Roaring cup:

Materials Required:

• A plastic container like a coffee cup or yogurt tub
• String
• Push Pin
• Water
• Optional: Toothpick

Procedure:

1. Use the pushpin to poke a hole in the center of the bottom of the container.
2. Cut a few feet of string.
3. Push the string through the hole in the container.
4. Tie a knot in the string on the end inside the container so you cannot pull the string out the bottom or you can tie a toothpick to the string inside the container.
5. Hold the container upright in one hand and dampen the other hand with water.
6. Hold the string with your wet hand, and pull down, letting the string slide through your grip.
7. Try making Roaring Cups out of different containers and see, hear, and feel what happens.

Tinker and play more:

• What happens if you grip the string tight or loose?
• What happens if you grip the string near the container or away from it?
• What would happen if you used a string twice as long?
• What if you made a Roaring Cup out of a bigger or smaller container?
• Why does the container vibrate when you slide your hand along the string?
• What happens to the string when the container makes a sound?

How does it work?

Sliding your fingers on the wet string creates a vibration in the string, which vibrates the container, which then vibrates the air in contact with the container.

The vibration travels through the air. When the air near us vibrates, it causes our eardrums to vibrate, and inside our eardrums are three tiny bones that vibrate.

The vibrations of those bones are transmitted to our brains.

Straw whistle

Terms to glimpse: sound, vibration, frequency

Vocabulary: Air column, sound, vibration, frequency

Material required: Straw, A pair of scissors

Procedure:  

1. Cut a straw at one end as shown in the figure.
2. Press the tapering end hard and almost flatten it. (Use hands only)
3. Blow air into the straw whistle from the end having the ‘V’ cut.

How does it work?

This is a simple experiment on vibrations! To keep it simple, the shorter the instrument the higher the sound.

Why? Inside your straw, you have a sound wave called a ‘standing wave.’ As you cut the straw you shorten the standing wave within it.  This increases the number of times the wave vibrates per second; changing its pitch.

What do you think will happen if you increased the length of the straw?

The pitch will be lowered, as you lengthen the standing wave and reduce the number of times the wave vibrates per second.

Put the points of the straws just behind your lips and gently pull forward whilst you blow. You’ll eventually find the ‘sweet spot’ where you’ll get the straw to vibrate. Do not blow hard but very gently.

The thickness of the straw:  Use the cheaper, thinner straws.  They work better than thicker ones.

Ear test ( Demonstration)

Terms to glimpse: frequency, pitch, vibration, human hearing range, hearing protection

Things required: mobile phone, small speakers(optional), 10Hz to 20kHz audio sound (available on YouTube)

Vocabulary: pitch, vibrations, frequency, wavelength, Hertz

Procedure: 

1. Make a setup with a mobile phone and speaker.
2. Play one audio track and note down when you start hearing audio.
3. Keep on playing the audio and note down when you stop hearing the sound
   https://www.youtube.com/watch?v=qNf9nzvnd1k&ab_channel=adminofthissite

How does it work?

1. Check your hearing with a list of tones that go from 8Hz to 22,000Hz. It’s fairly common for people who are over 25 years of age to not be able to hear above 15kHz  This online test will help you find out where your high-frequency hearing cuts off.
2.  The ear enables humans and animals to hear what goes on around them. Hearing is one of the five senses of the body.
3.  The ears help the body to pick up sound waves and vibrations. Sound travels in waves through the air, the ground, and various other substances. Sound cannot be seen, but it can be felt by vibrations.
4. The number of vibrations that are produced per second is called frequency. Frequency varies for each sound and is measured in hertz. One hertz is equal to one vibration per second. A sound with a low frequency will have a low pitch. Example- human’s heartbeat.
5. A sound with a high frequency will have a high pitch. Example- dog whistle. Humans cannot hear sounds of every frequency. The range of hearing for a healthy young person is 20 to 20,000 hertz. The hearing range of humans becomes less with age.
6. People lose the ability to hear sounds of high frequency as they get older. The hearing range for men worsens more quickly than for women.  So, women can hear notes of higher pitch than men of the same age.
7. Musicians have a higher risk of hearing loss than others.  Listening to an iPod for a long time can permanently damage your hearing.
   

