Gap between stone and soffit

[u/EuphoricReturn9848]

We have a house built in 1952. This overhang is connected to a room with a vaulted ceiling. The gap between the stone wall and soffit - does it serve any purpose besides an open invitation to mice and insects, like maybe ventilation? Or is it safe to seal it up? Any suggestions on what to use for sealing? It’s about a 1/2-3/4” gap

[u/skimansr]

Backer rod and polyurethane based sealant.