The development of Department of Defense aircraft reference noise measurement approaches

The key components for Department of Defense aircraft noise impact analyses are the accurate characterization of the noise source and its propagation through the atmosphere. The development of military aircraft noise data collection procedures started in the 1970s and was shaped by the integrated modeling assumptions at that time. The objective of these original data collection procedures was to obtain integrated reference noise levels. The procedures were refined through the 1990s as instrumentation improved. However, at the end of the 1990s, the next generation of military fighter aircraft had new nozzle geometries, vectored thrust capabilities, and more powerful engines. These changes have driven the development of simulation-based acoustical modeling capabilities. The expanded modeling approaches require more detailed characterizations of the aircraft noise source. This presentation focuses on the evolution of data collection procedures to obtain the improved characterization of noise generated by fixed-wing military aircraft, which is mostly documented in ANSI/ASA S12.75 standard. This presentation provides an update to the current data collection protocol based on recent measurements and serves as a discussion for further development in aircraft source noise characterization procedures.