12 Science Bulletin, July-August 2014
The Science of Sound
By Grant Regen
Sound is a necessity of human communication and advancement. From a simple tick of Morse code to an orchestra, the sense influences history. This phenomenon that we use every second of our life is taken for granted by humans and animals alike. So take a moment to discover how something as mystical as sound works.
The Ways of The Wave
Most simply defined as a wave, sound can be created by mostly anything: a tap of a foot, the whistling of the wind, or a strum of a guitar. Each action causes ripples in the air. These waves spread out until they are no longer audible. To visualize these waves think of a pond. Dropping a rock in the middle will cause the water to ripple away from the area of contact. These waves will spread out until they no longer hold momentum. By putting an upright brick in the water, some of the ripples will change direction. Now visualize this is a room. The dynamics are exactly the same! A room that echoes is simply reflecting sound waves back to you, the source.
Sound must travel in a steady medium, or a mass of the same material, such as air or water. Mediums can be solids, liquids, and most commonly gasses. Vibrations move through each of these mediums by compressing molecules as they travel. Just like an ocean wave, these compressions move throughout their medium by “bumping” into other molecules. Starting at the area of creation, the molecules exchange their motion to nearby molecules.
When we speak in daily life, humans use air as a steady medium. Our vocal chords modify the air as we breath out. Our voices create different vibrations that produce different pitches, some even moving at oscillations of four hundred vibrations per second. Other animals, such as whales, use the medium of water. Not only does this create a faster speed of sound, but also, by switching mediums, the sound is preserved better. Advantages such as