I was working this weekend on the transcript of a conference that Ollie Johnston gave in the 70s at CalArts and that will appear in a future issue of Walt's People thanks to Darrell Van Citters (who taped it and sent it to me) and Nancy Beiman (who transcribed it). I found this excerpt about the creation of Baloo fascinating:

[This next slide of Baloo... we hadn't arrived at a real personality yet. He's still just any bear. We thought this would give him kind of a nice, exciting feeling (to make him a yellow bear). Walt didn't go for it. So we tried a brown bear and he didn't like that, either. He said, "Why don't we try a grey bear?" We tried the grey bear and he thought that fit better into the jungle setting. So that's what we went with. Originally, the bear was only going to be in a very small part of the picture… just a cameo role. We had tried several different kinds of voices on the guy. It's very difficult to find a voice to fit the real character. We tried kind of a bungling comedian who we thought wasn't too bad. We tried kind of an Ed Wynn type voice. Then we thought maybe if we get some of these UCLA exchange students who have been to India, we might find something unusual in them that would give a different quality to the bear. Well, we tried that and it didn't work out. Then one day Walt said, "Say, I talked to Phil Harris at a cocktail party, and I told him I'd like him to come out and try for this."

Phil Harris came out. We were kind of horrified at that thought, but we decided to go along with it. Phil Harris said, “Gee, I can't do this. You want me to go 'Doobie, doobie, Doobie?' That's not my stuff and besides, I don't know how to be a bear!"
Anyway, we got him to try a few lines. We told him not to worry about being a bear but to just be himself. He did, and we animated a few scenes to his voice. When he came back he looked at it and said, "Gee, this'll make me immortal." In a way, it did. He never had any kids interested in him before. It was always the drunks who would come up to him on the streets. Now the kids come up and grab him by the arm because he brought a character to life. I think one of the big reasons was that he had a way of saying things that was his own. He didn't just read off our dialogue. He changed it into his own vernacular and made it sound like this character was really thinking. That's very important.]