Squealing tires and screeching brakes-loud distracting noises, which are usually associated with a race track or cross town travel. Not in this case, however. Inside a auto assembly plant, employees just in a shiny new car fresh off the assembly line, accelerate to 60 MPH and then stomp on the brakes. This is the first step in testing acceleration and braking on new vehicles fresh off the assembly line, which are then moved to an idle lane for additional tests. The auto manufacturer's policy of creating and maintaining high standards of employee comfort and benefits led to a desire to reduce the noise level exposure for workers in the surrounding area.
After extensive testing and analysis, engineers selected BSC-25 Acoustical Curtain Panels. As opposed to some of the rigid, metal type of noise control products available in the marketplace, flexible sound absorber/noise barrier composite products can offer maximum accessibility, visibility and affordability, while still offering significant noise reduction. It was recommended that three forty-foot long bays be created to separate the idle lane from the active lane. Acoustical Curtain Panel model BSC-25 combines a quilted fiberglass sound absorber on both sides of a loaded vinyl noise barrier. The modular curtain panels were fabricated with full width view windows, grommets at the top with hook and loop fasteners along each edge to join adjacent panels together to form the designed configuration. The BSC/full width view window panels are specifically designed to offer complete visibility into the area along with effective sound absorption and noise barrier characteristics.
The BSC-25 Acoustical Composite Curtain Panel satisfied the acoustical engineers requirements to provide separator partition walls between each bay by utilizing a single product that would serve as both a noise barrier material between bays as well as a sound absorption product within each bay. In general, ASTM laboratory testing standards are utilized to determine how effective various products perform regarding their ability to either absorb sound waves, rated as "NRC", or block sound waves, rated as "STC". The NRC (Noise Reduction Rating) of BSC-25 is .85. The STC (Sound Transmission Classification) is 29. Since a heavy duty one pound per sq. ft. flexible transparent vinyl noise barrier material is utilized as the view window section of the panels, there is minimal, if any, loss of acoustical performance thru the window area. A related Acoustical Curtain Panel, BBC-13-2", was used as an "end cap" on one of the bays. Its purpose was also to absorb and contain the noise. However, since these panels are in a high abuse potential area where they drive the cars and move other equipment into the bays, the BBC-13-2" Acoustical Curtain Panels are utilized because they have a very rugged, durable reinforced noise barrier exterior and the quilted fiberglass sound absorber on the interior side only. Even with large open areas and an open top, upon completion of the Acoustical Curtain Enclosure, employees noise exposure dropped by 7dB(A) bringing these employees within acceptable noise exposure limits and creating a better working environment for the auto manufacturer's employees.
Table showing how the human ear perceives noise reduction.
|Decibel Reduction||Reduction Experienced by Ear|