ISO 11821:1997

This International Standard specifies methods for evaluating the in situ sound attenuation performance of a removable screen, either indoors or outdoors. This engineering grade method is based on an insertion loss measurement that can be carried out either with shielding of the actual sound source(s) or using an artificial sound source.

The sound attenuation performance achieved by such a screen, as evaluated by the present International Standard, depends on:

• diffraction around the edges of the screen;
• transmission through the components of the screen;
• absorption of the panels of the screen, as well as in its surroundings;
• the room in which the screen stands if indoors.

When a specific work station is to be shielded, the in situ sound attenuation value describes the effect of the screen. However, when a complete area is to be shielded, the performance of the screen will vary depending on the positions used for measurement. Therefore, it is recommended that the maximum and minimum values of sound attenuation are given. The sound attenuation performance is determined in terms of insertion loss.

When assessing the performance of a screen located indoors, the room geometry and reflections from walls, ceilings and room fittings will influence the performance. As a consequence, the comparison of screen performance can only be made if the test conditions are identical.

This International Standard is applicable to screens with height and length greater than 1,5 m. However, it may also be used for smaller screens provided that the interested parties come to an agreement on this.

As environmental conditions can affect the measurements outdoors, it is recommended that measurements should be restricted to within 25 m of the screen. However, measurements may also cover a greater distance provided that the interested parties come to an agreement on this.

Differences can occur between in situ test results. Therefore, comparison of the performance of different screens can be made only on the basis of data based on the same measurement method performed at the same location.

This International Standard applies to a complete screen only and not to individual components from which it is made. Sound insulation and sound absorption for screen components (such as panel elements, doors, windows) should be measured according to other relevant standards.

This International Standard is not applicable to open plan offices screens nor to outdoor barriers dealing with community noise. It is also not intended for qualification purposes.