On any given day on the UI campus, most students probably listen to music on the way to class. Blasting songs through their earphones, they never think twice about the possibility that loud tunes could permanently damage their ears. "Most people my age don't protect their hearing, because they don't think [hearing loss] will affect them for 50 years," says freshman Stephanie Koch*. "They're not worried about it now."
Like many of her peers, Koch had a simple remedy to drown out background noise—crank up the volume on her iPod. That all changed after she took the UI's "iPod Music, High-Fidelity Sound and Hearing" course. The first-year seminar explores the many ways that sound enriches our lives—and examines the toll that acoustic overload can take on our hearing. Taught by Richard Tyler, 78PhD, a UI professor of communication sciences and disorders and otolaryngology, the course also invites students to explore careers in sound, such as speech pathology, audiology, and music therapy.
Tyler's 14 students, whose majors range from pre-dentistry to pre-med, first learn that sound happens when air molecules vibrate and move in pressure waves. When those sound waves hit our eardrums, the three smallest bones in the human body—the hammer, anvil, and stirrup—amplify the vibrations into the inner ear. The cochlea—a spiral-shaped chamber filled with fluid—then vibrates, setting in motion thousands of short, hair-like cilia that send messages through the auditory nerve to the brain. In the final stage of the hearing process, the cerebral cortex translates these signals into recognizable sound.
To appreciate the role of sound in communication, entertainment, and relaxation, the professor takes the class to a room where silence reigns. The anechoic chamber in the basement of the UI Wendell Johnson Speech and Hearing Center is designed to stop the reflection of sound and keep out exterior noise. Constructed in 1967, the concrete room contains a steel-walled booth that is built on springs and covered with acoustic fiberglass wedges. Here, audiology researchers can test hearing aids and musicians can record songs, free from the sound reverberations of a typical room.
The hush proves uncomfortable for students accustomed to living in a clamorous world. "It freaked me out, because I could hear the blood flowing in my ears," says freshman Brittany Giammona*. "It's the quietest I've ever been."
With today's ubiquitous acoustic assault of television or stereos, students can easily forget how far sound technology has come in recent times. Before 1877, music and other sound could only be heard live. Then came Thomas Edison's phonograph, which allowed users to speak into a mouthpiece while a mechanical needle indented the sound vibrations onto a wax cylinder. The original sound played back when the needle retraced its path. Since Edison's day, the analog sounds of phonographs—later followed by record and tape players—have given way recently to digitized personal music players. Digital music doesn't take up the physical space of records, tapes, or CDs, and it can be stored indefinitely without a decline in the sound quality.
As Tyler presents this history to the class, he invites students to imagine what sound playback systems will be like in another 50 years. Already, the choices in audio equipment range from an iPod nano as small as a stick of gum to the massive sound systems used in rock concerts. With so many options on the market, Tyler teaches his class how to read sound specifications and test manufacturers' claims. Undergraduates learn, for instance, that while companies may try to push stereo speakers with frequencies up to 40,000 Hertz, anything over about 20,000 Hertz can't be heard by the human ear.
The most invaluable lesson that Tyler imparts to his students, though, is the need to protect their hearing. If they're not careful, the hobbies that bring them pleasure may bring their eardrums pain. The cilia inside the cochlea can be bent and broken under stress, irreparably damaged and unable to send messages about sound to the brain. If students have to shout to be heard over noise, the environment is too strident—and potentially hazardous.
As an audiologist, Tyler frequently sees patients suffering from hearing loss due to noise from factory work or loud hobbies, such as woodworking with power tools or participating in motor sports. Hunters who don't use earmuffs are at particularly high risk. Any sounds exceeding 132 decibels SPL (sound pressure level) can cause acoustic trauma, resulting in immediate loss of hearing after only a single exposure. The average gun blasts at 140 decibels SPL. Rock concerts measure in at 120 decibels SPL and often leave audience members temporarily deaf and with ringing in their ears. Many rockers, such as Pete Townshend of The Who, have permanently damaged their hearing after years of such abuse through prolonged noise exposure and high volume.
Hearing loss is an inevitable part of aging, although ear protection can delay the need for hearing aids by decades. Hearing aids and cochlear implants can help the hearing-impaired—some 38 million people in the United States or about 12 percent of the population—regain some sense of sound and enjoy again the everyday interactions of life. Though such devices can cost thousands of dollars, Tyler says the price is well worth it. "There's nothing more important than communication," he says, "so you shouldn't be shy about paying for good hearing."
Many students in the class agree, having seen hard-of-hearing family members struggle with social isolation. Giammona shares how her grandmother's hearing loss has affected her quality of life. "It's really frustrating for her," says Giammona. "It's hard to hold a conversation, because she will ask, 'What?' and you have to look straight at her [when you talk]. She feels like a burden."
In the past 30 years, cochlear implants have become an option for people who are extremely hard of hearing or deaf, but with a functioning auditory nerve. Although controversial among some in the deaf community, the surgery has helped many children who were born deaf and others with acquired deafness. The implants send electrical impulses to electrodes coiled around the cochlea, stimulating the auditory nerve fibers that transmit sound messages to the brain.
The UI's reputation as one of the largest and most comprehensive research centers for cochlear implants first attracted Tyler to the university. In 1982, the UI Hospitals and Clinics became the first center in the United States to implant a multichannel cochlear implant system; in 1987, it performed a groundbreaking procedure to give a cochlear implant to a congenitally deaf boy. Since then, more than 600 children and adults have received cochlear implants at the UIHC.
Even if their career paths don't lead them to the UIHC, students benefit in other ways from the "iPod Music, High- Fidelity Sound and Hearing" class. They begin to fully appreciate the hearing that enables them to learn from a lecture, relax at a movie, chat with a friend, or safely cross a busy street.
They learn healthy new habits: to keep their iPods at about a moderate 80 decibels SPL and to wear earplugs in loud environments. Initially hesitant to use the devices for fear of not appearing "cool," they soon discover unexpected bonuses, including better concentration while studying.
Now, that sounds good.