Objective verification of continuous speech sound discrimination using the acoustic change complex

Area of Science:

• Auditory Neuroscience
• Speech Perception
• Neurophysiology

Background:

• Objective measures of speech sound discrimination are needed.
• The acoustic change complex (ACC) reflects neural processing of auditory events.
• Continuous speech stimuli present unique challenges for auditory processing.

Purpose of the Study:

• To assess the feasibility of using ACC as an objective cortical marker for continuous speech sound discrimination.
• To evaluate the reliability and reproducibility of ACC responses to Ling-six stimuli.

Main Methods:

• Cortical auditory evoked potentials were recorded from 10 normal-hearing adults.
• A continuous, pause-free sequence of six Ling phonemes was used.
• ACC responses were measured in a passive listening paradigm; reproducibility was assessed over one year.

Main Results:

• Robust ACC responses were elicited for all phonemic transitions in every participant.
• Cortical discrimination within the continuous speech stream was reliably indicated.
• Within-subject ACC responses showed strong reproducibility over a one-year interval (mean cross-correlation = 0.95).

Conclusions:

• Continuous Ling-six stimuli reliably evoke ACC responses.
• The ACC paradigm is a promising, efficient, and repeatable tool for objective auditory learning and sound discrimination assessment.
• This method is particularly valuable for populations where behavioral assessment is unreliable.