Sound in this frequency range can easily bend around corners by diffraction, the speaker aperture does not have to face the audience:
Can be mounted in the bottom of the enclosure, facing the floor
This is eased by the limitations of human hearing at low frequencies
Such sounds cannot be located in space because waves defract around head/ears
subwoofer systems must be solidly constructed and properly braced to avoid unwanted sounds from cabinet vibrations. As a result, good subwoofers are typically quite heavy
Subwoofer cabinets are often built with a bass reflex port, a design feature which if properly engineered improves bass performance and increases efficiency.
Woofer
200hz - 1khz
Mid-range driver
1–6 kHz
Tweeter
6 kHz -> 20 kHz
Soft-dome tweeters are widely found in home stereo systems, and horn-loaded compression drivers are common in professional sound reinforcement
A major problem in tweeter design is achieving wide angular sound coverage (off-axis response), since high-frequency sound tends to leave the speaker in narrow beams.
Ribbon tweeters have gained popularity as the output power of some designs has been increased to levels useful for professional sound reinforcement, and their output pattern is wide in the horizontal plane, a pattern that has convenient applications in concert sound
Coaxial Drivers
A coaxial driver is a loudspeaker driver with two or more combined concentric drivers