Intelligibility
Prediction of the acoustic quality
of activity spaces and tertiary sector rooms
Ó Tisseyre & Associés
IDDN FR 001 420 005 00 SP 1999 000 30500


Saint Jean d'Angely swimming pool

Presentation - Geometric modeling - Calculation - Activity room module - Open space module

PRESENTATION

The INTELLIGIBILITY software simulates the acoustic behaviour of a hall with the help of a meshing technique, so allowing a constraints analysis. It is based on the diffuse reflexion of sound hypothesis on the elements.
Adapted to volumes of any shape, it makes it possible to display and evaluate the acoustic quality, and therefore optimize, the design of the hall under study.

Two main families of volumes may be studied :

  • Activity halls : swimming pools, restaurants, airport and station halls, shopping centres, etc…
  • Open space type volumes, telephone exchange…

----------------

Modeling the hall

Each surface is represented by a polygon, to which an absorption coefficient is assigned.
A global assignement can be carried out on a whole set of surfaces with the same coefficient. The user can mesh each surface specifically, with a fineness selected according to the desired analysis precision.

Fig 1 : Model of the Atocha station - Madrid

----------------

GEOMETRIC MODELING

  • Creating the hall volume, possibly using Autocad

  • Displaying the volume ; various views, zoom, checking the constitution of the surfaces (automatic verification algorithm).

  • Meshing the surfaces : the user chooses the meshing fineness as a function of the specific acoustic constraints on each surface.

  • Setting the acoustic absorption coefficients on each surface.

  • Positionning sources and receiving points (or plans).

----------------

CALCULATION

  • Sound pressure levels, T60, echogram.

  • Attenuation of sound with distance.

This model calculates the ambiant sound levels, based on the database of acoustic powers due to each type of occupant as a function of its activity : restaurant, swimming pools, entrance hall, open space office, telephone exchange etc.

----------------

ACTIVITY ROOM MODULE

Mastering the acoustic atmosphere

Places such as restaurants, entrance halls, station or airport halls, sporting centres, receive a large number of occupants, each one generating some noise due to its own activity. This may lead to a high sound pressure level as a result of the desire to be understood, hence to emerge from the ambiant noise, which under certain circumstances may trigger what we name the cocktail party effect. This effect corresponds to an " acoustic overbidding " on the part of each person talking with its neighbour. The sound level increases and in turn makes speaking uncomfortable ; the place is then experienced as noisy, this should therefore be avoided.


Fig 2 : Ambiant sound pressure levels in the Caldea thermoludic centre - Andorra

Fig 3 : Frankfurt HILTON atrium

Fig. 4 : Attenuation with distance, Frankfurt HILTON atrium


Calculation of the temporal decay

Classic or statistical methods provide only a partial response to the calculation of the time decay of sound. The INTELLIGIBILITY software automatically provides an echogram over the early 300 milliseconds. Possible coupling between rooms can be made visible (Fig. 4).

----------------

OPEN SPACE MODULE

Calculation of the ambiant sound level

From the location of the occupants, the software calculates the sound pressure level, taking the effect of absorbing or reflecting screens into account.


Fig 5 : Sound pressure level map in an open space office, due to the sole activity of the commercial office.
TECHNAL open space office

Cartography of intelligibility

Control of intelligibility between two persons in the midst of a meeting room.


Fig 6 : Intelligibility map in % phonemes (meeting room within an open space office)
Niveaux sonores ambiants - Open space en activité
Free wall non traités, armoires traitées, pontets traités bi-face

Plan du local étudié

Présentation du volume et des traitements


Niveaux sonores ambiants - Free-wall traité Fonctionnement type call center


Performance d'isolement entre box, version n°1 : 10 dB(A)

Intelligibilité inter-postes

----------------

Main modelizations carried out to this day :

Large volumes : halls gare de l’Est, Tramway Strasbourg, Frankfurt Hilton, Singapore airport.
Swimming pools and sport centers : Vitrolles, Le Perreux, Lambesc, Fort-Mahon, Toulouse, Sète, Evry, Auxerre, Saint-Jean d’Angely, Caldea thermoludic centre.
(Open space) offices : France Telecom Toulouse, Washington Plazza Paris, Roissy Park Paris,…