Sonova Holding AG is an internationally active Swiss group of companies headquartered in Stäfa that specializes in hearing care. The Sonova group operates through its core business brands Phonak, Unitron, Advanced Bionics, AudioNova and the consumer product division of Sennheiser. According to market analyses, the group and its brands held an estimated 24% of the global hearing aid market in 2013. As of 11 September 2022, Sonova was a component of the Swiss Market Index.Wikipedia