What does Dolby printed on sound systems signify?

Dolby mentioned in tape recorders and other sound system actually refers to a noise reduction circuit used in them. Over the past 30 years, sound recording has been revolutionized by technical developments by Dolby labs founded by Ray. M. Dolby, a sound engineer. His first invention was a circuit that eliminates the noise, usually heard as a hiss, inherent in most tape recordings. Unlike the earlier antihiss technologies which distorted the quality of sound, Dolby’s method involved separating the acoustic components of a given sound into different electronic channels based on their frequency and amplitude, eliminating those signals that contributed most to noise and then recombining the other components.