I'm also in the "I haven't sung since childhood" camp. Sounds like there are a lot of us. I just tried humming a chromatic scale into the tuner, and while the tuner at least recognized the pitches and showed them to me in the proper order, I have some work to do to get to a 20-cent band around each note! I did take voice lessons once for a few months when my job put me in a position where I knew I would have to sing, and got better with pitch for a while. But my ear isn't naturally particularly discriminating, which I'm hoping isn't a fatal flaw when it comes to playing music. In high school my sax quartet won some awards, so at least at some times in my life I've been able to work at it and develop some sense of pitch.As such I am as untrained a voice as you can have. As an experiment, I took my timing app and did a blind test of humming a chromatic and was able to hum a chromatic for seven steps between 0 cents and 20 cents sharp.