Here is an excellent overview by Johns Hopkins…
In my original post under this title, I may have been guilty of contributing to the “Epidemic of Armchair Epidemiology” described in the article linked below.
[Original Post is below]
I’m posting the following links with a caveat: it’s opinion, it’s the author’s viewpoint. Although it appears that the author has done his homework, the article was published in Medium, which is an open forum not subject to editorial scrutiny and vetting. It’s not peer-reviewed science and may not stand up to rigorous scrutiny. When you open the article you will see this statement: “Anyone can publish on Medium per our Policies, but we don’t fact-check every story. For more info about the coronavirus, see cdc.gov.”Continue reading
Misinformation is circulating on social media and in viral emails. This article provides links to credible sources for information.
Why “Social Distancing” is critical.
The Washington Post published three graphic simulations that clarify what a strategy of social distancing does to preserve our ability to cope with a pandemic. Slowing the spread flattens the peak load on medical facilities so that severely ill people can be treated effectively thus reducing fatalities. Reducing the percentage of people out sick on any given day is another benefit of flattening the peak of an outbreak.
If you click here you can view the animations that show how mitigation works.Continue reading
It’s often hard to find suitable places to tie a temporary indoor banner. An “X” pole will keep it taught and allow it to be leaned against a wall or chairs. Poles made of 3/4″ PVC pipe are easily fabricated and may be joined by short scraps of 1″ PVC pipe as shown elsewhere on this site (see below).
Here’s a sketch:X-Support-for-Banner
Hooks made from coat hanger wire insert into the open ends of the pole and secure the top corners of the banner. The weight of the banner tends to splay the “X”, drawing the top edge of the banner tight. Further tensioning can be accomplished by securing the lower corners of the banner with bungee cords. This whole assembly may be leaned against a wall or lashed to chairs with additional bungee cords.
Here’s the article on pole fabrication:
Ever since I moved to the retirement community where I have lived since 2013 I’ve been struggling with the bad acoustics of our meeting hall. There is so much reverberaton that the sound from our PA system gets muffled and is prone to annoying feedback.
We are seniors, many with hearing loss. The staff does not include a crew of AV engineers to keep things tweaked up, and few residents are versed in how to use a microphone properly. So it’s not surprising that many meetings and performances were marred by bad sound.
Today audio engineers have hi-tech solutions to these problems: a digital toolbox of enhancements for the sound that compensates for the problems just mentioned. They have technical names like “equalizer”, “compressor”, “notch filter”, and “limiter.” They allow a public address (PA) to become a sound system tailored to the acoustics of the room. The categorical name for this technology is “Digital Signal Processors” or DSP.
A professional sound system for a medium-size theater can cost in the mid-five figures. We hired an acoustics expert to make a recommendation. He brought instruments and went about the hall firing a starter’s pistol and making other loud noises and in due course told us that acoustic wall treatments and such would not be much help, but that we should consider an advanced audio system featuring DSP for each of the speakers in the room. This would allow each speaker to be custom adjusted for each of the several different arrangements of chairs and performance areas.
These engineering adjustments would be saved in the audio console as presets so that house staff could simply select the preset that corresponds to the room layout for any given event. If successful, the result would be loud clear sound that was below the threshold of feedback.
We already had a DSP device capable of presets. It had been purchased and installed around the year 2000 and was a cutting-edge device with a price to match – about $1,200. The Sabine Graphi-Q converts the sound from an audio mixer to a digital stream, splits it into 31 one-octave “bands”, each of which has its own volume control. In addition is has 12 filters that can trap and tune out a squeal from feedback. But the processing doesn’t stop there, next it detects peaks of loudness in the stream and tamps them down (compression) essentially normalizing the loudest blasts. This has the effect of making the average audio less loud, the stream is amplified (gain) back to the original average level. And just in case the compression isn’t enough to prevent a super loud blast, there is another filter that imposes a loudness ceiling (limit).
All of this processing of the stream happens in less than two-thousandths of a second so it’s imperceptible to the listener. But if a room has more than one speaker, the transit time for sound is perceptible. Sound travels about 1,100 feed a second. If you are 50 feet from the source, the sound reaches you with a delay of about 50 thousandths of a second. When the sound from a second speaker close to the listener combines with the delayed sound, the interference between the sounds can make it fuzzy. That aggravates hearing loss issues. To fix this, the Graphi-Q has an adjustable delay setting that is set for the distance that the loudspeaker it controls is from the stage.
The delay is the last link in the chain of processes accomplished by the Graphi-Q processor. Installing and adjusting these devices is a lab course in digital signal processing techniques. It allows a novice technician to experience hands-on what he has learned about in textbooks.
The Graphi-Q is obsolete. On eBay you will find them offered for between $60 and $200, though Guitar City has one listed at the original $1,200 price. Sabine, the manufacturer, has closed its doors. But the company website has been preserved and archived (link below). That site is a gem of useful information because it includes whitepapers on signal processing techniques, acoustics, and the manuals and software for the Graphi-Q. This means that for about $100 you can buy a full featured laboratory to learn about DSP. It’s the lab course for Audio Engineering 101.
Hearing aids are a business and a technology product. But the sale of hearing aids has been cloaked in an aura of mystery and pseudo-medical veneer. Although audiology is a profession, and practitioners are licensed and awarded the title of “Doctor”, if there is something wrong with your ears, you see a physician, not an audiologist. For example, audiologists are obliged to refer you to a medical doctor if your ear canal is blocked by wax, or if there are other indications of pathology that affect your ability to hear.
The hearing aid is a prosthetic device that compensates for hearing loss. It can be much more than a simple amplifier of sound. The latest ones process the sound much as a sound engineer “mixes” the sound of a vocalist or an orchestra.
