Abstract: A sorting method is disclosed in which particles suspended in a fluid are conducted in a closed duct and pass a measurement location in which particles to be selected trigger a signal by a sensing device. At a downstream fork, a pressure wave generated in response to the signal diverts the stream containing the particles from one branch to the other. An apparatus for carrying out this method is disclosed and includes a supply duct for the particle stream, a measurement duct, a measurement position in the measurement duct, a fork downstream of the measurement duct leading to a sorting branch duct and waste branch duct, and a pressure wave generator which is disposed in one of the ducts leading away from the fork.