The current artificial intelligence (AI) boom has been the biggest driver of the stock market's gains over the past couple of years, and two companies that have seen phenomenal gains from AI are SoundHound AI (SOUN -5.82%) and Nvidia (NVDA 0.53%). Shares of SoundHound have soared 310% over the past three years, while Nvidia's stock has skyrocketed 910%.While both are AI stocks, they each play a unique role in the market, with SoundHound selling conversational AI services and Nvidia designing some of the mos ...