As Social Worker for LA County many times my voice was all there was to use to defuse sittuations or bring understanding to people in distress. Many times a different inflection or tone has brought a bad interview back to the realm of reality. My kids laughed and called it "the voice" either way it has served me well. I have also sold ice cubes to eskimos. My readings have been mainly in retirement and convalescent homes where the patients listened intently. They said they were entertained of course they were a captive audience.
I have never sold a recording however the tapes made at church readings and narrations were popular.
No professional training unless you include the School of Hard Knocks. Master there
Each project I have undertaken has been treated as a delight for me. I have a decent control of the spoken word and am pretty well read.
Reading to children is particularly rewarding as you see the understanding and interest light up their eyes.