New project to help control jet noise in tactical aircraft

Noise-reduction technologies will help lessen hearing damage to Sailors and Marines on flight decks

The deafening roar of supersonic aircraft can cause hearing damage to Sailors and Marines on flight decks, so the Office of Naval Research (ONR) is funding a new project to help reduce jet noise, officials announced April 12.

"The noise problem falls into two categories: noise exposure on the flight deck and noise impact on the communities surrounding air bases," said Dr. Brenda Henderson, deputy manager for the Jet Noise Reduction project, part of ONR's Noise-Induced Hearing Loss (NIHL) program. "We're funding the development of tools that we'll need to help control jet noise in tactical aircraft."

With support from ONR's Basic Research Challenge program-which funds basic research in new areas not already covered by other programs- the Jet Noise Reduction project is a long-term effort. Jointly funded with NASA, ONR is awarding grants and contracts to eight teams-six academic institutions and two commercial companies-to develop noise-reduction technologies, as well as measurement and prediction tools and noise source models to dampen the noisy jet plumes that emanate from naval aircraft.

Awards totaling more than $4 million were given to teams at Brigham Young University, California Institute of Technology, Cascade Technologies, Innovative Technology Applications Co., University of Illinois, University of Mississippi, Pennsylvania State University and Virginia Tech.

The intensity of sound perceived by humans is measured in decibels. For example, a person whispering is 20 decibels and a lawn mower is 90 decibels. Factories are required to institute a hearing protection program once noise levels reach 85 decibels. Shipboard aviation surpasses those limits. Jet noise from tactical aircraft can reach 150 decibels on the flight line, where Sailors and Marines prepare fighters and other aircraft for launching.

The research and tools produced by the eight teams in this project will help to create new approaches to noise-mitigation technology aimed at reducing levels of jet exhaust noise that, when combined with hearing protection, will result in safer noise environments for Sailors and Marines. In addition, the lower jet exhaust noise levels will aid in reducing noise complaints reported in communities near military bases.