Cal. Bus. & Prof. Code § 2538.20

It is unlawful for an individual to engage in the practice of fitting or selling hearing aids, or to display a sign or in any other way to advertise or hold himself or herself out as being so engaged without having first obtained a license from the board under the provisions of this article. Nothing in this article shall prohibit a corporation, partnership, trust, association or other like organization maintaining an established business address from engaging in the business of fitting or selling, or offering for sale, hearing aids at retail without a license, provided that any and all fitting or selling of hearing aids is conducted by the individuals who are licensed pursuant to the provisions of this article. A person whose license as a hearing aid dispenser has been suspended or revoked shall not be the proprietor of a business that engages in the practice of fitting or selling hearing aids nor shall that person be a partner, shareholder, member, or fiduciary in a partnership, corporation, association, or trust that maintains or operates that business, during the period of the suspension or revocation. This restriction shall not apply to stock ownership in a corporation that is listed on a stock exchange regulated by the Securities and Exchange Commission if the stock is acquired in a transaction conducted through that stock exchange.