Researchers have demonstrated a new side-channel attack that could allow malicious apps to eavesdrop on the voice coming out of your smartphone’s loudspeakers without requiring any device permission. The newly demonstrated attack takes advantage of a hardware-based motion sensor, called an accelerometer, which comes built into most Android devices. An attacker could then examine the captured readings, in an offline manner, using signal processing along with “off-the-shelf” machine learning techniques to reconstruct spoken words and extract relevant information about the intended victim.
Source: https://thehackernews.com/2019/07/android-side-channel-attacks.html