Austin Scelzo and fiddle at WNHH FM. Austin Scelzo hit the two bottom strings of his violin, struck a couple higher notes, launched a high-lonesome lament that seemed to stretch back eight decades to rural Appalachia.Trouble in my soulI know it’s wrong But it’s feeling so good …Did Bill Monroe originally sing this? Was it a gospel number repurposed for bluegrass barn dances? It sounded as though it leaped from an old vinyl 78, minus the scratches.Got a bad desireAnd it’s coming strongBeen trying to chase this feeling away for so longWhatever it was, Scelza was angel wrestling.Take away my sorrowWash it in waterI need healing in my soul …Scelzo fiddled and sang the song Thursday during an appearance on the WNHHFM’s tiniest-of-all-tiny desks ​“Acoustic Thursday @Studio 51” program.The song is called ​“Trouble in my Soul.” ​“Father of Bluegrass” Bill Monroe never sang it. In fact, Scelzo wrote it, true to bluegrass tradition.Scelzo, a 29-year-old professional musician and teacher who grew up in Wallingford, wrote the song in response to episodes in which he tried to square his Christian commitment with new life experiences. He continues to live with fellow members of Danbury-based nondenominational Community of the Cross, where he dived deeply into a spiritual life while also cultivating his musical chops as a Western Connecticut State University student.He is one of three members of On The Trail, a regional bluegrass band scheduled to perform Sunday at a benefit for New Haven’s Downtown Evening Soup Kitchen (DESK). (The music begins at 4:30 at Bethesda Lutheran Church, 305 St. Ronan St.) ​“Trouble in my Soul” is among the originals that will appear on the group’s upcoming album Where Do We Go From Here.Scelzo plays numerous instruments, wades in a wide array of musical genres. Bluegrass fiddle is his forte.His musical journey weaves in and out of his spiritual journey, he said. Sometimes, playing can feel like praying.“Music of any kind, if you can get into that space, is a spiritual practice. And there’s moments of magic and music that I think you can feel when all the ingredients are right,” he reflected.In between performing on ​“Acoustic Thursday,” Scelzo spoke of how, just as in ​“Trouble in My Soul,” the sacred and profane permeate and push up against each other in bluegrass music itself.“If you hear early first generation bluegrass, there was a lot of just a capella singing, or singing with just one kind of guitar, where the focus is on the words. They’re taken right out of four-part hymnal books that you would have heard in the churches back then,” Scelzo noted.“That’s been a running element of the bluegrass music, even until today. If you go to a lot of bluegrass festivals, they still have gospel hours in the morning where you perform like a whole hour of this, this kind of music.”Scelzo completed his ​“Acoustic Thursday” set with a rousing number that does in fact date back generations: the traditional ​“Gospel Plow.” The song began life as an African-American spiritual. Bluegrass and folk musicians have returned to it time and again. The chorus — ​“Keep your hand on the plow / Hold on” — became ​“Keep your eyes on the prize / Hold” as the song morphed an iconic Civil Rights Movement song. At each step, the world we walk each day marched alongside the world beyond.Click on the above video to watch Austin Scelzo perform unplugged on WNHHFM’s ​“Dateline New Haven” programPrevious ​“Acoustic Thursday @ Studio 51” performances:• Brandt Taylor & Chris DePino• Shellye Valauskas and Dean Falcone• Brian Ember• Ceschi• Wally• Sketch Tha Cataclysm• MJ Bones• Johnathan Moore• Charlie Widmer• Sam Carlson• Steve Mednick