Every sound frequency corresponds to a specific vibration speed, and an enclosure can amplify some frequencies more than others. When test tones at six frequencies are played through identical speakers mounted in different-sized boxes, the smallest enclosure boosts certain mid-range frequencies above the baseline. The larger enclosures produce a flatter response, meaning each frequency vibrates through the box without one speed of vibration dominating the rest.

The same speaker can produce different decibel readings depending on what surrounds it. You build three sealed plywood enclosures of different depths, mount identical 8-inch speakers in each, and play test tones at six frequencies. A meter placed one meter away records the level for each tone. The larger enclosures produce a flatter response across all frequencies. The smallest enclosure boosts certain mid-range frequencies above the baseline — making some tones noticeably louder than others even though the speaker itself never changes.

Every enclosed air space has a natural pitch set by its dimensions. When a sound frequency matches that pitch, the air inside vibrates strongly and grows louder. This experiment tests that effect across three sealed plywood enclosures of different depths, each fitted with an identical 8-inch speaker. Playing test tones at six frequencies and recording decibel levels one meter away, you find that the larger enclosures produce a flatter response across all frequencies. The smallest enclosure, by contrast, boosts certain mid-range frequencies above the baseline — making some tones noticeably louder than others.