sounds galore

Click on the picture of the ‘musical note’ and listen to the sound. Put your mouse over the blue circle above the note to see if you have guessed the sound correctly.

In helioseismology, we are searching for tiny differences in the Sun's vibrations or sound waves.

Comparing these tiny differences is something like trying to hear the difference between a guitar and a harp. Actually it's a lot harder than that - more like trying to tell the difference between two different makes of guitar.

How does sound travel?
When sound waves travel through air, the atoms and molecules of nitrogen, oxygen and other gases which make up our atmosphere bang into one another and pass some of their energy to their neighbours. In this way, waves of energy (sound waves) can travel at a speed of about 340 m/s in the Earth's atmosphere.

Native Amercian Indians would hear the sound of an approaching buffalo sooner if they listened to the ground rather than waited for the sound to reach them by air.

Sound can also travel through liquids and solids. In fact it travels faster through liquids and solids than it does through gases. Without the molecules in the air, solid or liquid, the sound can't travel. In a vacuum, there is silence.

A small hand bell produces a high-pitched sound, whereas a very large church bell produces a deep low-pitched sound. The bell vibrates when it is struck by the little hammer inside it. The bell is said to 'resonate'. Click on the images and listen for yourself...