Accoustically and visually optimized projection screen

1. A system for providing projection-based entertainment, comprising: a projection screen with a front projection surface; a projector operable to project light onto the front projection surface for reflection into a viewing space; an audio speaker operable to output sound into the viewing space and positioned behind the projection screen adjacent a back surface of the projection screen opposite the front projection surface; and a screen assembly including an acoustical screen with an outer surface facing toward the viewing space and adjacent the front projection surface and covering the audio speaker, wherein the acoustical screen comprises a plurality of holes with spacing material sandwiched adjacent between each pair of the holes and wherein the holes have at least a first size and a second size greater than the first size and wherein the holes of the first and second sizes are arranged in a pseudo-random pattern in the acoustical screen, whereby the output sound from the audio speaker is transmitted through the holes of the acoustical screen. 2. The system of claim 1, wherein the first size is in the range of 1/16 to ⅛ inches. 3. The system of claim 1, wherein the holes further comprise a third size greater than the second size. 4. The system of claim 3, wherein the holes have a circular cross sectional shape. 5. The system of claim 4, wherein the holes have outer diameters in the range of 1/16 to 3/16 inches. 6. The system of claim 3, wherein the pseudo-random pattern is defined so that each of the holes has only a single neighboring one of the holes with a matching size. 7. The system of claim 3, wherein the pseudo-random pattern is defined with a predefined ratio of the holes having the first, second, and third sizes and with the predefined ratio enforced when randomly selecting an order of placement of the holes in the pseudo-random pattern. 8. The system of claim 1, wherein the acoustical screen is coupled about its periphery with the projection screen and wherein the screen assembly further includes a backing fabric layer comprising an acoustically transmissive material extending over an inner surface of the acoustical screen. 9. The system of claim 1, wherein the acoustical screen is formed of thin sheet of a metal or a plastic and wherein the outer surface is painted with a paint of a color matching a color of the projection surface. 10. An acoustical screen for masking presence of an audio speaker while effectively transmitting its output, comprising: a screen body; in the screen body, a first set of circular holes with a first outer diameter; in the screen body, a second set of circular holes with a second outer diameter smaller than the first outer diameter; and in the screen body, a third set of circular holes with a third outer diameter smaller than the second outer diameter, wherein the circular holes of the first, second, and third sets are arranged in a pseudo-random pattern across a front surface of the screen body. 11. The acoustical screen of claim 10, wherein the screen body is formed from a thin sheet of metal or plastic and wherein the front surface is colored or treated for use as a front projection surface. 12. The acoustical screen of claim 10, wherein the third outer diameter is equal to or less than 0.0625 inches and the first and second outer diameters are in the range of 0.0625 to 0.25 inches. 13. The acoustical screen of claim 10, wherein the pseudo-random pattern is defined so that each of the circular holes has only a single neighboring one of the circular holes with a matching outer diameter. 14. The acoustical screen of claim 10, wherein the pseudo-random pattern is defined with a predefined ratio of the holes having the first, second, and third sizes and with the predefined ratio enforced when randomly selecting an order of placement of the holes in the pseudo-random pattern. 15. A method of generating a pattern for holes of an acoustical screen, comprising: selecting a number of sets of differently-sized holes for use in the acoustical screen, wherein the number is sets is greater than two; assigning a unique hole size to each of the sets of differently-sized holes; defining outer dimensions of the acoustical screen; generating a pattern based on the outer dimensions; with a hole pattern generation program run by a processor of a computing device, automatically selecting a new hole to place in the pattern formed in the generating step from the sets of differently-sized holes; with the hole pattern generation program, automatically positioning the new hole in the pattern at a random location, wherein the random location is selected to provide a predefined spacing between adjacent hole pairs; and repeating the selecting and the positioning until the pattern is filled. 16. The method of claim 15, wherein the hole pattern generation program performs the positioning of the new hole in the pattern by randomly selecting a drop location along a defined upper edge of the pattern and simulating a gravity-based drop of the new hole from the drop location. 17. The method of claim 15, after the repeating step, performing optimization to determine whether one or more of the holes has more than a predefined number of neighboring holes with a matching size and, in response to an affirmative determination, moving the one or more of the holes to a new randomly selected location in the pattern. 18. The method of claim 17, wherein the predefined number is equal to one. 19. The method of claim 15, further comprising defining a ratio of numbers of holes from each of the sets of differently-sized holes for inclusion in the pattern and wherein the selecting step is performed based on the ratio. 20. The method of claim 15, wherein the number of the sets of differently-sized holes is set to three, wherein each of the new holes is circular, and wherein each of the hole sizes defines an outer diameter in the range of 0.0625 to 0.25 inches.