ADDITIONS AND CORRECTIONS NEW IN VERSION 4.1 1. In the CONSTANTS window, the gas dynamic viscosity at 20EC is entered by the user and ENC calculated the value corresponding to the temperature entered in this window. Module 4 - Partition and double wall 2. Transmission loss values in 1/3 octave bands can now be exported to an excel spread sheet by pressing F8. 3. Problems with TL calculations for thick panels at low frequencies below the first panel resonance frequency have now been fixed. 4. When there are multiple TL curves displayed, the STC and Rw values now correspond to the curve with the cursor on it. Module 5 - Dissipative Mufflers 5. Duct bend attenuation. There is now an additional choice of the latest ASHRAE method. In addition, the confusion between rounded and mitre bends has been clarified in the software and in the user manual. Both types of bend can apply to circular section and rectangular section ducts and there is no difference between rectangular and circular section ducts. Curve F from Figure 9.25 in the text book is no longer used in ENC as curve E gives good results for all duct sizes. Module 5 -Pressure Drop and Flow Noise 6. This page has been completely revised and an additional method due to Ver and Beranek for calculating the dynamic pressure loss associated with a parallel baffle silencer has been included. 7. The textbook method now uses equations 9.123 and 9.124 in the 4th edition text book. 8. Users can now choose the type of wall in the silencer or duct as its roughness has considerable influence on the pressure loss. 9. An additional method following ISO14163-1998 has been included for calculating silencer self noise (or re-generated noise) Module 7 - CORTN Road Traffic Noise 10. Error in taking into account the percentage of heavy vehicles has now been corrected.