What is Dolby in the first place? Actually, Dolby is the name of a company headquartered in the United States, officially named "Dolby Laboratories Inc." The company name Dolby is derived from the founder's name, Ray Milton Dolby. "Laboratories" means laboratory or research institute in Japanese. So, what kind of experiments and research does this company conduct? While it now also develops the video technology "DOLBY VISION™", Dolby Laboratories started as a group of audio experts, continuing audio research for over 50 years. Today, Dolby has become a technology company involved in all aspects of entertainment. In this book, we want to explain the "audio technologies" that Dolby has brought to the world in a way that can be understood even by those who are not audio experts or engineers.