The use of auditory heart rate response for the test of hearing in infant children (author's transl)

Abstract

The clinical utility of the heart rate (HR) response as an index of hearing in infant children was investigated. Subjects were 16 normal infants aged between 1 and 10 months. The test was performed during the natural sleep or the sleep induced by oral administration of Tricloryl syrup. Beat-by-beat HR was recorded on a cardiotachogram and 10HR responses were averaged with an averaging computer. Pure tones of 250Hz, 1kHz and 4kHz were given to the subjects with intensity levels from 20 to 80dB above mean subjective thresholds of normal adults. The duration of the tone was fixed at 100 msec with a rise-decay time of each 10 msec.The most definite and consistent response is an abrupt and brief deceleration of the averaged curves with a peak latency of 1 to 1.5sec. Original tachograms revealed that this initial deceleration occured most frequently in the interval between the first and second beats after stimulus onset. The initial deceleration is usually followed by a slower acceleration with a maximum change at 2 to 3sec after onset of stimulation. For tone bursts of 250Hz and 1 kHz, the response was observed in 50, 80 and 100% of the subjects for stimulations of 40, 60 and 80dB respectively. This percentage was lowered a little for 4kHz stimulation. The incidence of a false positive response was as low as 5% in the averaged HR traces. Though there was an individual variability in the appearance of the response, the method was considered to be useful as a supplementary tool for evaluating hearing in infant children.