Researchers from the University of California

Researchers from the University of California, Irvine, tested the levels of two dozen separate toys and took 10 of the loudest to a specialist soundproof laboratory. The scientists found that all of the 10 exceeded 90 decibels and several reached 100 or more - equivalent to the noise of a chainsaw or underground train. Among the toys tested were the Tonka Mighty Motorised Fire Truck, Marvel Super Shield Captain America, Whac-A-Mole game, Sesame Street Let's Rock Elmo and Toy Story Buzz Lightyear Cosmic Blaster.

Dr. Hamid Djalilian, associate professor of otolaryngology at the University of California, Irvine, said problems could arise if a noisy toy was held too close to a child’s ears. “We tested the sound levels at the speaker and again at 12 inches, which is about the length of a toddler's arm,” 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 for a prolonged period can lead to hearing impairment.

Dr Djalilian said two factors contributed to this: loudness and duration. The louder a sound is, the less time it takes to cause hearing loss. He added that someone buying a noisy toy for a child should 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.