RESUMEN
Electrocardiogram [ECG] tracings were recorded from normal 28 male subjects in response to an attentive auditory task. Data regarding the changes in ECG that occur on listening to the rare tone bursts were calculated and compared with those on listening to frequent tone bursts. P wave showed longer duration and lower amplitude, in response to rare stimuli, indicating longer, but weaker atrial contraction. QRS complex and P-R interval did not show significant differences between the listening of the two types of stimuli. T wave showed shorter duration and lower amplitude on listening to rare stimuli indicating faster and less ventricular relaxation. The present work denoted that not only passive hearing, but also the active listening had changes in the cardiac cycle