Usability And Practicality of Speech Recording by Mobile Phones for Phonetic Analysis

High-quality speech recording is critical to phonetic analysis. However, when professional equipment or a sound-proof booth is not accessible, such as in random sampling or during the current pandemic period, is it reliable and valid to use non-professional devices to record speech data? We selected ten devices and examined the frequency range and signal-to-noise ratio (SNR) of speech data they recorded. We also compared recordings in a quiet room with noise at a moderate level. The results showed that all devices recorded a wide frequency range, which covered speech frequency well. But, their SNRs differed significantly. Environmental noise also appeared to affect recording quality. We then analyzed fine-grained phonetic parameters of data recorded in the quiet room, including suprasegmental, segmental and phonation-related parameters. F0 was found relatively consistent in the recordings from all devices, but certain differences were captured in F1, F2 and Center of Gravity (CoG). F3 as well as parameters relevant to phonation analysis, on the other hand, showed high variations. Therefore, our findings suggest that non-professional devices such as mobile phones are reliable substitutes of professional recorders, at least in prosodic analysis for general purposes. Cautions should be taken when values of F3 and phonation-related parameters are involved.