The Thomas More Lists: A Phonemically Balanced Dutch Monosyllabic Speech Audiometry Test

Speech audiometry tests are a crucial tool in clinical care and research. In Dutch, the common practice is to use lists of monosyllabic words with a consonant-vowel-consonant (CVC) structure. However, there are relatively few lists, and they are short. Here, the goal is to develop an adult speech audiometry test for Dutch (Flemish) consisting of phonemically balanced lists of 25 CVC words. The ISO 8253-3:2012 norm was followed. From a pool of 689 well-known words, an initial set of 26 lists was recorded by a female speaker. The lists were optimized for perceptual balance by means of two studies with young normal hearing listeners (N₁ = 24, N₂ = 32). The final corpus contains 16 phonetically and perceptually balanced lists. In a last study (N₃ = 25), the reference speech recognition curves in quiet and in speech-shaped noise were determined. Reference speech recognition threshold and slope values for phoneme scoring are respectively 20.3 dB_SPL in quiet (slope 5.2%/dB) and -7.7 dB_SNR (7.5%/dB) in noise, similar to existing materials. The lists may be a useful addition to the existing audiometric tests.