Are your headphones too loud?
Do you have a similar experience that when you put on your headphone, your parents start shouting “DON’T wear your headphone all the time!” ?
I often got super angry about my parents’ endless arguments on the harmfulness of the headphone when I was a little boy. However, I totally changed my mind after I read several scientific articles talking about this as I grew up. I love music, which is my life. Every time when wearing a headphone, I start wondering – are headphones so dangerous? Is there a safety level of using headphones? How long can I wear and how to know if it is too loud?
How dangerous is the loud sound?
First, we must know the function of our ears. External ear is like a megaphone (click to check image) which receives the sound, passes sound through auditory canal, and stimulate the eardrum to vibrate. After that, the ossicles (three tiny bones) convey it to the inner ear which contains sensory nerves connecting to the brain.
One of the most important functions through the process is the cochlea, which is a snail-shaped structure in the inner ear and where the organ of corti located. Organ of corti is the sensory receptors for hearing.
So, if it was damaged, the result would be that you cannot hear others well. Most importantly, this process is irreversible!
Damaged organ of Corti from a guinea pig. Left image shows healthy organ of Corti from a guinea pig. Right image shows a noise-damaged organ of Corti from the same pig exposed to sound at a 120-decibel level (similar to that experienced at a heavy metal rock concert). Cells are permanently damaged or dying. Credit: Robert Preston and Joseph E. Hawkins, Kresge Hearing Research Institute, University of Michigan, Ann Arbor, Mich.
You might think turning down the music could be helpful. However, it depends on whether you can tell which sound levels are too loud or not. So, let’s see a sound decibel chart showing average sound level from different sources that we can hear in everyday life.
Common sounds with decibels and typical response (own graph). Date source from: U.S. National Institute for Occupational Safety and Health
Apart from the loudness, according to World Health Organization (WHO), the safe listening levels also depend on the length of time and frequency of the exposure. The total sound level that a person can be exposed is limited to a constant: 8 hours a day at 85 dB is the limitation and higher than 85 dB will cause hearing loss in certain hours or minutes. A report from U.S. National Institute for Occupational Safety and Health reveals when exposure level higher than 110 dB, your hearing loss is in seconds. That means, even if you listen to music for 30 minutes a day at 95 dB, you may be still suffering hearing impairment in two or three years.
Do you often use headphones to listen music on trams, buses or planes? And do you always feel like you should increase the volume in these circumstances? If so, that would be a huge problem for you. When you can hear the music in the same level you expected, the decibels are much higher than you thought.
What can be done to make listening safe?
The first thing you can do is to ensure your volume lower than 60% according WHO advice.
If it is possible, a noise-cancelling headphone is the best option when you are in noisy environment, which will cut down the external sound exposure.
Another option is to measure the sound level. There are lots of sound meter apps on smartphones or computers available for you to measure the decibels you are hearing.
Of course, other good options include to take listening breaks and to enjoy music in a quiet place.
My headphone (own photo)