Strumming...AGAIN....
General mountain dulcimer or music discussions
A while back I was playing around in a music store and had an acoustic bass guitar on my lap. I don't play the bass but can fake it after decades of guitar playing. I was playing the bass line to Taj Majal's version of "She Caught the Katy" and was trying to sing, too. But I couldn't do it. When I expressed frustration, explaining that I can play guitar and sing with no problem, the owner of the store replied that I had to "own the bass" before I'd be able to sing along to it. I thought at first that he was trying to sell me the instrument, but what he meant was that before I'd be able to accompany myself singing I had to really know the bass line perfectly without having to think about it at all.
I think that's right. You can only work on one thing at a time. So if you have to think about where to fret the fingerboard or how you want to vary your vocal line, you can't also be thinking about strumming or picking with your right hand. You have to know one part so well that it's automatic, allowing you to think about the other part.
I don't know if there are any shortcuts. Just repetition. I developed a steady, back-and-forth strumming pattern on the guitar many years ago. It enabled me to become a passable mandolin player pretty quickly and also sped up dramatically my improvement on the dulcimer. I sometimes mess up my right hand in that I don't play the exact rhythm I had intended, but I never get off beat. My right hand just goes back and forth, out, in, out, in. Sometimes I strum all three strings, sometimes just two, sometimes I pick a single string, and sometimes I skip a beat and don't hit any strings, but my hand feels that back-and-forth movement anyway. In fact, if you see me play a half note you will often see an extra little jerk in my hand as I move just to keep the beat even though I am not playing a note. Before you will be really comfortable singing, your strumming hand has to become automatic. Not robotic, for you can still swing and play with feeling, but it has to be something you don't have to think about at all.
And think of how quickly you could learn new tunes if you only have to think about your left hand!
I would suggest muting the strings of your dulcimer with your left hand so that when you strum them you just hear that vamping scratch. Then put on your favorite CD or turn on the radio. Strum along. Find the beat and just strum out once per beat. Once you're comfortable, add the in strum, counting 1 & 2 & 3 & 4 & and strumming out-in-out-in-out-in-out-in. (You can reverse those outs and ins, but you have to reverse them all; be consistent!) Do that over and over and over. Once you're comfortable strumming in both directions, then try to replicate the rhythms you hear. It might involve skipping, accenting, or muting strums, but when you can hear a rhythm and replicate it with your right hand (always maintaining that steady, back-and-forth motion), then I think you'll be ready to sing or play and not worry about that right hand at all. By then you'll "own" it.