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[Craig Hauber]

https://www.nfhs.org/media/4029952/preliminary-testing-report-7-13-20.pdf

"Sizing measurements show particles are typically < 10μm
Concentrations,were relatively higher for instruments that had straight shapes from mouthpiece to bell (trumpet, clarinet)
Masks, nylon bell coverings all reduced particle concentrations"


https://www.medrxiv.org/content/10.1101/2020.07.31.20165837v1

"When playing with a barrier cover, the mean number of particles emitted fell to 2.60x106±2.11x105 Aerosol type particle/m3 and 5.20x103±8.02x102 Droplet type particles/m3. This barrier represented an average 78.5% reduction for the number of respiratory Aerosol type particles and 63.8% reduction for Droplet type particles compared to playing an instrument without the barrier covering."

Elimination would be nice, but reduction is helpful.

I haven't read the linked articles yet but I wonder what type of sound attenuation occurs?
And could this finally be a way to finally tame those overzealous horn sections from blasting out the house mix!

[Milt Hathaway]

I find it interesting that the CDC states the "percentage off deaths...is at 7.2%, while declining, remains above the epidemic threshhold".  Those deaths are pneumonia, influenza and covid al lumped together.  If you didn't lump them, would it still be considered an epidemic?  Obviously, whether or not it meets the definition of epidemic is immaterial to those personally affected.

https://www.cdc.gov/nchs/nvss/vsrr/covid19/excess_deaths.htm

[Jason Raboin]

Please explain the science behind a wind player wearing a mask that has a hole cut out in it.

That seems silly and not what I was responding to.  I agree there's a lot of security theatre, like border walls, TSA pat downs, etc.  But I'm not saying that based on an assumption or personal experience.  I'm basing it on scientific studies and data that show the effects on a macro level. 

The idea that because wearing a mask can still fog up glasses means it's not useful is what I was referring to.  There's a meme somewhere of someone peeing on someone else wearing pants vs. not wearing pants.  Good illustration.  Though honestly I don't know if that's how the transmission of Covid works.  I just trust experts who all say to wear a mask.

[Brian Jojade]

The point of the masks is to reduce the amount of contaminated air coming from our lungs into the environment. This is achieved by reducing velocity and volume with the material barrier. Nobody ever claimed it was a panacea. If 30 percent of an exhalation ends up fogging up glasses but 70 percent ends up in the mask, that is still a lot better than nothing, especially if maintaining distance from others. We like speakers with 6dB more output, right?

As far dirty masks go, the virus transmission is mostly airborne. Not touching our faces and washing our hands has long been an effective means of reducing mechanical transmission of germs.

This assumes that the mask is collecting and actually filtering the virus out of the air, and then safely trapping it within the mask.  The true fact is that isn't happening.  Instead of your breath going straight forward, it's dispersing out the sides of the mask.

If you are standing face to face with someone, having a mask on will reduce large particle spread. How effective that is in preventing anything has no solid data though.

The problem is, with masks on, people have to talk louder which means more infected air.  People stand closer to hear, which means more of that side spread. People touch their masks without immediately washing their hands, which means if the mask IS collecting the virus, you now end up with a higher viral load on your hands.

Interestingly enough, there HAVE been plenty of studies on mask use in controlled environments.  There have been repeated studies in operating rooms regarding mask wearing and infection rates of patients.  Surprisingly, in the cases where masks were not worn, there is a slight DECREASE in infection rate of patients.  This is in a controlled environment where masks are used properly and every sanitation precaution is taken.  If in the best case scenario they don't work, why would they work in the general populous?

I have yet to see any controlled study that shows the effectiveness of mask wearing while in public.  Everything is just theory that may sound good, but has not been proven to be the case.

Oh, and if you want to do your own tests, interestingly enough, many of us have tools that can create a visual representation of what happens.  A standard fog machine creates particles suspended in water vapor that are very close in size to virus particles.  Set up a fog machine and put a mask in front of it.  Run the for machine for a while and see how much fog ends up in the room.  You may be surprised how different materials allow the fog to simply pass through, only slightly dispersed.  Make sure you run the test for more than a few seconds, as the behavior of the materials changes pretty dramatically as they get saturated.

I ran the test with a fog machine in a chamber with several different masks.  After a period of about 2 minutes, I couldn't see any difference in the fog density no matter which mask type I used.  That fog still worked it's way out into the chamber no matter what.  None of them 'filtered' the fog out of the air.

[Seth Udoll]

That seems silly and not what I was responding to.  I agree there's a lot of security theatre, like border walls, TSA pat downs, etc.  But I'm not saying that based on an assumption or personal experience.  I'm basing it on scientific studies and data that show the effects on a macro level. 

