Table 5.

Ridge regression results on Pm.

K = 0.155	Nonnormalized coefficient		Normalized coefficient	t	P	R2	Adjusted R2	F
	B	Standard error	Beta
Constant	6.448	2.256	–	2.858	0.006***	0.973	0.97	333.656(0.000***)
Windy sound	0.402	0.018	0.382	22.114	0.000***
Birdsong	0.132	0.046	0.065	2.866	0.006***
Hydroacoustics	0.151	0.031	0.13	4.898	0.000***
Insect chirping	0.089	0.027	0.078	3.342	0.002***
Combined sound	0.399	0.017	0.412	23.721	0.000***

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