EPNL Helicopter/Aeroplane

The EPNL (Effective Perceived Noise Level) is useful for assessing the annoyance created by exterior flyover sounds, and it is widely used for aircraft certification. It is based on the Annex 16 of the International Civil Aviation Organization (ICAO). It takes into account the loudness of the sound (Stevens’ model), the possible presence of isolated tonal components and the duration of the flyover.

EPNL Helicopter and EPNL Aeroplane profiles provide the EPNL value (EPNLdB) respectively for a helicopter flyover and aeroplane flyover. Both profiles also provide three intermediary outputs:

• Tone-correction factor C (dB) over time, for isolated tonal components.
• PNLTM (TPNdB), which is the maximum value of PNLT.
• PNLT (TPNdB), which is the tone-corrected perceived noise level over time.