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We live in a noisy world. Young and old alike are troubled by sounds over which we may have little or no control: car and house alarms, motorcycles, loudspeakers, even movie previews.

We attend rock concerts, weddings, parties and sports events at which the music is so loud that you can hardly hear the person sitting next to you. At home, televisions, stereos and computer games are often turned up so loud that listeners cannot hear a doorbell or a telephone.

As if environmental noise were not enough, now we surround children with noisy toys and personal listening devices that can permanently damage their hearing. A series of studies conducted in 2002 indicated that even moderate (缓和的) background noise can interfere with how they learn language. In fact, children in classrooms on the noisy side of a school had lower reading scores than those whose classes were on the quiet side.

Noise-induced (噪音诱发的) hearing loss can come about in two ways: from a brief exposure to a very loud noise or from consistent exposure to moderate-level noise. Thus, there is much concern about the lasting effects of MP3 players that are turned up loud enough to block out surrounding sound, like street noise. An MP3 player at maximum volume produces about 105 decibels（分贝）— 100 times as severe as 85 decibels, where hearing damage begins.

So, before buying noise-making toys, parents would do well to listen to how loud they are. If the item comes with a volume control, monitor its use to make sure it is kept near the lowest level. Consider returning gifts that make loud noises, or disable the noise-making function. Children who play computer games and stereo equipment should be warned to keep the volume down. Most iPads have a control that allows parents to set a maximum volume.

Avoid taking children to loud action movies. If you do go and the sound seems deafening, ask the management to turn down the volume or insist on your money back.

The League for the Hard of Hearing urges parents to encourage participation in quiet activities, like reading, doing puzzles, making things with construction toys, playing educational computer games, drawing and painting, and visiting libraries and museums.

--- Whose schoolbags are they ?     --- They`re          .