The paper presents a comprehensive treatment of the essential considerations involved in measuring the noise-generating characteristics of hydraulic components. The need for the reduction of noise levels for all types of hydraulic machinery is discussed from the manufacturer's point of view. The mechanical and fluid dynamic aspects associated with hydraulic components which create undesirable and damaging noise levels are described. Special emphasis is placed on quantitative methods for establishing and comparing noise levels of operating hydraulic components. A cursory review of the necessary facility requirements and measuring techniques is included.