Variability of word discrimination scores in clinical practice and consequences on their sensitivity to hearing loss

Speech perception scores are widely used to assess patient's functional hearing, yet most linguistic material used in these audiometric tests dates to before the availability of large computerized linguistic databases. In an ENT clinic population of 120 patients with median hearing loss of 43-dB HL, we quantified the variability and the sensitivity of speech perception scores to hearing loss, measured using disyllabic word lists, as a function of both the number of ten-word lists and type of scoring used (word, syllables or phonemes). The mean word recognition scores varied significantly across lists from 54 to 68%. The median of the variability of the word recognition score ranged from 30% for one ten-word list down to 20% for three ten-word lists. Syllabic and phonemic scores showed much less variability with standard deviations decreasing by 1.15 with the use of syllabic scores and by 1.45 with phonemic scores. The sensitivity of each list to hearing loss and distortions varied significantly. There was an increase in the minimum effect size that could be seen for syllabic scores compared to word scores, with no significant further improvement with phonemic scores. The use of at least two ten-word lists, quoted in syllables rather than in whole words, contributed to a large decrease in variability and an increase in sensitivity to hearing loss. However, those results emphasize the need of using updated linguistic material for clinical speech score assessments.