Former Brighton defender Upson and Charlton Athletic goalkeeper Hamer are both Bosman signings.
"Matt Upson has plenty of experience," Pearson told the Leicester Mercury.
"He is in the latter stages of his career but what he comes with is know-how. He comes in off the back of a fantastic season on a personal level for him.
"Ben is also a promising young goalkeeper.
"I think it is important we add the right players to the squad.
"They have come in on frees but it depends on how people want to perceive it. If a player cost us £5million, then that might change people's perceptions.
"We are pleased with the players we have brought in. They have experience."
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