As a voice clinician, so many individuals have come into my clinic since the pandemic started and a very common theme is how many voice problems began after the individual began wearing a respiratory protective mask while vocalizing just as they always have. The kicker is that they don’t realize that they have been modifying their voice patterns behind the mask to be understood by others.
During the pandemic, Youri Maryn, Floris Wuyts and Andrzej Zarowski decided they wanted to find out which masks impacted the acoustic output of the speaker the most and the least so that if there was a choice, one could make it wisely regarding voice health vs respiratory health. In other words, if the respiratory protection wasn’t the main reason to wear a nose/face mask, which mask type would prevent voice overuse?
They wanted to find out how the masks influenced voice/speech measures to help teachers, health care providers, basically anyone needing to vocalize while wearing a mask.
LET’S GET TESTING
They looked at acoustic vocal output on Flemish Dutch-speakers some of whom had normal voices and some of whom had a variety of voice disorders like nodules or paralysis. Limitations of the study were that they used a dummy model of a human torso and head to keep sound signals consistent, so we interpret these findings with caution.
Four different types of masks were tested: 1) no mask 2) disposable surgical mask (with the 3 layers) 3) a FFP2 respirator and 4) a clear plastic mask with a cloth frame. Each was tested to see how they compared to the other to see how they impair (or if they impair) sounds of spoken speech. They looked at multiple different output measures, including the AVQI.
(Pictured above from left to right: a mask similar to FFP2 number 3 that I wear in close proximity to patients, Deborah Brooks Recine modeling a clear plastic cloth mask similar to number 4 that she wears in close proximity to demonstrate correct articulatory movements, a combo picture of the disposable surgical mask similar to number 2 and a KN95 similar to FFP2 number 3, and a single picture of a disposable surgical mask similar to number 2.)
Their findings were that because these face coverings may impair the sounds of human speech as it’s being spoken, they may influence intelligibility of the person to a conversational partner. Frequency (pitch) of the speaker’s voice was not impacted in any mask, however in the FFP2 and the clear plastic masks, speech sounds like /s,sh,t,f,z,d,v/ are all expected to have reduced energy (i.e. be harder to understand by the listener).
Because the speech tested in the study was least impaired in the disposable surgical mask, one might consider using it if proper distance can be maintained between the speaker and the listener(s) and intelligibility/volume is an important aspect. Speech was most impaired in the clear plastic mask, so if you needed to demonstrate the visibility of the articulators and were not so worried about the speech sounds, this might be preferred. If you needed to speak in front of a large group of hard-of-hearing individuals, you might prefer a disposable surgical one over a plastic one (despite the visibility of the articulators (lips, teeth, tongue) from behind the clear shield, and maybe you test this out with some trial and error.
This was a super cool study and influences how I take acoustic measures during the pandemic, and I hope this synopsis is helpful for you. My takeaway from the article is not to ditch the clear plastic mask if you use one, but to simply consider trying all of them to see if you personally experience any changes in your intelligibility (ability to be understood by others) as long as you’re considering the need for respiratory protection as well as voice saving power. This information can help you make informed decisions about your voice. If you’d like to read the entire article, click here:
Maryn Y, Wuyts FL, Zarowski A. (2021) Are acoustic markers of voice and speech signals affected by nose-and-mouth-covering respiratory protective masks? Journal of Voice, doi: https://doi.org/10.1016/j.jvoice.2021.01.013
Kristie Knickerbocker, MS, CCC-SLP, is a speech-language pathologist and singing voice specialist in Fort Worth, Texas. She rehabilitates voice and swallowing at her private practice, a tempo Voice Center, and lectures on voice science nationally. She is part of the Professional Development Committee for ASHA Special Interest Group 3, Voice and Upper Airway Disorders, and a member of the National Association of Teachers of Singing and the Pan-American Vocology Association. Knickerbocker blogs on her website at www.atempovoicecenter.com. She has developed a line of kid and adult-friendly therapy materials specifically for voice on TPT or her website. Follow her on Pinterest, on Instagram or like her on Facebook. Also check out what she and her partners are building at www.confidentclinician.com.