   Lip lock whistle 

Materials required: Paper (Postcard size)

Procedure:

1. Take an A6 size rectangular
2. Fold the paper breadthwise to obtain two equal parts.
3. Make an outward bend of 1cm at the free end of the paper on both ends
4. Now make two cuts of length 3.5cm on the left side of the folded region such that the two cuts meet
5. Give a gap of 1cm and repeat step 4.
6. Now hold the 1cm outward bent paper in between your fingers and blow
7. Note: The 3.5cm cuts (steps 4 and 5) should be made with proper care.

How does it work?
Blowing the lip-lock whistle forces the air through the diamond-shaped holes. Since the air rushes through such a small space with a high speed.  The air particles collide with the paper around the edges of the diamond cut and vibrates producing a sound.

Sound By Vibration (Demonstration)

Materials required:
Skewer or spoke or a metal/plastic scale (ruler)

Procedure:

1. Place the skewer over the edge of a table such that at least two-thirds of the skewer extends out.
2. Keep your hand on the edge of the skewer on the table to lock it in place.
3. Press down the free end of the skewer and release it. What do you observe?
4. Now change the length of the extended portion of the skewer by pulling it more inwards or outwards from the edge of the table.
5. Repeat steps 2 and 3.  Observe if there is any change in the sound

How does it work?

1. When the free end of the skewer is pressed and released, it starts to vibrate quickly against the surface of the table and produces a loud sound.

2. As the vibration stops, the sound also stops. Sound is produced only when something vibrates.  All sounds are produced by vibrations, moving like waves to our ears!

3. If there is no vibration, there is no sound. Whenever you hear a sound, find out where it comes from and what the cause is.

4. What is vibration? You can make sound by making things move to and fro about a point. This to-and-fro movement is called vibration. These vibrations cause the surrounding air to vibrate.

5. Vibrations make sound waves. We can make sounds in many ways e.g. by shouting, clapping our hands, banging the table, or by plucking a stretched rubber band.

6. When we play the drum, the sound is produced when the membrane of the drum is struck with a stick and the membrane vibrates.

7. In guitars, the vibration of the strings produces sound. Sometimes things vibrate so fast, or so slightly, that we cannot see them vibrating, for example, the vibration of a mobile phone that produces a slight buzzing noise.

Feel your throat

When we speak, scream or shout, we produce a sound! But how do we produce a sound?? We don’t vibrate!! Where does the sound come from??

Procedure:

1. Place your hand firmly mid-way on your throat.
2. Now say ‘aaaaaaaaa!’
3. Can you feel your throat vibrating??

 

How does it work?
 When we move our fingers around our throat, we find a hard lump in the middle of the throat.

This hard lump is known as the Voicebox.  The Voicebox is an organ inside our throat that is responsible for producing sound.

The voice box has vocal cords. When we want to talk, the air from our lungs moves upwards to reach our throat and makes these vocal cords vibrate, creating sound.

Screaming balloon

Procedure:

1. Squeeze a hexagonal nut through the mouth of the balloon. Make sure that the nut goes all the way into the balloon. Blow it.
2. Grip the balloon at the neck in your palm.  Your fingers and thumb must extend down the sides of the balloon.
3. While holding the balloon, palm down, swirl it in a circular motion. The nut may bounce around at first, it will then begin to roll around the inside of the balloon.
4. Why does the balloon make a spooky, screaming sound?

How does it work?

The nut keeps spinning inside the balloon even when you have stopped spinning it, as it cannot stop spinning instantly.

Friction occurs when objects rub against each other.  Friction slows down the nut as it rubs against the inside of the balloon. This rubbing is changed into the screaming sound as the sides of the nut vibrates against the inside wall of the balloon.