There are many reasons people may be reticent to wear masks, but one I hear about a lot is that it makes talking more difficult, and, in turn, affects speech comprehension. With masks come muffling and, even more problematic, no mouth visibility, something that has a significant impact on how well we can decipher what someone says. While masks may keep us safe, from a linguistic perspective, they open up a can of comprehension worms.
The mouth/ear connection
It may seem strange that you would need to see someone’s mouth to understand what they are saying. After all, we’ve communicated over the telephone without visuals for years and no one has yet to declare phones the gateway to communication hell.
But we tend to talk to people we know fairly well on phones, and have a specific topic and context to draw upon that we can use to heuristically fill in the speech blanks. Also, because we have no expectation of visual information on the phone, our brains are forced to rely only on auditory information for the task of speech processing.
When face to face we instead integrate multi-sensory cues, including both auditory (hearing) and visual information. Visual cues are part of what we call the ‘speech chain,’ the connection between how a speaker produces speech and how a listener receives it. When available, such information assists a listener in processing what a speaker says. In addition to cutting off visual cues, masks also render us less able to move our mouths normally and involve layers of fabric which dampen the acoustics frequencies of a sound.
The science behind the mask
The potential for hearing problems associated with masks is not new, and there has in fact been research investigating the impact of mask wearing on comprehension. After all, degraded hearing is not just a problem for those of us ordering a venti latte at Starbucks, but it has long been a critical issue for doctors and nurses, for whom miscomprehension can be the difference between life or death.
In a 2008 study, Mendal et al. compared speech through masks for both hearing impaired and non-impaired subjects and found surrounding noise significantly affected comprehension. A more recent study found that hearing impaired listeners did better when transparent masks were used, allowing them to integrate audio-visual information. In other words, masks did pose some, but not great, problems with comprehension.
But these studies looked only at surgical masks in a controlled medical setting. In today’s world, masks come in a variety of forms ranging from last ski season’s balaclavas to homemade fabric designs and we wear them in our noisy real lives. Aside from contributing to bank tellers’ unease, do such non-medical masks wreak havoc with our hearing?
In a 2013 study, forensic linguists examined how various types of masks affected mouth movement, sound absorption and comprehension. Somewhat surprisingly, none of the mask types, even those that obscured the mouth the most, obstructed motor movement (in other words, people’s mouths still moved normally), though the more a mask allowed a view a speaker’s face, and, in particular, their lips, the greater listeners’ accuracy in perception. But, overall, comprehension was still quite high.
The researchers found that, without access to lips, we seem to shift to using other visual cues, such as the movements of the cheeks and chin, to assist in decoding what sounds we heard. They hypothesize that tighter fitting masks that display more of the facial architecture may help provide such visual cues. Since this study was performed in pre-pandemic days, homemade fabric masks were not among those studied and the thickness and loose-fit of such masks may contribute to greater problems with comprehension.
Unmasking the takeaway
In effect, the results of the few studies of mask-wearing on speech production and speech perception don’t indicate that our days of easy comprehension are behind us. Instead, they suggest that we are still able to talk fairly well and hear fairly well despite our masked state, particularly in quiet contexts.
So, why do we still feel like we struggle to understand each other behind our masks? Probably because, as some of these experiments suggested, noisy conditions are a factor. Also, these studies did not require subjects be safely socially distant. Many of the places where we converse, like outdoors and in stores with background noise, are not conducive to speech comprehension even in the best of circumstances and the greater distance between us requires soundwaves to travel farther.
As a result of this combination of more space and less face, the loss of the integration of visual information in our speech processing then has a potentially greater effect. Throw in undiagnosed higher frequency hearing loss, which many of us less-than-spring chickens often have, and it is a recipe for hearing issues. The strategies we might have unknowingly been relying on to compensate for this loss (i.e. lip reading) are no longer available to us.
But the good news is that masks, in and of themselves, do not seem to have strongly significant effects on hearing if we can try to minimize noise and we have normal hearing. It is also important that they fit so that they do not obstruct our motor movement and even better if they display at least some of our face for us to use as compensatory visual cues. Transparent masks also seem to help. If you are still struggling to comprehend what people are saying behind the mask, it might be the universe telling you that it is time for a trip to an audiologist.
Atcherson SR, LL Mendel, WJ Baltimore, et al. 2017. The Effect of Conventional and Transparent Surgical Masks on Speech Understanding in Individuals with and without Hearing Loss. J Am Acad Audiol. 28(1):58-67.
Fecher, N., & Watt, D. 2013. Effects of forensically-realistic facial concealment on auditory-visual consonant recognition in quiet and noise conditions. AVSP.
Mendel LL, JA Gardino, and SR Atcherson. 2008. Speech understanding using surgical masks: a problem in health care?. J Am Acad Audiol. 19(9):686-695
Valerie Fridland is a professor of linguistics in the English Department. Her blog, Language in the Wild, appears in Psychology Today and her lecture series, Language and Society, is featured with The Great Courses. She is co-author of Sociophonetics (Cambridge) and co-editor of three collections on speech in the West.