Description:
<jats:p>The sensitivity of predicted ground noise levels for advanced turboprop aircraft to changes in atmospheric absorption losses is reviewed, and the resulting community noise environments evaluated in terms of possible criteria for acceptable levels. Atmospheric absorption coefficients at high altitudes are subject to possible errors of over ±70% due to the current uncertainty in atmospheric absorption prediction models at the very low humidities involved. However, the integrated absorption loss over the entire propagation path is nearly independent of the particular prediction model chosen. The humidity and temperature structure of the atmosphere is a more significant source of variation in the total atmospheric absorption loss. Based on a reference profile of humidity content versus altitude, and existing models for a standard atmosphere, estimates of enroute noise of advanced turboprop aircraft are made and compared with available data. The noise exposure on the ground is considered in terms of both the maximum sound level and sound exposure level for one overflight, and the day-night average sound level for various scenarios of daily operations. These estimates of the resulting community noise exposure are compared to possible criteria for acceptable levels for single and multiple aircraft flyovers. [This work was supported in part by the Federal Aviation Administration.]</jats:p>