DISCUSSION
Soft music decreased both sensation and distress of
active labor pain in the first 3 hours; it also delayed
increases in distress of pain for an hour, and for some,
relief was fairly substantial. Women listened to music
for a mean of nearly 3 hours and found it helpful for
pain, with two thirds reporting it helped moderately
to a lot. The sedative quality of the music helped
women to relax and distract themselves from increasingly
severe pain. The high power of nearly one was
due to the rigor of a randomized controlled trial with
a large sample and minimization to balance and equalize
the groups. The groups were homogeneous and no
confounding variables were found. Use of the pretest
score as a covariate decreased the error term and thus
increased the power.