Aircraft interior acoustics – background noise contamination



Aircraft interior noise is an important factor to be considered for cabin comfort.  In a cruising condition this noise source is mostly broadband in nature and is coming from the exterior, primarily the turbulent boundary layer (TBL) of the flow around the moving aircraft.  Capturing this noise to a high frequency is critical for designing the sound packaging. Also, this becomes important in the design of public announcement (PA) system for the aircraft cabin, i.e. the correct placement of speakers.   One of the metrics used for this acoustic design is speech transmission index.  Deterministic techniques like finite or boundary element techniques for low frequencies and ray tracing method to reach higher frequencies are better suited for getting the narrow band responses.  On the other hand, to characterize the background noise due to the TBL loads, statistical energy analysis (SEA) route is pursued.  In this paper the authors combine different techniques to capture the background noise and use them with PA sources and eventually capture the sound perceived at points of interest.  The articulation metrics are compared for different operating conditions of the aircraft.   In the presentation attempts will be made to play the auralized sounds.