There are many variables that would determine the proper STC value, including the physical proximity of the office building to the airport. To ensure that the specification is properly developed, an acoustic consultant should be engaged to determine the Outdoor / Indoor Transmission Class (OITC) values.
| STC Value | Rating | Description |
| 50-60 | Excellent | Loud sounds heard faintly or not at all |
| 40-50 | Very Good | Loud speech heard faintly, but not understood |
| 35-40 | Good | Loud speech heard but hardly intelligible |
| 30-35 | Fair | Loud speech understood fairly well |
| 25-30 | Poor | Normal speech understood easily and distinctly |
| 20-25 | Very Poor | Loud speech audible |