Test-Retest Reliability of Cortical Evoked Potentials Using Naturally Produced Speech Sounds

Abstract

Objective 

To determine if naturally produced speech stimuli evoke distinct neural response patterns that can be reliably recorded in individuals.

Design 

Auditory cortical evoked potentials were obtained from seven normal-hearing young adults in response to four naturally produced speech tokens (/bi/, /pi/, /ʃi/, and /si/). Stimuli were tokens from the standardized UCLA version of the Nonsense Syllable Test (NST) (Dubno & Schaefer, 1992). Using a repeated measures design, subjects were tested and then retested within an 8-day period.

Results 

Auditory cortical evoked potentials elicited by naturally produced speech sounds were reliably recorded in individuals. Also, naturally produced speech tokens, representing different acoustic cues, evoked distinct neural response patterns.

Conclusions 

1) Cortical evoked potentials elicited by naturally produced speech sounds can be reliably recorded in individuals. 2) Naturally produced speech tokens, representing different acoustic cues, evoke distinct neural response patterns. 3) Given the reliability of the response, this work has potential application to the study of neural processing of speech in individuals with communication disorders as well as changes over time after various types of auditory rehabilitation.

In Brief

P1-N1-P2 cortical auditory evoked potentials are typically recorded in response to clicks, tones, and synthesized speech sounds. This study examines cortical potentials evoked by naturally produced speech tokens from the standardized UCLA version of the Nonsense Syllable Test. Naturally produced speech stimuli evoke multiple overlapping P1-N1-P2 complexes, reflecting acoustic changes across the entire stimulus. This collection of overlapping potentials is called the acoustic change complex (ACC). In this study we found that the ACC can be reliably recorded in individuals and is stable over time. Also, naturally produced speech tokens, representing different acoustic cues, evoke distinct neural response patterns. Taken together, these results suggest that the ACC might be useful for studying neural processing of speech in individuals with communication disorders as well as changes over time after various types of auditory rehabilitation.