maad.spl.detection_distance

maad.spl.detection_distance(L_bkg, L0, f, r0=1, delta_r=1, t=20, rh=60, pa=101325, a0=0.02, rmax=10000)[source]

Compute the detection distance also known as detection range or detection radius or active space.

Parameters:

L_bkgscalar or array-like: sound pressure level of the background/ambient “noise” in dB SPL
L0scalar or array-like: Initial sound pressure level measured at distance r0
f: scalar or array-like: frequency in Hz
r0scalar: distance at which L0 was measured (generally @1m)
delta_rscalar: distance resolution in m
t: scalar, optional, default is 20: temperature in °C
rh: scalar, optional, default is 60: relative humidity in %
pa: scalar, optional, default is 101325: atmospheric pressure in Pa
a0scalar, optional, default is 0.02: attenuation coefficient of the habitat in dB/kHz/m
rmaxscalar, optional, default is 10000: define the maximal distance that is taken into account for active distance calculation. Default value is 10000m (i.e. 10km) which is OK for most of the purpose. If you increase the value, the calculation will be longer

Returns:

distance_maxscalar or array-like: maximum distance of propagation before the sound pressure level is below the ambient sound level

Notes

The maximum detection range is limited by the background noise or ambient sound also called noise. The signal is attenuated during the propagation until the level reaches the ambient sound level, meaning that the signal could not be disantangle from the background sound anymore.

Examples

Estimation of the active distance for an initial sound of 90dB SPL @2kHz with a background noise of 50dB SPL

>>> f, r = maad.spl.active_distance (L_bkg=50, L0=90, f=2000) 
>>> print('Max active distance is %2.1fm' %r)
Max active distance is 70.0m

Estimation of the active distance for an initial sound of 90dB SPL @10kHz with a background noise of 50dB SPL

>>> f, r = maad.spl.active_distance (L_bkg=50, L0=90, f=10000) 
>>> print('Max active distance is %2.1fm' %r)
Max active distance is 32.0m

Estimation of the active distance for an initial sound of 90dB SPL @2kHz with a background noise of 30dB SPL

>>> f, r = maad.spl.active_distance (L_bkg=30, L0=90, f=2000) 
>>> print('Max active distance is %2.1fm' %r)
Max active distance is 263.0m

Estimation of the active distance for an initial sound of 90dB SPL @2kHz with a background noise of 30dB SPL, in tropical rain forest atmosphere (t=30, rh=99)

>>> f, r = maad.spl.active_distance(L_bkg=30,L0=90,f=2000,t=30,rh=99) 
>>> print('Max active distance is %2.1fm' %r)
Max active distance is 247.0m

Estimation of the active distance for an initial sound of 90dB SPL @2kHz with a background noise of 30dB SPL, in cold dry forest atmosphere (t=5, rh=40)

>>> f, r = maad.spl.active_distance(L_bkg=30,L0=90,f=2000,t=5,rh=40) 
>>> print('Max active distance is %2.1fm' %r)
Max active distance is 225.0m