Physiological Responses, Peripheral

Respiration

Changes in respiration may be detected by the use of devices that measure variation in thoracic or abdominal circumference. Currently, the most commonly used devices are piezo-electric belts and respiratory inductive plethysmographs that respond to abdominal expansion. The output [Page 863]from such devices can provide information on the respiration rate, duration of inhalation/exhalation, and volume of air intake per minute.

Respiration rate tends to increase in response to happy or exciting music, and decrease in response to sad or calming music. The dominant musical cue underlying this response pattern appears to be tempo. Removal of melodic and harmonic structure in a piece of music does not influence respiration rate, as long as the underlying tempo remains constant. There is evidence to suggest that respiration rate entrains in response to the tempo. When listening to fast-tempo music, breathing rate increases, and when listening to slow-tempo music, it decreases. Musicians show a stronger response than nonmusicians in this respect. Increases in tempo also lead to shorter periods of inhalation and exhalation while increasing the volume of air intake.

Heart Rate

Changes in heart rate may be detected by directly monitoring electrical activity from the heart with an electrocardiogram, or indirectly by monitoring light absorption on the fingertip or earlobe with a photoplethysmogram. Heart rate has been reported to increase when listening to music that is high in arousal, and decrease when listening to music that is low in arousal. Some reports also find decreases for music that is negative in valence, which may be part of an orienting response, indicating allocation of attentional resources. Increases in heart rate have been linked to increases in tempo and use of the major mode, while decreases have been linked to decreases in tempo, the minor mode, and use of dissonance. However, because the mere act of listening to music is often stimulating, some studies have found increases in heart rate in response to music, regardless of its structural features.

Variation of heart rate over time is called heart rate variability (HRV). This variability is determined in part by respiration. Phasic increases occur during inhalation, and decreases during exhalation. A lack of variability in heart rate denotes dysfunction of the autonomic nervous system, and is associated with cardiovascular disease or acute stress. Increases in HRV have been observed in response to both excitative and sedative music. Music with higher tempo causes increases in HRV. However, this seems to only be the case for individuals with high baseline HRV, indicating that individuals with poor cardiovascular health do not experience this effect.

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