Roughly 5,000 people work on the USS Dwight D. Eisenhower and when a tactical jet aircraft takes off, it does not do so in absolute silence. In fact, the noise levels on the flight deck are reported to go beyond an astonishing 150 decibels (dBA). In many of the offices and staterooms below the flight deck, levels exceed 85 dBA and have been measured as high as 105 dBA during launch events. To reduce the health and safety risks that can be caused by exposure to such a noisy environment and improve the well-being of their workers, U.S. Navy partnered with Noise Control Engineering LLC (NCE), an acoustic engineering consulting firm. They immediately decided to use LMS Testing Solutions to assess the noise and vibration issues.
Conducting a thorough test for such an important matter and under such conditions is a journey. Instrumentation to collect essential data and validate noise reduction techniques required more than 100 channels along with microphones and accelerometers for more than 100 launches of jet aircraft.
The starting point was to perform high-level measurements on the sensitive areas of the carrier that were deemed more likely to generate noise. For this, NCE chose the ultra-compact LMS SCADAS Mobile data acquisition system. Its super accurate signal conditioning enabled them to characterize source levels right from the microphones placed on the deck. The data was then processed and analysed with LMS Test.Lab. LMS 3D Solid Sphere array was also successfully used to identify and locate the main noise sources in the compartments as well as validate the noise treatments.
*The pictures are courtesy of U.S. Navy.