Sensory Impairment

This weblog post looks at impairments related to the senses, hearing and seeing, in particular. It is targeted at older (60+) readers. Younger people are more adaptive when it comes to using technology to reduce the consequences of their impairments. They quickly master technological innovations. Many will receive systematic, professional follow-up and assistance throughout their lives. Those with serious hearing impairments learn sign language and to lip-read. Those with serious visual impairments, especially the blind, learn Braille, and attend special classes. Both groups will have professional help to choose technology that will make their impairments less debilitating. Such is not always the case with people who develop impairments later in life.

Technological overload is a very real problem for older people, even those living without an obvious impairment. There may be several different ways in which such a situation can be improved using technology, but older people with an impairment frequently lack the (cognitive) ability and/ or will to use them all. There are too many choices. The key, then, is to select the one or two different technologies that will maximize their return on time invested.

Web accessibility is increasingly important. It involves making the use of the internet, and the World Wide Web in particular, easier. The World Wide Web’s ( Web Accessibility Initiative (WAI) provides not only resources but also web content accessibility guidelines and checklists. Here are links to some of the resources. The resources section is a good place to start. This can be followed up by consulting these resources: Strategies, standards, resources to make the Web accessible to people with disabilities; Web Content Accessibility Guidelines 2.0; Web Content Accessibility Guidelines 2.0 quick reference.


One major aid to sight impairment, is the use of eyeglasses. These are typically made to correct the specific imperfections of each user’s eyeballs. Glasses are made specifically for screen usage. This blogger used such a pair for several years. They do ease eye strain and the unnatural head contortions that result from using progressive lenses. Currently, the use of a large (27″) screen, appropriately positioned, is now allowing this blogger to avoid having to wear glasses at all.

As an aside, people wanting to make their own eyeglasses, from scratch, may want to consult this YouTube video. Those preferring to make just the frames would benefit more from this YouTube video. Otherwise, this topic will not be developed further, except to say that the French-Italian vertically integrated EssilorLuxottica Group, has been allowed to develop a near-monopoly when it comes to eye-care products.

Background lighting is another important consideration, when using a computer. General information about lighting has been presented in another weblog post written in 2018. Similarly, some of the factors that should be taken into consideration, regarding displays/ monitors/ screens/ televisions has been discussed more recently in yet another weblog post in this series, Media Player.

In terms of computers and hand-held devices, all (?) operating systems provide assistive features. For visual impairments these include switches to allow high contrast backgrounds, large text, and a screen reader. Usually, there are individual controls that allow each of these to be tweaked.

Many older users are unaware that their computers are equipped with a mechanism that will read screen content, and even allow voice commands . In Windows the reader is called Narrator, while the voice commands are part of Speach Recognition, which can be set up to use a microphone for system input.

Apple has an even more sophisticated product, VoiceOver, that is more than a screen reader. It is used on both MacOS and iOS products. It also provide status information (such as battery level) as well as information related to a specific app being used. Voice Control (and not Siri) is Apple’s equivalent program for voice control.

On Android systems the screen reader is an open-source app called TalkBack. However, it also appears under other names, including: Screen Reader, Voice Assistant, SoundBack and KickBack. Voice Access is the Android app for controlling a device with spoken commands.

Speakup is a screen reader for Linux. It allows users to interact with applications and the OS with audible feedback from the console using a speech synthesizer and to navigate around the screen. As usual for Linux, there are multiple programs for speach control. Those interested in this topic are directed to this introductory Wikipedia article.

There be other reasons than vision impairment, including dyslexia, that may require a person to use speech synthesis for text-to-speech (TTS) purposes. For example, an e-book/ e-mail/ web-page can be read to a person doing a menial task (or anything else that provides a cognitive surplus) on a handheld-device (hopefully in a pocket). It is left as an exercise for interested readers to find a suitable app for their purposes and equipment. This wikipedia article, may provide some hints.


For those people who have a hearing impairment that does not require the use of a hearing aid, or choose not to use one, one way to improve hearing is to use over the ear headphones. Recently, this blogger acquired a Logitech G Pro X headset. It comes with several cables and adaptors that allow it to be used with hand-held devices, such as a smartphone, as well as laptop/ desktop devices with assorted characteristics.

One of the first challenges is to keep and maintain order. This means that the headset as well as the cables and adaptors have to have specific locations where they are stored when not in use.

The relevance of the remainder of this webblog post assumes that the hearing impaired person is equipped with a hearing aid, and that it improves their ability to hear in real-life, physical situations such as conversations involving one to a few other people, or other situations such as a store checkout where there can be background noise.

A hearing aid is equipped with a microphone, an amplifier that increases the sound pressure, and a speaker. When the hearing aid is initially set up, or adjusted, the various frequency areas receive differing degrees of amplification.

