How reliable are online speech intelligibility studies with known listener cohorts?

Although the use of nontraditional settings for speech perception experiments is growing, there have been few controlled comparisons of online and laboratory modalities in the context of speech intelligibility. The current study compares outcomes from three web-based replications of recent laboratory studies involving distorted, masked, filtered, and enhanced speech, amounting to 40 separate conditions. Rather than relying on unrestricted crowdsourcing, this study made use of participants from the population that would normally volunteer to take part physically in laboratory experiments. In sentence transcription tasks, the web cohort produced intelligibility scores 3-6 percentage points lower than their laboratory counterparts, and test modality interacted with experimental condition. These disparities and interactions largely disappeared after the exclusion of those web listeners who self-reported the use of low quality headphones, and the remaining listener cohort was also able to replicate key outcomes of each of the three laboratory studies. The laboratory and web modalities produced similar measures of experimental efficiency based on listener variability, response errors, and outlier counts. These findings suggest that the combination of known listener cohorts and moderate headphone quality provides a feasible alternative to traditional laboratory intelligibility studies.