Speech recognition in noise for cochlear implant listeners: Benefits of residual acoustic hearing

TLDR

The study investigates whether preserving low‑frequency acoustic hearing in cochlear‑implant patients improves speech recognition in competing backgrounds compared to traditional long‑electrode implants. Researchers conducted simulation experiments in normal‑hearing listeners and tested three short‑electrode cochlear‑implant users with preserved low‑frequency hearing, comparing their multitalker speech recognition to a larger group of traditional long‑electrode implant users. Both the simulations and the clinical tests showed a clear advantage for preserving low‑frequency hearing in multitalker backgrounds—short‑electrode subjects outperformed long‑electrode users, achieving a 9‑dB benefit when matched for quiet performance—supporting the benefit of residual acoustic hearing for voice pitch perception and segregation.

Abstract

The purpose of this study was to explore the potential advantages, both theoretical and applied, of preserving low-frequency acoustic hearing in cochlear implant patients. Several hypotheses are presented that predict that residual low-frequency acoustic hearing along with electric stimulation for high frequencies will provide an advantage over traditional long-electrode cochlear implants for the recognition of speech in competing backgrounds. A simulation experiment in normal-hearing subjects demonstrated a clear advantage for preserving low-frequency residual acoustic hearing for speech recognition in a background of other talkers, but not in steady noise. Three subjects with an implanted “short-electrode” cochlear implant and preserved low-frequency acoustic hearing were also tested on speech recognition in the same competing backgrounds and compared to a larger group of traditional cochlear implant users. Each of the three short-electrode subjects performed better than any of the traditional long-electrode implant subjects for speech recognition in a background of other talkers, but not in steady noise, in general agreement with the simulation studies. When compared to a subgroup of traditional implant users matched according to speech recognition ability in quiet, the short-electrode patients showed a 9-dB advantage in the multitalker background. These experiments provide strong preliminary support for retaining residual low-frequency acoustic hearing in cochlear implant patients. The results are consistent with the idea that better perception of voice pitch, which can aid in separating voices in a background of other talkers, was responsible for this advantage.