While masks have become the new fashion statement for many, it has raised troubles for people with hearing loss. But, researchers have found that the use of transparent masks during communication increases comprehension of speech by about 10 per cent for such people.
In the US, two models of masks with a see-through portion in the mouth area have been approved by the Food and Drug Administration and Centers for Disease Control and Prevention.
The study, published in the journal Ear and Hearing, measured the importance of visual cues to communication for people with normal hearing and hearing loss.
"Our findings show that wearing a transparent mask can facilitate communication for everyone, minimising stress and improving interaction. Protection obviously has to be the primary concern, and no clear models with proven effectiveness are sold in Brazil right now," said Regina Tangerino, Professor at the University of Sao Paulo's Bauru Dental School (FOB-USP) in Brazil.
For the study, the team posted on the internet a set of videos lasting 40 minutes, with Tangerino voicing several utterances against background noise without a mask, wearing a mask with a clear mouth panel, and wearing an opaque fabric mask.
The study used 154 volunteers recruited via social media or by email and were divided into three groups based on whether they had normal hearing, or confirmed or suspected hearing loss (with or without cochlear implants or hearing aids).
On average, the volunteers in all three groups correctly understood 83.8 per cent of the sentences spoken without a mask, 68.9 per cent of utterances with a see-through mask, and 58.9 per cent with an opaque mask.
"The difference of 10 percentage points (between the latter two averages) is statistically significant. This benefit applies to more than just comprehension: the participants also felt more self-confident and were able to follow what was said with less effort when the see-through mask was used," Tangerino said.
A follow-up study using audio only was conducted with 29 volunteers, who were not told which sentences were recorded with or without a mask.
"In this case, the average performance was actually worse for sentences spoken with a clear mask than with an opaque mask, confirming the significance of visual cues in the first study. They helped listeners surmount the problem of muffled sound when a mask is worn," Tangerino said.