In addition, many hearing aids contain a telecoil (t-coil) To use an induction hearing loop or the t-coil function on smart phones, a t-coil must be present and activated on the hearing aid.

A t-coil, is a small copper coil in a hearing aid that acts as a wireless antenna that links to a sound system or PA system, delivering customized sound to the hearing aid wearer. It is an option on most hearing aids and is generally in all cochlear implant processors.

Originally used to hear better on the telephone, the t-coil is necessary to hear within a loop system. Just increasing the volume on a hearing aid or cochlear implant doesn’t necessarily improve the clarity. That is the “wow” factor of a t-coil in a hearing loop system. The clarity and understanding is unequaled when listening in a loop.

With a t-coil installed in the hearing aid, the user simply pushes the button or switch for the “T” setting – no additional headsets or receivers are necessary to hear clearly in the induction loop or on the telephone.

The loop system consists of a microphone to pick up the sound (e.g. spoken words) and an amplifier which processes the signal, which is then sent to a loop cable. A loop cable is a fixed wire that is placed around the perimeter of a specific area. This area can be quite large, e.g. a theatre or a church, or quite small, a person’s living room for example or even down to a chair. A loop can even be fitted around the person’s own head (neck loop). The wire then sends the signal directly to the hearing aids of those who are in the room when their hearing aids are set in T-mode.

The telecoil in a hearing aid (also called t-switch or t-coil) is a tiny coil of wire around a core that will induce an electric current in the coil when it is in the presence of an activated loop system. Normally, a hearing aid picks up sound with a microphone and then amplifies the sound. With a telecoil, the hearing aid “hears” the magnetic signal from the loop system and then amplifies that signal.

Media Player

This television set made by Tandberg in Oslo, using the Radionett brand, is a Grand TV kabinett, from 1961. The CRT screen is bowed, as was typrical for the time. The varnished wooden cabinet is mounted on removable legs with white plastic wheels. It features stereo speakers, one on each side. Brass is used decoratively on the feet and around the screen. There are white plastic buttons under the screen, and black knobs on the side, to control the machine. “This is the TV model in greatest demand, with a 23″ large picture tubes, and two large concert speakers”, according to a Tandberg ad from 1961. This machine is in the collection of the Stiklestad National Cultural Center, in Verdal, a neighbouring municipality to Inderøy.

In 2020, a media player is a redundant piece of equipment – if one has a appropriate network attached storage (NAS) server, the topic of next week’s post. Yet, it is its own separate topic because of three different, but related, challenges.

First, people do not understand humankind’s physical capabilities and limitations when it comes to normal seeing and hearing. Normal is the operative term here. Visual impairment will be discussed in its own weblog post: 2020-11-24. Hearing impairment will be the topic one week later: 2020-12-01.

Second, this limited understanding results in the purchase of peripherals, such as speakers and screens, that don’t match user needs. On top of this they will purchase media players or a NAS that are neither suitable nor likeable, from hardware/ software/ operational perspectives.

Third, people tend to make evolutionary, rather than revolutionary, purchasing decisions. They replace components, rather than rethinking the components they need. For example, they may be used to having a television set with an attached recorder for watching video and the accompanying audio content. At the same time, they will have a separate stereo system for reproducing music. Unfortunately, such thinking belongs back in the twentieth century, not the current century that is already more than 20% over.

When we (along with the rest of our local community) updated to broadband, effectively at the beginning of 2019, a number of cable television options were available as a package for about NOK 1 500 a month, with an internet speed of 500 Mbits/s. We declined to have this, and opted for a 50 Mbit/s speed, without cable television, for NOK 600 a month.

A main purpose of a media player is to take content either from an online-source or from a file stored somewhere, including personal handheld devices aka mobile phones, and to send the video content to some form of display/ projector, and the audio content to some form of loudspeaker/ headset. Handheld devices, can be used to control the media player. In essence, they are the 21st century’s remote control.

If people use a particular processor or operating system on their laptop or desktop machine, they will often want to use the same one on their media player. This is understandable, for it keeps them in their comfort zone.

Unfortunately, there are still hardware issues with respect to Intel processors, and – to a lesser degree – those of Advanced Micro Devices (AMD). This design flaw has been known since the beginning of 2018. People are encouraged to use ARM or AMD, rather than Intel processors where these are available. Apple, has recently abandoned Intel and gone over to ARM.

An aside: In 1990 ARM stood for Advanced RISC Machines, a company that started life in 1983 as Acorn RISC Machine, referring to the processor in the Acorn Archimedes computer, used by many schools. From 1998 ARM is simply Arm, not an abbreviation for anything.

Yet, for example, Windows users will often complain about the bloatware on Windows 10, but not do anything about it, either on their personal computer, or a media player. More specifically, they will seldom explore open-source software, including operating systems, as an alternative to the commercial products on offer.

