Delayed auditory feedback elicits serial order errors (Malloy et al., 2022)

Purpose: Delayed auditory feedback (DAF) interferes with speech output. DAF causes distorted and disfluent productions and errors in the serial order of produced sounds. Although DAF has been studied extensively, the specific patterns of elicited speech errors are somewhat obscured by relatively small speech samples, differences across studies, and uncontrolled variables. The goal of this study was to characterize the types of serial order errors that increase under DAF in a systematic syllable sequence production task, which used a closed set of sounds and controlled for speech rate.

Method: Sixteen adult speakers repeatedly produced CVCVCV (C = consonant, V = vowel) sequences, paced to a “visual metronome,” while hearing self-generated feedback with delays of 0–250 ms. Listeners transcribed recordings, and speech errors were classified based on the literature surrounding naturally occurring slips of the tongue. A series of mixed-effects models were used to assess the effects of delay for different error types, for error arrival time, and for speaking rate.

Results: DAF had a significant effect on the overall error rate for delays of 100 ms or greater. Statistical models revealed significant effects (relative to zero delay) for vowel and syllable repetitions, vowel exchanges, vowel omissions, onset disfluencies, and distortions. Serial order errors were especially dominated by vowel and syllable repetitions. Errors occurred earlier on average within a trial for longer feedback delays. Although longer delays caused slower speech, this effect was mediated by the run number (time in the experiment) and small compared with those in previous studies.

Conclusions: DAF drives a specific pattern of serial order errors. The dominant pattern of vowel and syllable repetition errors suggests possible mechanisms whereby DAF drives changes to the activity in speech planning representations, yielding errors. These mechanisms are outlined with reference to the GODIVA (Gradient Order Directions Into Velocities of Articulators) model of speech planning and production.

Supplemental Material S1. Sound substitution errors by participant and delay. 

Supplemental Material S2. Other (nonsubstitution) errors by participant and delay.

Supplemental Material S3. This spreadsheet provides multiple worksheets, each of which provides a tabular summary for an individual generalized linear mixed-effects logistic regression model for one error type (see Error Patterns by Type section). Tables describe fixed and random effects and provide pairwise contrasts for delay.

Supplemental Material S4. Summary of coefficients for linear mixed effects model estimating the effects of delay, run number, and presence/absence of an error on intersyllable durations (see also main Table 4).

Supplemental Material S5. Summary of coefficients for linear mixed effects model estimating temporal measures onset interval and peak interval during syllable and vowel repetition errors (see also main Table 5 for overlap measure).

Supplemental Material S6. Estimated means interaction plot. 

Malloy, J. R., Nistal, D., Heyne, M., Tardif, M. C., & Bohland, J. W. (2022). Delayed auditory feedback elicits specific patterns of serial order errors in a paced syllable sequence production task. Journal of Speech, Language, and Hearing Research. Advance online publication. https://doi.org/10.1044/2022_JSLHR-21-00427