A concrete barrier $100mm$ thick is to built around a transformer station located outdoor. The top of the barrier is $2\mathrm{.}5m$ high above the transformer is located $10m$ from the transformer. The property line is located $30m$ from the transformer. The directivity factor for the transformer may be taken as $Q=1.$ The sound pressure level spectrum and the transmission loss for the barrier as a function of frequency are give in table $1$ below. Determine the sound pressure level spectrum without the barrier in place and with the barrier. Assume the transformer noise were continuous $($day$-$night$)=76dB(A),$ and the sonic velocity in the air around the barrier is $347\frac{m}{s}.$

Table $1$

$\backslash$table$[[,$Octave band center frequency, Hz$],[$Item$,63,125,250,500,1000,2000,4000,8000,,],[$Given data:,,,,,,,,,,$],[$L$,$ dB$,112,116,110,106,106,100,95,89,,],[$TL$,$ dB$,36,38,38,38,38,44,50,56,,]]$