Abstract: This invention provides for increased resonance quality and volume in a stringed instrument having a resonant chamber, where the chamber has a defined opening that is also known as a “sound hole.” Guitars and related instruments tend to have sound holes defined as rounded or circular openings. Violins and related instruments tend to have a more ornate sound hole, similar to an “S” or “f” shape. The increase in sound volume and quality is derived from resonance flanges, that are positioned adjacent to the sound hole, within the resonance chamber, and which define curved surfaces that affect the sound waves striking them. The resonance flanges are defined by internal expanding curved edges, that are attached to the inner side of the resonant chamber, adjacent to the sound hole opening, and exhibit a defined curve away from the sound hole opening.