“…Among these, only three had a control group (18,28,29) . Concerning the aspects of type of study, there were seven longitudinal analyses (5,(21)(22)(23)(24)(25)29) and six cross-sectional studies (13,18,20,(26)(27)(28) . Five studies combined the results of the CAEP electrophysiological tests with behavioral assessments, indicating that the decreased P1 latency is correlated with the improved communication behaviors (vocalization) (5) , improvement of speech and language skills (22) , and improvement of speech among children (13,26,29) .…”