Simple Explanation

Boost in bass when a speaker is placed near a wall or boundary.

Concise Technical Definition

Boundary gain refers to the increase in low-frequency sound pressure caused by the proximity of a speaker to room boundaries, such as walls, floors, or ceilings.

Layman-Friendly Analogy

Like shouting into a corner—your voice sounds louder and boomier because the walls bounce the sound back at you.

Industry Usage Summary

In room acoustics and loudspeaker setup, boundary gain is a critical consideration when placing speakers near walls. While it can enhance bass, it often causes boomy or uneven response, requiring compensation in both professional and home audio setups.

Engineering Shortcut

Boundary Gain = +6 dB bass boost when speaker is against a wall.

Full Technical Explanation

Boundary gain occurs because low-frequency sound waves radiate in all directions. When a speaker is placed close to a wall, the bass waves reflecting off the wall combine with the direct sound waves. This constructive interference increases the overall bass level, typically by about 6 dB. However, destructive interference can also occur if the speaker is placed a quarter wavelength from the wall at certain frequencies, creating phase cancellation (SBIR). Proper speaker placement or compensation is often required to correct this.