About
The NIOSH Sound Level Meter App is a free mobile application developed by the National Institute for Occupational Safety and Health (NIOSH), part of the U.S. Centers for Disease Control and Prevention (CDC). Designed to help workers, safety officers, and industrial hygienists assess noise hazards in the workplace, the app transforms a standard iPhone into a calibrated sound measurement device. The app measures A-weighted sound levels (dBA), which reflect how human ears perceive sound, as well as C-weighted peak sound levels to capture impulse noise hazards. It provides real-time readings of instantaneous sound pressure levels, time-averaged levels (Leq), and noise dose percentages based on NIOSH and OSHA exposure criteria. Users can view sound level history on a time-weighted graph and export data for reporting purposes. Key audiences include occupational health professionals, safety managers, industrial hygienists, researchers, and workers concerned about on-the-job noise exposure. The app has been validated against professional-grade Type 2 sound level meters and is suitable for preliminary noise surveys and awareness screening. Because it is developed and maintained by a federal research agency, the app carries no cost, no ads, and no subscription requirements. It is particularly valuable in industries such as construction, manufacturing, mining, agriculture, and entertainment where hazardous noise levels are common. With noise-induced hearing loss affecting millions of U.S. workers, the NIOSH SLM App is a practical first step in any hearing conservation program.
Key Features
- Real-Time Sound Level Measurement: Displays instantaneous A-weighted (dBA) and C-weighted (dBC) sound pressure levels in real time using the device's built-in microphone.
- Noise Dose & Exposure Assessment: Calculates time-weighted average (TWA) noise dose percentages against both NIOSH Recommended Exposure Limits (REL) and OSHA Permissible Exposure Limits (PEL).
- Sound Level History Graph: Records and visualizes sound levels over time, helping users identify patterns and peak exposure events during a work session.
- Data Export: Allows users to export measurement data for use in occupational health reports, audits, and hearing conservation program documentation.
- Validated Accuracy: Tested and validated against professional-grade Type 2 sound level meters, making it suitable for preliminary noise surveys and awareness-level assessments.
Use Cases
- A construction site safety manager uses the app to conduct a quick noise survey before deciding whether to mandate hearing protection for workers operating heavy equipment.
- An industrial hygienist uses the app during a preliminary walkthrough of a manufacturing facility to identify high-noise areas requiring follow-up assessment with calibrated instruments.
- A music venue employee checks live sound levels on the stage floor to assess whether staff exposure exceeds NIOSH recommended limits during events.
- An agricultural worker monitors noise exposure from machinery such as tractors and grain dryers to understand cumulative hearing risk over a workday.
- A university researcher uses the app in occupational health studies to gather noise exposure data from fieldwork participants in various job settings.
Pros
- Completely Free with No Ads: Developed by a U.S. federal agency, the app is 100% free with no in-app purchases, subscriptions, or advertising.
- Scientifically Validated: NIOSH validated the app against calibrated Type 2 sound level meters, giving users confidence in the accuracy of measurements for preliminary assessments.
- Dual Exposure Criteria: Compares noise exposure against both NIOSH REL and OSHA PEL standards simultaneously, giving safety professionals a complete compliance picture.
Cons
- iOS Only: The app is currently only available for iPhone, leaving Android users without an official NIOSH mobile measurement option.
- Microphone Limitations: Accuracy depends on the quality of the device's built-in microphone; results may vary between iPhone models and cannot fully replace certified professional sound level meters.
- No Advanced Frequency Analysis: The app does not provide octave-band or 1/3-octave frequency spectrum analysis, which is needed for engineering noise controls.
Frequently Asked Questions
Is the NIOSH Sound Level Meter App free?
Yes, the app is completely free to download and use. It was developed by the U.S. CDC/NIOSH as a public health resource with no cost, ads, or subscriptions.
Is the app accurate enough for professional use?
NIOSH validated the app against Type 2 professional sound level meters. It is appropriate for preliminary noise surveys and worker awareness, but full compliance testing may still require certified instrumentation.
What platforms is the app available on?
The NIOSH SLM App is currently available for iOS (iPhone) only via the Apple App Store.
What noise standards does the app measure against?
The app calculates noise dose against both the NIOSH Recommended Exposure Limit (REL) of 85 dBA and the OSHA Permissible Exposure Limit (PEL) of 90 dBA as an 8-hour TWA.
Can I export my noise measurement data?
Yes, the app allows you to export recorded sound level data, making it easy to include in occupational health reports, hearing conservation documentation, or safety audits.
