How Is Sound Produced?
Sound is a very important part of our life.
We wake up in the morning by hearing alarms, or the chirping of birds.
Sound helps us to communicate with another person.
We talk and express ourselves by using sound.
We hear and listen to others with the help of sound.
Let's discuss some sounds in our daily life.
A dog's bark lets us know that someone is coming.
A fire alarm warns us of a fire.
All these things show how important sound is in our daily life.
Have you ever thought about how are these sounds produced?
SOUND IS PRODUCED BY VIBRATIONS
Let us understand what is sound, and how is it produced, by taking an example of a guitar.
What happens when we pluck the strings of a guitar?
We hear sound.
What is producing this sound? Let us try to find out.
When a string of a guitar is plucked, it moves from one side to another in a back and forth motion or you can say it vibrates.
When the string moves to any one side, the surrounding air particles also shift to one side. When the string moves to the other side, the surrounding particles shift in the same way.
The continuously moving strings of a guitar shift the air particles in their respective directions. So, the vibrations of guitar strings set the surrounding air particles into vibrations, and this produces sound.
As the vibrations of the guitar strings come to a stop, the surrounding air particles also stop vibrating and we cannot hear any more sound being produced.
Now, let us see what happens when we hit the cover of a drum, called the membrane, with a drumstick.
The cover of the drum vibrates.
The surrounding air particles are also set into vibration, and as a result, sound is produced.
Let us see what happens when we blow air inside a flute or a trumpet. Here again, air particles vibrate and sound is produced.
So, sound is produced when an object vibrates.
Sound is a form of energy which is produced as a result of the vibrations of an object.
Now that you have understood what is sound and how it is produced, let us now talk about different sounds and some properties of sound.
PROPERTIES OF SOUND
First, let us compare the sound of a whistle with that of a drum.
You will notice that blowing a whistle produces a high sound, while a drum produces a low sound.
Do you know how we label such high and low sounds?
We say high sounds are high pitch sounds, while low sounds are low pitch sounds.
So, blowing a whistle produces a high pitch sound while hitting a drum produces a low pitch sound.
The pitch is the property of a sound which tells us how high or low a sound is.
Now compare the sounds produced by a violin and a human heartbeat.
High pitch sounds
Low pitch sounds
You will realize that a violin produces a high pitch sound, while human heartbeat has a low pitch sound.
In a similar way, chirping of birds is a high pitch sound, while a lion's roar is a low pitch sound.
Let us now compare the sound produced when a person whispers into someone's ears and the sound produced when the same person shouts for a friend across the playground.
You will notice that whispering makes a soft sound but shouting for a friend across a playground makes a loud sound.
And a loud or soft sound is identified by its volume, another property of sound.
Loud sound has a high volume while soft sound has a low volume.
Banging of a hammer and a car's horn are examples of loud sounds while playing of a piano and sound of blowing wind are examples of soft sounds.
How Is Sound Produced?
Sound is very important in our daily life. It helps us in communicating with people or warning someone.
Sound is a form of energy which is produced by vibrating bodies.
The pitch of a sound tells us how high or low a sound is.The volume of a sound tells us how loud or soft a sound is.
- Small Bell (High pitch bell) or other musical instrument that has a high pitch such as a flute (1)
- Toy drum (Low pitch drum) or other musical instrument that has a low pitch such as tuba (1)
- Small paper cups - 4 oz. (2 per student)
- Rice, beans, macaroni, paper clips, etc (small materials that can fit inside the paper cups) (a small handful for each student)
- Paper bowls or plates (4 per group of 4 students - these will be used to give a group of students the above materials - rice, beans, macaroni, paper clips, etc.)
- Plastic spoons - optional
- Duct Tape or Masking Tape (length of circumference of paper cup per student)
A. Identify Different Sounds
- Tell students that in order to review sounds and how they are made, we are going to awaken our ears. Instruct all students to close their eyes, and be quiet and still. Tell them that you are going to make two sounds and that you want them to listen. They have to describe what they hear.
