A resonance chamber uses resonance to amplify sound. The chamber has interior surfaces which reflect an acoustic wave. When a wave enters the chamber, it bounces back and forth within the chamber with low loss (See standing wave). As more wave energy enters the chamber, it combines with and reinforces the standing wave, increasing its intensity.
Since the resonance chamber is an enclosed space that has an opening where the sound wave enters and exits after bouncing off of the internal walls producing resonance, commonly acoustic resonance as in many musical instruments (see Sound board (music)), the material of the chamber, particularly that of the actual internal walls, its shape and the position of the opening, as well as the finish (porosity) of the internal walls are contributing factors for the final resulting sound produced.