Influence of face masks on speech intelligibility in hearing impaired individuals

Background When speaking through a face mask, not only sound transmission is reduced, but also lips of the speaker are covered. Previous studies have shown an increase in speech intelligibility among normal-hearing individuals when adding visual cues. The effect of face masks on speech recognition in hearing-impaired individuals will be examined during this clinical study.

Methods We examined a group of 20 persons with symmetrical hearing loss (age 72,1 ± 9,9 years) and 10 normal hearing individuals (age 64 ± 4,8 years). To investigate speech intelligibility participants underwent a modified version of the audiovisual Oldenburger Satztest (AV-OLSA). Generally, its aim is to evaluate speech reception thresholds in noise by synchronizing video recordings with the audio version of the OLSA. Additionally, face masks were added to the video material and the audio material was acoustically attenuated according to the mask type. Therefore, 5 conditions (audiovisual, audio only, visual only, surgical mask and FFP-mask) were used to evaluate speech reception in noise.

Results Preliminary results show increase of 80% speech reception threshold (SRT_80%) measured in dBSNR by 2,3 dB in hearing impaired individuals and by 2,2 dB in normal hearing participants when visual cues were added compared to ‘audio-only’ conditions. Deterioration of SRT_80%  accounted for 2,7 dB and 4,2 dB in hearing impaired individuals and for 2,8 dB and 3,8 dB in normal hearing individuals by using surgical and FFP-masks, respectively. This effect was achieved by acoustical and visual constituents.

Conclusion  Results show the decrease of speech intelligibility in hearing impaired and normal-hearing individuals when face masks are added to the speaker. FFP-masks have a greater impact than surgical masks.

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Artikel online veröffentlicht:
12. Mai 2023