| We are so accustomed to the many sounds | | | | Sound transmission can be measured using a |
| audible to us at any given time that we hardly | | | | metric known as the Sound Transmission |
| pause to distinguish what we are actually hearing | | | | Coefficient (STC). The STC rating is a numeric |
| or why. Hearing a combination of sounds around | | | | value which describes a wall, floor or ceiling’s |
| your home, such as the dishwasher running, cars | | | | propensity to prevent sound transmission. The |
| passing by and a neighbor mowing the lawn is so | | | | typical wall with studs and drywall averages an |
| commonplace that it does not generally warrant a | | | | STC rating of 38. A room with an STC rating of |
| second thought. However, there is an intricate | | | | 38, for instance, would affect a 38 decibel drop in |
| science behind sound behavior that explains why | | | | the audibility of incoming sound in a controlled |
| we hear certain sounds and with what intensity. | | | | environment. |
| A sound wave is an organized vibration which | | | | While decibels describe the intensity of a sound |
| passes energy from particle to particle through | | | | wave, Hertz is a measure of its frequency, or the |
| any molecular structure. You hear the voice of | | | | number of cycles occurring over a specified time. |
| someone in the same room speaking to you | | | | One Hertz is one vibration, or cycle, per second. |
| because the energy travels through the molecules | | | | Sounds with higher frequencies have a higher |
| of the air and reaches your ear. Likewise, you | | | | pitch. Low frequency sounds, such as bass, have |
| perceive sounds from outside such as traffic or a | | | | flatter, longer sound waves which travel more |
| lawn mower because the vibrations produced by | | | | easily through surfaces than do higher pitch |
| these sound sources travel through the molecules | | | | sounds. Higher frequency sound waves, having a |
| of the air and through the structure of your | | | | high Hertz value and thus more up and down |
| home to deliver a portion of the sound energy to | | | | movement in the cycle, are less successful at |
| your ears. | | | | traveling through surfaces because they must |
| In this illustration, when the sound vibrations | | | | overcome more distance and time within the |
| produced by the neighbor’s lawn mower | | | | structure. Comprehending frequency allows you to |
| change mediums, a portion of the sound is | | | | better understand why you are able to hear the |
| reflected off of the outer surface of your home | | | | low pitch lawn mower next door yet you cannot |
| while the remainder transfers through the surface | | | | hear the neighbors having a conversation from |
| and becomes audible within your home. The | | | | the same distance. |
| energy bouncing off of your home and remaining | | | | The behavior of sound waves of differing decibel |
| outside is sound reflection, while the energy | | | | levels and frequencies accounts for the highly |
| traveling through the structure and into your | | | | individualized nature of soundproofing and sound |
| home demonstrates sound transmission. Since | | | | reduction projects. It is advised to consult with a |
| wood, drywall, concrete and water are made up | | | | reputable soundproofing supplier prior to any |
| of molecules, sound energy travels as easily | | | | soundproofing endeavor so as to ensure that an |
| through such structures as it does through air. | | | | effective solution for your application is reached. |