A small manufacturing firm has a small building that houses it's manufacturing facility and it's offices. The owner is concerned because he can't see from the offices into the manufacturing facility. For safety reasons, he'd like to install a window in the existing brick wall so he can see into the manufacturing area without leaving the office. Currently, the adjoining wall from the office to the manufacturing area has a door that has an area of 2m with a transmission loss of 20dB. The wall in question is brick, has a transmission loss of 40dB. It is 15 metres long, and 3 metres tall. The window the owner wishes to install will be 3 metres long, and 1.5 metres tall with a transmission loss of 15dB. If the current sound levels in the manufacturing area are 90dBA, what will be the new sound level in the office? *Please note: the sound absorption in the office is 0.25