Ported
Ported Subwoofers: When size don't matter, for a dramatic cinematic experience
In a ported subwoofer design, a relatively large enclosure size is required in order to achieve both a deep system tuning frequency and sufficient port area to minimize chuffing artifacts (aka port noise) at high drive levels. A larger enclosure also greatly enhances system efficiency in the deeper octaves, with no need for additional EQ boost to achieve naturally deep bass extension. Ported subwoofers generally have flat frequency response, low distortion, excellent bandwidth linearity and a very deep tuning frequency (typically 20 Hz or deeper).
Ported subwoofers can deliver double to quadruple times more peak dynamic output in the 18-36 Hz octave as compared to a sealed subwoofer in the same price range. This makes the larger ported subwoofers a natural choice for system applications with larger rooms (where less room gain is present) and reference-level playback levels, particularly on demanding Blu-ray action and sci-fi movies with demanding LFE tracks.
Simply put, if you want the most room-energizing, gut-punching, floor-trembling cinematic experience possible, a ported subwoofer will deliver greater dynamic output at the lowest frequencies vs. comparable sealed models.