Improved face-worn PPE designs for use by the public and professionals to reduce audio-visual communication difficulties

Lead Research Organisation: University of Manchester
Department Name: School of Health Sciences


To reduce the transmission of COVID-19, personal protective equipment (PPE) is
required. PPE to protect the eyes, nose and mouth comprises face masks and transparent
visors. These range from a simple covering made from domestic fabrics for use by the
public, to FFP3/N99 rated air filters and wrap-around face visors in care settings. All these
PPE styles make spoken and signed communication harder. Everyone, not just the
hearing impaired, will struggle to understand in real-world conditions and background
sounds. This will result in increased listening effort, stress, communication errors and
potentially social withdrawal. Articles published in May 2020 by the PI and his group
leader in a professional journal
of-facemasks-for-people-with-hearing-loss) produced over 100 responses from anxious
adults, parents, public and professionals.
Both acoustic and visual cues are reduced by face coverings: (i) acoustic : the high frequencies of
the sound are attenuated, leading to a "muffled" perception (ii) visual : sight of the talker's mouth
movements that can be used by all listeners to supplement the muffling of speech and (iii) visual :
full-facial expressions that convey emotions, supplement lip-reading and are essential
components of (the non-acoustic) British Sign Language (BSL).
Employing user surveys, fabrication, and testing, this project will produce validated examples of
facemask and visor designs that preserve acoustic and visual cues thereby offering less effortful
communication in a variety of usage scenarios. It brings together acousticians, audiologists,
material scientists, and users to tackle an urgent problem that affects everyone now, and will also
outlast the current pandemic.


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Cox TJ (2022) Improving the measurement and acoustic performance of transparent face masks and shields. in The Journal of the Acoustical Society of America

Description The first aim of the project was to develop a facemask for the general public that was both acoustically and optically "near-transparent". This means that, as well as not muffling the sound of the talker, a clear view of the mouth and surrounding area of the face is provided. During communication, both spoken and emotional, this area of the face is important to enable more relaxed communication for both talker and listener.
We developed a mask with acoustic performance better than the routinely used surgical mask, but was also transparent.
We have produced a video as well as "how to assemble" documents to enable a "make-at-home" approach.
We incoporated the core feature of the mask into a face shield (visor) in order to improve acoustic transmission.
We produced a demonstrator mask of how this acousti-optic feature could also be combined with a novel filtration material developed in Manchester, in order to produce a mask capable of a very high standard of filtration.
We sought feedback from Deaf and hearing-impaired users on the effectiveness of the general-public mask design, and used this to refine the final version.
Exploitation Route We have produced a "proof-of-concept" and hope to engage with industry to look at upscaling the manufacture from the "make-at-home" concept.
The general design will have a use far beyond that of COVID since we have identified multiple use cases where the features enable better communication, eg in operating theatres, dental surgeries, health & safety.
Sectors Healthcare

Title Improving the measurement and acoustic performance of transparent face masks and shields 
Description This is the raw measured data that is analysed and presented in: T. J. Cox , G. Dodgson, L. Harris, E. Perugia, M. A. Stone, M. Walsh, Improving the measurement and acoustic performance of transparent face masks and shields, Journal of the Acoustical Society of America, 2022.Included:* Impulse responses for a head and torso with mouth simulator measured at a microphone 1m away, with and without a variety of face masks and shields.* Recordings of four talkers reciting prose with and without various face masks to a microphone 1m away.* Laser Doppler vibrometer measurements of various face masks.The "descriptions of files.docx" describes the contents of the zip archives.The file mask_construction_instructions_templates.pdf includes templates and instructions for making the final mask design. 
Type Of Material Database/Collection of data 
Year Produced 2022 
Provided To Others? Yes  
Impact Too early to quantify.