The influence of the sounds of crying baby and the sounds of violence on haemodynamic parameters and autonomic status in young, healthy adults.

INTRODUCTION

There is evidence that various stimuli affect the balance in the autonomic nervous system (ANS) and the functioning of cardiovascular system.

OBJECTIVE

The aim of the study was to assess whether the sounds of crying baby and the sounds of violence affected haemodynamic parameters and ANS in young, healthy adults and to measure differences in these reactions between the genders and these 2 stimuli.

METHODS

Haemodynamic parameters (measured non-invasively by the NEXFIN device), heart rate and blood pressure variability (HRV and BPV, respectively) and baroreflex sensitivity (BRS) were analyzed in 65 adults (21 women, mean age: 23years) during a 15-minute rest followed by the emission of two 5-minute acoustic stimuli: sounds of crying baby and sounds of violence emitted randomly and separated by a 4-minute pause.

RESULTS

Resting systolic blood pressure was lower, whereas indices of HRV (RMSSD, NN50, pNN50, high frequency component of HRV - HRV HF) and BPV (high frequency component - BPV HF) as well as BRS were higher in women as compared to men. During the emission of the sounds of crying baby, a decrease in diastolic blood pressure (DBP), systemic vascular resistance index, HRV HF and BPV LF (low frequency component of BPV) and an increase in stroke volume index were observed in the whole examined group, whereas during the emission of the sounds of violence subjects presented a decrease in DBP, mean blood pressure, HRV HF and BPV LF. The reaction to the sounds of crying baby (expressed as a decrease in HRV HF) was greater in women as compared to men (-0.28±0.49 versus -0.04±0.38ms(2), p=0.04). The comparison of the reaction between 2 stimuli revealed no differences.

CONCLUSIONS

The stronger decrease in parasympathetic drive in women exposed to the sounds of crying baby may be related to a particular role of this stimulus, which signals the baby's distress and compels the caregivers to react.