At Cliff Cottage on 2019-04-11, an Asus PN 40 computer was ordered to replace an Asus Tinkerboard, similar to a Raspberry Pi (RPi), as a media player. It is equipped with an Intel Celeron processor, effectively demonstrating that I don’t follow my own advice. The hardware on the PN 40 is more than adequate for its role as a media player. It includes: a Western Digital Green 3D Nand M.2 2280 triple-level cell (TLC) solid-state drive (SSD) providing 240 GB; and, 2 x 4 = 8 GB matched Corsair Vengeance SO DD4 2400 MHz, CL16, 1.2 V DC, non-buffered, non-EEC RAM cards.

The device is low-powered and fanless, but capable of playing videos and music stored on Mothership, the family Network Attached Storage (NAS) server. It is equipped with a LibreELEC = Libre Embedded Linux Entertainment Center, operating system, described as “just enough Linux for Kodi“, an open-source media player, which is also installed.

If the purchase of a media player had been delayed to now (2020-10) it would have been an Asus PN 50, a similar, low power (read: minimal watts), yet a machine with adequate processing throughput. It would be equipped with an AMD Ryzen 3 processor. At the time of purchase, these were not available in Norway. Cliff Cottage now has an Asus PN 50 with a Ryzen 7 4700U processor, but it is being used for other tasks.

An even cheaper, but perfectly adequate, media player can be constructed from a RPi 4 B with anywhere from 1 to 8 GB of RAM. Because of its tendency to overheat, cooling must be used. One approach is to place the RPi in a Flirc case.


The human eye is not impressive. For eyes to write home about, examine assorted species of mantis shrimp.

Boomers probably experienced cathode-ray tube black and white televisions in the 1950s with PAL providing 625 lines, and NTSC providing 525 lines, essentially 480i (interlaced). This was then upgraded to colour television in the 1960s.

In the 1990s, flat-screen televisions emerged and now dominate. High definition (HD) = 1920 x 1080 pixel resolution, became a standard with the high definition multimedia interface (HDMI), defined in 2002. A decade later, in 2012, ultra high definition (UHD) = 3840 x 2160, four times the pixel count of HD (hence, 4K) was defined, and in 2020, is now dominant.

Early flat-screen televisions used plasma technology, then came liquid crystal displays (LCD) that needed backlighting. LCD usually refers to the use of cold cathode fluorescent lamps (CCFL) for backlighting. LED screens are LCDs that use light emitting diodes (LED) for backlighting. This technology is actively used today. Organic light emitting diode (OLED) technology uses diodes to generate colour and light, like plasma screens, but they are smaller and thinner than LED-lit panels, and are capable of producing the best black levels available (highest contrast ratios). OLED screens are considerably more expensive than other screens.

A television in 2020 has 4K resolution. HD is out of date, while 8K is not only too expensive, it lacks content. A video refresh rate of 60 Hz is acceptable, 120 Hz is better, while gamers maintain that 144 Hz is best. Yes, this is a real consideration, if one is to avoid having multiple screens in a household. High dynamic range (HDR) refers to a colour standard that provides a more extensive range of colours, greater contrast levels and increased brightness, compared with the colour rendition on standard HD and 4K sets. Some users feel HDR offers more realistic colours. Others disagree, describing them as artificial. Most regard them as an improvement. OLED TVs typically provide better colour rendition than standard LCD sets, but are considerably more expensive. QLED TVs, where Q = Quantum, referring to photo-emissive particles, are a more affordable middle ground. Many reviews state that it is better to have four or more HDMI ports, with one or more in HDMI 2.1 format.

Currently, at Cliff Cottage there is a Samsung 40″ LED HD screen, made in 2010 but purchased used at half the new price (NOK 2 500 vs NOK 5 000) in 2012. We have never used more than two HDMI inputs. One is attached to the media player, the second has an HDMI cable permanently attached, that can be plugged into a laptop. When this screen ceases to function, it is uncertain if it will be replaced with another screen/ monitor. A 4K 55″ television now costs about NOK 5 000. A 4K 65″ is about NOK 7 000.

Projectors vs Screens

One main question is if the quality difference between a screen and a projector outweighs their respective ecological impacts. A large television/ screen/ monitor consumes many kilos of electronic components, that have to be recycled when the novelty/ economic/ physical lifetime of the product is over. My estimate is that a projector weighs < 10% of a television, although I have not undertaken any research to substantiate this claim.

Thus, we will be examining 4K projectors carefully, over the next few years. When our family was living in Molde in 2002-3, we regularly used a projector, borrowed with permission on weekends from the school where we worked. At that time, bulbs were expensive, used a lot of power and had to be replaced regularly. Today, most projectors are either LCD-based, or Digital Light Projection (DLP) based with a laser, LED, or LCOS (liquid crystal on silicon) light source.

