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.
Overview
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
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.
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:
Relevant publications and studies
NIOSH Science blogs
New NIOSH Sound Level Meter App
So how accurate are these smartphone sound measurement apps?
NIOSH smartphone studies
Smartphone-based sound level measurement apps: Evaluation of directional response Applied Acoustics, Vol. 171, January 2021
Evaluation of smartphone sound measurement applications – Journal of Acoustical Society of America
Evaluation of smartphone sound measurement applications (apps) using external microphones – A follow-up study – Journal of Acoustical Society of America
Improving the accuracy of smart devices to measure noise exposure – Journal of Occupational and Environmental Hygiene
Smartphone-based sound level measurement apps: Evaluation of compliance with international sound level meter standards. – Applied Acoustics