NBN ISO 23351-1:2021

This document specifies a laboratory method to facilitate the comparison of furniture ensembles and
enclosures with respect to their ability to reduce the speech level of the occupant speaking inside the
product.
In this method, the sound power level is measured in two scenarios: 1) without the product, and 2) with
the product. During scenario 1), the test signal is produced by the sound source in an empty room while
the product is absent. During scenario 2), the test signal is produced by the sound source inside the
product in the occupant’s position. Level reduction is the difference of the sound power levels measured
in the two scenarios in 1/1-octave frequency bands from 125 Hz to 8 000 Hz. Speech level reduction is a
single-number quantity that expresses the corresponding reduction in A-weighted sound power level of
standard speech within the entire frequency range from 125 Hz to 8 000 Hz.
The method is applicable for entire furniture ensembles or enclosures, which form a unity that serves
one or several occupants, and which are also used to provide improved speech privacy.
This method is not intended for single components used in workstations, such as a screen, a storage
unit, a table, a luminaire, a cupboard, a bookshelf, a standard chair, a wall absorber or a ceiling absorber.