Supplementary Material for: Comparability of Modern Recording Devices for Speech Analysis: Smartphone, Landline, Laptop, and Hard Disc Recorder

Background: Large-scale multi-site experimental and clinical speech protocols require high-fidelity, easy-to-use speech recording technologies. However, little is known about the reliability and comparability of affordable, portable and commonly used technologies with traditional well-validated devices (e.g., a hard disc recorder with a high-quality microphone). Objective: To examine the comparability of speech and voice samples acquired from protocols involving high- and low-quality devices. Methods: Speech samples were acquired simultaneously from 15 healthy adults using four devices and analyzed acoustically for measures of timing and voice quality. For the purpose of making initial comparisons, methods were deemed comparable if the resultant acoustic data yielded root mean squared error values ≤10% and statistically significant Spearman's correlation coefficients. Results: The data suggest that there is significant and widespread variability in the quality and reliability between different acquisition methods for voice and speech recording. Not one method provided statistically similar data to the protocol using the benchmark device (i.e., a high-quality recorder coupled with a condenser microphone). Acoustic analysis cannot be assumed to be comparable if different recording methods are used to record speech. Conclusions: Findings have implications for researchers and clinicians hoping to make comparisons between labs or, where lower-quality devices are suggested, to offer equal fidelity.