|"Well if it was blown, it wouldnt make sound at all."|
Not true. A speaker contains a coil of wire that is glued to a form which in turn, is glued to a cone. As the voltage goes from positive to negative it creates a magnetic field that interacts with a permanent magnet and that is what pushes the cone back and forth. sometimes this wire get too hot and will burn out but sometimes it gets hot enough to warp the form that the coil is glued to or burns the glue and separates from the form but the wire is still in tact and carries current. All these conditions are known as a blown speaker but if the wire has separated or the form is warped you will still hear sounds, they are just distorted.
Also, the speaker cone is held in place at the front and the back of the speaker. The front holder is known as the surround while the back holder is known as the spider. If one of these holders rips or comes unglued it allows the cone to travel too far and the form for the voice coil will bottom out and slam against the magnet causing the speaker to make poping sounds.
The surround is usually made from a type of foam rubber or neoprene. Rubber and neoprene don't last forever. it degrades over time. 17 years is a long time for it to last. Your speakers are due for replacement.