Strange animal noises in my woods lastnight.?

I live in Eastern Berks Co. in Pennsylvania , Lastnight i was sitting watchingt v and i heard something walking in the woods..was very loud..i went out to look nothing around about 15 min later i heard it again but this time it was in front of my house...my house is surrounded by woods...again i went out and seen or heard nothing..so 15-20 min later i heard this not a screech but a loud noise..so i turned the tv down and heard it again...was a shriek but not an owl i have owls here i know what they sound like..but this made like a high pitched yell then followed by a very low pitched yell...this went on for 3-4 minutes...my dog just sat staring into the woods and growled but didnt go after whatever it was..it stopped and about 2 min later u could hear it walking away...so it wasnt a bird of any sort...and i dont know of any animals in this area that make this noise...any ideas of what it may have been or anyone know of a site that has noises of animals here in eastern PA i can compare it to...ty for ur help