A University of Texas at Dallas researcher has published a series of papers about her investigations into the nature of primary muscle tension dysphonia (pMTD), a voice disorder that has proved hard to quantify or link to a cause. Many patients also have hoarse and rough vocal qualities and difficulties with vocal projection,” Shembel said. The findings showed few differences between the two cohorts, with motion capture footage indicating only increased variability in movement in the pMTD patients. “We think patients with pMTD are perceiving more vocal effort, strain and fatigue because their sensory system is less precise, less stable,” she said. “People with muscle tension dysphonia have a higher prevalence of conditions like fibromyalgia, irritable bowel syndrome and other central sensitivity disorders,” she said.