How does aeration in a hydraulic pump manifest audibly, and what does it indicate?

Aeration in a hydraulic pump, which is the presence of air bubbles within the hydraulic fluid, manifests audibly as a distinct knocking, rattling, or hissing sound emanating from the pump. This unusual noise is often described as sounding like gravel or small stones being pumped through the system. The sound is caused by the implosion, or rapid collapse, of air bubbles as they pass from a low-pre....