Perceptual Differences Between Low-Frequency Analog and Pulsatile Stimulation as Shown by Single- and Multidimensional Scaling.
Natalia Stupak, Monica Padilla, Robert P Morse and 1 others
PMID 30378468WHAT IT FOUND
Cochlear implant users perceive analog and pulsatile stimulation as having different sound qualities.
The difference is not about pitch height. Raising the pulse rate does not make pulsatile sounds match analog ones, so the gap comes from something other than the gaps between pulses.
Key findings
01Analog stimulation was perceived differently from pulsatile stimulation along a dimension separate from pitch, while the two types of pulsatile stimulation sounded similar to each other.
02Increasing the carrier rate of amplitude-modulated pulsatile stimulation did not eliminate the perceptual difference from analog stimulation, though it reduced it somewhat at 400 Hz.
03The perceptual difference between analog and pulsatile stimulation was not related to pitch height, as both were rated similarly high or low depending only on frequency.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The study used only a single electrode (Electrode 2) in a monopolar configuration, so findings may not apply to multichannel everyday listening. The term "Clean" was not formally defined, leaving interpretation subjective, though no correlation was found with duration of implant use. Participants were experienced implant users, which may bias their perception of "Clean" towards their everyday pulsatile strategies. The study did not test speech recognition or comprehension, only perception of simple tones.
Declared interests
Research Support, N.I.H., Extramural. No specific commercial conflicts of interest are declared in the text, but the study was conducted at New York University School of Medicine and the University of Southern California.
The easy way to misread this
Do not conclude that analog stimulation provides better speech understanding or that patients should switch back to it. The study only proves the sounds are perceptually different in quality, not that one is superior for communication.