Five types of prerecorded music compact discs (CD)
were created for this study. Each CD contained approximately
30 min of music, respectively, in five categories:
crystal music, nature sounds, classical music, lullabies, and
symphonic music. The tempo of the music selections was
selected to mimic the human heart rate (60—80 beats/min).
Participants in the experimental group were given the prerecorded
CD and asked to listen to the music at least 30 min
a day for 2 weeks, while they were at rest or at bedtime and
on a self-regulated basis, that they would feel more relaxed.
The participants listened to the music in their preferred category,
and were permitted to listen to the music either over
speakers or through earphones.