It is important to consider whether it is the conch itself that holds the authority to speak - or whether the right requires something more (personal integrity, a natural sense of leadership/authority of one's own?)
After all, remember it is actually Piggy who first finds the conch, yet it does not do him any good in terms of creating influence or charisma - although he is an ideas man. It is Ralph who gets a sound out of the conch by blowing it like a trumpet - and Ralph who has all the others listen to him,albeit with Jack hard on his heels.
It seems that the conch didnt confer power on just anyone who held it-it didnt have any magical properties - the authority it 'gives' is something we have put onto it as a symbol.The conch comes in, and goes out, with Piggy.
The symbol of authority in Lord of the Flies is the conch. The conch represents order in an uncivilized world. Whoever holds the conch holds the power and is the one that is able to speak. It is able to summon and bring the boys together when it is blown. The conch slowly loses its power as the boys descend deeper and deeper into the pit of savage rule. Once the conch is destroyed with the death of Piggy, so is all order on the island. They are now given over to their savage ways and they cannot go back.