The silencing effect is studied of exhaust mufflers for automobiles. The purpose of this experiment was to investigate the effect of the flow rate of an exhaust gas on the changes in noise attenuation in mufflers from the practical point of view. Ten fundamental types of reactive mufflers are tested by an engine, which has a cylinder volume of about 900 cc. The results are compared with those of a test by pulsating air flow at various flow rates. In general, the sound level in the pulsating flow test is lower in the low frequency range, but higher in the high frequency range. The noise attenuation in the engine test varies with engine load, and is generally lower under full load than in no load condition, especially in the high frequency range above 300 Hz. Author

  • Supplemental Notes:
    • Translated into English from Nippon Onkyo Gakkaishi (Tokyo) V27, N11, 1971, pp 568-578.
  • Corporate Authors:

    Scientific Translation Service

    Santa Barbara, CA  United States 
  • Authors:
    • Fujimoto, S
  • Publication Date: 1972-6

Media Info

  • Pagination: 12 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00261217
  • Record Type: Publication
  • Source Agency: National Aeronautics and Space Administration
  • Report/Paper Numbers: NASA-TT-F-14295
  • Contract Numbers: NASw-2035
  • Files: TRIS
  • Created Date: Oct 22 1974 12:00AM