A shout is a form of adventurer communication. When an adventurer shouts something, his or her voice is projected so that everyone on the same continent (not plane) will hear it unless they are deaf or have the shout channel turned off. In order to shout, all adventurers must use a ram's horn except those who have reached level 100.
The person doing the shouting will not be recognised unless the hearer is a God or has the recognition skill in Vision. Otherwise, what a shout sounds like will be characterised by the shouter's level. For example, a lower-level person might sound like "a weak and feeble voice" while a higher-level adventurer might sound something like "a powerful female voice".
It should also be noted that a shout can only be of a finite length. Attempting too lengthy a shout may cause an adventurer to momentarily pass out.