In this video we discuss the Dolby Noise Reduction systems found in consumer cassettes decks and how they work. Though technically very simple, Dolby B noise reduction provides a very effective means of reducing audible tape noise, and was ubiquitous throughout the cassette's life. Dolby noise reduction was such an important part of their legacy that the company still pays homage to it in their logo. The "D"s in the Dolby Double D logo are really the shape of audio tape heads.