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 1 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 2（测定，测量） in a soundproof booth at uc irvine medical center. they found that all exceeded 90 3 and several reached 100 or more, equivalent to the noise of a chain saw, subway train or power 4.
"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 5 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 6: 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."
收听单词发音 
