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Updated: Jul 12, 2026
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Digital Inline Holographic Microscopy (DIHM) of Weakly-scattering Subjects
Published on: February 9, 2014
Interior near-field acoustical holography in flight
E G Williams1, B H Houston, P C Herdic
1Naval Research Laboratory, Washington, DC 20375, USA. williams@genah.nrl.navy.mil
The Journal of the Acoustical Society of America
|October 29, 2000
Summary
This study combined boundary element methods (BEM) with near-field acoustical holography (NAH) to map airplane fuselage noise in-flight. The method successfully identified sound transmission paths from the engine to the cabin.
Area of Science:
- Acoustics
- Aerospace Engineering
- Computational Mechanics
Background:
- Aircraft noise is a significant concern for passenger comfort and regulatory compliance.
- Understanding noise sources and transmission paths is crucial for effective noise reduction strategies.
Purpose of the Study:
- To apply near-field acoustical holography (NAH) in-flight for the first time to measure fuselage surface velocity.
- To combine NAH with boundary element methods (BEM) for accurate acoustic analysis.
- To identify noise transmission paths from turboprop engines to the aircraft interior.
Main Methods:
- Mating boundary element methods (BEM) with near-field acoustical holography (NAH).
- Measuring acoustic pressure on a surface within the aircraft cabin.
- Reconstructing the normal velocity of the fuselage surface.
Main Results:
- Successfully reconstructed the normal fuselage velocity at the blade passage frequency (BPF) and its first two harmonics.
- Demonstrated the in-situ, in-flight application of NAH on an aircraft fuselage.
- Identified both structure-borne and airborne sound transmission paths.
Conclusions:
- The combined BEM-NAH approach is effective for in-flight acoustic diagnostics of aircraft.
- This technique can pinpoint noise sources and transmission routes within the aircraft.
- The findings provide valuable data for designing quieter aircraft interiors.
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