IEC 60534-8-2:2011 includes the method for measuring the sound pressure level due to liquid flow through a control valve and the method for determining the characteristic increase of noise due to the onset of cavitation. It also defines the equipment, methods and procedures for the laboratory measurement of the airborne sound needed to determine these characteristics. Two methods are provided for testing the noise generating characteristics of control valves. The first is a uniform method of measuring the radiated noise from the valve and the associated test piping including fixed flow restrictions through which the test fluid (water) is passing. The second is a procedure for measuring the sound pressure levels within pipe systems upstream and downstream of the valve under fixed operating conditions. This second edition cancels and replaces the first edition published in 1991 and constitutes a technical revision that includes internal noise measurement.