Transmission of Binaural Cues by Bilateral Cochlear Implants: A Comparison of Spectral Peak-Picking and Interleaved Stimulation Strategies.
Paul G Mayo, Andrew D Brown, Matthew G Goupell
The 'always-on' cochlear implant setting (CIS) kept spatial-hearing cues in the correct direction and more consistent than the 'peak-picking' setting (ACE) used by most Cochlear users, but this was measured on a manikin with no human listening tests.
Key findings
1For every stimulus tested (broadband noise, a spoken sentence, car horn, siren) and both cue types (interaural level differences and envelope interaural time differences), the always-on strategy produced cues that matched the natural acoustic values more closely than the peak-picking strategy.
2The peak-picking strategy produced level differences pointing in the wrong direction (toward the left when the sound was on the right) for low-frequency electrodes with broadband noise, car horn, and siren, but not with the spoken sentence; the always-on strategy never produced wrong-direction cues.
3The peak-picking strategy distorted or nearly eliminated envelope time differences compared with the always-on strategy for broadband noise, speech, and siren, leaving many values at zero or reversed.
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How it was doneWhat they found
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What it does not show
No human participants and no behavioural listening tests — the findings are about electrical signal properties on a manikin, not about what a person actually hears or localises. The authors state that behavioural studies are needed to confirm whether the improved cue preservation translates to functional spatial-hearing benefit. A single manikin and a single pair of sound processors were used, so results reflect one specific hardware combination. The peak-picking strategy was set to 6-of-12 rather than the clinical default of 8-of-22, chosen to match the electrode count with the always-on strategy. The authors argue this would reduce, not exaggerate, the peak-picking effects, but it is still a non-standard configuration. The spoken sentence was presented in quiet (effectively infinite signal-to-noise ratio). The authors note that at lower signal-to-noise ratios the speech result would be expected to shift toward the broadband-noise result, where the peak-picking effects were larger. Automatic gain controls in the sound processors could not be fully disabled and may have engaged momentarily, though the authors argue this is unlikely to explain the wrong-direction cues because those appeared only with the peak-picking strategy. The stimulus set, while broader than prior work, did not include speech in noise or a full range of environmental sounds.
Declared interests
Funded by the US National Institutes of Health (NIDCD R01DC020506 and NIDCD T32DC000046). The authors declared no conflicts of interest.
The easy way to misread this
Do not read this as evidence that switching a cochlear implant user from ACE to CIS will improve their sound localisation. The study measured electrical pulse trains on a manikin and found no human listening data; the authors themselves state that behavioural studies are needed to confirm whether the better cue preservation translates to functional spatial-hearing benefit. Additionally, the difference between the two strategies was smallest for the spoken sentence in quiet, which is the condition most relevant to everyday conversation.
Summarised by AI from the full paper, without a clinician reviewing it. Check it against the source before it changes what you do. Read it on PubMed →