V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

SBR
       Spectral Bandwidth Replication (MP3, AAC, EAC)


The Free On-line Dictionary of Computing (30 December 2018):

Spectral Band Replication
SBR

    (SBR) Guessing the nontransmitted higher
   frequency range of a compressed audio file by some helper bits
   (transmiited with the stream) and the transmitted base band.
   SBR allows a restoration (not reconstruction) of the upper
   frequency range without lots of bits.  It was developed by
   Coding Technology (http://codingtechnology.com/), and is
   useful for medium and high quality coding at low and medium
   data rates.  It is used by Digital Radio Mondiale and MP3
   Pro.

   (2004-12-10)