The Acoustical Theory for Design of Aircraft Cabins (ATDAC) is a computer program developed to predict interior noise levels inside aircraft and to evaluate the effects of different aircraft configurations on the aircraft acoustical environment. The primary motivation for development of this program is the special interior noise problems associated with advanced turboprop (ATP) aircraft where there is a tonal, low frequency noise problem. Prediction of interior noise levels requires knowledge of the energy sources, the transmission paths, and the relationship between the energy variable and the sound pressure level. The energy sources include engine noise, both airborne and structure-borne; turbulent boundary layer noise; and interior noise sources such as air conditioner noise and auxiliary power unit noise. Since propeller and engine noise prediction programs are widely available, they are not included in ATDAC. Airborne engine noise from any prediction or measurement may be input to this program. This report describes the theory and equations implemented in the ATDAC program. Mathur, Gopal P. and Gardner, Bryce K. Unspecified Center NAS1-18037; RTOP 535-03-11-03...

A description of motor vehicle noise sources and the potential for their control is provided. The report presents an overview of the suggested noise prediction methodology, which is a four step process that includes approximating noise impacts using a nomograph procedure to determine noise levels associated with given traffic and site characteristics; refining these predictions by more accurate representation of design parameters and use of a computer program that is able to plot as well as calculate noise impact; introducing appropriate noise-control options and evaluate them, using a noise barrier nomograph solution; lastly, selected options are fully evaluated using the computer program.