AIHce 2019: Q&A with Benjamin Roberts

Posted on Behalf of  Ben Roberts
Please read below for more information from Dr. Benjamin Roberts on his AIHce presentation.

1.      What was the title of your presentation?  

A Sound Meter in Every Pocket – An Evaluation of the NIOSH SLM Application for Non-Technical Users

2.      What was the scope of your research?

We compared noise measurements made by the sound level meter iOS application release by NIOSH to noise measurements made by a traditional noise dosimeter. Previous research had looked at the accuracy of various smartphone applications when paired with a calibrated external microphone, we used the application “as is” to simulate how a non-technical user would use the application. We collected measurements in offices, on commuter trains, in a coffee shops, restaurants, and spin classes to get a sample of measurements from locations that have been identified in the peer-reviewed literature and popular media to be excessively loud.

3.      What did you find?

The application, as a non-technical user would use it, was not as accurate as what had been previously reported in the literature when the app was evaluated with calibrated external microphones. Using a linear mixed model, the dosimeter was found to measure noise levels 1.2 dBA lower than the smartphones. However, using a Bland-Altman plot we found that on average that the dosimeter measured noise levels 2.2 dBA lower than the smartphone app. The difference between the paired measurements varied widely for noise levels below 75 dBA. Above 75 dBA the difference between the paired measurements was smaller, but the dosimeter was found to consistently measure higher levels of noise than the paired smartphone. These results suggest that non-technical users can use smartphones with the NIOSH app to make fairly accurate measurements in louder environments even without a calibrated external microphone, but professional level equipment is needed when measuring compliance with various environmental and occupational noise standards.

4.      What are the next steps / what other research is needed?

We identified several aspects of the NIOSH application we believe could be improved including 1) the data logging of noise levels over time, 2) the ability to simultaneously measure noise using multiple criteria, and 3) the ability to measure noise when the device is locked (i.e. when the screen is off). While these devices cannot be used for compliance measurements, there is a great potential for using these devices to construct community noise maps that can be used by community groups and regulators to estimate environmental noise levels.