Exploring effects of speaker and face mask type on speech intelligibility

Subsequent to the COVID-19 pandemic, face masks remain a consistent part of many individuals’ lives. While research on face masking has revealed effects on speech intelligibility, relatively few studies have examined speaker differences, the effects of masking on speaker behavior, and how these influence intelligibility. We report here on data from four healthy American English-speaking adults who produced low-predictability sentences in four face mask conditions: surgical, cloth, N95, and no mask. Typically hearing listeners (n = 89) heard sentences, mixed with multi-talker babble, from one of the speakers and typed the words they heard. Percent words correct was scored by a text-matching algorithm, allowing for morphological errors and homonyms. From all speakers, we obtained: long-term average spectra; first and second formant ranges in words with /i, ɑ, o/; sentence durations and average intensities; and phonetic features of common misperceptions. Error rates were highest for the N95 mask. Speakers demonstrated individual patterns of the above acoustic variables. The speaker with the lowest intelligibility displayed faster speech, lower intensity, and unexpectedly higher F2 ranges in the masked conditions. These results suggest that quantifying speaker differences in intelligibility and acoustics can better elucidate the effects of face masks on communication.