Auditory Responsivity in the Human Neonate

Abstract

ELECTROMYOGRAPHIC, autonomic and electroencephalographic responses were recorded from human neonates during stimulation with sine and square wave tones and with human voices. This communication will concentrate on the analysis of the electromyograms, both because of their importance in reflecting behavioural changes, and because changes in autonomic activity, such as heart rate acceleration, are associated with movements. The “artificial” sounds were chosen so as to have certain structural similarities to the “biological” sound: they were either sine wave components of it or selected fundamentals with superimposed high frequencies. Sine wave and square wave tones of the following frequencies, rising by octaves, were selected: 125, 250, 500, 1,000 and 2,000 Hz. Further sine and square wave tones at 70 Hz were added because preliminary studies had suggested that responses to sound frequencies lower than 100 Hz may have especially interesting properties. Recordings of a male and of a female voice saying “baby” were also included.