Users complain they have to crank it up to get rid of background noise and, with digital music, they can do that with little distortion.

Snug-fitting earbuds block more background sound and allow listeners to use lower, safer volumes for longer periods. And that's better for your hearing.

But these speakers, and more expensive models that generate sound waves to counter background noise electronically, also shut out everyday warnings like car horns, truck backup alarms and sirens.

Hearing damage has been a concern since headphones -- initially big clunky things that surrounded each ear -- first came on the market in 1957.

Portable headphones evolved by the mid '80s with the arrival of the Sony Walkman tape player followed in the '90s by the portable CD player. Most ear headphones can handle sound at 100 to 115 decibels (dB) without distortion.

Consider this:

* A jack hammer five feet -- 1.5 metres -- away or a circular saw one metre away each hit 115 dB.

* A rock band on stage: 110 dB.

* An 18-wheeler grinding up the Highway 20 hill: 96 dB.

* One of The Spectator's running presses flat out: 95 dB.

The guy running the jack hammer will be wearing ear protection rated for occupational health and safety. But the kid with the ear buds and loud iPod is hearing just as much noise.

It doesn't matter if it is Mozart or Metallica. Research shows it is the amount of time spent listening to high volume that does the damage.

Over time the delicate hair cells in the inner ear that transmit sound to the brain get damaged. It's something that won't be felt for years.

Boston audiologist Dr. Brian Fligor worries today's portable music users who play it too loud and too long will be used to the feel of a hearing aid -- which fits in the ear like an earbud -- by the time they will need one.

He has some simple rules to protect your ears. Keep your listening level down to 80 decibels or less. That's about 60 per cent of your player's maximum volume. If you want it louder than that, reduce your listening time.

Fligor says earbud speakers don't do more damage to your ears than the kind that ride on top of your ears. What matters is loudness and listening time. If other people can hear the tunes outside your head, it's too loud for you.

By John Burman
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