CALIFORNIA, U.S. - For years now, several smartphone users and experts have wondered if their handheld devices can eavesdrop on their private conversations - as has been reported by researchers many times. 

Seeking to find an answer to the question, lawmakers recently raised concerns that smartphones could "in some instances" collect data from nearby conversations, even if the user did not intentionally wake the voice assistants with "Hey Siri" or "OK, Google."

Subsequently, lawmakers addressed letters to Apple CEO Tim Cook and Alphabet CEO Larry Page, seeking information about how iPhone and Android devices collect audio and location data.

In its response to federal lawmakers, Apple first clarified that iPhones do not listen to what users are saying.

The iPhone maker further said that third-party app developers don't have access to audio data.

In the letter, Timothy Powderly, Apple's director of Federal Government Affairs, wrote, "iPhone doesn't listen to consumers except to recognize the clear, unambiguous audio trigger 'Hey Siri.' The customer is not our product, and our business model does not depend on collecting vast amounts of personally identifiable information to enrich targeted profiles marketed to advertisers."

Further, responding to lawmaker's request for information about limits Apple and Google place on developers in collecting data from users' devices, Apple said in its response that iPhone displays a visual alert when Siri is listening to someone's request. 

It also stated that the company's guidelines require developers to show some sort of visual indicator when their app is collecting audio via the microphone. 

Apple pointed out that users also must explicitly grant access to the microphone, and can revoke that audio access in Settings.

In the letter, Powderly wrote, "We believe privacy is a fundamental human right and purposely design our products and services to minimize our collection of customer data."