Is iPhone secretly eavesdropping on your conversations? How Hey Siri Really Works

In 2014, Apple added a feature to iOS 8 “Hey Siri”, which made it possible to activate the voice assistant in one phrase. Today this feature is supported by all Apple devices – iPhone, iPad, Apple Watch and MacBook.

But here’s the bad luck: it turns out that all devices are constantly listening to us in order to recognize the necessary phrase. What if they can eavesdrop on what they shouldn’t hear? What Apple has on this score guarantees?

In fact, the company has thought through everything and made the most secure system that will not allow Siri to hear your conversations. Now I will explain how it works.

Hey Siri used to work differently than it does now


I often use this when my iPhone is not at hand.

When Apple first added this feature in iOS 8, it was only possible to activate Siri with a phrase when the iPhone or iPad was on charge. The reason is simple – monitoring a passphrase was a rather energy-intensive process. The current iPhone 4s, 5, 5s and 6 did not have a special chip Always-on Processor (AOP).

He only appeared in iPhone 6sas part of the M9 coprocessor. Moreover, AOP runs on its own operating system RTKitOS… This chip is known to enable Hey Siri to keep track of the iPhone’s location in Find My, even if it’s turned off.

It is independent of iOS and in fact has constant access to the microphone. This is where the real magic begins.

IPhone Hears You Now, But Doesn’t Eavesdrop


Stages of work “Hey Siri”.

Apple developers have come up with a clever algorithm for identifying the key phrase. In a dedicated section on Apple’s website with technical documentation in 2018 came out a real research article that sheds light on many of the technical details of Hey Siri.

First, your voice references that you speak while setting up Siri are written directly to this chip. AOP… They are then supplemented with new voice keys almost every time you activate Siri. Thus, the iPhone learns to respond only to the voice of its owner.

And secondly, although the AOP has access to the microphone, it does not interpret speech into text. That is, it does not analyze what you are saying. This eliminates any chances of secret wiretapping of the smartphone user.


At first glance, a simple technology that is absolutely uniquely designed.

The chip constantly picks up sound waves, more precisely, their segments, total length 0.01 seconds at different intervals. If the user accesses the voice assistant, AOP collects a cluster of 20 references, with a total length of 0.2 seconds. Then they go to the neural network, which looks for matches with the recorded examples.

Only if the degree of coincidence reaches a certain point (how much Apple does not specify in percentage), does iOS receive a command to turn on Siri. Then the iPhone starts listening to what you say and interprets it into a request. Which Siri will (or won’t) execute afterwards.

Despite the large number of stages in the work of this function, Siri almost always responds to requests quickly and accurately. It is a pity that it does not work perfectly in Russian so far.

Do other voice assistants do the same?


Far from being a fact.

It’s hard to say whether other companies, such as Google, use similar methods in the development of voice assistants. I have not found similar documentation from other brands. And I would like to be more confident in privacy.

Therefore, with “Hey Siri” you don’t have to worry about privacy. Apple is unlikely to be secretly eavesdropping on its users – there is no need for that. It is resource intensive and inefficient. And such a counter almost does not take away the charge.


Source: iPhones.ru — Новости высоких технологий, обзоры смартфонов, презентации Apple by www.iphones.ru.

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