Comparison of speech recognition results for a one‐ and two‐formant speech coding strategy for a multichannel cochlear implant

Abstract

This study compared clinical results obtained from 96 postlinguistically deafened adults implanted with the Nucleus 22 channel cochlear implant system. Seventy‐one patients were fitted with a device that tracked the second formant of the voice, while 25 used one that tracked the first and second formant frequencies. Experience with the device averaged 3.7 months. Four subtests (four‐choice spondee, vowel, NU♯6, and CID sentences) of the Minimal Auditory Capabilities Battery (Auditec of St. Louis recording) were used. In addition, 209 patients were administered live‐voice measures (continuous discourse tracking and vowel/consonant identification) in three conditions: lipreading, lipreading plus device, and device only. Results revealed that the group using the two‐formant tracker performed significantly better than those using the one‐formant tracker on the following measures: (1) NU♯6 monosyllabic word test; (2) CID sentences; (3) continuous discourse tracking difference score (lipreading plus device minus lipreading); and (4) vowel and consonant identification in the device only condition. These findings suggest greater efficacy with the two‐formant tracker; this is the strategy commonly in clinical use at the present time.