I hold one patent for acoustics, as shown below. It is basically a system for modulating the fan of a system chassis to generate an audible alert. Since the fan is usually the loudest component of a system, modulating its sound output creates a very recognizable noise. The idea is applicable to PCs, servers, desktops, networking equipment or any system with a fan.
|2009||US7489092 B1||Method and apparatus for enhanced alert notification|