hearing loss when they mature. The recorded signal needs to be passband filtered between 28 Hz and 500 Hz. By this step, artifacts from eye movements and muscle activity independent of blink responses are removed. To avoid aliasing artifacts the sampling rate of the signal should be at least 1024 Hz which is larger than twice the upper bound of the bandpass filter (twice the Nyquist frequency). After filtering, the resulting signal is rectified and smoothed. Reporting the signal deflection evoked by the startle stimulus, the term mean amplitude (mA) refers to the average startle response excluding nonresponse trials. However, to calculate the mean magnitude (mM), nonresponse trials are set to zero before averaging. Dividing the number detected responses (number of trials used to compute amplitude) by the total number of eliciting stimuli yields the response probability (P). Thus, increasing response probability shifts average response magnitude towards average response amplitude. It is recommend to use the computed mean magnitude to report the average startle response. Since this metric includes also nonresponse measures, it exhibits increased validity compared to mean amplitude. Major features The magnitude of PPI is often significant, reaching as much as 65% in healthy subjects, with maximum inhibition is typically observed at 120 ms interval. The baseline startle response does not affect overall PPI levels – this finding was first discovered in rat studies and later duplicated in the studies of mice. The opposite reaction, Prepulse Facilitation (PPF)-- the tendency for a subject to have an increased startle response following a lower-intensity prepulse stimulus—is typically noted when the interval between stimuli lasts longer than 500 ms. PPF is thought to reflect, at least partially, sustained attention: the prepulse, if not followed within less than half a second by the pulse, will tend to make the subject more likely to have a startle response rather than less. Another moderating variable in prepulse inhibition and facilitation is sex difference, with men having higher PPI (i.e., when a prepulse is quickly followed by a pulse, all subjects tend to experience a reduced startle response, with men often experiencing lesser startle responses compared to women) and women having higher PPF (i.e., when the prepulse occurs more than half a second before the pulse, all subjects tend to experience heightened startle responses, with women tending to experience greater startle responses than men). For acoustic stimuli, monaural PPI is higher than binaural—the startle response