Ray Dolby had already introduced Dolby A noise reduction to professional recording studios in 1965, but 1968 is when a consumer-facing version, Dolby B, arrived. Dolby B was designed specifically to tame the tape hiss that plagued the relatively narrow, slow-moving tape used in cassette recording — a problem that had kept cassettes from being taken seriously by anyone who cared about sound quality. It would take a few more years before Dolby B showed up in a genuinely hi-fi-grade cassette deck, but 1968 is the starting point for a noise-reduction feature that would become a standard spec on tape equipment for decades.
Elsewhere in home audio, the shift toward solid-state component systems that had been building through the mid-'60s continued, with manufacturers steadily replacing tube designs across receivers and amplifiers. The ads from this period reflect an industry still finding its footing — component stereo hadn't yet become the dominant story it would be by the early '70s, but the pieces were already moving into place.