A Spearphone attacker can use the accelerometer in LG and Samsung phones to eavesdrop on any audio that s played on speakerphone, including calls, music and voice assistant responses. Because accelerometers are always on and don t require permission to provide their data to apps, a rogue app or malicious website can listen to the reverberations in real time, recording them or livestreaming them back to an adversary, who can analyze and infer private data from them. This could be exploited by advertisers, for instance, using the information gleaned from eavesdropped media content.
Source: https://threatpost.com/samsung-lg-android-spearphone-eavesdropping/146625/