Speech-in-Noise Recognition With More Realistic Implementations of a Binaural Cochlear-Implant Sound Coding Strategy Inspired by the Medial Olivocochlear Reflex.
Enrique A Lopez-Poveda, Almudena Eustaquio-Martín, Milagros J Fumero and 6 others
PMID 33136626WHAT IT FOUND
An experimental processor setting that links the two ears helped some cochlear implant users understand speech in noise, mainly with two implants and certain speaker-noise positions.
A fast version made speech harder in the toughest one-ear condition.
Key findings
01In two-ear listening with speech and noise in front, the two slower dynamic compression strategies improved average speech reception thresholds by 1.7 and 1.8 dB SNR relative to standard, while the fast strategy was 0.9 dB SNR worse.
02In one-ear listening with speech in front and noise on the listening side, the fast dynamic compression strategy was 4.2 dB SNR worse than standard on average, while the slower versions were slightly better by less than 1 dB SNR.
03Listening with two implants was significantly better than listening with one implant only for the two slower dynamic compression strategies, and not when speech and noise were widely separated.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
Only eight bilateral and two unilateral cochlear implant users were tested, and only eight were tested in bilateral listening. Children and unilateral users completed fewer conditions, and the two children had only one threshold estimate per condition. One bilateral user had not used the left implant for a month before testing because the audio processor was damaged. The sentence lists were reused, so participants may have learned sentences and thresholds may have been better than they would have been with fresh materials. The fixed compression setting used for the standard condition was not always the same as the setting in participants' clinical processors, so the comparison with everyday use is limited. The strategies were tested in short laboratory sessions, not after training or sustained use, and not in everyday free-field listening.
Declared interests
The study was supported by MED-EL GmbH, the Spanish Ministry of Economy and Competitiveness, and European Regional Development Funds. The authors declared no conflicts of interest.
The easy way to misread this
Do not conclude that these cochlear implant compression strategies are ready for clinical use. They were tested in a small lab study, and the fast version made speech harder to understand in the most difficult one-ear condition.