Background
- Perceived noise level is a scale developed originally by K.D. Kryter, in 1959 to measure the perceived
noisiness of jet aircraft by observers on the ground. The scale has been adopted by
the International Standards Organization for international use.
- Effective perceived noise in decibels (EPNdB) or Effective Perceived Noise Level (EPNL) measures the relative noisiness of an individual aircraft pass-by event. It is used
for aircraft noise certification and applies to an individual aircraft, not the noise
exposure from an airport.
- dB vs dBA. dB is commonly used when referring to measuring sound; however, humans do not hear
all frequencies equally. dBA is a weighted scale for judging loudness that corresponds
to the hearing threshold of the human ear. The main effect of this adjustment is that
low and very high frequencies are given less weight than on the standard decibel scale.
Sound levels in the low-frequency end of the spectrum are reduced as the human ear
is less sensitive at low audio frequencies than at high audio frequencies.
- dBA measurements underestimate the perceived loudness, annoyance factor, and stress-inducing capability of noises with low-frequency components, especially at moderate and high noise volumes.
Discussion