Briexp

Hi, I've recently rented a room in an apartment and found that after just a couple of nights, the noise from outside was really loud despite being on the 13th floor. After closer inspection, I noticed that there are large air gaps between the window fittings (as can be seen in the photos - light coming through gaps) which show absolutely no sign of sound proofing whatsoever. I feel that these windows were probably not originally designed for a bedroom! Does anyone have any suggestions that could temporarily dull out some of the outside noise? It doesn't have to be perfect, but a small reduction in noise could make a big difference. I'm only here for 4 months so only temporary and cheap DIY methods, tricks or tips would be viable. I appreciate your time!