As an Audiologist I often get asked to recommend safe listening levels for many different situations. There is no "one size fits all" rule, but I generally abide by the Occupational Safety & Health Administration (OSHA) guidelines when determining if a situation is noisy enough to warrant hearing protection. OSHA requires employers to provide hearing protection to any employee exposed to 85 decibels of continuous noise for an 8-hour work day. As the intensity of the workplace noise increases, OSHA further limits the amount of time that employee can be in that environment, even with hearing protection. For instance, employees are only allowed to be exposed to 95 decibels of noise for 4 hours.
Now, you may see decibels referenced as dBA, dBC, dBSPL, or dBHL. The algorithms that factor into each weighting system are too complex for this blog post. But suffice it to say, anything exceeding 85 dBHL on ANY decibel weighting scale CAN cause long lasting damage to the auditory system.
I have the National Institute for Occupational Safety & Health (NIOSH) sound level meter app downloaded on my iPhone and I use it frequently to decide if I should put in my earplugs or not. More information on this app can be found here. There are many other sound level meter apps available for free for both iOS and Android operating systems.
When listening to music via headphones I generally consider about 50% of the volume to be the loudest safe listening level. Studies have shown that more and more younger individuals are presenting with hearing loss related to unsafe headphone listening levels. My best tip for headphones is to get a good pair that makes a good seal in your ears to help block out ambient/environmental noise. When you can't hear your music or Podcast over the sound of public transportation or other environmental sounds the instinct is to increase the volume. Even though your PERCEPTION of what you're listening to may not be that loud, the sound pressure level in your ear canal may still be high enough to cause damage to the auditory system.
I also highly recommend anyone who enjoys listening to live music to invest in a good pair of earplugs. Now, I'm not talking about foam earplugs. Foam earplugs block more of the high frequency sounds, which can make live music sound muffled and generally leads to a less enjoyable experience. If you're looking for non-custom earplugs, Etymotic is a good place to start. If you're interested in custom earplugs, find an Audiologist to take ear impressions for you. It is possible to find websites that will send you an at-home ear impression kit, but I STRONGLY advise against trying this at home on yourself. Audiologists and hearing instrument specialists go through rigorous training to learn proper techniques for obtaining quality ear impressions SAFELY. Many things can go wrong, the least of which include an inadequate impression that would lead to a poor fitting product and ear canal bleeding and abrasions. Seriously, this is NOT a good thing to DIY. Westone Labs is a good resource for helping you find a professional who can take impressions for you. I have custom earplugs and I LOVE them.
Have you ever left a concert or other noisy event and felt like your hearing was muffled or you experienced tinnitus (ringing in the ears) afterward? If so, then you should have been wearing hearing protection! Lesson learned for next time, hopefully!
Finally, here are some additional resources regarding safe listening levels and hearing protection: