There's a noticable pause. The - whoever is in charge is thinking. Possibly how to relate information, not the information itself.

"You should focus on gathering more heart crystals -"

From the merchant, yelled through the wall: "-watching-"

Mumble mumble, "- deep underground."

Merchant: "- can hear -"

"There is something about it that causes monsters -"

"Check out - dirt blocks!" adds the merchant.