the street)

Some new vocabulary Remember that conductor, medium, insulator, and other “wave” and “heat” vocabulary still apply to sound Pitch-perception of the frequency of a sound …how high or how low a musical note is Vibration-a repeated back-and-forth or up- and-down motion …a rapid back and forth movement

More on vocab Sounds can change in shrillness or deepness- that is, in their pitch. Pitch is the number of vibrations that makes the sound high or low When we hear changes in pitch, it means that the sound waves coming to our ears are changing in frequency. Frequency is the number of sound waves that occur in one second. The higher the frequency is (and the faster it vibrates), the higher the pitch will be. The lower the frequency is, the lower the pitch will be. Therefore, the slower something vibrates, the lower the pitch.

High Frequency vs. Low Frequency What are the differences? What are the similarities?

Pitch The pitch of a sound is determined by the size (length, thickness) of the object making the sound. The faster something vibrates, the higher the pitch. This is true of the voice boxes of animals. For example: women usually have shorter vocal cords than men and have higher pitched voices as a result. Which would produce a higher sound—a thick guitar string or a thin guitar string?

Is it Music or Noise? Musical sounds have a regular wave pattern. Music is pleasing to our ears. Noise sounds have an irregular wave pattern. Noise is NOT pleasing to our ears.

Echo An echo occurs when sound waves hit a hard object and bounce back. Sound travels twice the distance when you hear an echo.

Using an Echo Bats and dolphins use something called echolocation to help them navigate and hunt. Submarines use sonar to navigate and to hunt. Police people use radar to find out your speed in a car. Doctors use ultrasound to see into a mother’s womb.

What happens to Sound? What happens when sound hits different types of objects? Reflected-It can bounce off if the object is hard. Absorbed-It can get “sucked in” if the object is soft.

The Speed of Sound Sound travels at about 1,000 feet (1,083 ft) per second through the air. Compare this to light which travels at 984,000,000 feet per second. That’s 7 ½ times around the world in one second! Sound travels at different speeds through different mediums. See figure 4 on page 42 of your science book on sound.

The Human Ear Most people can hear sounds from 20 to 18,000 vibrations per second. As we get older, our ability to hear high notes decreases. Loud sounds can cause hearing damage or loss. Your ear has many complicated parts. All the parts must be working well, or you will have trouble hearing. Remember that your eardrum is a membrane that can be torn and destroyed if it starts vibrating too fast or strong. Sound is cool, but be careful. Once your hearing is gone, it is usually gone for good.

Ear Diagram-Answers

Ear Diagram-in color

More vocab Decibels (dB)-the unit we measure sound with Hertz (hz)-the measurement of sound vibrations per second Wavelength Compression Rarefraction Amplitude

What they look like-

Volume What’s the difference? The more energy a wave has, the louder it seems. The intensity of a sound is the amount of energy it has. You hear intensity as loudness. The amplitude (height) is a measurement of the amount of energy a wave has.

Inventions & Sound Please list 8 inventions that use sound. 1- 2- 3- 4- 5- 6- 7- Eight items must be listed clearly.

Sound & Our Culture Please write a 3 paragraph(s) on why sound is important to our culture. Be sure to answer the following questions in your paragraph… A paragraph is at least 4 sentences. What would it be like with no sound? (1 para) What would it be like with no music? (1 para) Why is sound and music so important to us as a society? Why is it important to you? (1 para)