Effects of stimulus level on vocal suppression in neonates.

Abstract

In 4 separate 4-min sessions, the crying behavior was recorded in msec of 45 normal neonates in either a calm or a crying state. In the sessions a random noise (RN) was or was not presented at 60, 70, or 80 db SPL. In the crying state, all Ss cried significantly less during RN than in quiet. The 15 Ss in Grp III cried significantly less to RN at 80 db than the 15 in Grp I at 60 db, while the 15 in Grp II at 70 db was not significantly different from either of the other 2 groups. Thus, vocal suppression occurred even for relatively low-level stimuli and there appears to be a linear relationship between stimulus strength and response strength. In the calm state, All Ss tended to remain calm regardless of stimulus presentation and there were no significant differences across groups. Similar test procedures may improve response reliability and validity in behavioral observation audiometry.