Absorption (a) and Transmission Loss (TL) in Seawater

To use the calculator below, enter the frequency of interest and the values of water temperature , salinity, depth and PH . Furthermore, choose a spreading model by radio button. When a calculation button is pushed, the values for the absorption(a) and transmission loss (TL) are displayed on your screen. The calculation result was arrived at by four following different equations. However, you must be careful so that ranges of validity of the parameter of each equations are different.

(1) Equation of "Thorp", J. Acoust. Soc. Am., Vol.33, 1961

(2) Eqation of "Schulkin and Marsh " , J. Acoust. Soc. Am.,Vol.34, 1962

(3) Equation of  "Fisher and Simmons", J. Acoust. Soc. Am., Vol. 62, No. 3,  1977

(4) Equation of  "Francois and Garrison", J. Acoust. Soc. Am., Vol. 72, No. 6,  1982

(5) Equation of  "Ainslie and McColm" , J. Acoust. Soc. Am., Vol. 103, No. 3, 1998


As for the Thorp  algorithm  , a parameter except the frequency is not considered. When using water other than the Lyman and Fleming standard (S = 35, pH = 8), the Fisher & Simmons algorithm  is invalid. You must be careful so that ranges of validity of the parameter of each equations are different.


The calculation of the Sound Absorption profile of the depth direction.  A CSV (D,T,S) file  is necessary for the calculation.


Please input a necessary value into the following columns.

Frequency (kHz)

Temperature (degrees Celsius)

Salinity (parts per thousand ) (Input "35" in the case of the Fisher & Simmons. )

Depth (meters)

PH  ( Input "8" when there are not data.)

Propagation Range (km)

Spreading Model (Choose either model of spherical  or cylindrical spreading .

Spherical Spreading (20log R)   Short distance propagation  (In the case of a echo sounder, a fishfinder etc. )
Cylindrical Spreading (10log R)  Long distance propagation  ( In the case of long-distance propagation such as  ocean acoustic tomography.)



Please describe reference site (http://www.tsuchiya2.org/) when you use the result of the calculation by this site.