Cases of noise-induced hearing loss are rising almost as fast as the popularity of the portable music players that may cause problems.

Noise-induced hearing loss has always been an issue with people who use headphones, said Julie Rhoades, an audiologist at Penn State's Hershey Medical Center. "In general, if someone else can hear what you [are listening to], it is too loud," she said.

More young people are developing noise-induced hearing loss, said Elise Uhring, an instructor of communication sciences and disorders. It is directly related to the use of personal music devices.

Damage is caused to a person's hearing if the noise level is above 85 decibels for an extended time, said Uhring.

"For every five decibel increase, you should limit your exposure by half," said Claire Yeargers (senior - communication sciences and disorders).

Rhoades explains that 10 decibels is a soft sound and 100 decibels is a loud sound. A person can be in an 85-decibel environment safely for 8 hours. At a 90-decibel environment, a person can only remain safely for four hours, she said.

Many Penn State students use iPods, or similar devices to listen to music between classes. Listening to mp3 devices, such as an iPod, can gradually diminish a person's hearing, said Rhoades.

"It scares me when I walk across campus, and there's a student walking 10 feet in front of me listening to music, and I can hear and feel the sound coming out of the headphones," said Uhring. "I know what damage is being done."

The damage takes place in the inner ear, where the loud noises destroy the frequency-sensitive hair cells inside the cochlea, Uhring said. The hair cells, which convert vibrations of sound waves into electrical impulses for the brain to understand, are arranged from high frequency to low. This is why high frequency hearing usually is the first to be affected by noise-induced hearing loss, she added.

"The longer and more intense [the noise], the faster you will get noise-induced hearing loss," said Emily Angert (senior - communication sciences and disorders).

High frequency hearing is used to distinguish sounds from background noise, said Uhring.

Angert, secretary for Penn State's chapter of the National Student Speech Language Hearing Association (NSSLHA), said without higher frequency hearing, it is difficult to understand speech.

Consonants come from higher frequency sounds, and are the intelligibility of speech, she said. Vowels use the lower frequencies and contain "the power of sound," she added.

For example, the average volume of speakers at a concert at the Bryce Jordan Center is 120 to 130 decibels, Angert said.

"If you have been to a concert and your ears are ringing and muffled, you have done some damage," Rhoades said.

Laura Wentzel (sophomore-kinesiology) listens to her iPod while walking to classes or exercising, she said."I usually listen to my iPod at a reasonable volume [when walking to class] so I can still hear my surroundings," she said, but admits, "when I exercise, I usually have the volume turned up." Wentzel said she doesn't worry about increasing her risk for hearing loss.

Hearing loss cannot be fixed like vision can, Uhring said. "Where glasses can restore eyesight to 20/20, hearing aides won't give perfect hearing," Uhring said.

A hearing aid only amplifies or limits sounds that enter the ear, Rhoades said.

Hearing loss affects individuals differently, she said. Two people could be exposed to the same amount of noise, and it may affect one but not the other.

Students who fear they may be developing hearing loss can contact Penn State's audiology clinic. Uhring said the clinic provides thorough evaluations for students that are having trouble hearing.

Jill Morin (senior-communication sciences and disorders) said free hearing screenings will also be offered at the Oct. 28 career awareness day sponsored by NSSLHA. Morin, NSSLHA vice president, said students are welcome to bring in their cell phones and portable music players to find out the decibel output.

"Hearing loss from noise is preventable," Rhoades said.

Students should make sure that they keep the volume level relatively low.

"If the music is loud enough that you can't carry a conversation over it, there's a potential for damage," Uhring said.