Most smart speakers and assistants—Amazon’s Alexa, Google Assistant, etc.—do listen for their wake word 24/7 and send that audio to the cloud once they think you said it. Siri’s “Hey Siri” detection runs entirely on your iPhone thanks to Apple’s on-device processing, and Apple keeps your requests tied to random IDs, not your personal profile. Android’s always-listening mics and scattered OEM privacy policies can feel less transparent.
If you’d rather not have Siri passively listening, go to Settings > Siri & Search and disable “Listen for Hey Siri,” then just hold the side button when you need help—same convenience, extra peace of mind.