Aircraft noise measured with a microphone Research conducted by the Structural Acoustics Branch (StAB) can be grouped into three broad areas:

—  Understanding, predicting, and controlling the excitation and response of aerospace structures to fluctuating pressures
—  Performing subjective acoustics research in order to establish verified, quantifiable noise criteria for the impact of noise on communities and passengers
—  Developing and optimizing acoustic liners for engine nacelles and airframes

A major objective of the first area is to develop validated analytical and numerical models of sound transmission in and through aerospace structures such as fuselage sidewalls. These models are used to design quieter sidewalls that meet structural requirements, or to develop and optimize noise control treatments. This area of research includes the development of novel structures to reduce sound generated by aerodynamic sources such as the flow around high-lift surfaces on an aircraft.

The subjective acoustics research area includes the study of human response to sonic booms with a concentration on sonic booms experienced inside a building. This includes atmospheric propagation Actuators for active controland structural transmission studies to improve the prediction of noise and sonic booms experienced under a variety of conditions. The subjective acoustics area also includes auralization of aircraft sounds, whereby predicted aircraft noise levels are converted to waveforms in order to create realistic aircraft sounds that can be played to listeners in the lab.

In the area of acoustic liners, StAB researchers rely on experiments and analyses to understand, predict, and develop specialized acoustical absorbing materials for jet engine inlets and aft bypass ducts, and for areas of the airframe that are in the path of engine noise or are close to airframe noise generation sources. Areas of the airframe that could benefit from acoustical liners include the fuselage surface, flap side edges and landing gear doors.

The research in all of these areas utilizes unique facilities housed within StAB for simulating the noise and vibration environments experienced by flight structures, passengers and crew, and communities exposed to aircraft noise.