Today you will learn: How sounds are made and what they are. How we measure sounds How we can change sounds from high to low How sounds can travel in different materials How your ear works

Sound helps us to understand the world around us. When we speak or listen, messages are being sent and also received. We are warned of danger when gunshots or the screeching brakes of a car are heard. We relax when we listen to peaceful background sounds. Many sounds, eg music can give us pleasure or comfort. Sounds therefore have purpose. They can either be pleasant or unpleasant to our ears. What do you hear ? Close your eyes and listen to the sounds around you. Try to identify them. Which sounds are pleasant and which sounds are definitely unpleasant to you? The Importance of Sound

When objects move backwards and forwards very fast, they are vibrating. We call this movement a vibration. Vibrations make sound. An example that best explains this is when you use your vocal cords when speaking. If you place a finger on your throat, you will feel your vocal cords moving. Sound is made because the air passing through your vocal cords causes them to vibrate. How are Sounds Made?

Watch a video at What is sound? Sound is a form of energy, just like electricity and light. Sound is made when air molecules vibrate and move in a pattern called waves, or sound waves. Think of when you clap your hands, or when you slam the car door shut. That action produces soundwaves, which travel to your ears and then to your brain, which says "I recognize that sound."

Measuring Sound Scientists measure the loudness of sounds in units called "bells", named after the inventor of the telephone, Alexander Graham Bell. Talking softly is about 30 decibels. Speaking in a normal way is about 60 decibels. But an airplane, a boom box, or a rock concert can be 100 to 140 decibels, and that is loud enough to cause a permanent hearing loss.

Changing Sounds We can tell the difference between sounds by listening carefully to whether it is a high or low sound. This is called the PITCH of the sound. Remember: A low sound is caused by SLOW vibrations A high sound is caused by FAST vibrations The BIGGER the vibration the louder the sound The SMALLER the vibration the quieter the sound Animal Sounds:

How does sound Travel?

How do we hear sounds?

The Ear We use our ears to hear sounds all around us. Our ears help us learn new sounds. There are five parts to the ear.

The Five Parts of the Ear. The outer ear. The ear canal. The eardrum. The 3 bones of the ear. The cochlea.

1. The Outer Ear The outer ear collects sound waves and sends them to the ear canal. It is known as the Pinna

2. The Ear Canal The sound waves in the ear canal make the eardrum vibrate.

3. The Ear Drum Often called the eardrum because is resembles the skin stretched across a drum. The ear drum is only a fraction of a centimetre in size. The sound waves makes the “drum” vibrate.

4. The Three Bones of the Ear. The hammer The anvil The stirrup The bones are named for their shapes and are the smallest bones in the human body. These bones work to transport sound vibrations to the inner ear.

1. The Hammer The hammer is the first of the ear’s three bones. The sound vibrations move the hammer which in turn activates the anvil

2. The Anvil The anvil is the second bone of the inner ear. Its’ vibration moves the stirrup

3. The Stirrups The final and smallest bone of the ear is the stirrup. The stirrup passes the vibration through the oval window and into the inner ear.

The Cochlea A minute, bony, spiral shaped tube that looks like a snail shell. It has tiny hairs which sense the type of sound wave entering the ear The Cochlea sends the information to the brain through the auditory nerve.

Our brain then “interprets” the impulses into the sounds we hear. Can you label the different parts of the ear

Video of Ear

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