Archive for the ‘Audio’ Category
Acoustic Insulation for the Noisy Workplace
Most small businesses that involve some manufacturing or fabrication facilities are well aware of the regulations surrounding industrial pollution and the steps needed to keep them within the law. They know all the OSHA rules and use the necessary equipment and procedures to keep their employees as safe as possible. One of the areas that OSHA provides guidance is in hearing protection for employees on a noisy shop floor. The heavy OSHA rated noise reduction ear covers, however, are often used as a last resort because they can interfere with communication and some employees find them uncomfortable.
If the noise level on your shop floor is near the border of the loudness which triggers OSHA hearing protection rules, then the application of acoustic insulation within the workplace may be enough to reduce ambient noise levels to below harmful levels. OSHA regulation 1910.95 states that if an employee is subject to a time-weighted average noise level of 85 decibels or more for a period of eight hours per day, then a systematic monitoring program must be enacted by the employer. This requires hearing protection for those employees subject to noise levels of 90 decibels and an annual audiogram of each employee subject to noise levels equal to or exceeding 85 decibels on average over the eight hour workday. Furthermore, for noise levels exceeding 90 decibels the time of exposure is significantly reduced on a graduated basis. Employees may not, for example, be exposed to noise levels in excess of 100 decibels on a time weighted average for more than 2 hours each day.
While those environments that are significantly over the limit are not likely to be dramatically improved by the addition of acoustic insulation and other treatments to the workspace, those right on the edge might be kept under the trigger level with the right acoustic treatments. Sound levels can be measurably amplified by reflections from solid surfaces, such as walls and solid floors like those made of cement or hardwood. By applying acoustically absorptive materials to the walls and ceilings of the workplace, these reflections can be reduced or eliminated so that they don’t add to the noise level in the shop.
Another source of noise may be reverberations of things like air ducts or other thin panels in noisy environments. These panels can be acoustically excited by certain frequencies of sound causing them to vibrate in sympathy and “sing.” This noise will add to the noise level in the shop as well. Padding or damping air ducts and other similar panels or surfaces can prevent this resonance from occurring. In some cases, adding suitable acoustic insulation around just a few of the noisiest pieces of equipment or enclosing them within sound-proof boxes may lower the overall ambient noise of the workspace enough to keep it under the 85 decibel limit required to trigger OSHA’s monitoring rules.
Working with an acoustic engineer or a workplace safety expert can help identify the right steps to take for your specific space.