- Once all students have their eyes closed, ring the bell. Ring the bell twice. Now bang on the toy drum. Hit the drum twice. Now hide the musical instruments. Ask students what they heard. What was the similarity and difference between the two sounds? Accept all appropriate responses. Hopefully, students will mention pitch and volume from the 'self-learning' portion of the lesson. Have students share what musical instruments they thought they heard. Ask students what type of sounds and instruments they hear in their favorite music. Encourage all responses (voice, violin, drum, guitar, etc.). Revisit with students the fact that all sounds are made from a vibration which means to move back and forth.
B. Identify high and low pitch sound
- Bring out the bell and drum again. Ask students to explain how each creates sound. The drum created sound when you hit it causing vibrations to occur off the top of the drum and the bell made a sound when the clapper (the part inside of the bell) hit the inside surface of the bell.
- Review with students about pitch, and a high or low sound. Ask students if they think the bell made a high or low pitch sound. What about the drum - did it make a high or low pitch sound?
- Review with students that the pitch is determined by how fast or slow an object vibrates. If an object moves back and forth quickly, it will cause a high pitch sound, such as that of a bell. If an object moves back and forth slowly, it will cause a low pitch sound, such as that of a drum. The pitch of a sound is determined by how quickly or slowly an object moves back and forth. So, low pitch means slower vibrations and high pitch means faster vibrations.
- Ask students if they can name other high pitch sounds. Accept all appropriate students' responses, such as a baby crying, nails on a chalkboard, etc. Have the students try making a high pitch sound with their voice while saying the words "high pitch."
- Ask students if they can name other low pitch sounds. Accept all appropriate students' responses, such as thunder, an owl, etc. Have the students try making a low pitch sound with their voice while saying the words "low pitch."
C. Make your own Musical Instrument
- Tell students that they are now going to make their own musical instrument by making a shaker using a variety of materials and two paper cups.
- Have students divide into groups of four. Tell students that you will be passing out materials, and to not touch anything until instructed to do so. Give each student two paper cups, and each group of four students cups/plates full of the different materials (rice, beans, etc.) to fill the shakers with.
- Tell the students that they can choose which material in front of them they want to fill their paper cup with. Tell students that they can only fill a paper cup half way. As a model to students of what half-full is, draw a line on the outside of the cup showing how high half-full is. (If necessary, draw a line on the inside of each cup to show students what level to fill up the cup to.) Remind students to not spill material as they are filling their cups; you may wish to have the students use spoons to fill up their cups.
- Have each student pick up one cup and fill it up. Give students 5-10 minutes for this and ask them to join it with the other paper cup using a masking tape along their circumference as shown below.
- Encourage them to try different materials and to create their own unique sound. Be sure to monitor student behavior, and make sure they are following directions. At this time, ask the students to cover their cups filled with different materials completely.
- Gather the students' attention. Tell them you want to hear their musical instruments. On the count of three, have them all shake their instruments for five seconds. Ask students if they think their musical instrument can make a different sound Can they make a lower pitch sound? A higher pitch sound? Accept appropriate student responses. Now, have students set the shaker on their desk. Have them tap the top of the paper cup with their fingernails and then their fingers. Have students share how the sound they made was different than the shaking sound.
- Have the class use their shakers to make a high pitch sound. Remind students that a high pitch sound can be made by making fast vibrations (or moving their musical instrument back and forth). Be sure to walk around the classroom to pay attention to the sounds they are making. (This is a great way to assess their learning informally.) Now have the class use their shakers to make a low pitch sound. Remind students that a low pitch sound can have slower vibrations, or maybe they can tap instead of shaking their shakers.
- Gather the students' attention, and have them make a soft sound and then a loud sound. If there is time available, have students turn to each other and share their musical instruments, and show how they can make a high pitch, low pitch, soft, and loud sound.
- Gather students' attention. Ask students how a sound is made (from vibrations made by objects hitting one another). Encourage students to share their musical instruments with their friends and families, and to show them what sounds they can make including different pitches and volumes (soft and loud).