The FAA uses the ____________________ method of calculation as the standard to be used for forecasting cumulative noise exposure under part 150 studies.

• A. Day/Night Average (DNL)
• B. Leq (Equivalent Continuous Sound Level)
• C. Sound Exposure Level
• D. Peak Noise Level

Answer: (A)

The standard method used for forecasting cumulative noise exposure in Part 150 studies is Day/Night Average. This metric combines a 24-hour time frame with a weight that adds a 10 dB penalty to nighttime periods, reflecting the greater annoyance and disruption caused by nocturnal noise. By producing a single daily value, it provides a consistent basis for comparing communities and illustrating overall exposure through noise contours, which is essential for evaluating the impact of aircraft operations and planning mitigations.

Why this fits best: it captures both the level of daytime noise and the heightened sensitivity to nighttime noise, giving a more realistic picture of total community impact over a typical day. Other metrics don’t serve the same purpose: Leq is a general energy average that doesn’t apply the night penalty and isn’t specifically tailored to reflect the diurnal pattern of annoyance; Sound Exposure Level summarizes a single event’s impact rather than daily cumulative exposure; Peak Noise Level focuses on the maximum instantaneous value of a single event, not the accumulated exposure over time.