"The whole strata community owes a huge debt of gratitude to you and the OCN executive. Much appreciated."
DnTw is the equivalent of Rw, but measured onsite. Rw is the value measured in an acoustic laboratory, while DnTw is measured on-site. An on-site measured value of DnTw + Ctr is permitted to be 5 points lower than the Rw + Ctr value. Where the BCA may call for an Rw + Ctr > 50, the same requirement may be satisfied by measuring DnTw + Ctr > 45 on-site.