Yes, my apologies I did not phrase myself properly, I agree with you, what I meant was if there was no MSCP to mitigate the noise impact, then 5th floor would suffer much worse than 15th floor.
To get a good gauge of noise intensity for Penrose, I took a google maps image of PIE leftmost lane facing SUO.
The noise intensity is determined by the number of noise sources with line of sight to the recipient, as well as their direct distances.
In the case of the lowest floor (A), we can see that there is limited line of sight from most noise sources as its shielded by the MSCP while (B) has direct line of sight. However (B) has a slightly longer direct distance than (A).
Does this mean that (B) is noisier than (A)? Highly Possible, but it wouldnt be so easy to make a conclusion as we need to see the other lanes as well
However if we take findings from studies, they find that noise magnitude declines exponentially with distance, tapering off at around 15 stories in height. Hence its highly possible that 15th floor is far less noisy compared to (A).