Understanding Acoustics

Sonic-Shield’s Three Keys to Understanding Acoustics

Understanding acoustics, specifically indoor acoustics, is important for your interaction with a soundproofing company. Three important acoustical concepts must be understood:  decibels (dB), Sound Transmission Class (STC) and Noise Reduction Coefficient (NRC):

  • Sound pressure levels are typically measured and expressed in terms of decibels (dB), and are often weighted to simulate the sensitivity of the human ear (A-weighting, or dBA). For purposes of comparison, typical noise levels inside a quiet home at night in a rural or suburban environment are from 30-40 dBA, and a quiet home during the day will reach levels of 40-50 dBA. Outdoor noise during the day in an urban environment will be about 60-70 dBA and over 80 dBA near busy roads or transportation hubs. Below is a chart that outlines the United States Occupational Regulations for Noise Plus Acoustics which outlines permissible decibel levels which will enhance your understanding of acoustics.
    Understanding Acoustics by reviewing the U.S. Occupational Regulations for Noise plus Acoustics
    Occupational Regulations
  • The STC of a wall describes how well the wall reduces (or attenuates) airborne sound. STC is generally related to the amount of noise that the wall can reduce from one side to the other.  For example, a typical wall in a house or office has an STC of 33, meaning that it can attenuate 33 dB from one side of the wall to the other.  Since normal human speech reaches levels of 65-70 dBA, one could hear garbled speech through a typical wall.  Loud music (at levels of over 80 dBA) could be heard clearly from one side of the wall to the other.
  • The NRC, on the other hand, is an indication of the amount of sound energy absorbed upon striking a particular surface.  An NRC of 0 indicates perfect “bounce back” or reflection (such as a smooth concrete surface) and an NRC of 1 indicates perfect absorption.  We have all experienced such rooms (or restaurants) with acoustically hard and reflective surfaces (NRC=0), where unwanted noise is amplified, making it difficult to hear speech or music.  This often makes us speak louder or increase the volume of audio equipment, further increasing the overall sound levels within the room.

Sonic-Shield offers a full range of soundproofing products and develops customized soundproofing solutions to solve even the most demanding noise problems. Our team of acoustic experts can help you pinpoint sources of noise and rapidly develop cost effective solutions to eliminate, block or absorb the noise.

Sonic-Shield believes that while there may be similarities, no two noise pollution problems are exactly alike. Accordingly, our soundproofing solutions reflect our ability to identify, and when necessary, develop and fabricate the appropriate soundproofing materials for your particular needs. We hope that understanding acoustics has made you more comfortable with our process of developing a solution for your problem and will enable you to have a higher comfort level in evaluating our recommendations.