Effects of Stimulus Duration on Event-Related Potentials Recorded From Cochlear-Implant Users.
Alessandro Presacco, Hamish Innes-Brown, Matthew J Goupell and 1 others
PMID 28475545WHAT IT FOUND
Using short 170-ms speech sounds to record brain responses in cochlear implant users distorts the P2 wave.
The artifact removal process creates a false spike at the sound's offset, which overlaps with the P2 peak. Longer 400-ms sounds preserve the wave shape.
Key findings
01Removing electrical artifacts from cochlear implant recordings using a 170-ms stimulus created a false spike that distorted the P2 brain response, whereas a 400-ms stimulus did not.
02The distortion occurred because the end of the 170-ms sound coincided with the timing of the P2 wave (150-250 ms), causing the artifact removal algorithm to introduce an error at that specific moment.
03Earlier brain waves (P1 and N1) were not distorted by this process because their timing is far enough from the end of the sound.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The study only tested ten participants. The researchers used only one specific vowel sound (/a/) and one specific artifact removal method. The study focused on the morphology (shape) of the wave rather than its clinical utility for diagnosis or programming.
Declared interests
The authors reported no conflicts of interest. Funding came from university departments, NIH grants, and the Bionics Institute. Cochlear Ltd. and Advanced Bionics provided equipment and technical support.
The easy way to misread this
Do not interpret the sharp spike seen in 170-ms recordings as a genuine neural response. It is an artifact created by the data processing when the sound ends at the same time the brain wave is expected. Use longer sounds to avoid this error.