High levels of machine noise result in health issues for those people exposed to the machine for extended periods. Machine noise is becoming a more significant design consideration, often because of legislative requirements. Decanting centrifuges are machines with a rotating bowl. They have a number of noise sources, the most significant being structural noise, vortex/turbulence noise and siren noise. Due to the size, mass and speed of the rotating bowl, the bowl is the main source of structural noise. The structural noise is produced by all surfaces that are directly coupled to the bowl’s bearings. Due to the speed of rotation of the bowl, the turbulence from the various trailing edges generates broad spectrum vortex noise. Siren noise due to air flow through the bowl also generates significant noise especially at the lower harmonics of the bowl rotation frequency. Strategies to reduce decanter machine noise include: • Decoupling the surfaces of the from the main bearings of the rotating bowl and hence reduce the amount of structurally transmitted noise. • Smoothing the surface of the bowl to minimise the edges that produce vortices that are shed and produce vortex/turbulence noise. • As siren noise is produced due to flow through the rotating bowl, which is integral to the function of the decanter, the exit ports should be designed so that the noise is produced within parts of the sound spectrum that have low noise levels.