National Institute of Occupational Safety and Health uses Trident software to study smartphone sound level meter applications.

We get asked all the time: “Why can’t I just use a sound level meter on my smartphone?” and the answer to that question can be answered by this study that the National Institute of Occupational Safety and Health (NIOSH) did using our Trident software.
“Abstract:
This study reports on the accuracy of smartphone sound measurement applications (apps) and whether they can be appropriately employed for occupational noise measurements. A representative sample of smartphones and tablets on various platforms were acquired, more than 130 iOS apps were evaluated but only 10 apps met our selection criteria. Only 4 out of 62 Android apps were tested. The results showed two apps with mean differences of 0.07 dB (unweighted) and −0.52 dB (A-weighted) from the reference values. Two other apps had mean differences within ±2 dB. The study suggests that certain apps may be appropriate for use in occupational noise measurements.”
Read more in the NIOSH blog, or read the full paper published in the Journal of the Acoustical Society of America.