Mobile Digital Recording: Adequacy of the iRig and iOS Device for Acoustic and Perceptual Analysis of Normal Voice

Objective. To determine whether the iRig and iOS device recording system is comparable with a standard computer recording system for digital voice recording. Methods. Thirty-seven vocally healthy adults, between ages 20 and 62, with a mean age of 33.9 years, 13 males and 24 females, were recruited. Recordings were simultaneously digitalized in an iPad and iPhone using a unidirectional condenser microphone for smartphones/tablets (iRig Mic, IK Multimedia) and in a computer laptop (Dell-Inspiron) using a unidirectional condenser microphone (Samson-CL5) connected to a preamplifier with phantom power. Both microphones were lined up at an equal fixed distance from the subject's mouth. Speech tasks consisted of a sustained vowel ah at comfortable pitch/loudness, counting from 1 to 10, and a glissando ah from a low to a high note. The samples captured on the iOS devices were transferred via SoundCloud in WAV format, and analyzed using the Praat software. The acoustic parameters measured were mean, min, and max F0, SD F0, jitter local, jitter rap, jitter ppq5, jitter ddp, shimmer local, shimmer local-dB, shimmer apq3, shimmer apq5, shimmer apq11, shimmer dda, NHR, and HNR. Results. There were no statistically significant differences for any parameter and speech task analyzed for both iOS devices as compared with the gold standard computer/preamp system (all P values > 0.050). In addition, there were no statistical differences in the perceptual identification of the recordings among devices (P < 0.001). Conclusion. In the present study, the iRig and iOS device may provide reliable digital recording of normal voices.