The idea that because wearing a mask can still fog up glasses means it's not useful is what I was referring to.  There's a meme somewhere of someone peeing on someone else wearing pants vs. not wearing pants.  Good illustration.  Though honestly I don't know if that's how the transmission of Covid works.  I just trust experts who all say to wear a mask.

So, here in California, the statewide mandate is to wear "a face covering" when indoors at a public location and outdoors when closer than 6' from people that aren't in your household.  Not sure what it is for other areas across the country.

I suppose me saying "it's all bullshit" is a bit of an overstatement.  Of coarse there are times that wearing a properly designed and properly applied/worn face mask is appropriate to protect the wearer and others within the vicinity from possible airborne contaminants.

From the limited research I've done on the subject, it doesn't seem likely that a face mask stitched together by a grandmother with fabric she had on hand, or one that you can buy at the gas station/liquor store/grocery store made of pretty standard fabrics, or even the blue disposable hospital style is going to lower the spread at a rate that justifies the mandate to wear them.

From what I've read, they're mostly effective in reducing the projection of respiratory droplets due to a sneeze or cough... which could be done (IMO) just as effectively lifting my T-shirt collar above my nose and sneezing/coughing into my shirt.

Since you like anologies/illistrations; back when AIDS was the big talk all over the world, it was said that natural lamb skin (lamb intestine) condoms were porous enough to allow the AIDS virus to pass through, yet small enough to keep sperm from passing through. 

The AIDS virus is about 120nm diameter.  SARS-CoV-2 is between 60 nanometers (nm) to a maximum diameter of 140 nanometers.

... And a face mask made in China out of T-shirt material, or paper medical mask is gonna filter it all out and keep you safe?  Okay.  I guess they'd make an effective condom too.    (<sarcasm meant to be fun, not argumentative)

That's just my take on it.  But, I'm not a scientist.

[Tim McCulloch]

After working for months with guidance from national and international epidemiologists, the CDC and WHO, I will say about 10% of what I'd like to say (the other 90%? Fowler would have to ban me)...

PPE use and behavioral changes for infection transmission reduction is a "system".  The system only works when all the parts are utilized.  "Hey buddy, the PA sounds better when you have console between the mics and amps..."  It's the consistent use of the system that brings about a reduction in transmissions and positive % testing rates.

The current "super spreader" events are actually small gatherings among familiar people and family (who do not reside together).  Birthday parties, pot luck BBQs, weddings... frat parties, crowded bars and restaurants.

We know how respiratory virii spread, we know what products and behaviors, when used together, help reduce that spread.  Employees are required to use PPE and follow practices in our Covid-19 safety plan, as that is partial fulfillment of our obligation to provide a safe and healthful workplace under the Occupational Safety and Health Act.

[Brian Jojade]

We know how respiratory virii spread, we know what products and behaviors, when used together, help reduce that spread.

I'm going to disagree with that. We have ideas, but for many of the things that are being done, there are theories, but no scientific evidence that they are even mildly effective.  In fact, many things that are being recommended today just a couple of years ago were tested and shown to be ineffective. Why are they now known to reduce spread??

[Randy Pence]

From the limited research I've done on the subject

That's just my take on it.  But, I'm not a scientist.

The scientists and doctors say to wear masks

[Randy Pence]

Oh, and if you want to do your own tests, interestingly enough, many of us have tools that can create a visual representation of what happens.  A standard fog machine creates particles suspended in water vapor that are very close in size to virus particles.  Set up a fog machine and put a mask in front of it.  Run the for machine for a while and see how much fog ends up in the room.  You may be surprised how different materials allow the fog to simply pass through, only slightly dispersed.  Make sure you run the test for more than a few seconds, as the behavior of the materials changes pretty dramatically as they get saturated.

I ran the test with a fog machine in a chamber with several different masks.  After a period of about 2 minutes, I couldn't see any difference in the fog density no matter which mask type I used.  That fog still worked it's way out into the chamber no matter what.  None of them 'filtered' the fog out of the air.

I'm impressed if your breathing displaces as much volume and as quickly as a fog machine. My lungs are pretty good at blowing up a balloon, but pressurized air always wins that race.

As far as the mask pushing the flow behind you when speaking to someone, isn't that better for the person in front of you? If the people behind you maintain proper distance, the particles will be more likely to fall to the floor than catch in someone's sinus cavity.

[Randy Pence]

I'm going to disagree with that. We have ideas, but for many of the things that are being done, there are theories, but no scientific evidence that they are even mildly effective.  In fact, many things that are being recommended today just a couple of years ago were tested and shown to be ineffective. Why are they now known to reduce spread??

Why do surgeons wear masks?

[ProSoundWeb Community]