When applied to oceanography, the natural sound waves produced by the wind and currents create ambient noise, which is comparable to ambient light. An underwater target will perturb this ambient noise to produce "noisy" signals, just as ambient light reflects off objects in a room. Even though the ambient noise does not come from a specific source as in conventional sonar imaging, it can still "illuminate" objects.
應用到海洋探測上，海洋學者將海洋中因為風、水流造成的自然聲波當作背景，正如密閉的房間；當有某目標物擾動聲波背景傳出雜訊，就像屋內的散射光，雖不是特定波源，仍可用來反射物體。