A way of making windows soundproof is through the use of soundproof glass for the windowpanes. Other ways include using soundproof window curtains and using window plugs.
Make window plugs using a thick acoustical mat to make windows soundproof. Insert the mat into the window frame, and leave a space between the plug and the glass. The space helps to increase the efficiency of the mat. The mat blocks light from passing through but is removable.
Use heavy-duty window curtains to block noise. They have a material that has soundproofing qualities. They are heavier than normal curtains and therefore need special mounting devices, and they block out light. Making ordinary curtains heavier and including pleats on them improves their soundproofing qualities.
Soundproof windows have a high sound transmission class rating than other methods of soundproofing windows. Installing them involves more work because you need to remove the old windows then install the new ones. A workaround to that is fitting an extra pane in the window frame to increase the soundproofing qualities of the existing window. This is economical because you do not need to replace the window. The extra pane is also transparent, so light can still get through.
Filling in the gaps between the window frames and the wall using caulk, especially acoustical caulk, further helps in cancelling noise.