User: Who is the company Sonova
Assistant: Sonova Holding AG (Phonak Holding AG before 1 August 2007) is an internationally active Swiss group of companies headquartered in Staefa that specializes in hearing care (hearing instruments, cochlear implants, wireless communication). 

The Sonova group operates through its core business brands Phonak, Unitron, Hansaton, Advanced Bionics, AudioNova and Sennheiser. It is one of the largest providers in the sector worldwide. The group and its brands hold 24% of the global hearing aid market in sales. As of 11 September 2022, Sonova is a component of the Swiss Market Index.