Super Bit Mapping (SBM) is a Noise Shaping process, developed by Sony for CD mastering.[1]
Sony's SBM, a process that is intended to raise the standard of 16-Bit recording and playback quality. The basic theory is that when you record on an SBM enabled device through its 24-bit analog converters using SBM, the SBM processor filters the 24-bit audio to yield a final product that should sound better than normal 16-bit quality. SBM does this by weaving out the least significant 8-bit information into 16-bit filtered data.
Sony claims the reshaped noise pattern results in deeper bass and more dynamic midrange. According to Sony, by reorienting quantization noise to frequencies above 15,000 Hz - where human hearing is far less sensitive - the SBM process can achieve a result that is comparable to nearly 20-bit quality, yet you can still play the resultant 16-Bit data on any 16-bit recorder/player.[2]
This processing takes place in dedicated hardware inside the recording device. A similar process is used in Sony's DSD to PCM conversion and is called SBM Direct.[3]