A manufacturer of analogue and digital audio equipment in the fields of tape noise-reduction systems and cinema and domestic surround-sound equipment.
Dolby’s noise-reduction systems included types B, C and S for domestic and semi-professional machines, and types A and SR for professional machines. Recordings made using one of these systems must also be replayed via the same system.
These systems varied in complexity and effectiveness, but essentially they all employed the principlals of spectral noise-masking in ever-more complex ways using multiband encode/decode processing to raise low-level signals during recording, while reversing the process during playback.