For Blackjack: You move to the first door, listening only briefly, and hear a lot of voices speaking in the Goblin language on the other side. You then move to the second door to listen, but don't get a chance to really hear anything because the rest of the party turns the corner, and Hagar shouts at you.
As the rest of the party turns the corner, Hagar shouts at Blackjack, who you now see is further down the hall. Several things happen all at once.
First, you see that there is a door in the hallway just to the north of you. It slams open, and you see a large group of goblins inside. Two are obviously guards who are now standing right in the doorway, and they attack Angar and Amethist who are the two closest to them.
Second, you see that Blackjack is crouching at a second door further down the hallway, ear to the keyhole, listening to see if he can hear anything through it. Hagar's shout startles him, and he turns to look at the rest of the party.
Third, behind Blackjack, at the end of the hallway, the stone wall moves, and a secret door opens and four goblins jump out and attack Blackjack from behind.
Take a look at the map to see where everyone is standing.
Because of your good Surprise rolls, no one is surprised enough that you can't attack or defend in the first round of combat. Hagar and Whisper will need to use missile weapons to attack in the first round.