Tinnitus — a condition characterized by whooshing, ringing, buzzing and hissing noises in the ear — can be triggered by a variety of factors, including exposure to loud noises, inner ear damage and stress. And while experts say the stress of the pandemic could be linked to worsening tinnitus symptoms, there's growing evidence that the virus itself could also play a role. A study published Thursday in the journal Frontiers in Public Health found that 40 percent of people who had symptoms of Covid-19 reported a worsening of their tinnitus. The research included more than 3,000 participants who self-reported whether they had experienced changes in their hearing since the pandemic started. Around 250 participants reported Covid-19 symptoms, although only 26 had tested positive for the virus.