Noise and Hearing Loss

NIOSH Sound Level Meter App

What to know

The NIOSH Sound Level Meter (SLM) app measures workplace noise to determine if workers are exposed to hazardous noise. The free app combines the best features of professional sound levels meters and noise dosimeters into one simple tool.

Screen shot of the sound level meter app.


The NIOSH SLM app was created to empower people to test noise levels in their workplace. This helps workers make informed decisions about their noise exposure which can prevent occupational hearing loss.

Download the app‎

Visit the Apple App Store to download the app today. The app is free to download. Please note the app is only available on iOS devices.

Key features

  • Developed by experienced acoustics engineers and hearing loss experts.
  • Tested and validated.
  • Free to download.
  • Provides an accurate measurement of noise levels using any iOS device.
  • Provides informational screens about:
    • hazardous noise levels
    • conducting noise measurements
    • selecting a hearing protector, and
    • hearing loss guidelines.
  • Provides relevant metrics found in professional instruments.
  • Connects to technical support from NIOSH hearing experts.

Technical specifications

  • Accurate within ± 2 dBA.
    • Tested according to standards in a reverberant chamber at the NIOSH acoustics laboratory.
  • Meets Type 2 requirements of IEC 61672:3 SLM standard with calibrated external microphone.
  • Includes multiple metrics:
    • Averages such as LAeq and TWA, Max and Peak Levels, Noise Dose and Projected Dose
    • All three major weighting networks (A, C, and Z)
  • Capability to calibrate either internal or external microphone.
  • Ability to report and share data.
  • Only available on iOS devices.
    • Verifying the accuracy of an Android-based app is not currently possible.

How to use the app

Refer to the Help Guide for an overview of features and functions.

Frequently asked questions

Why is the app only available on iOS devices?

iOS devices share common hardware and software architecture that is optimized for audio applications. Therefore, we have been able to verify that the NIOSH SLM app will perform as expected on any iOS device. On the other hand, the Android device marketplace is fragmented among many manufacturers with different requirements and specifications for microphones, audio/signal processing chips, and software tools. As a result, testing and verification of the accuracy and functionality of an Android-based app in our laboratory is not currently possible.

How can I provide feedback or request help?

Please email us using the following links: