Developments in aircraft interior acoustics—Recent progress and directions

Abstract

Aircraft interior noise is a continuing problem for a wide range of aircraft types. High interior noise levels in general aviation aircraft make any communication difficult, significantly impact pilot endurance, and are considered important to the reemergence of this class of aircraft. For passengers in propeller-powered commuter aircraft, conversation is difficult at best and becomes oppressive on the passengers for long periods. It is also regarded as one reason for the replacement of propeller commuter aircraft by the emerging regional jet. In business jets, the passengers are often interested in conducting meetings during flights. This calls for low SPL and SIL for which the aircraft incurs both space and weight penalties. Large commercial aircraft pay a significant weight penalty for current interior noise levels considered acceptable. With the drive for more weight-efficient airframes, the challenge becomes even more difficult. This paper will overview current efforts to develop both design and noise control techniques. These range from improvements in the quantification of the noise sources, to considerations in the overall structural design, and to the use of both active and passive control tools. In addition, the emerging use of predictive and measurement tools will be discussed and applications to aircraft highlighted.