ITU-T P.330-2003 Speech processing devices for acoustic enhancement SERIES P: TELEPHONE TRANSMISSION QUALITY TELEPHONE INSTALLATIONS LOCAL LINE NETWORKS Subscribers' lines and sets Study Group 12; Covering Note Amendment 1: 9/2003
It is recommended to avoid extremely long rooms (Length >> Width, Height) and rooms with extremely low ceilings (Height << Length, Width), and also rooms with all the side dimensions nearly identical.
ITU-T P.330-2003 history
2003ITU-T P.330-2003 Speech processing devices for acoustic enhancement SERIES P: TELEPHONE TRANSMISSION QUALITY TELEPHONE INSTALLATIONS LOCAL LINE NETWORKS Subscribers' lines and sets Study Group 12; Covering Note Amendment 1: 9/2003