Investigation of the effects of temporal and spatial interactions on speech-recognition skills in cochlear implant subjects

Forward masking was investigated as a measure of spectral and temporal inte ractions. Such interactions may adversely affect speech recognition in coch lear-implant subjects. Seven subjects, implanted with the Nucleus 22 device , performed a forward-masking task. They also performed an electrode-discri mination task in order to measure spectral interactions without temporal in teractions. Correlation analysis indicated a significant relationship betwe en data obtained in the two tasks (p<0.1). The two tasks were also correlat ed with the subjects' scores from five measures of speech recognition. Forw ard masking and electrode discrimination were strongly correlated with meas ures requiring consonant and phoneme recognition, respectively. These resul ts indicate that the relationship between forward masking and speech recogn ition may be due, in part, to a lack of spectral resolution. The data also indicate that consonants may be more readily masked than vowels. Forward-ma sking data measured for all clinically programmed electrodes in three of th e seven subjects were used with a model of the spectral maxima sound proces sor (SMSP) to estimate the number of electrodes stimulated during a consona nt that might be masked by prior presentation of a vowel. These results sug gest that temporal interactions across electrodes may be a factor in speech -recognition abilities of some cochlear-implant subjects. (C) 1999 Acoustic al Society of America. [S0001-4966(99)03902-8].