A dynamic passive acoustic panel device comprises an enclosure having a front opening, an absorbent panel of sound absorbent material mounted in the enclosure behind the front opening, and a reflective surface mounted in the front opening in front of the absorbent panel. The reflective surface comprises a tessellated array of reflective panels of matching shape arranged in a series of rows, each row being mounted for rotation about a central axis so as to vary the angle of inclination of the reflective panels in each row relative to the absorbent panel from zero degrees to ninety degrees to the absorbent panel, so as to vary the reflection and absorption characteristics of the panel device. A control system controls rotation of the rows of reflective panels, so as to vary the reflection and absorption levels between maximum reflection and maximum absorption based on desired acoustic properties of a space in which the panel device is located.