iPhone Screenshots


The NIOSH Sound Level Meter (SLM) app automatically provides a readout of the instantaneous sound level in A, C, or Z weighted decibels using the smartphone’s built-in microphone (or preferably using an external, calibrated, microphone). The weighting is user-selectable and can be accessed from the ‘Settings’ screen. The app also reports the main metrics that are of importance for proper occupational and general purpose noise measurements – mainly the run time (total time), the A-weighted Equivalent Sound Level (LAeq), the Maximum Level measured during the current run time, the C-weighted Peak Sound Pressure Level (LCpeak), the Time-Weighted Average over 8-hour (TWA), and the percentage of the daily noise Dose and Projected Dose. You can select whatever metric to display on the main screen by tapping on that metric. The app contains some basic information on noise and hearing loss prevention. In addition, the app allows the user to save and share measurement data using the smartphone communication and media features. If location services are enabled, the app can utilize the GPS feature to provide general geospatial location of the noise measurement. The app is validated and calibrated for each iOS device at our lab but we recommend that users perform proper calibration using a known noise source or by using an external microphone before and after each noise measurement. Calibration can be accessed from the Settings screen. For additional information, instructional videos, and detailed user guidance and how to interpret the various metrics, please visit the NIOSH SLM app page at: https://www.cdc.gov/niosh/topics/noise/app.html or share your comments on the NIOSH SLM science blog at: https://blogs.cdc.gov/niosh-science-blog/2017/01/17/slm-app/

The app is targeted at safety and health professionals, industrial hygienists, and researchers to use as an initial noise assessment tool, but it does not replace the need for professional instruments or expertise. The app can also be used by workers and the public in general to help make informed decisions about the potential hazards to their hearing, and promote better hearing health and better prevention efforts.

The app was tested and verified for accuracy (± 2 dB) against a reference type 1 Sound Level Meter at the NIOSH Acoustics Laboratory (see NIOSH webpage for links to studies). EA LAB and NIOSH researchers are working towards achieving class 2/type 2 instrument compliance with IEC 61672/ANSI S1.4 Part 3 (Periodic Tests) Sound Level Meter Standards, when the app is used with an external calibrated microphone.

What’s New

Version 1.0.7

In this version we have improved iPhone X accuracy and fixed the incorrectly displayed C-weighting for instantaneous parameter.
This version also includes minor improvements and bug fixes.

Ratings and Reviews

FinnMcCool60 ,


Very helpful app for monitoring noisy workers.

...............doesntwork ,

Doesn’t work please help

This app does not seem to work on my iPhone 7

Developer Response ,

Hello, the app works well for thousands of users every day on all different iOS devices. We have a help/support email on the NIOSH SLM website where you can contact us directly with any issues.

It is tough to diagnose a problem without much details except "app doesn't work", However, almost every issue with "my app doesn't work" report happens to be because the user did not grant permission for the microphone to be used when the app first launches a pop message asking for permission. Please try that and let us if we can be of further assistance?

Field Officer ,

Perfect for Law Enforcement and Security Foot Patrols



EA LAB d.o.o.
25.8 MB
Requires iOS 10.0 or later. Compatible with iPhone, iPad, and iPod touch.
Age Rating
Rated 4+
© 2016 EA LAB


  • Family Sharing

    With Family Sharing set up, up to six family members can use this app.

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