After months of revelations and apologies, all the major smart assistant makers have revamped how they handle human review of audio snippets. Amazon Alexa, Google Assistant, Apple Siri, and Microsoft Cortana were all using third-party contractors to transcribe and vet recorded snippets, adding some human brain power to underlying machine-learning algorithms. But the backlash over the lack of transparency spurred new customer controls. And with the release of Apple's iOS 13.2 on Monday, you now have one more way to rein that data collection in.

Even if Siri isn't your smart assistant of choice, it's still a good time to take stock of how you have things set up on whatever platform you use. Each service has its own mix of options and controls. Here's how to take the human element out of Siri, Alexa, Google Assistant, and Cortana. Once that's done, tell a friend to do the same.

Siri

Apple paused human review of Siri user audio snippets at the beginning of August and published an apology later that month for the lack of transparency. Now, almost three months later, human review resumes, but it's opt-in and only with Apple employees rather than contractors.

With iOS 13.2, your Siri snippets no longer get passed along for human review by default. Now Apple asks you whether you'd like to opt in during the iOS 13.2 setup flow. If you make a mistake and opt in when you didn't mean to, or change your mind down the road, you can go to Settings > Privacy > Analytics & Improvements > Improve Siri & Dictation and toggle the switch off.

Crucially, even if you enable this data sharing, you can now delete all the audio Apple has collected from you at any time. To do so go to Settings > Siri & Search > Siri & Dictation History > Delete Siri & Dictation History to wipe everything out.

Alexa

Following significant blowback, Amazon was the first smart assistant company to centralize and expand its user controls for voice recording retention. You can review the voice recordings Amazon has stored for your account by going to Settings > Alexa Privacy in the Alexa app or through Amazon's website. There you can delete entries one by one, by date range, by device, or en masse. You can also delete recordings by device on the Manage Your Content and Devices page. When you're there, you can also enable voice deletion directly, creating a clean slate by saying "Alexa, delete what I just said," or "Alexa, delete everything I said today." To turn that on in the Alexa app or Amazon's website go to Settings > Alexa Privacy > Review Voice History.

To opt out of sending your Alexa recordings for human review, go to Alexa Account in the Alexa app then Alexa Privacy > Manage how your data improves Alexa and turn off Help Develop New Features and Use Messages to Improve Transcriptions.

Keep in mind that these settings control only what Amazon retains, and don't necessarily apply to third-party developers that may have collected your voice data through Alexa Skills.

Google Assistant

Google offers a number of ways to stop audio snippet retention or delete recordings. This page lays out the different flows for deleting or opting out in a desktop browser, on Android, or on iOS. To delete recording on desktop, open your Google account and choose Data & personalization in the left navigation panel. There, under Activity controls, choose Web & App Activity and then Manage Activity. Here you can scroll through the list of entries—those with an audio icon next to them include a recording and you can delete individual items one at a time. Or on this same page click the More hamburger menu in the upper right, choose Delete activity by and under Delete by date select All time. Then at the bottom choose Delete.