Understanding How Sound Suppresses Pain

National Institutes of Health (NIH)

Studies dating back decades have shown that music and other kinds of sound can help alleviate acute and chronic pain in people. This is true for pain from dental and medical surgery, labor and delivery, and cancer. However, how the brain produces this pain reduction, called analgesia, was less clear.

An international team of scientists set out to use mice to explore the neural mechanisms through which sound blunts pain. The team was led by researchers at NIH’s National Institute of Dental and Craniofacial Research (NIDCR); the University of Science and Technology of China, Hefei; and Anhui Medical University in Hefei, China. Their study was published in Science on July 8, 2022.

The scientists first exposed mice with inflamed paws to three types of sound: a pleasant piece of classical music, an unpleasant rearrangement of the same piece, and white noise. Surprisingly, all three reduced pain sensitivity in the mice when played just slightly louder than background noise (about the level of a whisper). The effect lasted well beyond the sound itself—for at least two days after exposure to the sound three days in a row for 20 minutes. When played louder, the sounds had no effect on the animals’ pain responses.

Pain perception can be affected by emotions and stress. However, the scientists discovered that low-intensity sound didn’t affect the mice in tests of stress and anxiety. The finding shows that this particular type of sound affected the animal’s perception of pain through another mechanism.

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