A method for encoding input audio signals , the method comprising: deriving , from one or more input signals , a baseband signal and a residual signal , the baseband signal comprising spectral components in a set of first frequency subbands, the residual signal comprising spectral components in a set of second frequency subbands wherein the set of second frequency subbands comprises higher-frequency subbands, and wherein the set of first frequency subbands comprises lower-frequency subbands: calculating, for each frequency subband in the set of second frequency subbands of the residual signal , a square root value of a sum of a plurality of spectral power values for a plurality of spectral components in that frequency subband in the set of second frequency subbands of the residual signal ; generating , for each frequency subband in the set of second frequency subbands of the residual signal , a scale factor based at least in part on a respective square root value of a sum of a plurality of spectral power values as calculated for that frequency subband in the set of second frequency subbands of the residual signal ; encoding the baseband signal , along with control information , into an encoded signal , the control information including a set of scale factors, each scale factor in the set of scale factors being respectively generated for a frequency subband in the set of second frequency subbands of the residual signal based at least in part on a square root value of a sum of a plurality of spectral power values as calculated for that frequency subband in the set of second frequency subbands of the residual signal . deriving , from one or more input signals , a baseband signal and a residual signal , the baseband signal comprising spectral components in a set of first frequency subbands, the residual signal comprising spectral components in a set of second frequency subbands wherein the set of second frequency subbands comprises higher-frequency subbands, and wherein the set of first frequency subbands comprises lower-frequency subbands: calculating, for each frequency subband in the set of second frequency subbands of the residual signal , a square root value of a sum of a plurality of spectral power values for a plurality of spectral components in that frequency subband in the set of second frequency subbands of the residual signal ; generating , for each frequency subband in the set of second frequency subbands of the residual signal , a scale factor based at least in part on a respective square root value of a sum of a plurality of spectral power values as calculated for that frequency subband in the set of second frequency subbands of the residual signal ; encoding the baseband signal , along with control information , into an encoded signal , the control information including a set of scale factors, each scale factor in the set of scale factors being respectively generated for a frequency subband in the set of second frequency subbands of the residual signal based at least in part on a square root value of a sum of a plurality of spectral power values as calculated for that frequency subband in the set of second frequency subbands of the residual signal . <EOS>