FIG. 1 is a perspective view of an aural/visual signalling instrument showing my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is an end elevational view thereof;

FIG. 4 is a bottom plan view thereof; and

FIG. 5 is an opposite end elevational view thereof.

The broken line showing of the human hand in FIG. 1 is for illustrative purposes only and forms no part of the claimed design.