If the projector route is taken, a Philips PicoPix Max provides a minimalist solution. It is a wireless native HD projector, running under the Android OS, with a control touchpad on top. Its built-in battery lasts for three hours of projection. It has Wi-Fi, Bluetooth and USB-C connectivity. Its LED projection source should last for 30 000 hours, and project up to a 120″ (3 meter) image. A more expensive alternative is the Aaxatech 4K1 mini-projector, that costs US$ 1 000. It offers 3840 x 2160 (4K) resolution, 1 500 lumens and 30 000 hours of illumination. Another choice is an Xgimi H2 that uses DLP with four channels of LEDs to beam content. Providing 1350 ANSI Lumens of brightness, requires an effective cooling system. This increased light reduces the wash-out of colours and allows daylight viewing. With its own camera, it is able to adjust focus automatically. It also provides auto keystoning. In terms of sound it provides 16 W through two speakers for treble and mid-range, and a diaphragm for the bass. One major problem with many manufacturers is their repeated attempts at vendor lock-in.

Personal comments: 1) For many years, I had hoped that the Gigabyte Brix Projector would evolve into something useful. Currently, it offers a machine with 75 ANSI lumens, which is inadequate for all but the darkest of localities. 2) The use of a projector like the Xgimi H2 will probably mean that the Asus PN 40 can be repurposed, as the projector is its own media player.


The human audible frequency range stretches from about 20 Hz to 20 000 Hz (20 kHz). The (Harry) Nyquist (1889 – 1976) – (Claude Elwood) Shannon (1916 – 2001) sampling theorem states that sampling must exceed twice the maximum frequency. This means that the rate has to be 40 kHz or more.

In practice, two sampling rates are used. The first, 44.1 kHz used on compact disks (CD) was inherited from pulse code modulation (PCM) adaptors used to transfer data from recording studio tape to CDs, with a sampling depth of 16 bits/ sample. This capability was developed by Philips and Sony, starting in the 1970s. The second, the digital audio tape (DAT) format of 1987, uses a sampling rate of 48 kHz, which is the standard for professional audio.

The HDMI TV standard (2003) allows both 44.1 kHz and 48 kHz standards, although DVD-Video and Blu-ray Discs use only 48 kHz. Most PC sound cards contain a digital-to-analog converter capable of operating native at either 44.1 kHz or 48 kHz. The average human has no need to exceed these capabilities.

Sound reproduction

There are two major ways of getting sound into the ears of listeners: loudspeakers and headsets. The main advantage of loudspeakers is that they distributes sound to multiple people throughout a venue/ house/ room. This is precisely its main disadvantage. There are numerous types and quantities of loudspeaker systems available. Flat-screen displays often come with built-in speakers that are too thin to give a dynamic range people want. Thus, it is common to augment/ replace these speakers with soundbars, mounted either above or, more typically, below the display, to improve acoustics. They are easy to set up, and are usually less expensive than other stereo sound systems. Some soundbars have left, center, and right speakers plus detachable rear-left and rear-right speakers, and a sub-woofer, to provide surround sound. Premium soundbars come equipped with equalizers, which allow the sound to be tuned to compensate for the shortcomings of room dynamics. Despite these augmentations, some people are critical of their small size and/ or position, and opt to use speakers placed throughout the space.

The main advantage of headsets (earphones/ earbuds) is that sound can be individually adapted for each listener. At the same time, people who are not interested in listening to something can avoid it. Perhaps the greatest disadvantage is that every person must have their own headset. Headsets can be wired or wireless. The main advantage of wireless systems is that they allow a person greater mobility. The main disadvantage is their cost.

Appendix: HD vs 4K Displays

Guidelines from the Society of Motion Picture & Television Engineers recommend viewing at a distance where the screen fills up about 30° of the field of vision. Unfortunately, this recommendation does not take screen resolution into account. If one sits too close to a screen, the individual pixels become visible, detracting from the viewing experience. This is also dependent on the size of the pixels. With HD (1920 x 1080), a given size screen requires a person to sit further back, because it is the pixel size that has to be optimized. With UHD/ 4K (3840 x 2160), it is the field of vision that has to be optimized. .

Type/ limiting factor40″45″55″65″
HD/ pixel size1.561.742.142.50
4K/ field of vision0.710.800.981.25
Optimal viewing distance in meters proposed by Rtings

People are creatures of habit. If they are used to one particular viewing position, they will try to keep that constant, preferring to change the size of the screen, rather than moving closer. This means that consumers are often willing to spend more money to buy a larger screen that optimizes their field of vision, when pixel size issues are resolved.

Other considerations include refresh rates which should be 60 Hz for most activities, although gamers prefer 144 Hz. There is no need for anything beyond this. Note: HDMI 2.0 is needed for 4K video at 60 Hz with 24 bit/px colour depth.