The Physics of the Sound Wave and its Effects on the Human Ear
Could you imagine living in a world without sound? It would be enormously different from the world that we know. Our primary form of inter-human communication would be based on visual or tactile imagery. Our sense of perception would be changed. Telecommunication would be different. We would not have the pleasure of music or the soothing sounds of nature. Sound has had an immense impact on our world. This essay will explore the unseen world of sound waves and how humans perceive them.
Generally, people hear sound waves traveling through air. These waves cannot be seen, but are heard or felt via vibration. Sound waves originate from vibrating objects and travel in longitudinal waves through mediums (such as a solid, a liquid, or a gaseous material). These types of waves are defined by the textbook as: “…wave[s] in which the vibrations of the medium are parallel to the direction the wave is moving.1” Figure 8.52 shows an excellent example of a tuning fork producing longitudinal waves, which are perceived as sound. It is apparent that as the prongs are struck, they move outward. As they move outward, the neighboring air molecules are compressed together creating what is called compression. The tuning fork prongs reverse the pressure as they move inward and cause a rarefaction (the opposite of a compression) in the neighboring air molecules. The process is repeated until the tuning fork returns to its resting state.
As previously stated, sound waves can travel through various mediums. The universal formula to obtain the speed of a sound wave is:Speed=distance/time.
“The faster which a sound wave travels, the more distance it will cover in the same period of time3.” In air, sound travels 343 meters per second (m/s). The speed can very by changing external factors such as altitude and temperature. If the medium is a gas, speed may also vary based on its density. Sound travels at about 1500 m/s in water and up to 5000 m/s in solids.
Two factors, density and elasticity, cause the variances in the speed of sound through changeable mediums. The first factor is the density of a medium, which is referred to as its inertial property. “The greater the inertia (i.e., mass density) of individual particles of the medium, the less responsive they will be to the interactions between neighboring particles and the slower the wave3.” Sound always travels faster through less dense material. Due to its lower mass, helium conducts sound three times faster than the air we breathe. The second important factor is the elastic property of a medium. If the medium is highly elastic, like steel, there is small deformation of shape, resulting in faster speeds. Meanwhile, a flexible object like a rubber band deforms easily, causing the sound waves to pass through it slower. This general pattern is usually observed with elastic properties:Vsolids > Vliquids > Vgases, where V=331 m/s + (0.6 m/s/C)*T...