Sound levels in movie theaters may injure children's hearing

Going to the movies may be dangerous to children's hearing. A Hawaii-based researcher found that while sound levels in movie theaters do not exceed government safety standards, the volume may still be loud enough to damage hearing.

"We're not suggesting that parents keep their children out of movie theaters," said W. Thane Hancock, MD, family practice intern at the University of Hawaii Family Practice and Community Health Residency Program. "But I would like people to think about the exposure. Even one movie can be enough to produce temporary hearing shifts with ringing in the ears and muffled sounds. Repeated temporary threshold shifts can produce permanent hearing loss over time."

Excessive sound exposure that damages the hair cells of the cochlea is the second most common source of hearing loss after age-related loss, Dr. Hancock reminded pediatricians at the AAP 2004 National Conference and Exhibition Monday. An estimated 12% of US children between 6 and 19 years of age have noise-induced threshold hearing shifts in one or both ears. The resulting hearing loss is entirely preventable by avoiding exposure to excessive noise levels.

Dr. Hancock and his research team took sound meters into 23 movie theaters in eight different multiscreen complexes in Hawaii. The highest measured sound level reached 96% of the maximum exposure recommended by the Occupational Health and Safety Administration: 85 dBA over eight hours.

The loudest movie reached 130 dBA at its loudest, louder than the sound of a jet taking off 100 meters away. According to the decibel meters, action films were the loudest and documentaries the least loud. Children's films were as loud as action films, Dr. Hancock noted.

"I don't know that they need to be that loud," he said.

The average rock concert comes in at 100 to 110 dBA, Dr. Hancock noted, and rock concerts are a widely recognized source of hearing damage.

Sound levels are set by projectionists in each movie theater, he said. Movie studios and distributors recommend sound levels for their films, but the final loudness can vary widely. In general, he said, newer theaters with stadium-style seating and larger theaters are the loudest.