The Associated Press
MOUNTAIN VIEW, Calif. — When Google first introduced its phone-calling digital concierge Duplex in May, some thought it sounded too human. Others worried that it would secretly record calls with people.

The search giant says it has been working to address these concerns.

For starters, Google says that the bot will identify itself as an automated assistant upfront and will disclose that it's recording calls. Human operators will be standing by as backup should a call go off the rails.

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As for Duplex's tendency to use speech fillers like "ums" and "ahs," Google notes that this technique improved the assistant's ability to book appointments by interacting more naturally with humans on the other end of the line.

The search giant provided these and other details in a demonstration for reporters Tuesday ahead of the system's gradual rollout this summer.

The company is taking great pains to assure that Duplex conforms to a set of principles around artificial intelligence it released earlier this month. Among them: only develop tools that are socially beneficial and that incorporate privacy by design.

"We're not trying to trick people," Scott Huffman, Google's vice president of engineering for the Google Assistant, told reporters. To demonstrate the point, he played a recording of an early Duplex prototype in which a computerized, British-accented male voice tried to book a restaurant reservation for four, and filled an awkward silence with an off-kilter "Hello."

"The system didn't sound very good," Huffman said. "People would hang up on it. They got uncomfortable with the conversation. The team began to iterate on, 'How do we make it sound more natural?' As they did that, with every step, we found that our success rate went up."