iPods - Safe Tech Tips

This week is the Apple iPod's fifth year anniversary. I can't turn a corner without bumping into one of the 68 million people using this sleek MP3 player. It's a great device that provides music, keeps the peace between teens and adults, makes those long road trips tolerable, and keeps me sane when I travel. But how long and how loudly can you listen to an iPod safely?

A recent study was published that gives some guidelines for safe listening. The researchers, Cory Portnuff and Brian Fligor studied 5 MP3 players with 5 models of earphones with each player and with different types of music.

"Typical individuals can tolerate about two hours a day of a decibel unit known as 91-dBA before risking hearing loss, Portnuff said. The term dBA stands for "A-weighted decibels, a scale that takes into account that the human ear has different sensitivities to different frequency levels," he said".

The table below is their recommendation for maximum listening time with different earphones without damaging the hearing. **There was no difference in the genres of music or the MP3 players**. It's really all about volume control and how long you spend listening. Please note that these are just general guidelines. Some people have more sensitive ears than others.
Maximum Listening Time Per Day

% of Volume Control	Earbud	Isolator	Supra-Aural	stock earphones
10 - 50 %	No limit	No limit	No limit	No limit
60 %	No limit	14 hours	No limit	18 hours
70 %	6 hours	3.4 hours	20 hours	4.6 hours
80 %	1.5 hours	50 minutes	4.9 hours	1.2 hours
90 %	22 minutes	12 minutes	1.2 hours	18 minutes
100 %	5 minutes	3 minutes	18 minutes	5 minutes

Table 1. Maximum listening time per day using NIOSH damage-risk criteria. “Earbud” includes stock earphones and iPod In-ear earphones. “Isolator” includes Etymotic ER6i earphones and Shure E4c earphones. “Supra-Aural” includes Koss headphones that rest on top of the ear. ©2006 Cory D.F. Portnuff, B.S. and Brian J. Fligor, Sc.D.

Bottomline is that if you are going to listen to the MP3 player for an extended period of time then it seems safest to play it at a level of less than 70% of the volume. Above the 80% volume damage to the hearing could be done fairly rapidly. Similar findings were found in a study of personal stereo systems.

References: please see specific links.
Photo: courtesy of ipodlounge