How to use smartphone apps to measure noise

Inexpensive decibel apps can capture noise data

How loud is that noise?

The next time you hear construction noise outside your window or get blasted by your neighbor’s leaf blower, you don’t have to wonder how loud it is — you can measure it right from your smartphone. You just need to know which decibel apps to install and how to use them.

Soundproofist posted an article in 2019: “Decibel meters, perception, and you” to explain why sometimes a decibel meter might not give you a reading that matches your perception of loudness. We differentiated between meters that measured strictly A-weighted decibels (dBA) versus C-weighted decibels (dBC). The C-weighted decibels can detect some of the lower frequencies. But since we originally published this article, we’ve used some smartphone apps that also measure sound frequency (in Hertz) while they measure decibels. And these dual measurements are particularly helpful.

Why frequency matters

Let’s say your neighborhood has a construction site that seems very loud inside your home, and you measure the noise through a closed window. Your decibel reading might be 68-70 dBC. Conversely, if you measure conversation at a normal volume inside your home, that might also read as 68-70 dBC. Yet the quality and (the annoyance factor) of these two different sounds is markedly different.

This is where measuring the frequency of that sound can assist you with understanding the nuisance factor, as well as help you to identify potential soundproofing methods. A very low-frequency sound (or vibration) typically registers at under 150 Hz, where conversation noise could range from 500 Hz to 8000 Hz. The very low-frequency sound (which is like a hum, a boom, or a droning noise) is the one that bothers you the most, and it penetrates walls and windows, and can travel through a building frame, whereas normal conversation is less likely to penetrate the building structure, or at least it will be easier to mitigate if it does.

The apps

We’ve used a few smartphone apps and put together some videos on how you can use them. A preferred app will meet this criteria:

Accuracy
Multiple decibel weighting options
The ability to save data or generate a report
Simultaneous frequency measurements (along with decibels)

Let’s take a look at some apps that you might use.

NIOSH sound meter

This is a free decibel app from the CDC’s National Institute for Occupational Safety and Health. It runs on iOS (iPhone), but unfortunately, not on Android devices. You can set the frequency weighting for dBA, C, or Z. The app generates a report that you can export as a PDF or HTML and share with others. Watch our video on how to use the NIOSH app here.

Decibel Meter

The Decibel Meter app (developed by Ashraf Thoppukadavil) also has a free version. Like the NIOSH app, it’s available on iOS. It measures dBA and dBC, as well as B weightings and Z weightings. What’s more, it simultaneously displays the frequency level in Hertz above the decibel readings, so you can see both at the same time.

Both measurements display numerically, and they also display as a meter at the top and bottom of a circular dashboard. For a small one-time fee, you can get the Pro version. And yes, it generates reports that you can view as a graph or a moment-by-moment chart of peak values. Watch our demo on how to use the Decibel Meter app here:

Android apps

We’re on a quest to find comparable Android decibel apps that offer similar features to our preferred iOS apps. For starters, we tested two Android apps: SoundMeter and Sound Spectrum Analyzer.

SoundMeter included an option to save the data for a minimal report, but offered only dBA and no frequency measurements. Sound Spectrum Analyzer offered dBA measurements and real-time frequency measurements, but at this time, it has no “save” or report options.

A third app, Decibel X (from SkyPaw Limited, also available for iOS), appears to have many of the features we desire (dBA/dBC, frequency measurements, and a reporting feature). But it starts with a 3-day trial that will automatically convert to a $34 annual (USD) subscription after the three days have passed. Your credit card data is already on file with Google Play (or the App Store) when the trial begins. We’ll continue to seek out and test other Android apps until we can find the best recommendations for you. (Update: see our November 2023 review or just watch the video of a terrific Android app called SmarterNoise Pro!)

Here’s our video report on the first few Android app tests:

And out preferred Android app, which ticks all the boxes:

Even if you don’t have the perfect app on your smartphone, using a decibel app (and getting acquainted with decibel levels) is ultimately very helpful in protecting your ears and addressing noise issues.