A subwoofer is a loudspeaker that reproduces low-pitched frequencies such as bass and sub-bass.
The subwoofer will take low-pitched audio signals and convert them into sounds that woofers aren’t able to generate.
This answers the question of what a subwoofer does, but how much bass is it boosting as part of a traditional audio setup? Subwoofers deliver sounds in frequencies between 20-200 Hz. Woofers, by contrast, can only go down to about 50 Hz in the most advanced speakers. This means that subwoofers let you feel the bass’s sound in a song, movie, or any other sound that you’re listening to. The lower the low-frequency response of a subwoofer, the stronger and juicier the bass.
Subwoofers are particularly popular as part of a car audio system. Sonic Electronix sells car stereo subwoofers that are usually classified by size (8”, 10”, 12”, etc.) with the lowest frequency getting down to about 20-22 Hz.
While it’s harder to find portable speakers that will support a low-frequency sound down to 20 Hz, newer models are increasingly supportive of low frequencies. The Sony SRS-XB501G will support low-frequency sounds down to 20 Hz while the Samsung WAM750 goes all the way down to 8 Hz.