Using more realistic speech material to enhance ecological validity in the Everyday Conversational Danish Sentence Test

Traditional audiological tests often fail to replicate real-world listening environments, potentially leading to discrepancies between clinical assessments and patient experiences. Common tests involve sentences read aloud verbatim, which do not represent real-life speech and language. This study outlines the development of a more ecologically valid speech material and compares its psychometric properties to those of the more traditional, clear-speech Danish Sentence Test (DAST) corpus. Sentences were extracted from recordings of dialogues between a female talker and two partners, communicating in quiet and noisy conditions to elicit normal and raised vocal efforts. A total of 400 sentences were included in the Everyday Conversational Danish Sentence Test. These sentences were presented to 40 normal-hearing participants in stationary noise spectrally matched to each vocal effort, across five signal-to-noise ratios (SNRs) ranging from -10 to 0 dB in 2.5 dB steps. A psychometric function fitted across all sentences revealed a speech reception threshold (SRT) of -5.3 dB SNR and a slope of 12.1%/dB, similar to the psychometric properties of DAST (SRT: -5.17 dB SNR; slope: 11.5%/dB). Vocal effort significantly affected intelligibility, but the direction of the effect varied with SNR. Sentences were intelligibility-normalized and grouped into balanced lists for future implementations.