The amplitude behavior of several hundred VLF whistler mode pulse signals and of their associated artificially stimulated emissions (ASE's) has been analyzed with digital signal processing techniques. A survey of the results indicates that the pulse signals characteristically show exponential growth with time that is highly repeatable over short periods. However, the growth rate varies widely from time to time, covering a range of 25--250 dB/s. During the exponential growth phase of te pulse there is no observable change in frequency. Emission may begin when growht stops or when the input pulse terminates, whichever occurs first. Low growth rates and falling emissions characterize the beginning and ending of extended periods of emission activity. Rising emissions are prominent at the height of activity. ASE's triggered by station NAA (14.7 kHz, 1 MW radiated) begin when the transmitted Morse dash terminates (dash length, 150 ms). Some ASE's triggered by pulses from Siple Station, Antarctica (1.6--7 kHz, ?1 kW), and Omega, New York (10.2 kHz, 100 W), show similar behavior: others, however, begin prior to the termination of the triggering pulse when the pulse length exceed 200 ms. Growth and frequency change of the ASE tend to be independent of one another. For transmitted pulses of sufficient duration the amplitude saturates prior to termination. Signal amplitudes may reach 30 dB or more above the initial level. During growth the measured bandwidth of the signal remains near the minimum possible (~27 Hz) with the given analysis resolution (~30 ms, ~50 Hz). By comparison with mathematicl models it is shown that the observed signals have the maximum possible coherence for the measured values of growth rate and duration. These observations are in qualitative agreement with a model that attributes signal growth and ASE's to an interaction between coherent waves and counterstreaming gyroresonant electrons.