An audiology app for iPhones and iPads, called AudCal, is accurate and correlated with a standard audiogram, according to a study of 110 adults published in Acta Oto-Laryngologica. The study was conducted by researchers affiliated with various hospitals and universities in Spain.

According to the researchers, hearing impairment is the most frequent sensory deficit in humans. It affects more than 250 million people worldwide.

AudCal, which is designed to assist otolaryngologists, was first released on the Apple App Store in May 2013, but a more recent version came out in December 2014. The app helps users calculate hearing impairments and assess the pure-tone air conduction threshold.

Researchers had the participants sit through two hearing evaluations in both the right and left ears. The first test, which was performed by certified staff members from participating institutions, was conducted in sound-treated booths using calibrated ISO stardard audiometers and headphones. Audiologists then tested particpants with the AudCal app following built-in instructions under the minimal ambient noise level sound conditions using Apple's EarPod headphones. Six frequencies, ranging from 500–8000 Hz, were tested.

Researchers found that the standard test identified hearing loss in 83 individuals and the AudCal test identified hearing loss in 84 individuals. Researchers said the results showed that AudCal had excellent reliability, based on the high concordance between standard audiometry and the application’s hearing sensitivity assessment test.

They also explained what new features they would add to the app in future versions. These potential features include bone conduction thresholds and adding more sound frequencies to test and analyze, like 125 Hz and 250 Hz, which researchers said are common in clinical practice.