Table 3.

Extended indicators.

	Indicators and Description	Physical Descriptive Power	Perceptive Descriptive Power
Energetic indicators	LeqT continuous equivalent sound pressure level during time period T Ln continuous equivalent sound pressure level during night period Lden, day, evening, night combined indicator [20,21,22]	Cumulative energetic indicators. A, C or Z frequency weighting	Correlated to long term health effects
Statistical indicators	L90 [23], 90% percentile level	Describes background noise	Does not emerge from studies
	L50, 50% percentile level [24]	Good for discriminating sound environments	Very good correlation with perceived sound intensity and sound pleasantness
	L10, 10% percentile level [23,24,25]	Describes contribution of loudest events	Outperforms LAeq to describe perception of high noise levels
Spectrum and source related indicators	Sound ecology indicators: NDSI, normalized difference soundscape index; ACI, acoustic complexity in; entropy; BIO, bioacoustic index; ADI, acoustic diversity index; AEI, acoustic evenness index [11,26]	Good for discriminating presence of biophonic sounds and anthropogenic sounds in urban sound	Likely to be correlated with the time presence of the described sound sources
	The normalized time and frequency second derivative: TFSDmean, 4k Hz (birds); TFSDmean,500 Hz (human voices) [27,28]	Can be computed from octave band 1 s dataset. Good for discriminating presence of biophonic sounds and anthropogenic sounds in urban sound environment	Likely to be correlated with the time presence of the described sound sources
	Leq (63 Hz–500 Hz); 1/3 octave band continuous sound pressure level [28,29]	Good for discriminating sound environments frequency content	Correlated with the time presence of Traffic
	LCeq-LAeq, difference between A- and C-weighted equivalent continuous sound levels [30,31,32,33,34]	Describes the amount of low frequencies	Differences of 15 to 20 dB show an effect on annoyance and perception of vibrations
Emergences and noise variation indicators	LAmax, maximum A-weighted noise level; NA, number of events above a threshold; time above a threshold [35,36]	NA80, number of events above a 80 dBA, or TA80 time above 80 dBA (additional thresholds can be considered)	Awakening probability with increasing LAmax The number of high noise level events may affect sleep motility. For aircraft noise, also an effect on annoyance is suggested
	Calculated from percentiles. Fluctuation: defined as the difference between the (single) source event and the source background level. Emergence: Difference between the source event and the overall background level (L10–L90 or L1–L99) [37,38,39,40,41,42]	Good description of the energetic increase produced by a source	Field investigations on annoyance and hypertension yield some support in the context of mixed sound exposure and low background levels (main roads). No consensus concerning the perceptive effects
	Intermittency ratio (IR). Ratio between the sound energy contributions of events, and the overall contributions during the measurement period [43,44,45,46]	Expresses the energetic share of noise exposure created by individual noise events	Highly intermittent nocturnal noise is correlated with increased risk of cardiovascular diseases. In a fully adjusted hypertension model the IR made an additional contribution beyond the Lden in mixed source exposure situations. IR has an additional effect on %HA and can explain shifts of the exposure-response curve of up to about 6 dB.