This document summarizes a seminar presentation on silent sound technology for voice conversion. It introduces the technology as a way for those who have lost their voice to still communicate by phone by transmitting information without using vocal cords. It discusses two main methods - electromyography and image processing. Electromyography detects electrical signals from muscle movement and converts them to speech, while image processing uses ultrasound to view tongue movement. Some advantages are helping those who lost their voice and enabling silent calls. Disadvantages include unnatural speech and high cost. Future applications could include incorporating the sensors into phones for more natural use.