David AI Labs Inc. a startup selling audio data sets to help train artificial intelligence models, has raised $50 million from investors in a new round of funding — signaling a growing market for startups that provide the building blocks for AI development.David AI was founded by former Scale AI employees Tomer Cohen and Ben Wiley, and has reached a valuation of $500 million in the latest round, including dollars raised, according to people familiar with the matter. That valuation is about four ...