The NIOSH Sound Level Meter mobile app, newly available for iOS devices, is intended to measure sound levels in the workplace and help raise workers’ awareness about noise exposure and occupational noise-induced hearing loss. The app, which reports instantaneous sound levels in A, C, or Z-weighted decibels, is free to download and was designed for industrial hygienists, occupational health and safety managers, and workers who may not have access to professional sound measurement instruments.
NIOSH researchers evaluated 192 sound-measurement apps for iOS and Android devices in 2014 and discovered that most apps lacked the accuracy and functionality for conducting occupational noise measurements. That study helped prompt NIOSH’s collaboration with app developer EA LAB to develop an app able to measure and characterize occupational noise exposure similar to professional instruments. NIOSH’s Science Blog post about the new Sound Level Meter app notes that the app was subjected to the same testing requirements that were established in the NIOSH laboratory study. When used with an external calibrated microphone, the new app measured sound levels within ± 1 dB of the reference type 1 sound level meter over the testing range of 65–95 dB sound pressure level (SPL) in the laboratory.
“While the app is not meant to replace a professional sound level meter or a noise dosimeter or be used for compliance purposes, we recommend that those interested in making proper noise measurements use an external microphone that can be calibrated with an acoustical calibrator for improved accuracy,” NIOSH’s blog post reads.
The app can serve as a practical tool to collect noise exposure data and help workers make informed decisions about potential hazards to their hearing. In addition, NIOSH researchers hope that the app will eventually become a research tool.
“A long-term goal is that this app will become a research tool that people can use for doing workplace surveys,” said Capt. Chucri (Chuck) A. Kardous, MS, PE, a senior research engineer in the NIOSH Division of Applied Research and Technology who worked on the app. “Noise surveys are very costly and time-consuming. In Europe they’re doing a lot of work with crowdsourcing environmental noise, and we think this app could work as a crowdsourcing tool for occupational noise. If that kind of technology translates into the workplace, the information could be useful to researchers in the future. For instance, they could crowdsource data fairly easily, quickly, and cheaply instead of having to hang a dosimeter on five workers and follow them for five days.”
The app is only available on iOS devices because NIOSH researchers found that testing and verifying the accuracy and functionality of an Android-based app in the agency’s laboratory is not currently possible.
“The Android marketplace is very fragmented,” Kardous explains. “The same circuitry exists in an iPod or an iPad or an iPhone, so we’re able to test something and verify it will work on iOS-type devices. We couldn’t do the same with Android; there are hundreds of devices, and even the same manufacturer will use different parts. For instance, the Samsung that you buy in the U.S. is different than a Samsung that you buy in Japan. We also found out that the microphone elements that they use in the U.S. are different than the ones they use in Asia.”
More information about the app, including a video highlighting its features and a link to download it, is available on NIOSH’s website.