stages consistent with the described approach for example by combining multiple stages into a single stage or by splitting a single stage into multiple stages delta noise level module 504 is invoked by band scalefactor estimation controller 502 to perform a first stage of the band scalefactor estimation process in which a delta noise level i e a change in noise level across all sfbs in a frame as a result of a change in the scalefactor is generated for example an equation that may be implemented by delta noise level module 504 to determine such a delta noise level is represented at equation 11 below in equation 11 above if the sfb for which the deltanoiselevel is being determined is the first sfb of a first frame in a channel the value of scf_delta is assumed to be zero if the sfb for which the deltanoiselevel is being determined is the first sfb of a subsequent frame in a channel the value of scf_delta is set to be the sum of the global scalefactor adjustments framescfadj applied to the previous quantized encoded frame of the channel as described below with respect to fig7 and fig1 delta scalefactor module 506 is invoked by band scalefactor estimation controller 502 to complete the second stage.