Attention Hearing Care Professionals:
Stevens and Davis (1938) said, “There are, in general, two conditions under which a normally effective auditory stimulus may fail to arouse a sensation. One is when it is accompanied by another sound which obliterates or masks it; the other is when it is preceded by a sound which leaves the organism unresponsive or fatigued.”
Previous and subsequent researchers spent substantial laboratory time explaining this concept to those that performed audiological assessments each day. For now, throw away those masking formulas and the Hood Plateau Method as in 2020 to mask or not to mask and effective masking have a very different meaning.
COVID-19 has added a strange dimension to masking rules. It has changed what effective masking actually means to hearing healthcare providers.
New Masking Rules for COVID 19
The hierarchy of controls presented by the Center for Disease Control (CDC) to rid the virus and is included in at least three of these levels involves the use of masks to reduce the spread of the disease. Until recently, most hearing healthcare clinics and personnel simply considered masks as a method of reducing patient exposure to airborne droplets from colds and other issues that they might be experienceing during their clinic visits. It was rare to see masks in use outside of the hospital.
While there are certain caviates amplified by the White House Task Force on COVID-19, in the next few days America will be masking themselves for trips outside for essentials, a situation that seemed unthinkable just 3-4 weeks ago. In the COVID-19 climate, as in masking for hearing assessment, it is not simply that any masking will be effective. The type and degree of masking that should be used must meet the situation.
What effective masking means for the general public and most hearing healthcare professionals is still confusing and a bit ethically murky but as use increases it is necessary to continue to keep social distancing, hand washing and reduce facial touching. There is a lethal shortage of medical masks — both the rigid, snug-fitting N95 respirator type and the looser-fitting surgical masks more suited for health care workers. Unfortunately, there will be even fewer of both of these types if the general public purchases them. Thus, the general public, including hearing healthcare providers are discouraged from using these masks. The new tendency is for the general public to move toward making homemade masks from craft kits or old T-shirts but it is still unclear how much these will reduce or prevent the wearer from contracting and/or spreading COVID-19.
For obvious reasons first responders and physicians, nurses and others on the front lines of the COVID-19 disease require the most protection against the virus. Let’s look at the masking necessary for various issues to define their use according to the CDC. The N95 respirators and surgical masks (face masks) are examples of personal protective equipment (PPE) that are used to protect the wearer from airborne particles and from liquid contaminating the face. The differences at a glance are presented by the National Institute for Occupational Safety and Health and the Center for Disease Control for surgical masks and N95 respirators. This notice describes the purposes, advantages and disadvantages for both as well as their appropriate deployment. A third type of mask can even be homeade, but they have their limitations.
There are various types of masks that can be used:
- N95 Respirator (Mask). An N95 FFR is a type of respirator which removes particles from the air that are breathed through it. These respirators filter out at least 95% of very small (0.3 micron) particles, known to be part of the COVID-19 virus. N95 FFRs are capable of filtering out all types of particles, including bacteria and viruses. At this point in the virus pandemic, they are reserved for virus victims and front line personnel working with victims each and everyday for hours at at time.
- Surgical Masks. Medical or surgical masks may help reduce the chance of spreading airborne diseases. Many wear them during flu season to avoid infecting others or being infected. They are popular during the COVID-19 outbreak as well but they are not designed to protect the wearer from inhaling airborne bacteria or virus particles and are less effective than respirators, such as an N95 mask. These also are reserved for those second line healthcare workers that require more efficiency in non front line areas of the hospital, such as cleaning crews, food service, etc.
- Homemade Cloth masks. A Do It Yourselfer with a bit of fabric, elastic and rudimentary sewing skills could assemble a series of masks rather easily. There are numerous videos online that will walk you through the process. The CDC has directions for the making of these cloth masks. There are commercial vendors of these masks, such as Etsy, online for reasonable prices.
While these are simple they are certainly not a replacement for the N95 or surgical masks. Even when high quality cloth is used in the fabrication of these masks, public health experts state that fabric masks aren’t intended to protect wearers from getting sick, but rather, to prevent a person from spreading the virus to others.
The COVID-19 outbreak public health guidance for the type of mask to use will continue to exclude using surgical or medical grade masks for the general public, which public health experts indicate should be reserved for people who are sick and for the health care workers who care for them.
Segal (2020) conducted a study to determine how protective the homemade masks were for those who used them. While unpublished and not peer reviewed, he studied about 400 homemade masks created from 13 designs by community volunteers, to determine which masks removed particles 0.3 to 1.0 microns in diameter – the size of many viruses and bacteria. Compared to surgical masks (62% to 65% filtration) and N95 masks (95% filtration), the highest performing masks reached 79% filtration, while the lesser performers had as little as 1% filtration. Segal reported that in his study, the highest-performing masks were made from two layers of high-quality, heavyweight “quilter’s cotton” with a thread count of 180 or more or those made from especially tight weave and thicker thread such as batik. A double-layer design with cotton outside and flannel inside also performed well.
