Fact · Dictation
55subjects
In a 2019 laboratory study of 55 people, the speech transmission index, which measures how intelligible background speech is, had a significant effect on performance decrement, mental load and discomfort.
Checked against its source on October 16, 2026
In the source's own words
“Results show a significant effect of the STI on the DP, the mental load and the discomfort.”
Irrelevant speech effect in open plan offices: A laboratory study, Krist Kostallari et al., arXiv (eess.AS), preprint, 2019, Abstract (Results).
Open the original- What it measures
- Subjects did a working-memory task in silence and in four sound conditions with speech at STI values from 0.25 to 0.9. The DP is the decrease in performance.
- What it does not show
- A laboratory memory task, not real office work or dictation. The authors note that performance did not rise at the highest STI values, so the plateau in the model is not rejected.