ABSTRACT
OBJECTIVE: To investigate the correlation of word recognition with cochlear implant (CI) and spread of the electric field. STUDY DESIGN: Prospective, noninterventional, experimental study. SETTING: A tertiary referral center. PATIENTS: Thirty-eight adult CI users with poor (n = 11), fair (n = 13), and good (n = 16) word recognition performance. MAIN OUTCOME MEASURE: Transimpedances were measured after 37 µs. Word recognition score was recorded at 65 dB SPL for German monosyllables in quiet. Transimpedance half widths were calculated as a marker for spread of the electric field. RESULTS: Narrow and broad spread of the electric field, i.e., small and large half widths, were observed in all word recognition performance groups. Most of the transimpedance matrices showed a pattern of expansion along the diagonal toward the apical electrode contacts. Word recognition was not correlated with transimpedance half widths. CONCLUSIONS: The half width of the spread of the electric field showed no correlation with word recognition scores in our study population.
Subject(s)
Cochlear Implantation , Cochlear Implants , Speech Perception , Adult , Humans , Prospective StudiesABSTRACT
The aim of this study was to measure how age affects the speech recognition threshold (SRT50) of the Oldenburg Sentence Test (OLSA) and the listening effort at the corresponding signal-to-noise ratio (SNRcut). The study also investigated the effect of the spatial configuration of sound sources and noise signals on SRT50 and SNRcut. To achieve this goal, the study used olnoise and icra5 noise presented from one or more spatial locations from the front and back. Ninety-nine participants with age-related hearing loss in the 18-80 years age range, specifically in the 18-30, 31-40, 41-50, 51-60, 61-70, and 71-80 age groups, participated in this study. Speech recognition and listening effort in noise were measured and compared between the different age groups, different spatial sound configurations and noise signals. Speech recognition in noise decreased with age and became significant from the age group of 50-51. The decrease in SRT50 with age was greater for icra5 noise than for olnoise. For all age groups, SRT50 and SNRcut were better for icra5 noise than for olnoise. The measured age-related reference data for SRT50 and SNRcut can be used in further studies in listeners with age-related hearing loss and hearing aid or implant users.
ABSTRACT
Channel interactions caused by spread of the intracochlear electric field and, thus, the spread of neural excitation constrain frequency selectivity and speech recognition in cochlear implant (CI) users. Studying the influence of the spread of electric field (SEF) on the spread of excitation (SOE) can help us better understand the electrical-neural interface. The primary aim of this study was to examine the influence of the SEF on the SOE. In 38 Nucleus (Cochlear Ltd. Sydney, Australia) CI recipients, we assessed the spatial SEF by measuring the voltage drop (transimpedance) and the SOE through neural responses (electrically evoked compound action potentials [eCAPs]) along the electrode array. Transimpedance was recorded using the monopolar (MP2) mode as the stimulation and recording mode. Biphasic square-wave pulses with an amplitude of 110 CL and duration of 37 µs were used for stimulation. SOE was measured at the probe active electrodes E5, E13, and E18. The stimulation amplitudes were set individually to the thresholds of the neural response telemetry (T-NRT), which were measured by the AutoNRT protocol. The transimpedance half-widths were between 0.00 electrodes and 8.55 electrodes. The SOE half-widths reached values between 0.54 electrodes and 5.70 electrodes. Considering individual transimpedance and SOE half-widths, the SEF and SOE showed a significant positive correlation only at electrode E13. Furthermore, this study shows a significant negative correlation of the SEF and SOE in consideration of mean half-widths.
