Almost 48 million Americans suffer from some sort of hearing loss—and while many could benefit from a hearing aid, some are reluctant to wear them for aesthetic reasons. “There is a lot of stigma around hearing loss,” says Christian Gormsen, whose company, Eargo, spent eight years building a device that works almost entirely out of sight. Eargo Max ($2,450) is a rechargeable hearing aid made specifically for people with mild to moderate hearing loss. Traditional hearing aids wrap around the ear and typically require several fittings and appointments with audiologists. Eargo Max, by contrast, fits comfortably inside the ear and can be bought online with help from a specialist. So far, customers have been receptive: Eargo expects to end the year with 20,000 active users.