Estimated effective root-mean-square source level of the secondary frequency and the resulting distance over which these signals would be audible assuming spherical spreading in seawater (values assuming cylindrical spreading shown in parenthesis).

<p>Estimated effective root-mean-square source level of the secondary frequency and the resulting distance over which these signals would be audible assuming spherical spreading in seawater (values assuming cylindrical spreading shown in parenthesis).</p>