Mid-Range and High-Frequencies
The speakers that handle mid-range frequencies can also typically handle higher range frequencies – this is why you can have a 2.1 system that handles everything from deep rumbles to high-pitched people’s voices.
The center speaker focuses on handling a very specific middle range, the range of the human voice. Your other two speakers on either side of the center speaker handle ambient sounds, or typically those found in the higher or slightly lower ranges. Thankfully, your system does all this independently for you.
Your receiver has many different outputs for this reason exactly. They exist so that when you start playing a movie or song, the decoder in the player knows which channel to pump the sound through. The player will then send the signal to the receiver, which acts as a control center for all the operations related to sending the audio out over multiple channels.
Your tweeters and woofers will be able to handle frequencies that are significantly higher than those that your sub can handle.
Now that you have a handle on how sound works in your home theater system, I would suggest you start by configuring your setup to have the right amount of bass and treble and use the right type of sound, be it DTS or Dolby.