INFLUENCE OF AVERAGING TIME IN THE MEASUREMENT OF ROAD TRAFFIC NOISE

A-weighted level distributions over a range of averaging times have been determined for samples of road traffic noise. The ensuing distributions are approximately Gaussian or log-chi-square distributions, the latter being consistent with a simple model of the noise generating process. Results indicate that simple noise indices (l1, l10, L50, l90, lnp) are substantially independent of the averaging time in the range 10 to 2000 ms. Further it appears that rc-integration and true integration of the intensity yield similar results when the duration t of a true rectangular time window is about 5 times the time constant of an exponential time window. Finally, several procedures to estimate equivalent continuous sound level from various fractiles of level distributions have been investigated, and their accuracy determined. A useful approach is based on l28 (standard deviation 0.32 db), and a prediction based on l10 and l90 was found to be even more accurate (standard deviation 0.26 bd). (Author/TRRL)

  • Corporate Authors:

    National Physical Laboratory, England

    Queens Road
    Teddington, Middlesex,   England 
  • Authors:
    • Borruso, P
    • Lyregaard, P E
  • Publication Date: 1979-5

Media Info

  • Features: Figures; References; Tables;
  • Pagination: 62 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00309079
  • Record Type: Publication
  • Source Agency: Transport Research Laboratory
  • Report/Paper Numbers: AC91 Monograph
  • Files: ITRD, TRIS
  • Created Date: Apr 22 1980 12:00AM