It's now part of daily life for many of us - struggling to work out what someone in a supermarket or at work is saying when they're wearing a face mask.
But for people who are deaf or have hearing loss, masks can prevent them understanding anything at all.
"You might as well be speaking in French," says Fizz Izagaren, a paediatric doctor in the UK who has been profoundly deaf since the age of two.
"I can hear one or two words but it's random, it makes no sense… When someone is wearing a face mask I've lost the ability to lip read and I've lost facial expressions - I have lost the key things that make a sentence."
It is a problem she shares with the some 466 million people around the world who, according to the World Health Organization, have disabling hearing loss.
Standard face masks, which have become widespread as countries try to stop the spread of coronavirus, muffle words and obscure the mouth.
But now charities and manufacturers alike are coming up with a solution.
Main dans la Main (Hand in Hand), an association which supports deaf and hearing impaired people in Chevrières, northern France, is among the organisations around the world that have created a mask with a transparent window.
Its founder Kelly Morellon worked with her mother Sylvie to devise a design that covers the nose but makes the mouth visible, and can be washed at a high temperature to reduce infection.
"The basic aim of these transparent masks is to allow deaf and hearing impaired people to read the lips of someone speaking to them," Kelly told the BBC.
"But they are also very useful for autistic people, people with learning difficulties and small children who might be scared of masks or need to be able to see facial expressions.
"In any case, a transparent mask allows you to see each other's smiles, and at this sad time this could not be more important."
Unlike some companies around the world - in Scotland, the US and Indonesia, for instance - Kelly and her mother are not able to produce their masks on a commercial basis.
Instead, they are advising people on how to make their own and there are multiple guidelines online to help. Their top tip is to use a little washing up soap to stop the plastic screen fogging up.
But one setting where homemade masks are not suitable - but where both PPE and communication are vital - is in hospitals.
There is just one company in the US that has secured Food and Drug Administration (FDA) approval to make clear masks for clinical use.
Five hundred of these masks are being used at Brigham and Women's hospital in the US city of Boston. At the moment they are being reserved for staff to wear when they are speaking to patients with hearing loss, or vice versa. Sign language interpreters, who use facial expressions and lip movements alongside body movements to create more complex and culturally rich signs, also wear them.
"When we saw the Covid-19 pandemic beginning… we soon realised there was going to be a challenge because of the escalated use of PPE and how that would create communication barriers," said Dr Cheri Blauwet, who leads the disability task force at the Brigham.
"We've had glowing feedback from patients and we're getting broader requests from other parts of the hospital, especially the paediatric floors."
In the UK, there are no approved manufacturers providing clear masks to hospitals. And the sole US manufacturer is not taking any more orders as it deals with overwhelming demand.
Fizz Izagaren, a paediatric registrar at Frimley Park Hospital in Surrey in the UK who is also deaf, says standard masks prevent her from taking patients' histories verbally. She also says she feels isolated at work because she is not able to speak to her colleagues.
"Clear masks should be the norm for everyone in a healthcare setting," she says.
She is now working with a product designer to try to come up with a mask that the NHS could use widely. But even once a design and a manufacturer are found, this could take time to roll out.
In the meantime, there are concerns the current PPE could stop medical staff getting the required consent from patients.
An intensive care nurse working in London, who is profoundly deaf, told the BBC she had one experience where a patient, who also had hearing loss, was not able to understand her or her colleagues when they were explaining a procedure. The patient could not give consent and the procedure could not go ahead.
"[Clear masks] would make things a lot easier for me," she said.
"I would be able to do my jobs properly and safely. I would have more independence rather than having to rely on others."
In the UK, eight charities have written to NHS bosses calling for clear masks to be commissioned, warning of "potentially dangerous situations" arising from communication problems. NHS England has not yet responded to the letter, or to the BBC's request for comment.
The UK government says it is supporting CARDMEDIC, which provides digital flashcards and other communication aids to NHS Trusts. There are also apps that transcribe speech into text on a mobile phone.
But deaf workers say these workarounds are not always suitable for sensitive or emergency situations.
"As masks become more widespread in the community - it's going to get harder and harder," Dr Izagaren says.
"I'm worried the public are going to get more and more frustrated and there will be more discrimination towards the deaf community."
It is not just people with hearing loss who could benefit, she says.
Experts suggest that other professions such as taxi drivers or even teachers may find clear masks useful as the coronavirus crisis continues.
A niche product initially designed to help the deaf community, could in fact make everyone's lives better.