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21 April 2011

IPod generation risks hearing loss

If it’s too loud, you’re too old, right? Wrong. Listening to loud music for long periods of time is no joke, and research shows that the iPod generation is most at risk.

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If it’s too loud, you’re too old, right? Actually, if it’s too loud you’re going to get permanent ear damage. Listening to loud music for long periods of time is no joke, and research shows that the iPod generation is most at risk.

In the US there have been reports of an increase in young adults and teens being diagnosed with hearing at the level of 50-year olds. They are the ones listening to their IPods or MP3s for hours every day - and Lisa Nathan, an audiologist at Cape Town Medi- Clinic says that it’s a problem facing South African youths, too.

"Unfortunately this is only the start for this generation. Accumulated noise damage develops slowly and insidiously. It can take a few years before the real damage begins to show, and the individual may experience noticeable hearing problems.

"For example, a 15 year old teenager who regularly listens to his IPod or MP3 at loud levels for hours at a time may only notice hearing difficulties in his mid- to late-20s. It also depends on lifestyle and exposure to other noise sources, such as an individual who frequents nightclubs or plays in a band can also experience the long term effects on his/her hearing," she says.

How the ear 'hears' sound
Nathan explains that all of the sound information in our world enters through our ears, goes into our auditory cortex, and is understood and memorised to ensure that we function normally. Everything we do, throughout every day relies on our sense of hearing.

The ear itself is made up of various delicate parts that work together to allow an individual to listen to, process and make sense of the world around us. But when the noise around us is very loud, the delicate outer hair cells in the inner ear are damaged.

"At first, these hair cells are damaged only temporarily, and symptoms include a feeling like one’s ears are blocked up. Often this is accompanied by tinnitus, which is a ringing or buzzing in the ears.

"Tinnitus is normally a good warning sign that damage has occurred, even if it is temporary. But the more often this ‘temporary’ damage occurs, the more likely the damage will become permanent because the hair cells have been irreversibly damaged, or have died and cannot regenerate. This results in permanent and irreversible loss of hearing."

How loud is too loud?
Yet many of us know that when our favourite song comes on the radio, or we’re at the gym working out to our favourite tune, it’s almost habit to turn it up and sing along.

Which is fine, Nathan says, as long as you don’t always listen to music at the same deafening volume.

But how do we know how much volume is too much?

Nathan explains that sound is measured in decibels (dB), with '0' the faintest sound the human ear can detect, and ‘180’ the noise a rocket would make as it launches into space.

"Average conversation level would be at the 60dB level, a loud rock concert would be at around 115dB and a jet engine would be at 140dB. The experts believe that continued exposure to more than 85dB is dangerous – the longer you are exposed to these levels, the higher the risk of damage," she says.

The top volume on MP3 players is around 100dBA, and a level of 85dB is safe. Anything much louder than this, Nathan says, can potentially cause serious damage.

The following table is used as a guide for audiologists when advising patients how to appropriately present volume control levels:

% Max volume control

‘free-field’ equivalent

Time to max permissible exposure level

25%

65

Indefinite

30%

68

Indefinite

40%

73

Indefinite

50%

81

19 hours

60%

87

271 min (4.5 hours)

70%

92

98 min (1.6 hours)

80%

98

23 minutes

90%

106

4 minutes

100%

111

1 minute

Type of earphones makes a difference
As technology as progressed, so the size and design of earphones for MP3’s and IPods have changed. It therefore stands to reason that if you’re wearing the more common insert-earphones and listening to music at a high volume, the damage will be more intense.

Research backs this up, and has shown that insert earphones can produce higher sound levels relative to over-the-ear earphones – although Nathan says they are only dangerous if the user chooses to listen to a volume that is turned up too high for an extended period of time.

She recommends noise-cancelling earphones are the best option, as they will help reduce background noise which should allow the user to listen at more comfortable and 'acceptable' sound levels.

Are you at risk of damaging your hearing?
Nathan says that the susceptibility of a user acquiring a hearing loss from listening to music through earphones depends on several variables, including:

  • The volume level selected by the user,
  • The amount of time spent listening,
  • The pattern of listening behaviour,
  • The individual genetic susceptibility of the user’s ear to noise damage to the inner ear and
  • Other noisy activities that contribute to the individual’s lifetime dose of noise, such as firearms, power tools, recreational vehicles and loud music.

Common causes of hearing problems
Nathan deals primarily with the elderly, and therefore sees the more common "wear-and-tear" types of hearing loss.

“This loss is normally more high frequency in nature, and the individual has problems listening to conversations in restaurants and other places with background noise. Voices tend to sound muffled and in the beginning stages the high frequency soft consonants such as "s", "f", "sh", "h" and "t" become difficult to hear.

"With time, the loss progresses and so the individual may experience more widespread problems with understanding speech. Saying this, noise induced hearing losses present the individual with similar difficulties and affects one’s quality of life. Imagine having the same difficulties as your grandmother when you are in your late 20s – but the difference is, yours was preventable," she says.

Treatment for hearing loss
The type of treatment for hearing loss or hearing damage depends on the type of hearing loss, and where the damage has occurred. Nathan explains that some hearing losses can be treated medically or surgically by an ear-, nose- and throat (ENT) surgeon, whilst the rest often need to be managed by the fitting of hearing aids by a registered Audiologist.

Tips to keep your ears safe
Nathan suggests the following tips when listening to music to ensure you don’t damage your ears:

  • The louder the volume, the shorter the listening time.
  • If you can hear sound leaking out of the earphones, or if you can’t hear someone speaking to you at a typical conversation level and that person is just an arm’s length away, the volume is probably too loud.
  • Two basic rules to follow are: keep the volume down (a good guide is to set the volume level at half) and limit listening time – after rest and recovery, hearing can return to normal levels.

This video shows you how to limit the volume on your iPod.

Reference: Lisa Nathan (BSc(Audiology), University of Cape Town; M(Audiology), Stellenbosch University) , Dr P.S. Traub Inc, Cape Town Mediclinic.

(Amy Henderson, Health24, updated April 2011)

Read more:
MP3 users risk hearing loss
Club music: how the ears survive

 
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