Given the threat they represent to hearing, should people continue to use headphones? Mai Samih finds out "Watch out!" a bus driver in a crowded Giza square calls out. Everyone in the bus looks out of the windows to see a teenager with earphones in his ears being scolded by the driver who has nearly run him over. "What's wrong with you? Didn't you hear the horn? Did you fall on your ears or what?" "Sorry," says the boy, who surprisingly still has his earphones on, playing the latest track of a popular rock star. Such scenes have become familiar in the streets of Egypt, where many young people in particular choose not to hear what is going on around them. One hundred years or so ago, earphones were only used by telegraph personnel, developing from the earpieces used in telephones. Looking at first like head bands, on which the ear pieces were mounted, and causing considerable discomfort to those wearing them, these early forms of technology were only used in office environments and were never used in public. Then came the "walkman"-type headsets of the 1980s, which, padded and designed for prolonged listening, soon caught on among young people. From here, it was an easy step to today's mobile phones and MP3s. Finally, there are the Bluetooth earphones that look like earrings. According to Mohamed Shabana, a professor of audio technology at Cairo University, there are two main types of headphones, one that can be inserted into the ear, which is used for I-pods and mobile phones and is mounted at the entrance of the ear's external canal, and the other which is wholly outside the ear and is called a "supra-oral phone". "By 'supra-oral' is meant the fact that both the headphone and the receiver, if there is one, are outside the ear," Shabana explains. Whatever the type of technology used, today's young people rely more and more on headphones. According to Mohamed Abdel-Fattah, 18, a law student, the technology has many uses, especially Bluetooth technology. He often alarms his friends by answering incoming phone calls using Bluetooth earphones without carrying a mobile, and he admits to using earphones to pass the time in academic lectures. "They are a cool solution for passing the time in any boring lecture," Mohamed says. "I just put them on and listen to songs." Another student, Dina Said, believes that earphones can be a relief from the daily noise she has to cope with. "They help me to live in my own private world and listen to my favourite songs and radio programmes without being bothered by intrusions, such as the horns of cars or friends' gossip." Said says that she often wears earphones when she's doing chores, shopping, or doing her hair. "Behind the protective walls of my earphones, I have the kind of privacy that is rare these days," she says. Michael Kamel, 17, a law student agrees. He has more than one reason to praise the invention of earphones. "It's a matter of personal freedom," Kamel says. "I use them in order not to disturb anyone while listening to my favourite music, or making phone calls." For Kamel, earphones save the battery of his mobile phone and make music sound better. His friend, Mohamed Sherif, 19, also a law student, always has earphones in his ears. "They keep me entertained and give me my own space while listening to music," Sherif says. According to Shabana, there are three factors to bear in mind when assessing whether the use of earphones or headphones is harmful. These factors are "the level of the sound introduced into the external ear canal, the duration the earphones are inserted into the ear, and finally the quality of sound." If the sound produced by the earphones is very distorted, Shabana says, it will be more injurious to the ear. Shabana explains that loudness is measured in decibels, and for a normal person the minimum sound that the ear can detect is in the range of 0 to 20 decibels. If an individual has a hearing problem, the minimum would be more than 20 decibels. "When someone puts MP3 phones in his ears and plays music to the point that he cannot hear any other sound, this means that the sound introduced into the ear is around 75 decibels. At this point, the ears are unable to detect conversational speech," Shabana explains. If sound is played over earphones throughout the day, for four to six hours or more, then this will affect hearing. The human hearing system consists of an external ear canal, which collects sound and delivers it to the eardrum. This then vibrates, and the vibration is passed to small bones inside the middle ear that vibrate in turn and transmit this vibration to the inner ear. In the inner ear, the vibration is changed into hydrodynamic energy, which causes tiny hairs within the inner ear to vibrate. This vibration is changed into electrical energy and sent down the hearing nerves to the brain. According to Shabana, very loud sounds transmitted to the inner ear can fatigue the hair cells and eventually cause them to stop working. "This means that the hair cells begin to die," he said. Each person is born with around 12,000 hair cells, and if these are lost the body is unable to renew them, which explains why the best way of preserving one's hearing is to prevent damage to these cells. Yet, Shabana's advice seems not to affect earphone users like Abdel-Fattah and the members of his generation of young people, who are reluctant to abandon their earphones even if they could cause damage to the inner ear. "I can easily keep them on for four hours, as we usually have lectures that go on for two hours. When one lecture ends, another begins. So, I keep them on for the two lectures," Abdel-Fattah says. Sherif also wears his headphones for up to five hours a day. He is, he says, a self- described "earphone-aholic". "I wear them between lectures, and when I go home by bus. I also use them to listen to music in my spare time, and when I am studying I like to listen to classical music," Sherif says. Said also considers earphones to be a kind of companion. "I like to wear earphones on my way to work, during lunch break, and even if I have nothing to do. If I'm travelling, I might wear them all day," she says. Kamel, on the other hand, uses his earphones more wisely. He does not wear them for more than half an hour at a time, and he thinks that anyone who knows the harm that earphones can cause will avoid using them. It is true that in order to avoid harm to the ears, earphones should be used carefully. Anyone who uses earphones for more than six hours at a time without giving his ears a rest is risking damage to the hair cells of the inner ear. When listening to music with headphones or earphones, Shabana advises taking the headphones off after an hour or so to give the ears a rest of around 15 minutes. Then, the headphones can be used again. "By doing this, you will be resting the inner ear, saving the hearing elements and hair cells," he explains. If such procedures are not followed, then hearing loss can be the result, and Shabana describes five main degrees of hearing loss. The first degree of loss is where an individual cannot detect sound of less than 25 decibels. Mild hearing loss sets in with an inability to detect sound from 20 to 40 decibels, and moderate hearing loss sets in when an individual cannot detect sound from 40 to 55 decibels. After this, there is moderately severe hearing loss, where sound from 55 to 70 decibels can be barely detected, and then comes severe hearing loss, which is the inability to detect sound of more than 70 decibels. "Some companies have pre-employment hearing tests. If a person is able to hear from 20 decibels, their hearing will be considered 100 per cent, but if this figure falls to 25, they are sometimes ranked as suffering from hearing loss," Shabana said. Exposure to noise has what Shabana calls a "cumulative" or "storage" effect on hearing. For example, if someone works in a factory for 10 years with constant exposure to noise, and then goes to a quiet place like the countryside and then moves back to the factory, he or she will still have an accumulated 10 years' worth of exposure to noise, which could lead to hearing loss. Finally, Shabana has three pieces of advice for those who are tempted to overuse earphones. First, choose high-quality headphones that will play music undistorted. Second, limit the use of earphones to less than one hour a day to prevent them from being injurious to the inner ear, and third, change the ear used for a single earphone in order to rest the ears and not keep the earphone in the same ear all the time. "Everyone should use earphones or headphones wisely in order to avoid their potentially harmful effects on hearing," he concludes.
