Single driver speakers

Our hearing covers 30 Hz to 20.000 kHz.
To produce bass you need to move a lot of air, hence a big and strong driver.
To produce treble you need a very fast driver , hence a small and light one.
The standard solution is to use dedicated drivers, a woofer and a tweeter.
The consequence is you need a crossover somewhere in the midrange.

A full range driver doesn’t need a crossover but it is very challenging to combine big and strong with fast and light.
In practice full range drivers roll off both the lower bass and the upper treble.

Frequency response Seas full range driver H1597-08 FA22RCZ