ISO 20998-1:2006描述了测定分散在液体中的一种或多种材料相的尺寸分布的超声波方法。胶体、分散体、泥浆和乳液在ISO 20998-1:2006的范围内。此类分析的典型粒径范围为10 nm至3 mm，但也成功测量了该范围以外的颗粒。根据连续相和分散相之间的密度对比，可以测量分散相的浓度，范围为0.1%（按体积计）到50%（按体积计）或更多。这些方法可用于监测粒度分布的动态变化，包括浓缩系统中的凝聚或絮凝。

ISO 20998-1:2006 describes ultrasonic methods for determining the size distributions of one or more material phases dispersed in a liquid. Colloids, dispersions, slurries and emulsions are within the scope of ISO 20998-1:2006. The typical particle size for such analysis ranges from 10 nm to 3 mm, although particles outside this range have also been successfully measured. Measurements can be made for concentrations of the dispersed phase ranging from 0,1 % by volume up to 50 % or more by volume, depending on the density contrast between the continuous and the dispersed phases. These methods can be used to monitor dynamic changes in the size distribution, including agglomeration or flocculation in concentrated systems.