SIGNAL ATTENUATION AS A FUNCTION OF INTEGRATOR TIME CONSTANT AND SIGNAL DURATION

In some laboratories, eyeblink electromyogram is rectified and smoothe d before the analog signal is digitized. The relationship among the in tegrator time constant, the duration of the response, and the attenuat ion of the data was investigated by passing a number of signals at dur ations of 5, 10, 20, 50, and 100 ms into a contour-following integrato r (Coulbourn model S76-01), which first rectifies and then smooths (in tegrates) the signal. Integrator time constants of 10, 42, 70, 144, an d 300 ms were used. The output of the integrator was sampled (1,000 Hz ) and stored on a Macintosh SE computer. The integrator attenuated the signal, and the amount of attenuation increased as the duration of th e signal decreased and as the time constant of the integrator increase d. For brief inputs, the integrator does not charge fully, so only the early portion of the charge limb is present, and this early portion i s the steepest part of the charge limb. Therefore, the longer the time constant, the less likely that small or brief responses will be detec ted.