I agree with the above. Time and patience and he'll start to understand his new world. It's a natural reaction on your part to comfort him when he seems scared but don't. Don't say things like "It's alright" and "Whose a good boy" and giving him a cuddle or stroking him etc. as that will reinforce that he's right to be scared. Ignore any scary noises, carry on with what you were doing and then give him a treat when he's calmed down again.