Noisemap
Noise mapping in industrial halls
Ó Tisseyre & Associés 1997
IDDN.FR.001.420005.00.S.P.1999.000.30500

The software - Main functions of Noisemap

THE SOFTWARE

The Noisemap software's main purpose is to establish noise maps in a room in the presence of multiple sources, as a function of the acoustic treatments: at the source, by barriers, by absorbing treatment of the hall's envelope.

The hall's modeling is achieved with the help of a meshing technique. The hall may be of any shape and the envelope's parts are cut into as many elements as required by the presence of the various materials.

The simulation is based on the diffuse reflexion hypothesis on the envelope's elements.

Noisemap calculates the attenuation of sound with distance and the time decay for an acoustic treatment scenario.

Then, from the attenuation applied to each source, Noisemap calculates the acoustic sound level at any point in the volume. The cartographic representation is done either in grey shades, or in color. The grey or color scale is itself controlable : maximum level, step.

From two acoustic treatment scenarios, the proogram lets you calculate a gain map, i.e. a map of the improvement of the noise level obtained between an initial state and acoustic treatment situation, or between two treatments (figure 3).

Adapted to volumes of any shape with any number of sources, it makes it possible to evaluate and to display the sound levels, and therefore to optimize the design of halls.

Fig 1 : Noisemap : existing situation
Fig 2 : Noisemap : situation after treatement

MAIN FUNCTIONS OF NOISEMAP

I - Geometrical modeling

  • Creation of the hall's volume, through the use of Autocad or not.
  • Display of the hall, various views, zoom, checking the envelope's constitution by an automatic checking algorithm.
  • Meshing the envelope : the user chooses the meshing fineness as a function of the acoustic treatments on each element.
  • Assigning the absorption coefficients on each part of the envelope.
  • Positioning the sources and the receiving points for the time decay and for the attenuation of sound with distance.
  • Positioning the noise sources.


Figure 3. Gain map between existing situation and after treatment.

II -Calculation of noise and gain map

  • Noise sources parameters : name, position, power, in service or not.
  • Calculation of the attenuation with distance and the time decay.
  • Calculation of the energy level received on any plane : noise cartography.
  • Calculation of the gain between two acoustic treatment situations.
  • Superimposition of measurements values and comparison with :
  • attenuation with distance,
  • time decay,
  • noise maps.