When evaluating performance in acoustic ceiling tiles, you’ll want to reference two general ratings: Noise Reduction Coefficient (NRC) and Ceiling Attenuation Class (CAC). NRC tells you how much sound a ceiling panel will absorb, thereby lessening the noise within a room. CAC rates the tile's efficiency as a barrier to airborne sound transmission – meaning how much sound travels to adjacent rooms. The higher the rating, the better the ceiling is at noise control. There are various options of material, color and size available in the market, but you should keep in mind the NRC and CAC values before application.
There are two closely related products which comprise what most people refer to as "acoustical ceiling tile". One is acoustical ceiling tile, which is a 12 inch square, by 1/2 inch thick tile with a toungue and groove edge all around. It is comprised of mineral fibers compressed into a uniform shape with a painted (white) perforated surface having improved acoustical properties. Typically this product is used to reduce noise levels in noisy spaces, when glue-applied to drywall ceilings, when access above the ceiling is not required. There are also suspension systems available which allow for "dropped ceiling" application, without a drywall substrate. The look of an acoustic tile ceiling is monolithic (uninterrupted) in appearance. In my experience it is not commonly used.
The other product, which is often mislabeled as acoustical tile is technically an acoustical panel ceiling . It is the most common type of acoustical ceiling and is recognizable by its 2ft. by 2ft. Or 4ft. square or rectangular grid pattern. Available products are all but unlimited in surface texture, color and acoustical properties. Aside from the wide variety of panel choices, the ceiling system utilizes a metal suspension 'grid', offered in equally varietal options. The beauty of the entire system allows the panels to lay in the grid by gravity and be easily lifted or removed allowing virtually unlimited access to the space above the ceiling. In today's construction, access to the ceiling plenum for servicing of the multitude of mechanical and electrical devices hidden there is absolutely necessary.