In a recent paper,Longuet-Higgins <1980>, using theoretical arguments, estimated a relation between the mean square wave amplitude and variance of the signal for a wave field composed of waves of different frequencies. Using data collected in 90 m of water from the Washington continental shelf, we confirm the trend for the influence of bandwith on the ratio, ā2/2mo, which was predicted by Longuet-Higgins. The mean square wave amplitude is ā2, and mo is the variance of the wave record.