Humming noise from front axle/Transfer case

My 4WD Blazer has regular tires...but it sounds like I have big mudders on it. Not squeeling. I thought it may was stuck in 4WD but not the case after jacking all 4 tires and in drive. Any suggestions?? Thanks.

Does the noise change with MPH?
Does it change when you turn the wheel right or left a little?
Can you hear it more on coast or pull or all of the time?
Hot or cold make any duifference?
All fluid levels ok?
Did it start all at once or sneak up on you?
How long has it been doing it?
Lot of questions but we can not hear it over the net.
So describe all you can about it.
What year is it and how many miles on it?
MT

Thanks for your reply. I've come to the conclusion my right frony wheel bearing is bad. With the front end jacked up I spin the wheel and hear something unusual on the right as where the left seems O.K. I had just replaced both front 5000 miles ago due to the speed sensors gone bad . The ABS was going crazy. So much for new parts. I do have reciepts. If anyone has anything to add to this please do. Thanks

You are welcome.
You may be on the right track.
Any play in it?
Always use BCA or Federal/National or good brand bearings.
Lot of 90 day wonder el cheapo bearing running around making a lot of noise after a while.
Good Luck
MT