Dear 
Members of the List:
 
I have 
a question regarding the “perceptual weighting filter” used in the AMR-WB (also 
in the AMR-WB+) codec that is standardized in 3GPP and ITU. 
 
Please 
check the 2002 Journal article from the developers of AMR-WB, where they present 
the perceptual filter (pages 8-10, and Figures 3 and 4).
 
Is 
this the best that one can achieve? 
I would like to know if there are any recent research efforts made to improve this perceptual weighting filter to improve the quality of wideband speech. If so, any pointers in that direction will be highly appreciated.
Thanks in advance.
Best 
Regards,