Intelligibility of face-masked speech depends on speaking style: Comparing casual, clear, and emotional speech.

This study investigates the impact of wearing a fabric face mask on speech comprehension, an underexplored topic that can inform theories of speech production. Speakers produced sentences in three speech styles (casual, clear, positive-emotional) while in both face-masked and non-face-masked conditions. Listeners were most accurate at word identification in multi-talker babble for sentences produced in clear speech, and less accurate for casual speech (with emotional speech accuracy numerically in between). In the clear speaking style, face-masked speech was actually more intelligible than non-face-masked speech, suggesting that speakers make clarity adjustments specifically for face masks. In contrast, in the emotional condition, face-masked speech was less intelligible than non-face-masked speech, and in the casual condition, no difference was observed, suggesting that 'emotional' and 'casual' speech are not styles produced with the explicit intent to be intelligible to listeners. These findings are discussed in terms of automatic and targeted speech adaptation accounts.