Sometimes I like to sit back and pump some jams. Before the invention of all this modern technology such as speakers and cds and digital audio, such things just weren't possible. Music had to be performed. But with the invention of electrical speakers that all changing. People were able to finally jam out.
The common speaker relies on the principles of electromagnetism. In the center is a magnet (attached to a speaker cone), surrounded by a coil. As the current through the coil fluctuates, the magnet and cone move, vibrating to reproduce the encoded sound. However, all things have inertia, so it can take time to reverse the momentum of the cone, creating a loss in audio quality in the event that the speaker cone is too heavy. Similarly, if the cone isn't stiff, it will delay its movement and creating quality losses that way as well. These losses are most noticeable with "harsher" waveforms (such as squarewave, which, as the name implies changes position very quickly at wave boundaries), or with more complex sounds, such as violin or saxophone.
Because of these drawbacks good sound systems often have multiple speakers, all tuned to a different frequency. Subwoofers are typically larger because lower frequencies are less audible, and lower frequency waveforms are easier to reproduce in terms of speaker design. Tweeters are smaller for the opposite reasons - they need better accuracy because higher pitches involving larger shifts in momentum with respect to time, so they are typically smaller to achieve this. Also, because every material has a resonant frequency (where it will absorb a lot of energy), the materials in each are tailored to avoid this.
Next time you're cruisin', bumpin' along to your favorite song, remember this. And invest in a better sound system.