Methods - Soundscape Ecology: Principles, Patterns, Methods and Applications - page 239

Fig. 9.15 Representation
of the pressure level
equivalent with time.
L p ¼ pressure amplitude,
L eq ¼ pressure level
equivalent

From this metric is possible to add partial L eq e, T according to the following
formula:

10 log 10 X

n

T i
T 10

L eq , 1
10

L eq ¼

1

X

n

where T ¼ T i

i

9.7.1.2 Sound Exposure Level

Sound exposure level (SEL, L AE ) is defined as the total noise energy produced from
a single noise event such as an aircraft takeoff.
The SEL is calculated in a precise temporal interval t 1 t 2 .

Z t 2

p 2 ðÞ

p 0 T

t T

T 0

L E;ðÞ ¼ 10 log 10 ¼ L eq , T þ 10 log 10

t 1

where

T ¼ t 2 t 1 , the time interval considered

p 2 ( t )

¼ the squared instant pressure

p 0 T

the square of reference pressure
L eq, T ¼

¼

equivalent continuous noise level

T 0 ¼ 1s

This parameter is expressed in decibels and can be weighted for frequency with
an A-Weighting .

9.7.2 Spectral Analysis

This approach, very popular in bioacoustic and environmental studies, is based on
analysis of the spectral representation of sound when resolution of different
frequencies the relative intensity of the sound is considered with a specific time
lag (e.g. Joo et al. 2011 ).