Interaural Time-Difference Discrimination as a Measure of Place of Stimulation for Cochlear-Implant Users With Single-Sided Deafness.
Joshua G W Bernstein, Olga A Stakhovskaya, Gerald I Schuchman and 2 others
PMID 29623771WHAT IT FOUND
Listeners with single-sided deafness could detect timing differences when pulse trains were sent to one implant electrode and the hearing ear.
A best frequency was estimated for 17 of 26 electrodes, but the test is not clinically usable yet.
Key findings
01A best acoustic frequency for timing-difference sensitivity was estimated for 17 of 26 electrodes, and for at least one electrode in each of the eight listeners.
02The best timing frequency averaged 1.15 octaves above the standard manufacturer frequency allocation and 0.50 octaves above each listener's clinical frequency allocation.
03The average precision of the best-frequency estimate was ±3.20 mm along the cochlea, equivalent to ±0.67 octaves.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The study included only eight men, so it cannot say how women or more diverse cochlear-implant users would perform. The timing differences tested were much larger than those produced by real sounds, so it is unclear whether listeners used everyday binaural cues. The test took hours and is not a realistic clinical tool in its current form. Frequencies below 1000 Hz could not be tested, so the apical part of the implant array was not estimated. Loudness balancing was done with a single quick adjustment rather than repeated bracketing, which could have introduced level bias. The timing reference was not centered to offset delays between the implant processor and the hearing ear, and processor delay may have varied. No real-world speech, hearing, or communication benefit was measured.
Declared interests
The supplied publication types list Research Support, N.I.H., Extramural. No author conflict-of-interest statement or commercial sponsor detail is included in the supplied text.
The easy way to misread this
Do not conclude that changing a cochlear-implant frequency map will improve everyday hearing in noise. The study measured artificial timing changes that were much larger than normal sounds, used a laboratory task, and did not test speech-in-noise benefit or a clinical mapping change.