Consonant recognition loss in hearing impaired listeners.

This paper presents a compact graphical method for comparing the performance of individual hearing impaired (HI) listeners with that of an average normal hearing (NH) listener on a consonant-by-consonant basis. This representation, named the consonant loss profile (CLP), characterizes the effect of a listener's hearing loss on each consonant over a range of performance. The CLP shows that the consonant loss, which is the signal-to-noise ratio (SNR) difference at equal NH and HI scores, is consonant-dependent and varies with the score. This variation in the consonant loss reveals that hearing loss renders some consonants unintelligible, while it reduces noise-robustness of some other consonants. The conventional SNR-loss metric DeltaSNR(50), defined as the SNR difference at 50% recognition score, is insufficient to capture this variation. The DeltaSNR(50) value is on average 12 dB lower when measured with sentences using standard clinical procedures than when measured with nonsense syllables. A listener with symmetric hearing loss may not have identical CLPs for both ears. Some consonant confusions by HI listeners are influenced by the high-frequency hearing loss even at a presentation level as high as 85 dB sound pressure level.