Mr. Rain’s HAL has become the default reference, not just for the voice, but also for the humanesque qualities of what a sentient machine’s personality should be. Just ask Amazon’s Alexa or Google Home — the cadence, the friendly formality, the pleasant intelligence and sense of calm control in their voices evoke Mr. Rain’s unforgettable performance. As we warily eye a future utterly transformed by A.I. incursions into all aspects of our lives, HAL has been lurking.

To Scott Brave, the co-author of “Wired for Speech: How Voice Activates and Advances the Human-Computer Relationship,” HAL 9000 is a mix between a butler and a psychoanalyst. “He has a sense of deference and of detachment,” Mr. Brave said, adding that he saw a ripple effect on, for example, the iPhone’s virtual assistant. “When I listen to something like Siri I feel there is a lot in common.”

Even when Kubrick was making the film, the director sensed HAL’s larger implications. He said in a 1969 interview with the author and critic Joseph Gelmis that one of the things he was trying to convey was “the reality of a world populated — as ours soon will be — by machine entities that have as much, or more, intelligence as human beings. We wanted to stimulate people to think what it would be like to share a planet with such creatures.”

So how was this particular creature created?

The “2001” historian David Larson said that “Kubrick came up with the final HAL voice very late in the process. It was determined during ‘2001’ planning that in the future the large majority of computer command and communication inputs would be via voice, rather than via typewriter.”