I've never heard any barking on the previous flights I've been on. On time though when I was flying Delta Song, the flight attendant was really snapping at a young lady in front of me. She had a miniature yorkie in a carry on and she was just letting him pop his head out of the soft carrier to be comforted. Everytime the flight attendant (male) saw this he would stand there and insist that she zip the carrier shut. The young woman pleaded with him that her pup couldn't breath and she wasn't letting him out she was just letting his head pop out. The flight attendant got very angry! He was like "If I see the head of that dog outside of the carrier one more time, you will suffer the consequenses upon landing!" He intentionally walked back and forth throughout the flight to make sure the little dogs head was in the carrier. I thought he was really kinda mean!