Methods to eliminate stimulus transduction artifact from insert earphones during electroencephalography

Area of Science:

• Neuroscience
• Biomedical Engineering
• Auditory Electrophysiology

Background:

• Electroencephalography (EEG) is crucial for assessing auditory function.
• Insert earphones are preferred for their comfort and acoustic properties.
• Stimulus transduction artifacts can contaminate EEG recordings, particularly with insert earphones.

Purpose of the Study:

• To investigate and mitigate stimulus transduction artifacts in EEG.
• To enable high-fidelity recording of auditory evoked potentials using insert earphones.

Main Methods:

• Assessed Reference Equivalent Threshold Sound Pressure Levels (SPLs) for Etymotic ER-4B insert earphones in 15 volunteers.
• Recorded Auditory Brainstem Responses (ABRs), Middle Latency Responses (MLRs), and complex ABRs (cABRs) to click and /dα/ speech stimuli.
• Employed a single-case design to evaluate artifact reduction techniques.

Main Results:

• Raw EEG recordings exhibited stimulus transduction artifacts.
• Artifacts were successfully eliminated using shielding, counter-phasing (stimulus averaging 180° out of phase), or rereferencing techniques.
• These methods preserved the integrity of the electrophysiological signals.

Conclusions:

• Clinical-grade ABRs, MLRs, and cABRs can be reliably recorded with standard digital EEG systems and high-fidelity insert earphones.
• Effective artifact reduction is achievable through the application of specific signal processing techniques.
• This facilitates more accurate assessment of auditory pathway function.