Masked and filtered simulation of hearing loss: effects on consonant recognition

Hearing threshold configuration of the impaired ear was simulated via two different methods in the normal ear of each of 6 subjects with unilateral sensorineural hearing loss. The two hearing loss simulation methods were frequency-specific attenuation (filtering), and masking by shaped masking noise. Identification responses to 20 consonant-vowel nonsense syllables were obtained from the normal ear of each subject in the two hearing loss simulation conditions, as well as from the impaired ear. Speech data were scored both for overall percent correct consonant recognition and for error patterns on a set of eight consonant features. The computed correlation between gross error difference scores and a similarity metric for feature error pattern was essentially zero, indicating that these may be relatively independent measures of speech recognition, and thus may reflect different aspects of subjects' behavior. For 3 subjects, both masking and filtering successfully simulated the effects of sensorineural hearing loss on consonant feature error patterns. For 1 subject, only filtering produced feature error patterns similar to those of the impaired ear. For the remaining subjects, neither simulation was successful.