Kicking off the tech giant's annual developers conference, Google chief executive Sundar Pichai argued that its AI-powered digital assistant had the potential to free people from everyday chores.

Pichai played a recording of the Google Assistant independently calling a hair salon and a restaurant to make bookings -- interacting with staff who evidently didn't realise they were dealing with artificial intelligence software, rather than a real customer.

Tell the Google Assistant to book a table for four at 6 pm, it tends to the phone call in a human-sounding voice complete with "ums" and "likes," and sends you a message with the details.

"Our vision for our assistant is to help you get things done," Pichai told the conference in Google's home town of Mountain View, California.

"It turns out that a big part of getting things done is making a phone call."

"Many of us feel tethered to our phones and worry about what we'll miss if we're not connected. We want to help people find the right balance and gain a sense of digital wellbeing," Pichai said.

The conference opened with Silicon Valley facing a wave of criticism over issues such as private data protection, the spread of misinformation and the use of tech platforms for hate speech and violence, and with intense scrutiny of Facebook over the hijacking of data on millions of its users.

Pichai acknowledged the criticism while maintaining that Google's innovations are "helping us solve problems for our users."

"We're at an important inflection point in computing, and it's exciting to be driving technology forward," he said.

"It's clear that technology can be a positive force and improve the quality of life for billions of people around the world. But it's equally clear that we can't just be wide-eyed about what we create."

He added that "we feel a deep sense of responsibility to get this right."

Much of the focus was on Google Assistant, the artificial intelligence application which is competing against Amazon's Alexa and others.

Google Assistant is being taught to better understand people and interact with them more naturally -- and will be getting new voices, including one based on the voice of singer John Legend, as well as programming making it better at conversation.

"Thanks to our progress in language understanding, you'll soon be able to have a natural back-and-forth conversation with the Google Assistant without repeating 'Hey Google' for each follow-up request," Pichai said.