Figure 12.

Smoothed 1/24-octave sound spectra of selected polyphasic sinusoidal pulses with Gaussian amplitude envelope. The sound has notable coil-specific components at 600, 1100, 2000, 2600, and 4300 Hz, and a pulse-specific component at twice the characteristic frequency of each pulse (15, 20, 30, and 40 kHz, respectively; the peaks for the two highest frequency pulses, 50 and 60 kHz, were above the recording bandwidth). The level of coil-specific components depends on pulse duration, and is in general lower for briefer pulses.