What Is a Sound Wave ?

A sound wave is a type of pressure wave caused by the vibration of an object in a conductive medium such as air. When the object vibrates, it sends out a series of waves which can be interpreted as sound. For example, when someone hits a drum, it causes the membrane of the drum to vibrate, and the vibration is transmitted through the air, where it can reach the ear of a listener. Not all sound waves are in audible range. Humans hear around 12 Hz to 20 kHz, meaning that sounds above and below this range cannot usually be heard, and some animals can hear at higher and lower ranges.

Some sound waves move as transverse waves, moving in a classic wave-like pattern outwards from the origin of the sound. The movement of the wave is perpendicular, and could be compared to dropping a rock in the water and watching the outward ripple effect. They can also present as longitudinal waves, in which the movement is horizontal, creating alternate areas of compression in the medium to generate sound.

Like other waves, a sound wave can be described in a number of ways. For example, the frequency of a sound wave is a term used to describe the number of complete cycles within a set period of time, expressed in Hz or hertz. In the case of hertz, the frequency is expressed in cycles per second. The greater the number of cycles, the higher the pitch of the sound.

Another characteristic of sound waves which can be important is wavelength. The wavelength of a sound wave is described as the distance it takes for a complete cycle to be completed. A complete cycle moves from peak to peak or trough to trough of a sound wave. Wavelengths are directly related to both the speed of the sound wave and the frequency.

Sound waves have a number of traits which make them interesting to humans. They can travel through almost any medium, including gases, solids, and liquids, but they cannot travel in a vacuum. This means that space is silent, because there is no air to conduct sound, despite what Hollywood may think. Sound waves also move very quickly, making measurement of the speed of sound in various media a topic of interest for researchers. Especially high speed aircraft have managed to break the sound barrier, traveling faster than the sound waves they generate.