Effects of multi-talker competing speech on the variability of the California Consonant Test

The interference effects of multi-talker speech babble on the California Consonant Test scores were examined. Phoneme recognition was assessed in a sound field in quiet and under 4 message-to-competition ratio conditions for normal-hearing subjects and in three MCR conditions for listeners with bilateral high-frequency sensorineural hearing loss. The noise interference functions for both subject groups were characterized by a gradual decline in recognition performance as the signal-to-noise ratio decreased. The slope of the function for the 2 groups was parallel with the mean scores for the hearing-impaired subjects approximately 30% lower than those for the normal hearers. Test-retest reliability across conditions was examined via correlational analysis and by computing test-retest difference scores for individual subjects. These data are discussed in terms of sampling theory for full-list and half-list presentations and probabilities of measurement error for determining significance between 2 scores.