Measure Noise Pollution using Free NIOSH Sound Level Meter Phone App

[updated 04/15/18] I think the general public should be able to use a free reliable SLM (Sound Level Meter) phone app for measuring noise pollution and comparing to World Health Organization and EU noise pollution exposure limits. There are lots of apps out there, but many don’t take accurate noise measurements, and most aren’t free. Most that look free actually cost money to change the default settings to internationally recommended measurement settings most sensitive to noise damage.

The only accurate free one I’ve found is the NIOSH SLM iOS app. I don’t know if they’re coming out with an Android version. NIOSH developed this SLM app to be freely used by the general public, not just the workplace safety and health community. I’ve been using it for about 6 months now. It’s great for measuring noise pollution or product noise e.g. tools, appliances, etc.

Download the NIOSH SLM iOS app and change default settings to internationally recommended measurement settings most sensitive to noise damage:

• Standard NIOSH
• Threshold level 80 dB
• Exchange rate 3 dB
• Time weighting Fast
• Frequency weighting A filter

Currently C-filter frequency weighting is not available on NIOSH app to measure dBC avg. The C-filter is sensitive to total noise risk including low frequency and vibronoise that can cause imbalance, tinnitus and worse NIHL than from noise alone. C-filter can be set on this app, but only to measure instantaneous level.

Total run time = how long noise measured.

Instantaneous Level Quick Scan (big numbers on screen) = current noise level
Loudness of noise as it happens. dBC avg if C filter set. dBA avg if A filter set.

LAeq = dBA avg
Average noise over time measured. Measured in dBA no matter which filter set. Average includes max or peak noise loudness over time measured.

The more constant the noise, the less time you need to measure. If the blender is buzzing on high, it’s going to be about the same loudness no matter how long you measure. If it’s an up and down or off and on type noise, you need to measure long enough to get a sample that represents the noise that was in your environment e.g. airplane flying overhead. Other mobile apps are also available including Flightradar24 that tracks the airplane identification data (airline/flight number).

If C filter is set, and instantaneous loudness is 10 dB louder than the LAeq average noise, there’s a lot of low frequency and vibronoise that can cause health damage.

Max level = dB Max
Highest or peak loudness level that happened during measurement time. Automatically included in the LAeq dBA avg. General public doesn’t need to measure Max separately. If you accidentally bump the mic on the phone, app will measure a big Max that isn’t from actual noise. Max is mainly for general interest e.g. how loud does your dog bark for dinner? My dog’s dinner bark is 105.6 dB Max level.

LCpeak = Don’t use it. Faulty. Measurements too high.

TWA = General public should never use TWA. Only for 8 hour equivalent work shift. Calculated TWA will always be less than measured dBA avg.

Dose % = Don’t use outside of workplace; only applies for 8 hour equivalent work shift.

NIOSH App Notes:

• Buttons from left to right are: Start measuring, Stop, Delete current data, Save on app and Upload.
• Before measuring you need to Delete current data.
• The app needs Wi-Fi or cellular to work.
• When you save noise measurement results, they save sorted by date with dB TWA shown; which will be blank for shorter measurement times.
• Operator/Location Information for saved data on app won’t let me edit it. I’d like to be able to make notes on what I measured and any factors that could affect results. If anybody figures this out, please let me know in comments.
• If you have any problems with the app, contact NIOSHNoiseresearch@cdc.gov. Please include the model of your device and iOS version.

Night noise guidelines for Europe WHO/Europe, 2009

Burden of disease from environmental noise. Quantification of healthy life years lost in Europe WHO/Europe, 2011

Guidelines for community noise (PDF) WHO, 1999

Photo Credit: George Desipris at Pexels

Jan L. Mayes MSc Aud(C) RAud writes horror fiction and non-fiction, and is an international Eric Hoffer Award winning author, blogger and audiologist specializing in ghosts, noise, tinnitus-hyperacusis, hearing health education and plotting murders. Her writing has been featured at Tinnitus Today, Communique, silencity.com, The Right to Quiet Society, and The Horror News Daily.