The influence of lexical-access ability and vocabulary knowledge on measures of speech recognition in noise.

OBJECTIVE The main objective was to investigate the effect of linguistic abilities (lexical-access ability and vocabulary size) on different measures of speech-in-noise recognition in normal-hearing listeners with various levels of language proficiency. DESIGN Speech reception thresholds (SRTs) were measured for sentences in steady-state (SRTstat) and fluctuating noise (SRTfluc), and for digit-triplets in steady-state noise (DIN). Lexical-access ability was measured with a lexical-decision test and a word-naming test. Vocabulary size was also measured. For the SRT, keyword scoring and sentence scoring were compared. STUDY SAMPLE To introduce variation in linguistic abilities, three groups of 24 young normal-hearing listeners were included: higher-educated native, lower-educated native, and higher-educated non-native listeners. RESULTS Lexical-access ability was most accurately measured with combined results of lexical decision and word naming. Lexical-access ability explained 60% of the variance in SRT. The effect of linguistic abilities on SRTs was up to 5.6 dB for SRTstat and 8 dB for SRTfluc. Using keyword scoring reduced this effect by approximately 1.5 dB. For DIN the effect of linguistic ability was less than 1 dB. CONCLUSIONS Lexical-access ability is an important predictor of SRTs in normal-hearing listeners. These results are important to consider in the interpretation of speech-in-noise scores of hearing-impaired listeners.