EVALUATION OF THE ACOUSTICAL PERFORMANCE OF NOISE BARRIERS BY THE MAXIMUM LENGTH SEQUENCE TECHNIQUE

Noise barriers are used successfully to protect people against traffic noise and their acoustic performances have been theoretically and experimentally studied by many authors. This paper presents a new measurement procedure for the determination of sound attenuation of barriers which is based on the maximum length sequences (MLS) technique. This technique is used to compute the impulse response of linear and time invariant systems. In the MLS technique, the input signal is a pseudo-random unitary pulses sequence, the impulse response is obtained by sampling the output signal and then performing a digital cross-correlation with the original MLS sequence. The original set up introduced by Papadopoulos and Don is revisited and improvements are proposed. A scale model is used for the measurement together with an adequate geometry (source, barrier's top and microphone positions) for the determination of the excess attenuation (EA). As the measurements, with and without screen, for a given geometry compares sound pressure levels at the same distance of the source, differential attenuation is not considered. Excess attenuation are computed for incident and diffraction angles and the experimental results are confronted to the Kurze and Anderson's formula. For the covering abstract see IRRD E104312.

Language

  • English

Media Info

  • Features: References;
  • Pagination: p. 477-80

Subject/Index Terms

Filing Info

  • Accession Number: 00790201
  • Record Type: Publication
  • Source Agency: Transport Research Laboratory
  • ISBN: 0-9622072-3-3
  • Files: ITRD
  • Created Date: Apr 11 2000 12:00AM