Explore the fascinating world of modulated light and its applications in covert communication through this ANYCon 2017 conference talk. Delve into the history of light-based communication, starting with Bell's Photophone, and learn about modern techniques for transmitting and receiving audio signals using light. Discover how to build basic Photophone equipment, including simple receivers and amplifiers, and witness demonstrations of audio modulated into ambient light. Investigate the potential of infrared lasers in surreptitious listening devices and explore natural reflections and attacking methods. Gain insights into cutting-edge applications, such as using smartphones as modulated light decoders, and understand the implications for security and surveillance. This talk covers both DIY approaches and commercial solutions, providing a comprehensive overview of this intriguing technology and its potential uses in various fields.