This page details the algorithms used in Sonar Calculator.
Where:
c = speed of sound (m/s),
a = absorption coefficient (dB/m)
T = temperature (°C)
S = salinity (ppt)
D = depth (m)
f = frequency (kHz)
where -2 < T < 30
25 < S < 40
0 < D < 8000
where -2 < T < 23
30 < S < 40
0 < D < 500
where 0 < T < 95
D = 0
where:
This algorithm applies to all oceanic conditions and 200 Hz < f < 1 MHz.