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. Unless an adventurer has reached level 100, they must use a ram's horn to shout.
The person doing the shouting will not be recognised unless the hearer is a God or has the recognition skill in Vision. What a shout sounds like will be characterised by the shouter's level. For example, a lower-level person might have "a weak and feeble voice" while a higher-level adventurer might shout with "a powerful female voice".
It should also be noted that a shout can only be of a finite length. Attempting too lengthy a shout will cause an adventurer to momentarily pass out.