Method for evaluating the attenuation of acoustical covers used in high-end computer systems

High-end computer systems, such as those used in the Information Technology and Telecommunications (ITT) industry, have become increasingly noisy in recent years, due to the amount of airflow needed to keep them functioning properly. As sound power levels increase, the systems run the risk of exceeding their noise-limit specifications. One solution is to incorporate acoustical covers as a noise control measure. By attenuating the amount of noise emitted from the machine, the overall measured sound power level will decrease, thereby allowing the system to pass specifications. However, a method for evaluating the amount of attenuation these acoustical covers provide is needed. To date, the attenuation has been measured by using actual system frames that are under development, which are often hard to acquire and introduce too many variables into the measurement. Also, both front and rear covers are needed for the measurements, so that the attenuation of just one cover is not easily obtained. This paper proposes the use of a test box as an evaluation tool for measuring the attenuation of a single cover. The test box provides a uniform and repeatable method that yields a more useful metric for rating cover performance.