Guys i have a problem and i hope that you sifus can help me.

I'm currently using Altec Lansing ADA880. When i watch movie on my pc, the sound effect like bombing or gun shooting always seems very loud, but when the actor starting to speak or converse the sound is so soft. Hardly can hear what they are saying until i turn on the volume on my speakers, but that's a mistake as well because if the movie suddenly very explosive and all, everyone in the house can hear...

So any solution for me? Is it movie quality? Mostly the movies i watch are dvd quality. or is it my speakers?