Table 6.

Ridge regression results on Pa.

K = 0.185	Nonnormalized coefficient		Normalized coefficient	t	P	R2	Adjusted R2	F
	B	Standard error	Beta
Constant	3.842	3.119	–	1.232	0.224	0.96	0.956	220.931(0.000***)
Hydroacoustics	0.157	0.029	0.156	5.493	0.000***
Windy sound	0.118	0.037	0.081	3.187	0.003***
Birdsong	0.291	0.024	0.298	12.047	0.000***
Insect chirping	0.088	0.031	0.085	2.881	0.006***
Combined sound	0.365	0.021	0.397	17.507	0.000***

1. Dependent variable: Pa 2. ***, ** and * represent significance levels of 1, 5 and 10% respectively.