Our hearing is a sense. To hear well is to correctly perceive the sounds we are interested in within a torrent of irrelevant sounds. Our ears must convert sound waves into nerve impulses, and our brain must then interpret the stream of impulses. Lots can go wrong along the way.
Interfering noises, and poor quality of sound at the source can be compensated for with external devices. Most of the benefits of hearing aids come from processing the sound to optimize it for the ear.
But neurological conditions, cognitive issues, and individual perceptual talents all contribute to the ability or inability to hear well. Most of these are not helped by devices. Training those we communicate with to speak more slowly, enunciate carefully, face us when speaking, and give us get the context for a remark are all beneficial in compensating for the internal processing of spoken communication.
As a sound engineer and technician, I’m often asked about hearing aids and other devices that help people hear better. The first step is to gain an understanding of your individual hearing problem. See a doctor first, then shop audiologists. The quality of testing, and the value vs. price of the products varies widely. An advanced technology hearing aid from Costco can be half the price of a less capable device sold by an independent audiologist. Audiologists sell certain brands and not others, so you can expect them to promote what the have. This may or may not be in your best interest.
Past abuses in the hearing aid field have prompted many states to mandate a 90-day full money back satisfaction guarantee. A thorough hearing exam will test the sensitivity of your ears to sounds of different loudness levels at different pitches. This is critical to adjusting a hearing aid to compensate so that you hear more like someone with no hearing loss. They may also test your ability to discern sound in a mix of background noise. Some tests check your ability to discern the difference between similar words. A thorough test will allow the audiologist to predict how helpful a hearing device may be.
Once these tests were done, my audiologist at Costco programmed a pair of demo hearing aids for me and let me walk around the store and chat with people to see if they were beneficial. (They were and he made the sale that day.) I’ve been an enthusiastic customer ever since.
If you are thinking about hearing aids, here is a table of features and benefits to help you decode the technical jargon.
The relentless march of new technology make digital devices obsolete in five years or less. Manufacturers have no incentive to make software and hardware “imporvements” compatible with legacy products. Consequently all of us have old laptops, old phones, and old tablets that won’t accept the latest software upgrades.
Our legacy devices still can do what we bought them for. But if we upgraded to newer operating systems, or later editions of Microsoft Office, they get slow and we get dissatisfied.
What to do? I’ve been experimenting with changing over from Windows and MAC operating systems to Linux. Linux is a non-proprietary system created by the community of developers who release their products for the common good, making them free for all non-commercial uses. It has evolved and branched into a number of different “flavors” that trace their digital genealogy back to the original Linux. Many of these easily install on Legacy devices.
On my old HP laptop that runs Vista, I installed Q4OS and was delighted to find it runs much faster. I added the freeware programs discussed in my earlier blog post and the computer is a servicable tool again.
I was not successful in installing Linux on Marguerite’s seven year old MacBook Pro laptop, so I simply replaced the harddrive with an inexpensive solid state hard drive which is eight times faster. I used Apple’s built in restore feature (Option-R) to put the original version of MAC OS10 back onto the comptuer, in effect making it the same as it was when she purchased it in 2012 – but eight times faster in booting up!
As with the Vista computer, I downloaded and installed the suite of freeware applications to make it fully functional and lightning fast. We’ll be giving that computer away. One of our friends will soon be happily surfing the web, corresponding, collecting photos, and doing all those everyday computer tasks without having to lay out big bucks for a new computer.
A friend asked me where I get the news. Mostly I read. I subscribe to several newspapers: NY Times, Wall Street Journal, Washington Post, LA Times. I also get The Economist, The Atlantic, and the New Yorker — all as digital online editions.
But there are many free sources of news and analysis. Here’s what I suggested to her:
The writer I most appreciate is Doug Muder, http://weeklysift.com.
Other writers you may enjoy:
Red for the Blue: https://mailchi.mp/redfortheblue/red-for-the-blue-what-the-right-is-saying-dogn1ba0da?e=78e666ec52
With major media like the NY Times you get the benefit of ethical editors vetting what they publish. Not so with blogs – you must be a critical thinker and savvy about bias and journalistic integrity. I pay for subscriptions because I want to support investigative reporting and editorial oversight.
You can read three articles in the times free each month before the paywall kicks in. If you subscribe to the blogs of your favorite columnists, you can track what they are writing about without buying the paper.
The Guardian still has no paywall.
For a general news overview check out News 360. It’s an aggregator that you may program for topics that interest you. Then when you open the App on your device, you will be served visuals and links to articles on the web.
There are many blogs that you listen to rather than read. These can be subscriptions that come to your computer or phone. Here is a survey article about how to get them.
The Microsoft Office suite and the Adobe Creative Suite of software have become the top of the line options for many. But, for many, if not most users, more features don’t add benefit. As the marginal benefit to uses of upgrading for the new features has diminished, both publishers have adopted a subscription-based business model to keep their revenue flowing.
The new subscription plans are prohibitively expensive for many. So how about something more affordable? Consider these open source free products:
Crystals can form in the fluid of the inner ear and cause benign paroxysmal positional vertigo (BPPV). When they stimulate the nerves that give us our sense of balance the room “spins.” While it’s happening our eyes dart (nystagmus) and we experience vertigo. You should always consult a medical professional and not try to doctor yourself or your friends. These movements may not be appropriate for some individuals. That said, here is what I have found in my internet research:
The Epley Maneuver
These three videos demonstrate how to deal with a BPPV instance at home.
The Kanalith Maneuver
A rose by any other name? These videos describe the moves differently but the goal is the same.