WHY NOISE ANNOYS AND HOW ANTI-NOISE COULD STOP IT

The article analyses the causes of noise, vibration, and harshness in cars, and explains an acoustic approach to reduce vehicle noise. Rapidly moving vehicles generate internal and external aerodynamic noise; though the external noise has been steadily reduced, it is very difficult to remove internal noise from wheel and wheelarch turbulence. Impressive progress has been made in isolating car occupants from engine and transmission noise and harshness. Designers also need to consider drive-unit shake, resulting from a car hitting bumps. Noise from tyres, often called 'road noise', is difficult to control, let alone eliminate; it is the major source of interior noise in all modern cars. Previous attempts to remove road noise have only had limited success. Stiffening a body shell makes it unreasonably heavy. Attaching the suspension to subframes is usually not very effective. A new, more radical, approach is the use of 'noise cancellation', which can theoretically cancel out road noise. A noise generator, built into the car radio, and sampling the road noise, emits sound with a complementary wave pattern through the radio's loudspeakers. There are many practical difficulties to be overcome, but Lotus Engineering has sold a system to Nissan, which claims that 10dB attenuation has been achieved over the important 600-3000Hz range.

  • Availability:
  • Corporate Authors:

    Institute of Road Transport Engineeers

    1 Cromwell Place
    London SW1 25F,   England 
  • Authors:
    • SCARLETT, M
  • Publication Date: 1996-6

Language

  • English

Media Info

  • Pagination: p. 36-7
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00726611
  • Record Type: Publication
  • Source Agency: Transport Research Laboratory
  • Files: ITRD
  • Created Date: Oct 28 1996 12:00AM