Abstract: Furniture such as desks and other items are provided with sound absorbing features consisting of micro-perforations extending through structures having vertical surfaces. The micro-perforations are formed using a LASER cutting tool or a punch and are either cylindrical or frustoconical. The micro-perforations are formed in drawer facings, doors, support structures, and free-standing objects and storage devices having vertical surfaces. The micro-perforations have diameters in the range of 0.20 to 0.70 mm. The micro-perforations have been found to increase sound absorption of a desk by as much as 4 Sabins within the frequency range of 100 to 5,000 Hz. Structural panels consisting of front and rear micro-perforated panels surrounding a porous central core may be employed in such furniture.

Abstract: A plurality of tri-rectangular tetrahedrons are mounted in an array to reflect sound waves back to their source. The array filters out the acoustic range below the normal range of frequencies for the spoken voice. The array is combined with a sound absorber to absorb frequencies the user does not want to have returned to the source. One example of such absorbers consists of rendering the returner somewhat porous with microperforations or microslits so that sound waves below the desired frequency range can travel through the porosity and into an absorbing area which may include fiberglass or other sound absorbing fabrics. Examples of environments of use for the present invention are an office setting or nursing station in which a large room is divided up into spaces or cubicles by partitions. Acoustical returners can be mounted above each space or cubicle, for example, in ceiling mounted arrays or clouds above each space or cubicle.

Abstract: The present invention contemplates regularly spaced or variable width slats having equal width, but with heights determined by an inverted QR sequence, which converts focusing concave areas into beneficial, diffusing convex areas for improved diffusion, especially in the near field. The inverse sequence provides longer resonator necks, between adjacent slats, needed to provide a lower average resonant frequency. Slats are uniformly spaced with inverted QR slat heights have widths determined by the ground states of a Bernesconi sequence. Uniformly spaced, inverted QR slat heights have widths determined by the same QR sequence used to determine heights. Alternatively, uniformly spaced, inverted QR slat heights have widths determined by a Prime 7, primitive root sequence. The uniformly spaced slats have curvilinear forward facing surfaces with their heights based on either a regular or inverted QR sequence, as well as a primitive root or other number theory or optimized sequence.

Abstract: The present invention contemplates regularly spaced or variable width slats having equal width, but with heights determined by an inverted QR sequence, which converts focusing concave areas into beneficial, diffusing convex areas for improved diffusion, especially in the near field. The inverse sequence provides longer resonator necks, between adjacent slats, needed to provide a lower average resonant frequency. Slats are uniformly spaced with inverted QR slat heights have widths determined by the ground states of a Bernesconi sequence. Uniformly spaced, inverted QR slat heights have widths determined by the same QR sequence used to determine heights. Alternatively, uniformly spaced, inverted QR slat heights have widths determined by a Prime 7, primitive root sequence. The uniformly spaced slats have curvilinear forward facing surfaces with their heights based on either a regular or inverted QR sequence, as well as a primitive root or other number theory or optimized sequence.