For future review, Apple said users will have the option to opt-out. (Tony Gutierrez/AP)

Apple and Amazon announced Friday they would curtail the use of humans to review conversations on their digital voice assistants, a move that gives users more privacy controls over their communications.

Apple said it would stop using contractors to listen in on users through Siri to grade the voice assistant’s accuracy after an Apple whistleblower had told the Guardian that the contractors responsible for “grading” the accuracy of the digital assistant regularly overheard conversations about doctors’ appointments, drug deals and even couples having sex. Their job was to determine what triggered Siri into action — whether the user had actually said, “Hey, Siri” or if it was something else, such as the sound of a zipper.

Apple said it would suspend the global analysis of those voice recordings while it reviewed the grading system. Users will be able to opt out of reviews during a future software update.

“We are committed to delivering a great Siri experience while protecting user privacy,” said Cat Franklin, an Apple spokeswoman, in an email to The Washington Post.

Later Friday, Amazon updated its privacy policy regarding voice recording made by its Alexa service. Amazon will now let users opt out of having humans review those recordings, selecting a new option in the settings of the Alexa smartphone app. Amazon employees listen to those recordings to help improve its speech-recognition technology.

The company tweaked Alexa privacy features in May, giving users the ability to delete recordings of their voices. And users could already opt out of letting Amazon develop new features with their voice recordings.

Many smart-speaker owners don’t realize that Siri, Alexa and, until recently Google’s Assistant, keep recordings of everything they hear after their so-called “wake word” to help train their artificial intelligences. (Amazon founder Jeff Bezos owns The Washington Post.) Google quietly changed its defaults last year, and Assistant no longer automatically records what it hears after the prompt “Hey, Google.”

Apple said it uses the data “to help Siri and dictation . . . understand you better and recognize what you say,” Apple said. But this wasn’t made clear to users in Apple’s terms and conditions.

“There have been countless instances of recordings featuring private discussions between doctors and patients, business deals, seemingly criminal dealings, sexual encounters and so on,” the Apple whistleblower told The Guardian. “These recordings are accompanied by user data showing location, contact details, and app data.”

In response, Apple said that the recordings accounted for only 1 percent of Siri activations and lasted just a few seconds. They also were not linked to users Apple IDs.

Apple contractors in Ireland told the Guardian that they had been sent home for the weekend and were told it was because the global grading system “was not working.” Managers stayed on site, but said that no one knew how the system’s suspension would affect their employment.

The Apple whistleblower said the Apple Watch and the HomePod, a smart speaker, were especially prone to accidental activation. A 2018 study from investment firm Loup Ventures found that HomePod’s Siri was accurate in answering standardized questions 52 percent of the time.