OpenAI CEO Sam Altman was a star speaker at the annual AI for Good conference Thursday, addressing the U.N. telecommunications agency’s annual gathering about how to tap the societal promise of artificial intelligence technology.

But Altman spent part of his virtual appearance fending off thorny questions about governance, an AI voice controversy and criticism from ousted board members.

Altman’s appearance to talk about AI’s benefits comes as his company has been battling a rising tide of concern about its business practices and how it handles AI safety.

Altman talked at length about themes related to AI in an interview with Nicholas Thompson, CEO of The Atlantic. But he avoided answering questions about a few sensitive topics, such as explaining the ChatGPT-maker’s use of an actor’s voice that resembled Johansson’s.