A recent study by a group of academic researchers highlights the development of a new method of acoustic eavesdropping using still images captured with smartphone cameras.

Acoustic eavesdropping

The researchers were able to extract sounds from the images by analyzing the minute vibrations that sound waves create on objects in the environment. They used a smartphone camera to capture images of objects that were being exposed to sound waves and then used an algorithm to analyze the images and extract the sounds.

How does it work?

This is not the first time researchers have been able to extract audio from still images. In fact, researchers at Northeastern University have developed a tool called Side Eye that can extract audio from static photos and silent videos using AI and machine learning 2. The tool takes advantage of the image stabilization technology that is now virtually standard across most phone cameras.

To ensure a shaky hand doesn’t make for a blurry photo, cameras have small springs that hold the lens suspended in liquid. An electromagnet and sensors push the lens in equal and opposite directions to reduce camera shake. However, whenever someone speaks near a camera lens, it causes tiny vibrations in the springs and bends the light ever so slightly. 

Implications and consequences

The impact of this technology is far-reaching. It could be used for surveillance purposes, allowing law enforcement agencies to eavesdrop on conversations without needing to install microphones or other listening devices. It could also be used for more benign purposes, such as enhancing video calls by allowing users to hear what is being said even when they are muted.

But there are also concerns about privacy and security. If this technology falls into the wrong hands, it could be used for nefarious purposes like spying on individuals or stealing sensitive information. There are also concerns about how this technology could be used to violate people’s privacy rights.