The filtered words test and the influence of lexicality.

Purpose: In the present study, the authors aimed to investigate the language confounds of filtered words tests by examining the repetition of real words versus nonsense words as a function of level of filtering.

Method: Fifty-five young, native-English-speaking women with normal hearing were required to repeat 80 real-word and 80 nonsense-word monosyllables that were matched for phonemic content and low-pass filtered. Thirty participants were tested using a harsher filter range of 2000 to 500 Hz, and 25 participants were tested using a milder filter range of 3000 to 1500 Hz.

Results: Paired-sample t tests compared accuracy (percentage of phonemes correct) for word and nonsense-word stimuli at each filter level. At filter levels between 3000 and 1750 Hz, performance for word stimuli was significantly better than for nonsense-word stimuli. Conversely, at filter levels between 500 and 1250 Hz, performance was significantly better for nonsense words.

Conclusions: The linguistic content of real-word stimuli benefits performance on low-pass filtered speech tests at filter levels above 1500 Hz. Caution must be taken when using real-word stimuli in low-pass filtered speech tests as part of an auditory processing diagnostic test battery, because language ability will impact on performance.