Earbuds place the sound closer to the ear drum, enhancing volume by as much as 9 decibels and damaging the ears permanently. REUTERS

Earbuds used in personal music systems enhance the volume and affect the ear drum, permanently damaging the hearing of the new generation, warn experts.

Hearing loss among today's teens is about 30% higher than in the 1980s and 1990s.

"You (once) had a Walkman with two AA batteries and headphone thongs that went over your ears," Sreekant Cherukuri, an ear, nose, and throat specialist from Munster, Indiana, told NBC News.

"At high volume, the sound was so distorted and the battery life was poor. Nowadays, we have smart phones that are extremely complex computers with high-level fidelity."

Cherukuri, who believes iPods and smart phones are responsible for the hearing loss, tells young patients to stop using earbuds, which place the sound closer to the ear drum, enhancing volume by as much as nine decibels.

Around 1.1 billion teenagers and young adults are at risk of hearing loss due to over-exposure to audio devices, including smartphones, besides the damaging levels of sound at noisy entertainment venues such as nightclubs, bars and sporting events, according to the World Health Organization.

Data showed that among teenagers and young adults aged 12-35 years, nearly 50% are exposed to unsafe levels of sound from the use of personal audio devices while 40% are exposed to potentially damaging levels of sound at entertainment venues.

WHO recommends safe levels of sounds at exposure below 85 decibels (dB) for eight hours or 100dB for 15 minutes.

The National Institutes of Health also recognizes that repeated exposure to sound over 85 dB can cause hearing loss. Permanent damage can happen in minutes, experts say.

Nicole Raia, a clinical audiologist at the University Hospital in Newark, New Jersey, sees more tinnitus in young people, an early sign of hearing loss, but, "we don't catch them until they are in their 20s and 30s".

Best protection

According to experts, the best way to protect young ears is to apply the 60/60 rule: Keep the volume on the MP3 player under 60% and only listen for a maximum of 60 minutes a day.

There are also ways to block higher volumes in smartphones by using passwords to lock the system.

Nerve synapses can be more vulnerable to damage than hair cells in the inner ear. When young animals were exposed in a study to loud noise, even just once, they had accelerated hearing loss later in life.

France already has existing laws that limit the volume of portable audio devices to 100 dB, while the EU has a mandatory safety limit on all personal music players of 85 dB that warns users of dangers of higher sound levels.