With the invention of the smart phone, users have an endless amount of audio at their fingertips.

From audio books to podcasts to music, hours of content are available, with the majority of that content consumed through earbud headphones. Because of the availability and ease of use, experts say more people are experiencing hearing loss than ever before — particularly teenagers.

A study by the American Osteopathic Association suggests that 1-in-5 teens has some form of hearing loss due to excessive volume and lengthy use of such headphones. That is 30 percent higher than it was 20 and 30 years ago, the association says.

According to Betsy Sears, an audiologist at Cranberry Hearing & Balance Center, young people’s ears tend to be more sensitive to sound than adults, including in the range of frequency. This makes them more susceptible to damage, which often can be permanent and is different from a “temporary threshold shift.”

“Often times, when leaving a noisy area or something loud such as a concert or live music venue, people notice either that they have to raise their voice to hear themselves even when the noise is no longer present, or they may notice a ringing in the ears,” she said of the temporary shift. “This typically goes away after several hours.”

However, permanent damage is also a possibility, and has become more common.

“Permanent damage ... can happen from even just one instance of noise exposure, but the odds of this occurring increases exponentially with longer periods of noise exposure,” she said. “This used to be limited to noisy events, but the use of personal audio systems ... has made it much more possible for people to be in these loud environments, without having to go anywhere at all.”

Using earphones at any volume higher than half, on an earpiece that goes directly to the ear, can cause permanent damage, Sears said. While that threshold may seem low, Sears said it is all about perspective and surroundings.

“In our noisy world, sometimes people feel that they cannot even hear what they want to listen to with the volume that low ... because of the noise around them, and they start pushing the volume higher and higher,” she said. “This is where long-term use can cause serious long-term effects, and where we are seeing an increase in hearing loss with children and teenagers.”

Sears said there is no way to reverse such hearing loss, and hearing aids can only lessen the symptoms.

She said following the “half-way rule” of 50 percent volume is a good guide for listening to personal audio devices. However, if that is not loud enough, the “80/90” rule is also an option. This indicates a person can listen to earphones at 80 percent of maximum volume for a total of 90 minutes per day.

“With the volume higher, the amount of total time per day used decreases,” Sears said. “If longer use is necessary, try decreasing the volume, or increasing the distance between yourself and the sound source — use a speaker at a bit of a distance, rather than an earbud or headphone right at ear level.”

Sears said education is key to prevent hearing loss from becoming a problem earlier in life than it has for previous generations.

“Keep informed, and help inform those around you,” she said. “If you can hear the music or sound of a personal audio system that someone else is listening to, when standing an arms length away from them, their volume level is likely damaging to them. Remind them that you want them to always be able to enjoy the sounds around them, so turn the volume down, to ensure they are not causing avoidable damage.”

Evelyn Wiest-Kertz of Wiest Audiology in Butler said manufacturers have made strides in trying to limit overuse or misuse of personal headphones.

Technology such as ambient noise reduction lessens environmental sound, making it easier to listen at lesser volumes. Some devices also alert the user to harmful levels of audio and prolonged use.

“They’re starting to try and do guidelines to help with the safety factor,” Wiest-Kertz said.

Wiest-Kertz said parents should read instructions and warnings for devices.

“Parents should kind of take a look at that too. They should see that there are safety guidelines on any of those items that they’re using,” she said.

Wiest-Kertz said for some people loud noise is unavoidable. She said some industrial companies require custom ear protection for their workers, which is molded to the ear and provides more protection, longevity and savings over disposable ear plugs.

Wiest-Kertz said another specialized plug is meant specifically for musicians, which is where she sees a lot of damage in teenagers.

“We always recommend that they use custom musician plugs that they can have made to protect their ears while they play their instruments,” she said. “They are very effective.”

Wiest-Kertz said it’s always a good idea for everybody, especially teenagers, to get screened for their hearing or have a diagnostic evaluation done, if struggling.

“Basically monitoring and using the hearing protection is a good guideline,” Wiest-Kertz said.

Eagle staff writer Nathan Bottiger contributed to this report.