This part of ISO 13099 describes in general electroacoustic effects that can be defined as high frequency electrokinetic phenomena. Particular attention is given to two methods of measurement of electrophoretic mobility of particles suspended in a liquid at high concentration above 1 % v/v, colloid vibration current (CVI)[2] and electric sonic amplitude (ESA),[3] [4] respectively. Estimation of surface charge and determination of zeta potential can be achieved from measured electrophoretic mobility using proper theoretical models, which are described in detail in ISO 13099-1.