Impact of face masks on speech comprehension

An outstanding health-policy goal -until the development of a vaccine- is to mitigate the spread of SARS-CoV-2 in the population. It is unclear when such a vaccine will be widely available and how protective it will be. This means that for a long time to come, the most effective means for combatting the virus is the adaptation of human behaviour. Next to social distancing and hygiene practices, many countries recommend or even prescribe the use of face-masks, especially in situations when minimum distances cannot be upheld. A rarely noted side effect of this virologically meaningful measure is that it deprives interpersonal speech communication of an extremely important cue: the lip movements of the speaker. This visual information supports speech comprehension, especially in challenging listening situations (e.g. conversation in a noisy café). While this can be said in general also for normal hearing individuals, it applies even more strongly to individuals with hearing damage, i.e. approximately 1.3 billion humans worldwide according to estimates of the WHO from 2017. This “disadvantage” of these individuals through face masks has to be seen from two sides: 1) a qualitatively reduced speech comprehension, in particular by missing lip movements; and 2) an increase of the necessary listening effort as a compensatory consequence. Also in light of the fact that hearing damage is an important predictor for developing dementia in future, it is vital to quantitatively determine this putative “disadvantage“ and to understand it ideally in functional terms. The goal of this Urgent-Funding project is to understand how occluded information of lip movements by the use of face masks affects overt speech-related processes (e.g. comprehension, subjective effort) as well as those inferred from neural data (e.g. tracking, physiologically based estimates of comprehension and effort).