Power of sound strengthen apparatus and its acquisition must correspond the sizes of apartment and his acoustic features for providing of highquality sound in a hall and on the stage. All equipment, involved on a concert, including shallow accessory, must be corrected and preliminary tested.
· compressive strength of vertically fluted corrugated fiberboard shipping containers (2,3). This method may also be used for comparing the edgewise compressive strength of different lots of similar combined boards or for comparing different material combinations (4,5). 3. Apparatus