Too bad they omitted the details of implementation and resulting quality change. Dolby vs pre-NR was much more than an incremental step at higher volumes. They

Too bad they omitted the details of implementation and resulting quality change. Dolby vs pre-NR was much more than an incremental step at higher volumes. They effectively used an eq to boost frequencies known to reproduce badly or contain noise before recording, and then evened them back out for playback.