If instead of elliptical cones, right circular cones are employed, then • • 8 and only the expression for B is changed. In particular for a fixed 8, this causes the 1R. A. Rasmussen and N. E. Head, "Characteristics of High Frequency Sea Reverberation and Their Application to Turbulence Measurement," J. Acoust. Sec. Am. 59, 55-61 (1976). 2E. J. Sullivan and K. A. Kemp, "The Significance'of Beam ...