INVESTIGATION OF ACOUSTIC PROPERTIES OF A RIGID FOAM WITH APPLICATION TO NOISE REDUCTION IN LIGHT AIRCRAFT

A analytic model of sound transmission into an aircraft cabin was developed as well as test procedures which appropriately rank order properties which affect sound transmission. The proposed model agrees well with available data, and reveals that the pertinent properties of an aircraft cabin for sound transmission include: stiffness of cabin walls at low frequencies (as this reflects on impedance of the walls) and cabin wall transmission loss and interior absorption at mid and high frequencies. Below 315 Hz the foam contributes substantially to wall stiffness and sound transmission loss of typical light aircraft cabin construction, and could potentially reduce cabin noise levels by 3-5 db in this frequency range at a cost of about 0:2 lb/sq. ft. of treated cabin area. The foam was found not to have significant sound absorbing properties.

• Corporate Authors:

  Bolt, Beranek and Newman, Incorporated

  50 Moulton Street
  Cambridge, MA  United States  02138
• Authors:
  • Holmer, C I
• Publication Date: 1972

Media Info

• Pagination: 79 p.

Subject/Index Terms

• TRT Terms: Absorptivity; Acoustic properties; Acoustics; Aircraft; Aircraft cabins; Engines; Foams; Mathematical models; Noise; Noise control; Polyurethane foams; Rigid structures; Small aircraft; Sound absorption; Sound transmission; Vehicle compartments
• Uncontrolled Terms: Noise reduction
• Old TRIS Terms: Engine noise
• Subject Areas: Aviation; Environment; Vehicles and Equipment;

Filing Info

• Accession Number: 00175032
• Record Type: Publication
• Source Agency: National Technical Information Service
• Report/Paper Numbers: NASA-CR-132333
• Contract Numbers: NAS1-9559
• Files: TRIS
• Created Date: Apr 26 1978 12:00AM