It is easy to question the importance of a mere logo, however there are certain instances where the symbolism of a logo transpires its medium and becomes an untainted mark of excellence. This is a rare occurrence but the Dolby double D has achieved this mythical status.
This logo first appeared back in the 70's. It promoted the fact that pre-recorded cassettes carrying this logo were encoded with the Dolby B-type noise reduction so that they would have low noise when played on players equipped with Dolby B-type noise reduction technology.
UK label Decca was one of the first to use this technology -
An ideal sales opportunity for Dolby who, using a policy that SUN Microsystems would follow, licensed their technology to producers for free to ensure that they set the standards.
It established the Dolby double-D logo as a symbol of sound quality as early as the mid 70's. With the need for noise reduction tailing off when CDs were introduced the company moved into other mediums, with the logo now embodying advanced audio set-ups such as used in cinemas or high end home systems and also videocassette, laser disc, video game, and DVD releases.
It is a good example of ingredient branding.