While Road Rippers Lightning Rods, Let's Rock Elmo and the I Am T-Pain musical microphone might be sought-after gifts this holiday season, parents should ensure that their children don't risk permanent hearing damage by misusing¹ them. Researchers from UC Irvine's Department of Otolaryngology measured the noise levels of two dozen popular toys in stores and purchased the 10 loudest for precise gauging²（测定，测量） in a soundproof booth at UC Irvine Medical Center. They found that all exceeded 90 decibels³ and several reached 100 or more, equivalent to the noise of a chain saw, subway train or power mower⁴.

"Generally, toys are safe if used properly," said Dr. Hamid Djalilian, associate professor of otolaryngology（耳鼻喉科学） and director of neurotology（耳神经学） and skull⁵ base surgery. "We tested the sound levels at the speaker and again at 12 inches, which is about the length of a toddler's arm."

But problems can arise if a noisy toy is held too close to the ears, he said: "Children are very sensitive to loud and high-pitched sounds. Unfortunately, hearing loss from noise damage is permanent and not currently curable."

According to the American Academy of Otolaryngology, unprotected exposure to sounds above 85 decibels（分贝） for a prolonged period can lead to hearing impairment. Two factors contribute to this, Djalilian noted⁶: loudness and duration. The louder a sound is, the less time it takes to cause hearing loss.

He suggested that someone buying a noisy toy for a child pay attention to the speaker's location -- under the item is often better than on top. Djalilian also recommended that an adult hold the toy as a youngster would and listen to its sound. "If it hurts your ears," he said, "then it's probably too loud for a child."