Trials with the auditory response cradle III: head turns and startles as auditory responses in the neonate.

The Auditory Response Cradle was used to record neonatal head turn and startle responses. Pure tones of 250 and 1,000 Hz, broad band noise and no-sound controls were presented unilaterally in random order at a level of 90 dB SPL. Clear head turn and startle responses were obtained after the onset of the sound. The frequency of occurrence was highest for the noise. No responses attributable to stimulus off were detected. The response rate for head turn was found to be unaltered by the initial head position but babies lying to the right, generally turned to the right and vice versa irrespective of the side to which the sound was presented. The response latency varied with stimulus. The mean broad band noise and 1,000 Hz pure tone values were 1.7 and 1.9 secs respectively while the 250 Hz results were similar to the 2.4 secs of the controls.