- Scarf or Bandana. The U.S.Public Health service is now urging the public to wear fabric face masks in public when leaving the house for essential activities. Scarf and bandana options are part of most wardrobes and will, to some degree, reduce the spread of the virus in close quarters, such as at the grocery store or other places where close encounters may occur. For these face shield options, the thicker the better and diligence with cleaning, disinfecting, washing your hands and limiting your social interaction is still necessary.
A little-known technology is now available in scarfs and hoodies from G95 Gear which claims to be better protection than an N95 rated filter. As mentioned above, the N95 blocks out 95% of particles .3 microns (about the size of the COVID-19 virus) and their claim is that the G95 has been tested to filter out 99.75% of all particles .1 microns.
Effective Masking of Speech
As hearing healthcare providers use these masks both pre and post the COVID-19 pandemic, careful consideration should be used considering the recent study by Goldin, Weinstein, & Shinman (2020) just published in Hearing Review this week. Their data demonstrate that each type of medical mask in this study essentially functioned as a low-pass acoustic filter for
speech, attenuating the high frequencies (2000-7000 Hz) spoken by the wearer by 3 to 4 dB for a simple medical mask and close to 12 dB for the N95 masks. This means that the speech quality degradation, in combination with room noise/reverberation and the absence of visual cues, renders speech close to unintelligible for many patients with hearing loss.
Their data indicate that it is important for hearing healthcare providers to not only be aware that there is reduction of speech cues when wearing these various types of masks, but when compounded by hearing loss, virus effects and co-morbidity issues, front line providers need to understand that communication can be difficult. This will also be important in the post COVID-19 period where it may be prudent to wear masks in hearing healthcare clinics.
While not without some of the aforementioned speech reduction, a relatively new company, ClearMask™ is now available to healthcare professionals that would at least allow lipreading. The ClearMask™, a startup company in 2018, is the first, patent-pending transparent face mask with full-face visibility. According to their site, this mask provides assured protection with a smart design optimized for comfort and breathability. Unlike other masks, the ClearMask™ allows patients and individuals to see each other’s full faces and facial expressions, while making communication more human, natural, and accessible, especially to the deaf and hard of hearing. During the COVID-19 pandemic, these masks are only available to hospitals and front-line workers but since they are not yet cleared by the FDA, they carry the following warning:
DUE TO THE COVID-19 PANDEMIC, THE CLEARMASK™ IS CURRENTLY AVAILABLE FOR USE IN HOSPITALS AND BY HEALTHCARE PROVIDERS WITHOUT OBJECTION FROM THE FDA. THE CLEARMASK™ IS A FACE MASK THAT MAY BE USED WHEN FDA-CLEARED MASKS ARE UNAVAILABLE. PER THE FDA, USE OF THESE MASKS IN A SURGICAL SETTING, OR WHERE SIGNIFICANT EXPOSURE TO LIQUID BODILY OR OTHER HAZARDOUS FLUIDS MAY BE EXPECTED, IS NOT RECOMMENDED.
While not available to hearing healthcare providers at this point this type of mask could be of great benefit during the post COVID-19 period as patients begin to return to the clinic and for certain clinical procedures.
So, for now, masking has taken on a totally new meaning for all healthcare providers but especially for those of us that have studied it for most of our careers. Masking no longer totally relates to the assessment of hearing, but it has now taken on a self-preservation definition by the need to wear masks or other protection when leaving homes for those essential items. Further, as the country hopefully reopens in the next few weeks, questions will surely arise as to the use of masking for clerical and professional employees involved in direct patient care during the post COVID-19 period. It will be up to practitioners to make the decisions pertaining to whether enough time has passed when masking in hearing healthcare can return to the Hood Plateau Technique.
- Center for Disease Control (2020). Strategies for Optimizing the Supply of N95 Respirators. Retrieved April 3, 2020.
- Goldin, A. Weinstein, B. & Shinman, N. (2020). How Do Medical Masks Degrade Speech Reception? Hearing Review, April 1, 2020, Retrieved April 4, 2020.
- National Institute for Occupational Safety and Health (2020). Difference Information graphic surgical masks and N95 respirators. Retrieved April 3, 2020.
- Segal, D. (2020). Performance of homemade masks. Wake Forest Baptist Medical Center, Department of Anesthesia, Wake Forest, NC.
- Stevens, SS & Davis, H. (1938). Hearing: It’s Psychology and Physiology. New York: Wiley.
**A previous version of this post originally appeared at RobertTraynor.com