Speech Electrophysiology: Brain Activity in Speech Processing and Disorders

Researchers in the Department of Speech and Hearing Sciences (SHS) aim to better understand the physiologic processes involved in stuttering to improve the identification of children at risk of developing a stutter, predict which children will grow out of stuttering, and improve treatment efficacy.

The researchers use EEG, eye tracking, and survey methods to study how the sensory and motor systems interact during speech perception and production. They also explore the neurophysiology of stuttering, a sensorimotor-linked speech disorder, by examining the brain activity of people who stutter and people who do not.

Sensory-Motor Integration in Speech Processing

SHS researchers study sensorimotor activity in speech perception and production to improve our understanding of speech in clinical and non-clinical groups. Sensorimotor integration is how we use input from our senses to coordinate, monitor, and refine our physical movements. Developed in early childhood, integration skills are important for developing speech, handwriting, balance, and other abilities.

Perceiving and producing speech are interactive processes. We adjust how we speak based on what we hear, see, and feel, which is called acoustic, visual, kinesthetic, and proprioceptive feedback. SHS researchers study how the brain integrates feedback from multiple sensory modalities during speech perception and production in people who stutter and people who do not.

People who stutter likely have difficulty integrating auditory and kinesthetic feedback during speech production, but this sensorimotor difficulty can be hard to distinguish from ordinary brain activity supporting speech. SHS researchers are employing a novel speech perception paradigm to investigate how the brains of people who do and do not stutter integrate mismatched auditory and visual signals to isolate the sensorimotor process and identify the underlying neural difference in people who stutter.

Neurophysiology of Stuttering and Stuttering Recovery

SHS researchers aim to improve the diagnosis and treatment of stuttering and expand foundational scientific knowledge about neural activity in speech by using electroencephalography (EEG), which measures electrical activity in the brain using electrodes on the scalp. This novel application of EEG technology to stuttering and stuttering recovery allows researchers to characterize baseline neural differences in people who stutter and people who do not, improving our understanding the underlying neurophysiology of stuttering.

One goal of this research is to identify neural biomarkers that predict stuttering onset and stuttering recovery in order to improve the effectiveness of speech therapy and to make it possible to identify children at risk of developing a stutter so they can receive timely intervention. Approximately 5% of children begin to stutter during early childhood, and nearly 80% of them will experience spontaneous recovery, but currently it is not possible to predict which children will begin to stutter and which children will grow out of it.

SHS researchers also use EEG to investigate the variability in stuttering. Specifically, they aim to understand why people who stutter do not stutter all the time. While many factors influence this, including time pressure, communicative pressure, anxiety, and linguistic familiarity, WSU researchers hope that understanding the brain processes underlying speech breakdown at some times and in some situations will result in improved stuttering management.