NIOSH Sound Level Meter 4+


Designed for iPhone

    • 4.7 • 12.3K Ratings
    • Free

iPhone Screenshots


Protect your hearing.

This award-winning app combines the best features of professional sound level meters and noise dosimeters into a simple, easy-to-use package.
- Developed by experienced acoustics engineers and hearing loss experts.
- Completely FREE – No ads, no limited features, and no in-app purchases.
- Tested and validated (accuracy ± 2 dBA) according to standards in a reverberant chamber at NIOSH acoustics lab – the only proper method to validate accuracy.
- Trusted source and world-class expertise in noise and hearing research.
- Meets Type 2 requirements of IEC 61672:3 SLM standard when used w/ external microphone.*
- Provides the most relevant metrics found in professional sound instruments today. Averages such as LAeq and TWA, Max and Peak Levels, Noise Dose and Projected Dose according to NIOSH and OSHA standards, and all three major weighting networks (A, C, and Z).
- Capability to calibrate either internal or external microphone. Reporting and Sharing data.
- Up-to-date informational screens on what noises are considered hazardous, how to conduct a noise measurement, how to properly select a hearing protector, and guidelines for preventing hearing loss, all at the palm of your hand.
- Excellent and timely support from NIOSH hearing experts.
- Support for Apple's Health (Hearing) app.

* Celestina M, Hrovat J, Kardous CA [2018]. Smartphone-based sound level measurement apps: Evaluation of compliance with international sound level meter standards. Applied Acoustics, 139:119-128.

More resources (including instructional videos and a user manual), a science blog, FAQ, and information about how to interpret results can be found on the NIOSH SLM website

What’s New

Version 1.2.6

This version adds support for iPhone 14.

Ratings and Reviews

4.7 out of 5
12.3K Ratings

12.3K Ratings

Satisfied 3 ,

NIOSH sound level meter

I love the convenience of this app, and how simple it is to use.

I have protected my hearing since I was a child when I found out that some of my relatives were very hard of hearing because they had been exposed loud noises in their lives. I still jealously guard my hearing, as I have worn glasses since I was a kid and don’t want to lose a second sense.

When I am exposed to loud noises by people who don’t seem to care, or it doesn’t sound that loud to them because they have already damaged their hearing, it gives me an opportunity to show them that it is loud enough to damage hearing and they need to turn the volume down a bit for everyone’s sake, or it shows me that although I’m uncomfortable, it’s still in the safe zone, and I just put in my earplugs. Or if it’s someone like my husband who is hard of hearing from all his years in construction and not protecting his hearing and needs the volume up like that to hear it, I just hand him the headphones.

I pulled your app out to use it this time because all the hammering going on inside my house right now (a construction project inside my own home) is hurting both my ears and the dog’s, so I was checking to see how much damage is being done and are the dog and I safe without hearing protection.



Robert_3rd ,

Can save environmental noise data to Apple Health

Great app to use if you don't have an Apple Watch or can't afford one. It will keep the screen on and drain the battery, but I don't use my iPhone as my main phone. I use it as a portable media player and now also as a decibel meter at work. I run this app while I'm working --with the phone in my pocket, with the mic up and sticking out of my back pocket-- my warehouse job. I save the data to the Health app to make sure my job isn't causing me irreversible hearing damage over time.

I'll also run it in public places such as grocery stores, and in the car while driving.

Me 1024 ,

Well done

I have been using this app for over a year and through several updates. It has always worked well and accurately. It has been a useful tool for monitoring the noise exposure and deciding where and when I need to wear earplugs. The only feature it lacks (in my opinion) is the ability to run as a background process with the phone asleep (similar to the way you can play music), which would allow to have the screen off and use less battery when monitoring for long periods of time. Aside from that personal preference, this app has been reliable and helpful. I would highly recommend it.

App Privacy

The developer, EA LAB, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy.

Data Not Collected

The developer does not collect any data from this app.

Privacy practices may vary, for example, based on the features you use or your age. Learn More

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