More than half of high school students surveyed reported at least one symptom (症状) of hearing loss connected with the use of portable music players, like iPods and other MP3 players.
Does your child turn up the volume (音量) on the television or radio, even though everyone else can hear just fine? Does your child say “what？” or “huh？” repeatedly? It could be their ear－bud head－phones, which, like the ones typically used with iPods and other portable music players, project sound directly into the ear canal (耳孔)．
Sound levels are measured in decibels. Generally, decibel levels lower than 80 or so are not harmful to hearing. But a MP3 player can put out levels in excess of 100 decibels, and children sometimes stay plugged in for hours.
Like generations of mothers, Lynette Cook shouts across the house for her children to turn down the volume of their music, only they're not listening to stereos. They're rocking out to music on tiny iPods, listening through very small speakers tucked into their ears.
Hearing damage occurs when loud sounds destroy tiny hair cells in the inner ear. These cells turn sound waves into electrical impulses (脉冲) and send them to the brain. Destroy just 25 to 30 percent of these cells, and hearing loss occurs.
Carmen Lappen, the nurse at South Mountain High in Phoenix, is amazed when the children surveyed admitted they had hearing problems. Students at her school love their iPods and other
MP3 players. She laughed, “They're not going to tell me they hurt.” Lappen worries when she can hear students' tunes, even when they're wearing ear buds. “If I can hear it, it is too much for their ears. ” She won't buy an MP3 player for her 17－year－old son.
Lappen and Cook offer age－old advice：“Turn it down！” Or, better yet, “Turn it off ！”
1. According to the passage, the word “decibel” is a unit ________.
A. to show whether a sound is harmful or not
B. to suggest the price of a MP3 player
C. to show the listening level of students
D. to show the volume of sound
2. The reason why Lappen won't buy an MP3 player for her son is that ________.
A. she's afraid it may affect her child's hearing
B. she can't afford an MP3 player
C. the MP3 player will make her child's study worse
D. MP3 players are forbidden to use in school
3. According to the passage, it can be inferred that ________.
A. sounds over 25 decibels will cause hearing－loss
B. man can hear depending on the hair cells outside ears
C. children's hearing problems surprised Lappen
D. Cook doesn't like students to listen to music by headphone
4. What would be the best title for the passage?
A. Be Careful with Your iPods and MP3 Players
B. Headphones May Make You Lose Hearing
C. No Worry about Your MP3 Players
D. Mothers' Worry about Their Children's Hearing