International Space Station Acoustics – A Status Report

It is important to control acoustical noise aboard the International Space Station (ISS) to provide a satisfactory environment for voice communications, alarm audibility, and restful sleep, and to minimize the risk for hearing loss. Acoustic monitoring is an important part of the noise control process on ISS, providing critical data for trend analysis, noise exposure analysis, and validation of acoustic analyses and predictions. This data is also used to provide strong evidence for ensuring crew health and safety, thus allowing Flight Certification. And since the primary noise sources on ISS include the environmental control and life support system�s air revitalization system (fans and airflow) and active thermal control system (pumps and water flow), acoustic monitoring will indicate changes in hardware noise emissions that may indicate system degradation or performance issues. This paper provides the current acoustic levels in the ISS modules and sleep stations, and is an update to the status presented in 2018. Since the last status report, the speed of the Common Cabin Air Assembly air conditioning fan and the speed of the Pump Package Assembly cooling water pump have been increased in the US Laboratory module. And in the Node 3 module, the T2 treadmill has been replaced with a new quieter serial unit. Also, a significant number of science experiments have been added to the Japanese Experiment Module. This paper will present the acoustic levels resulting from these changes. Finally, a new type of sound level meter is being used for the noise surveys. This new Acoustic Monitor has additional capabilities, allowing for narrow-band and other analyses of the on-orbit measurements and also allowing for more-frequent measurement activities. Benefits of this new measurement hardware will be discussed.