Using the iPhone for Voice Recordings in Laryngology

Objective: 1) Evaluate the adequacy of an iPhone for voice recording enabling acoustic measurement of voice quality, and 2) demonstrate the usefulness of an iPhone-based acoustic analysis for identifying voice aberration and monitoring voice changes after phonosurgery. Method: Twenty-two voice patients, aged from 25 to 92 years (mean, 54.8 years; SD, 18.5 years), read sentences taken from a standard passage. An iPhone (Model 1303) with an internal microphone was used for voice recording. Vowels segmented from the sentences were submitted to an acoustic analysisprocedure to yield measures. Results: Compared with the simultaneous voice recordings via another direct digitization method, the iPhone voice recordings showed relatively high measure-remeasure and acceptable between-system reliabilities for aselection of acoustic measures. In patients with pre- and posttreatment recordings, perturbation measures, including percent jitter, percentage shimmer, and signal-to-noise ratios, and the vowel space area consistently demonstrated positive changes after treatment. Measures of the amplitude difference between the first 2 harmonics, which has been related to breathiness, reflected subtle voice changes due to treatment. Changes in singing power ratio were found to be vowel-dependent, while those in spectral tilt might be gender or pathology-dependent. Conclusion: Voice recordings using the iPhone model with a high sampling rate are adequate for acoustic measurement of speech and voice quality. However, due to large inter-subject variations, most of these measures are more useful for intra-subject than for norm-referenced comparisons inmonitoring the progression of the disorder or treatment effect.