A study is being undertaken in order to gain a better understanding of how compressor noise is produced. To facilitate mathematical analysis, the noise-generating mechanisms of axial-flow compressor blades have been investigated using flat blades. Analytical expressions are given for calculating the compressor noise due to blade thickness, loading, and vortex shedding. Measured values of compressor noise show good agreement with analytical predictions. It has been found that the lift, or loading noise, dominates the blade thickness noise. Rotor-stator spacing is an important parameter in rotor noise generation.