Sound Energy
What is sound?
Sound is a wave that is produced whenever an object vibrates. The object could be a string on a guitar, a flat surface such as a drum skin, the diaphragm in your vocal cords or even a loud speaker.
Sound transfers energy away from the vibrating object, and it needs something to travel through like a solid, liquid or gas.
Sound cannot travel through a vacuum. In outer space, no one can hear you scream!
Sound is a wave that is produced whenever an object vibrates. The object could be a string on a guitar, a flat surface such as a drum skin, the diaphragm in your vocal cords or even a loud speaker.
Sound transfers energy away from the vibrating object, and it needs something to travel through like a solid, liquid or gas.
Sound cannot travel through a vacuum. In outer space, no one can hear you scream!
Speed of sound
The speed at which sound travels from one place to another depends upon the medium and how closely packed the molecules are in the matter. A medium is a substance that allows sound waves to travel through it. Sound is much slower than the speed of light. Light travels nearly a million times faster through the air than sound does. This is why you hear the thunder clap after you see lightning in a thunderstorm, and why the sound of someone hammering some distance away does not match the hammer blows. |
Reflection
Sound waves can reflect from the surface of an object. This is called an echo. Hard surfaces reflect sound better than soft surfaces. Some animals use echos -- sound waves reflected off objects in their path -- to navigate and find food at night or in dark locations such as caves. This is known as echolocation. Bats emit pulses of high-pitched sounds -- beyond the range of human hearing -- and then listen for the echoes that are produced when these sound waves bounce off objects around them. The folds in a bats ear are uniquely suited to detect these echoes which give them information on the location, shape and size of surrounding objects, including really small objects such as mosquitoes. Bats can also use echoes to tell the direction an object is moving. Absorption Hard objects reflect sound but soft objects absorb sound waves. Soft items such as carpet and curtains will help to absorb sound and make a room quieter. Absorption panels are hung on the wall in recording studios to contain sound waves and minimize echos. |
Loudness
The loudness of a sound depends upon the size of the vibrations. Big vibrations transfer more energy than small vibrations, so they are louder.
Pitch
A sound can range from a high to a low pitch (high to low note). The pitch of a sound depends on how fast the original object is vibrating. If there are lots of vibrations per second, the frequency is high and the sound has a high pitch. If there are few vibrations per second, the frequency is low and the sound has a low pitch.
The loudness of a sound depends upon the size of the vibrations. Big vibrations transfer more energy than small vibrations, so they are louder.
Pitch
A sound can range from a high to a low pitch (high to low note). The pitch of a sound depends on how fast the original object is vibrating. If there are lots of vibrations per second, the frequency is high and the sound has a high pitch. If there are few vibrations per second, the frequency is low and the sound has a low pitch.
Hearing
We hear because sound waves enter the ear and cause the eardrum to vibrate. Three small bones in the inner ear carry these vibrations to the cochlea (pronounced ‘kok-lee-a’). The cochlea contains tiny hairs, which send messages to the brain when they vibrate.
Hearing damage
Our hearing can be easily damaged. As we get older, we find it more difficult to hear very low or very high sounds. The three small bones may join together as we age, so they are not so good at passing along the vibrations from the eardrum to the cochlea.
Loud sounds can eventually damage our hearing. If the eardrum is damaged, it may repair itself again, but if the cochlea is damaged, the damage is permanent. People with damaged hearing may find it difficult to follow conversations and may need a hearing aid.
We hear because sound waves enter the ear and cause the eardrum to vibrate. Three small bones in the inner ear carry these vibrations to the cochlea (pronounced ‘kok-lee-a’). The cochlea contains tiny hairs, which send messages to the brain when they vibrate.
Hearing damage
Our hearing can be easily damaged. As we get older, we find it more difficult to hear very low or very high sounds. The three small bones may join together as we age, so they are not so good at passing along the vibrations from the eardrum to the cochlea.
Loud sounds can eventually damage our hearing. If the eardrum is damaged, it may repair itself again, but if the cochlea is damaged, the damage is permanent. People with damaged hearing may find it difficult to follow conversations and may need a hearing aid.
Range of Human Hearing