The following are a set of preliminary tests I did to determine relative speech sound performance while wearing a mask. I'm particularly interested in the context of mask-wearing in a classroom, but this could be helpful in many other workplaces.
I tested a number of masks in my dining room. Audio levels were measured using an Apple iPhone 13 Pro and the NIOSH Sound Level Meter (SLM) app on July 1, 2022. The phone was in a Lifeproof case and supported on a tripod with a clamp. A small speaker was placed inside a plastic mannequin head and a 1kHz sound file generated in Matlab and was played from the headphone jack of a MacBook Air. The phone was placed approximately one meter away from the front of the mannequin.
These are all preliminary results. Take them with a big grain of salt. As the pandemic continues, please think of safety first and use the mask that fits you best. Sound levels are important, but not as important as getting a good fit on your face.
The LAeq result from the NIOSH SLM app was used. This is the "A-weighted equivalent sound level" [manual]. Three tests were done per mask, the LAeq result recorded. The mean value was taken from these three tests and then rounded to produce the graph shown below. Matlab was used to generate the graph and I superimposed sketches of each mask.
The baseline LAeq sound value without a mask was 66dB (avg; rounded). The following masks and respirators were examined, in order of best sound performance:
- Covergals cloth mask (66dB; site)
- CanadaMasq CA-N95 Blue (65dB; site; via CanadaStrong)
- Draeger X-plore 2100 (65dB; site; via Donate A Mask)
- PrescientX [breathe] (65dB; site)
- Vitacore CAN99 (65dB; site; via CanadaStrong)
- PrescientX Nanomask (64dB; site)
- 3M 1870+ (64dB; site; via UnitedCanada)
- Dentec ComfortAir N95 (S/M) (62dB; site; via Donate A Mask)
- GVS Elipse SPR 643 (S/M) (61dB; site)
- Dentec Comfort-Air P100 (M/L) (53dB; site)
A few things stand out. First, cloth masks let nearly all sound through -- but they don't protect you very well against COVID. Second, disposables like the CanadaMasq CA-N95, Vitacore CAN99 and 3M Aura 1870+ all do very well. This is good news, because disposable N95-class masks are better than cloth or surgical masks at protecting you from COVID. Elastomerics with front-facing filters (Nanomask, [breathe], X-plore 2100) do really well, seeming to focus the sound forward, a bit like a megaphone does. Elastomerics with side-facing filters (GVS, Dentec models) fare worse, but both the Comfort-Air N95 and GVS models have decent performance. The Comfort-Air with the P100 filters really don't have great audio -- I've used them for teaching but they work best with a microphone attached.
So, are you considering wearing a mask at work or at school and want to be heard? Disposables like the CanadaMasq CA-N96, Vitacore CAN99 and 3M Aura (like the 1870+ model) are very good choices. I know many teachers who use them every day (my wife, for instance, teaches gym in a CAN99). Elastomerics, which may give you a better seal could also be good options for you. Of the elastomerics, the PrescientX [breathe] has really good audio and doesn't look as goofy (very subjective term!) as the Dräger X-plore. Of course, the GVS Elipse and Comfort-Air N95 are also good options, but sound will be reduced with those. I personally have used the P100 version of the Comfort-Air but without a microphone you may have difficulty being heard in the classroom.
Please note that none of these results are peer-reviewed and there are many limitations to them. None of these results should be considered definitive. Ideally, I wish to verify the results using professional calibrated sound generation and measurement equipment. At the moment I'm working with the tools I have access to. More tests, with different sound profiles and frequencies are planned.
James Andrew Smith is a Professional Engineer and Associate Professor in the Electrical Engineering and Computer Science Department of York University's Lassonde School, with degrees in Electrical and Mechanical Engineering from the University of Alberta and McGill University. Previously a program director in biomedical engineering, his research background spans robotics, locomotion, human birth and engineering education. While on sabbatical in 2018-19 with his wife and kids he lived in Strasbourg, France and he taught at the INSA Strasbourg and Hochschule Karlsruhe and wrote about his personal and professional perspectives. James is a proponent of using social media to advocate for justice, equity, diversity and inclusion as well as evidence-based applications of research in the public sphere. You can find him on Twitter. Originally from Québec City, he now lives in Toronto, Canada.
Note: I am not an HVAC, PPE or public health expert. While I have an engineering background (degrees in both EE and MecE) and have done work in Biomedical Engineering, I am not formally trained in either HVAC, PPE or public health. If you're looking for professional design or testing advice or services, please hire a professional engineer who is an expert in the area of interest.
Conflicts of interest: none that I am aware of. I do not work for or have financial interest in any PPE, HVAC or public health company or agency. While I have communicated with companies and employees at PPE and HVAC companies, I do not work for any, nor have I received money or contracts from them. All products that I have received were paid for either personally or through my employer or were acquired through friends or family (none of which work for a PPE or HVAC company to my knowledge) -- none have been donated or loaned to me by manufacturers, suppliers or distributors.