Impact of hair cell preservation in cochlear implantation: combined electric and acoustic hearing

Abstract

Objective: This article reviews some of the potential benefits of preserving low-frequency residual hearing using a short-electrode cochlear implant. Both the status of the inner ear and acoustic characteristics of speech cues are important factors. How does the magnitude of the potential benefits depend on the candidacy criteria for implantation with a hearing-preservation electrode?

Background: Previous research has demonstrated that preserving residual hearing in cochlear implantation can provide significant advantages for the understanding of speech in background noise as well as for the aesthetic qualities of music and other sounds. Developing optimal candidacy guidelines for these devices is a current goal.

Methods: In a large group of patients with Hybrid (acoustic + electric) cochlear implant, performance in the recognition of speech in background of other talkers is measured and compared with patients with traditional long-electrode implant. In addition, a number of patient characteristics are compared to success with the short-electrode implant.

Results: Age and duration of hearing loss are found to be predictive factors for the success of the short-electrode approach.

Conclusion: Optimal criterion for candidacy for the use of the short-electrode versus a traditional long electrode can improve the outlook for patients with severe-to-profound high-frequency hearing loss.

Figure 1

Approximate acoustic region of spoken speech in relaton to the auditory threshold curve.

Figure 2

The Iowa/Nucleus Hybrid Electrode

Figure 3

The Signal to Noise ratio for 50%-correct recognition of spondee words in a background of competing talkers (SRT) for individual patients using either a traditional long-electrode or the A+E Hybrid device.

Figure 4

The relation between the duration of hearing loss for Iowa Hybrid patients and their electric-only recognition of CNC words. The open-circle data point represents the single patient with a hearing loss that occurred at a very young age.