The results of listening to contrasted tracks selected by X-System was compared with watching nature films with no sound track. Physiological measures of Heart Rate (HR) were taken with sensors, but there were not appropriate conditions to take physiological measures of Heart Rate Variability (HRV), so subjects reported on the effect of valence – related directly to HRV and vagal power – in response to a simple, culturally adjusted, psychometric question. X-System predictions proved to be accurate in terms of ranking and profile for both HR and subjective valence responses to music. The responses were far more vivid for the music than for the films The results were highly statistically significant.
A population of 40 schoolchildren was selected, with an equal number of girls and boys, from the same age group (11-12) with a similar level of educational achievement, as assessed through methods approved by the National Council of Educational Research and Training (NCERT).
A computer randomisation program, was used to choose 20 children, 10 girls, 10 boys. The chosen children were further divided randomly into two groups: A and B, each with 10 children, 5 girls, 5 boys n=20 (10 plus10) To a certain extent, this may be considered to be a single blind study; although the children participated in making choices, they were not aware of the purpose of the experiment.
For group A
Children were tested individually, by one researcher, in one 45-minute session
During the session the children listened to four 5-minute tracks of Carnatic vocal music with the kind permission of Sudha Ragunathan, predicted by X-System to be, respectively,
- Negative valence Sarvam Brahmanayam
2. Low Arousal. Ragam-Tanam-Pallavi-Dhamavati
- Positive Valence. 05-Mamavathu………
4. High Arousal. 01-Era Napai…..
(Sarvam) (Dhamavati) (Mamavatu) (Era Napai)
The children wore X-System wristband heart rate sensors; there was a minute-long silence before each track to establish an HR baseline, and a pause after each track, where the children answered a simple question (How did the music make you feel?). The track order was not randomised and remained the same for every child.
A 3-minute game of naughts and crosses was played between tracks 1-2, 2-3 and 3-4.
For group B (control group)
Children were tested individually, by one researcher, in sessions lasting 45 minutes
During the session. Children watched four 5-minute video clips of nature, with as neutral a mood and sense of arousal as possible, and no sound.
The children wore X-System wristband heart rate sensors; there was a minute-long pause before each clip to establish an HR baseline, and a 5-minute pause after each clip, where the children answered a simple question (How did the film make you feel?)
A 3-minute game of naughts and crosses was played between clips 1-2, 2-3 and 3-4.
Sensor data for the music and control groups was collected by means of a Sony wristband sensor and X-System commercial i-phone app. Data from tracks with dropouts was eliminated (two from both sets of data). For each of the remaining tracks, the average HR was calculated.
The values for the music group were as follows:
X-System predicts the ranking correctly. There is a relatively strong range of HR values for the music sensor data, i.e. a range of 4.16 bpm. The average HR for the four tracks (92.22), represents a generally high level of excitement above average HR for 12-year-old children (70)
For the control (silent film) group the average HR values were:
This is far less profile than for the music group results. There is a relatively weak range of HR values, I.e. a range of 1.71 bpm, and a generally far lower level of excitement (average 83.28), indeed 41% lower than the music group.
The difference between the music and control group results was highly statistically significant p = 0.000351, t = 3.5804
X-System furthermore predicted subjective valence scores with accuracy: