What we interpret as sound is actually a collection of systematic vibrations which travel from molecule to molecule through practically any medium. If you have ever been to an indoor rock concert, you have probably physically felt these vibrations as they traveled through the molecules in the floor and resonated from all of the surfaces in the arena. When a sound wave travels through the air and reaches your ear, the eardrum vibrates at the same resonance as the sound wave, and the resulting energy is interpreted by the brain as sound. The intensity of sound reaching your ear, the background noise in a crowded room and the vibrations you feel at a rock concert are all results of the behavior of sound waves. Let us take a look at some characteristics of sound wave behavior in order to gain a better understanding of the sounds we hear every day.
Any source of sound, whether it is a person talking, a drum beat or a clock ticking, produces vibrations, which create the fluctuations in the atmosphere known as sound waves. Not actually waves, the vibrations which make up sound waves travel over distance and time and through most any medium. Though it may be tempting to assume that noise would be contained within the four walls of a standard room, the walls, ceiling and floor actually serve as ideal means through which sound vibrations can travel. In fact, sound travels about nineteen times faster through drywall than it does through air!
Imagine for a moment the behavior of a set of racked billiard balls as they are struck by a cue ball on the break. As the cue ball strikes the front ball, energy transfers from ball to ball, resulting in their movement. This structure borne transfer of energy mirrors the behavior of sound waves as vibrations travel among the molecules in a molecular structure.
When sound waves traveling through air reach a denser medium, such as a wall, some of the energy will pass through the wall structure into the adjoining room, while the balance of the wave will reflect off of the structure and remain within the room. Sound energy passing to the next room is sound transmission, and energy reflecting back into the room is called sound reflection. When you are in a crowded room and must raise the level of your voice in order to be heard, you are actually speaking louder to overcome the jumble of sound reflections caused by other voices and sounds within the room. Sound reflection is the reason many restaurants and other establishments implement sound reduction treatments aimed at the absorption of sound vibrations, resulting in less background noise and a more pleasant atmosphere.
Solutions supplied by companies specializing in sound reduction and soundproofing treatments are often aimed at containing sound waves within a desired area and reducing their ability to resonate and create unwanted background noise. It is advised to consult with a professional soundproofing company prior to attempting a soundproofing treatment in order to ensure that all variables of your application are considered.