How much attenuation does TNM contribute for building rows?
In the case of multiple building rows, TNM first identifies all building rows that interrupt the effective source-receiver path. Rows that do not interrupt the propagation path are ignored. For each row that interrupts the path, TNM determines which building row has the most effective attenuation at the 630 Hz frequency band. For this building row, the actual attenuation is calculated for all 1/3-octave frequency bands. For each remaining row that interrupts the propagation path, an attenuation of 1.5 dB is applied to each 1/3-octave band. The maximum attenuation for any number of building rows has been set to 10 dB. For a listing of maximum attenuation for each 1/3-octave band please refer to Table 13 on Page 100 in the TNM Tech Manual.
