Masks can obscure a smile, muffle a voice, and make lip reading impossible.
But those are minor obstacles to human interaction, says Lindsay Yazzolino, who is blind.
"It's interesting to me how face-seeing is considered to be the be-all and end-all in so many contexts," she says.
That's why Yazzolino says she is puzzled by the current debate over masks in the classroom.
Some parents express worry that masks might interfere with children's ability to learn or to socialize. Other parents fear that unmasking will lead to more COVID-19 cases.
Amid the debate, a small but growing body of research is offering hints that masks do not have a significant impact on speech or social skills.
Some of that research involves people like Yazzolino, who are blind. Their ability to master language and social skills shows that the human brain is really good at finding a way to communicate.
Yazzolino, an accessible-technology consultant, has been blind since birth. But she went to school with sighted kids.
"I always had a really great experience in school," she says. "I had a lot of really supportive teachers, I was reading at an early age. I loved math and science."
She relied on braille to read and write. And it was hard for her to get some course materials in that format.
But social interactions were never a problem, she says.
"You hear emotion in people's voices, so I definitely used that as a cue," she says. "And I talk to people."
The brain finds a way
Yazzolino's experience is unsurprising, scientists say, because the human brain is really good at finding a way to communicate.
"We tend to underestimate how flexible our mind and our brain is," says Marina Bedny, an associate professor at Johns Hopkins University who studies brain development in people who are blind.
For example, areas of the brain usually devoted to visual information are used to process sounds in people who are blind, Bedny says.
"We've also found that people who are blind have some superior abilities at understanding spoken sentences," she says, "perhaps because language is such an important source of information."
This sort of research suggests that when sighted children encounter masks in the classroom, their brains adapt quickly.
"Whether the person who is teaching them is wearing a mask is just not something that would, to me, seem like it would matter at all for a child's development," she says.
There's not much research to directly back that claim, though.
Studies show that children tend to watch mouths and faces closely when learning to speak and read emotions. But it's less clear what happens when these visual cues aren't available in the classroom.
Masks in class may encourage more speech
At least one unpublished study has found that pandemic masking isn't an obstacle to learning, even for children as young as 3 or 4.
"We're seeing really similar amounts of talking, really similar amounts of vocabulary development, language growth, language development, with or without masks, says Lynn Perry, an associate professor in the psychology department at the University of Miami.
Perry is part of a team that has been monitoring speech development in pre-school students since before COVID-19 arrived. The students wear a device that monitors the language sounds they produce.
The team compared a class from early 2020, before masks arrived, with a class in 2021, when masks were required. And they found no difference in the amount of language production.
The team also found that the complexity of speech sounds was higher in children wearing masks.
"Maybe they talk a little bit more to get their meaning across," Perry says. "Maybe the teachers change the way that they're talking to make sure that they're being understood."
About half the children in the study used hearing aids or cochlear implants. And those kids also did fine with masks, says Samantha Mitsven, a doctoral candidate at the University of Miami.
"These results were particularly encouraging because these children with hearing loss often benefit from these early education programs," Mitsven says.
In different contexts, masks pose different challenges
Masks do pose a challenge for deaf or hard-of-hearing students who aren't already fluent in American Sign Language or ASL, says Tyrone Giordano of the Clerc Center at Gallaudet University. The center offers elementary and secondary schools for children who are deaf or use hearing aids or cochlear implants.
Facial expressions and mouth movements are an integral part of signing, and masks covering up the face means the brain needs to work harder to process what is being said, especially for those who are acquiring ASL, says Giordano, who is deaf.
While Gallaudet University now permits teachers to remove their masks during presentations, the Clerc Center continues to encourage masking to protect vulnerable students. The center does permit the use of clear masks or clear plastic shields for some interactions, such as speech therapy or audiology.
But students have adapted to mask requirements in other settings, Giordano says. "They're reaching their benchmarks, so we're not worried."
Despite reassuring reports, the long-term impact of masking in schools remains unclear, says Stephen Camarata, a professor of speech and hearing sciences at Vanderbilt University.
"This idea of doing selective access to faces is really not a well-researched topic at this point, he says.
Camarata thinks most children won't have any long-term effects from masks in classrooms. But he's concerned about some students with autism who have difficulty adapting to even small changes in their environment.
"When they go in the classroom and everything's changed, it's just really disorienting," Camarata says. The result is often disruptive behavior and a lack of learning.
Another problem for some children with autism has to do with the way that their brains combine what they see and what they hear.
"Children with autism actually do not bind auditory signals in the way that typical children do," he says.
For many, it's like watching a movie where the soundtrack is out of sync. And the problem is worse when these children are unable to see a teacher's mouth move.
Despite this, Camarata says, for many children with autism, even a classroom with masks is better than virtual learning on a computer or tablet screen.
"When you give a child with autism an iPad, they just tend to get into games that they like and play them over and over again," he says, "and they're missing other learning opportunities."