Two methods have been studied and utilized to statistically characterize short vertical wavelength (high‐mode) internal waves. One technique uses broadband, low‐frequency, simulated pulses transmitted hundreds to thousands of kilometers in conjunction with tomography, the other uses high‐frequency signals transmitted less than a few kilometers. In the first technique, the internal waves cause directional fluctuations of the arriving long‐range rays, which can also be considered as pulse wave front distortions with time and length scales of hours (or less) and hundreds of meters, respectively. Recent frequently sampled, vertical‐array recordings of long‐range pulses enable comparison with theoretical numerically calculated predictions. Understanding the long‐range acoustic fluctuations is required to enable remote monitoring of volumetrically averaged internal waves. In the second technique, unsaturated theory should describe variations in amplitude and phase. Spectra of the short‐range fluctuations can be modeled using ocean sound‐speed spectra, and comparisons to observations are made. The Fresnel length determines the sensitivity in the ocean‐structure wavenumber domain, and adjusting this from tens of meters to a meter or so (a rough limit imposed by absorption) shifts sensitivity from fine structure to microstructure.