3. Noise

Background
Pressure changes that occur in and propagate through a medium and eventually reach the ear, are interpreted by the brains as noise. In order to speak of noise, a source, amedium and a receiver are always needed: for example, a loudspeaker (source) can create air pressure changes that propagate as a sound wave through the air (medium) (at a rate of approximately 340 m/s), which can put our tympanic membrane (receiver) into motion. The rate at which pressure changes follow each other, determines the soundfrequency (in Hz) while the size of the pressure changes determines the sound intensity (in Pa). The human ear is sensitive to sound frequencies between about 20 and 16,000 Hz and intensities between 20 µPa (hearing threshold) to 200 Pa (pain threshold) (factor of 10 million). This scale is difficult to use, so in practice often the derived logarithmic unit “sound level” (in dB) is used. This sound level is calculated as 10 * log (intensity / hearing threshold): 0 dB at the hearing threshold and 140 dB at the pain threshold.

Legislation

Standards

  • NBN EN ISO 9612:2009 Acoustics - Determination of occupational noise exposure - Engineering method (ISO 9612:2009)
  • NBN EN ISO 9921:2003 Ergonomics - Assessment of speech communication (ISO 9921:2003)
  • NBN EN 61672-1:2004 Electroacoustics - Sound level meters - Part 1 : Specifications (partially replaces NBN EN 60651)
  • NBN EN 61252/A1:2001 Electroacoustics - Specifications for personal sound exposure meters
  • NBN EN ISO 4869 (-1 to -4): Acoustics - Hearing protectors
  • NBN EN ISO 3382(-1 to -3):2008 to 2012 Acoustics - Measurement of room acoustic parameters
  • NBN S 01-401:1987 Acoustics - Maximal noise levels in buildings
  • NBN ISO 1999:1992 Acoustics - Determination of occupational noise exposure and estimation of noise-induced hearing impairment (ISO 1999:1990)
  • NBN EN 352-1:2002 Hearing protectors - General requirements - Part 1: Ear-Muffs
  • NBN EN 352-2:2002 Hearing protectors - General requirements - Part 2: Ear-plugs
  • NBN EN 352-3:2002 Hearing protectors - General requirements - Part 3: Ear-muffs attached to an industrial safety helmet
  • NBN EN 352-4/A1:2006 Hearing protectors - Safety requirements and testing - Part 4: Level-dependent ear-muffs
  • NBN EN 352-5/A1:2006 Hearing protectors - Safety requirements and testing - Part 5: Active noise reduction ear-muffs
  • NBN EN 352-6:2003 Hearing protectors - Safety requirements and testing - Part 6: Ear-muffs with electrical audio input
  • NBN EN 352-7:2003 Hearing protectors - Safety requirements and testing - Part 7: Level-dependent ear-plugs
  • NBN EN 352-8:2008 Hearing protectors - Safety requirements and testing - Part 8: Entertainment audio ear-muffs
  • NBN EN 24869-1:1995 Acoustics - Hearing protectors - Subjective method for the measurement of sound attenuation (ISO 4869-1:1990) (ISO 4869-1:1990)
  • NBN EN ISO 4869-3:2008 Acoustics - Hearing protectors - Part 3: Measurement of insertion loss of ear-muff type protectors using an acoustic test fixture (ISO 4869-3:2007)
  • NBN EN ISO 4869-4:2000 Acoustics - Hearing protectors - Part 4: Measurement of effective sound pressure levels for level-dependent sound-restoration ear-muffs (ISO/TR 4869-4:1998)
  • more information on http://www.nbn.be

Documentation

Tools

Websites

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