Hospitals and charities are now using transparent face masks so that people can better communicate with each other during the Covid-19 outbreak.
Standard face masks, which have become mandatory in many countries, often muffle words as well as obscure the mouth.
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.
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.
Five hundred specialist clear masks are currently 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.
Experts suggest that other professions such as taxi drivers, shop assistants and teachers may find clear masks useful when schools reopen, as the coronavirus crisis continues.
