Effect of fractal quality of Indian classical music on autonomic function

Abstract

Music is an external stimulus that affects physiological systems; both the quality of music and the resultant physiological changes can be quantified, which presents an unique opportunity. To quantify the complexity of a musical phrase we have used the Higuchi fractal dimension. We then compared the response of autonomic system (blood pressure, ECG, heart rate variability) in healthy subjects while listening to Indian classical music of different fractal qualities. Indian classical music has the unique quality of slow transition between notes, with consequent changes in dimensions of the string being played, which we have quantified. 25 healthy volunteers were recruited, all 18–35 years of age; the subjects were randomised into three groups: sinewave, low fractal and high fractal, depending on the type of musical intervention. The subjects were placed in a quiet room and asked to perform deep breathing exercises for relaxation. Electrocardiogram (ECG) and Non invasive BP (NIBP) leads were placed and continuous measurements started 10 min prior to intervention. At 0 min, the standardised musical intervention/ control was played. During intervention, the fractal dimension of the BP waveform showed a significant difference between subjects of high fractal group and low fractal group. In addition, the increment in heart rate variability (measured by standard parameters) during intervention showed an increasing trend from high to low fractal to sinewave. Whether the changes are due to direct contact with source of music or through a cerebral mechanism can be ascertained by further studies.