Hearing Impairments

So what is a hearing impairment?

A hearing impairment is unsurprisingly when a person has difficult hearing. This could be from birth or from a condition that occurs later in life. In general they are catagorised from if it began before or after speech development, as before could heavily impact their language development. As we’ll look at later when talking about speech impairments.

 What are the characteristics of a hearing impairment?

Hearing impairments can either occur in one ear or both and can be diagnosed by being unable to detect sounds in the environment, or the inability for the brain to process the sounds.

The causes of hearing loss are varied and sometimes unknown. Some known causes are prenatal infections, genetics, noise exposure, various diseases and age. Sometimes hearing loss can be corrected with hearing aids, cochlear implants or surgery.

As speech and language may be affect the person may develop skills in sign language (AUSLAN), reading lips and other non-verbal cues. Deaf Culture is also very common with many choosing not to treat their deafness as a disability but rather embrace it through a strong and vibrant community.

What are the range of hearing impairments?

The way in which hearing impairments are categorised are to do with how well they hear on the decibel scale (dB) in the preferred ear.  So if you started at the higher end and decreased the volume at what point would they be unable to hear. The chart below shows some examples of sounds at various decibels.

Decibel Range Chart

Decibel Range Chart

In Australia you are catagorised at profound hearing loss or deafness if you, as an adult, cannot hear at levels less than 91dB. So they may be able to hear a jet or gunshot,  but not a drum. Children are catagorised as having hearing loss if they are having problems with sounds at less than 31dB.

Mild to severe hearing loss is between 25dB and up to 90dB. Normal hearing is classified as being able to hear sounds at less than 20dB, or being able to hear someone whisper.

What is the prevalence of hearing impairments?

Hearing impairments are one of the largest groups with roughly 1 in 6 people in Australia affected by hearing loss, with 30,000 of those with total hearing loss.

As with visual impairments the rates of hearing impairments tend to increase with age, particularly in males who are older than 55, which levels can reach as high as 30-40%. Few children are born with profound hearing loss, approximately 1 in 1000.

How does this impact their computer use?

Provided there is no sound on the site there is not much impact on computer use. Sites which have videos should have closed captions. Videos uploaded to youtube will have some by default, though make sure to proof read for accuracy and update if needed.

Some websites will have sounds to indicate events occurring such as errors, so making sure there is a text equivalent. Some will also play sound or videos by default, FaceBook is currently in the habit of doing this. While this may not bother the user, it may bother the people around them.


Visual Impairments

So what is a visual impairment?

Last week I wrote about the different types of disability that may impact on how a person accesses information through your website or application. Over the upcoming weeks I’m going to write about each specific disability, their characteristics, range, prevalence and how it impacts their ability to use a computer.


What are the characteristics of a visual impairment?

There are many technical aspects regarding how a visual impairment is classified. Simply put it is the inability to “read and detect fine details or objects at a distance”.

The two broad categories are blindness (including legal blindness for government and welfare purposes) and low vision.

People with blindness perceive little very little to no light. As a result the person relies on using their other senses, such as hearing, to perform every day tasks.

Someone with low vision perceives light fine but has significant trouble making out detail or objects. In some cases this can be corrected with glasses, contacts or surgery.

If someone with low vision currently has it corrected, say through glasses or surgery (like myself), the person no longer has a visual impairment and are categorised as having functional vision.

Colour blindness can also be included as a visual impairment, although is not severe enough to be catorgorised as a disability. The most common type is red-green where the person has trouble seeing the difference between red and green. There is also blue-yellow and monochromacy which is seeing no colour at all.

What are the range of visual impairments?

There are a wide range of visual impairments with many different causes. Some are from birth whilst others may come about through disease such as glaucoma or diabetes and may be cured through surgery.

Colour blindness is hereditary on the X chromosome so is passed down and is more common in men. Women are generally carriers, so will not be colour blind but their sons will be.

As a person ages their eyesight in also ages and can become worse over time. This is usually because inside the eye are muscles which focus the lens to see objects that are far away or up close. Over time, or without enough exercise, say from looking away from the screen often enough, the muscle degraded like any other muscle and their eyesight worsens.


What is the prevalence of visual impairments?

Last week I quoted the estimate of the population of Australia with visual impairments to be between 1 and 2% (from Vision Australia). This included people with blindness and low vision.

However in practical terms there could be a lot more. Some studies show that when people self report a visual impairment tends to be lower than when they are examined by an Optometrist. This could be that some people don’t want to admit they are having trouble seeing. I have seen quite a few people for example reading the paper at arms length loudly proclaiming that they can still see fine.

This also does not include people with colour blindness, which is estimated at around 10% of the male population.


How does this impact their computer use?

For a person who is blind they can use screen or braille readers to read out what is on the screen, using the keyboard (touch typing) to issue commands and move the focus around. Some, while legally blind, may still be able to see a little so may have the screen on but under high contrast conditions to assist with their use.

People with low vision may also choose to have high colour contrast settings to help them read the content. They may also increase the font size by zooming in the screen until they can see.

Someone with colour blindness will likely be able to view all sites fine, until there is dreaded red text on a green background or instructions that are to push the green button not the red button. Thankfully this is a lot less common though still not unheard of (though some train stations in Melbourne still rely on this).

There are many ways to improve your site so people with visual impairments can access information quickly and easily. I will be going through these techniques in detail in future posts.

Who are accessible websites for?

Traditionally when people think about making a website accessible for people with disabilities their first thought are for people who are blind or deaf. While this is technically true it is more complicated than that as the range of disabilities is very long and covers both permanent and temporary conditions (here is a great list with many examples).

The W3C list of disabilities covers the following, I have also included some statistics about the prevalence of each in Australia. 18.5% or 4.2 million people have a permanent disability that impedes their day to day living according to the ABS results in 2012. I also obtained some data from a study conducted by the Australian Institute of Health and Welfare and the Australian Network on Disability. (Please note that as some stats are from different studies and some people have more than one disability, the numbers do not add up nicely).

Number of people with disabilities in Australia
Type of disability Percentage of population Number of people in millions
Visual Impairments 1-2% 0.35 MM
Hearing impairments 17% 3.8 MM
Motor impairments 11% 2.4 MM
Cognitive impairments 4% 0.87 MM
Speech impairments 1-2% 0.35 MM

So roughly 1 in 5 Australians has a permanent disability which affect how they use a computer and the internet, with many more having temporary conditions. These could range from having a repetitive stress injury, broken bones, the flu or sleep deprivation.

This isn’t to scare people into accessibility, merely to make people aware of the range and variety of disabilities that can affect how people use the internet. In reality most modern websites are set up ok, HTML 5 has come a long way in terms of making sure the site is accessible, particularly for screen readers.

There are always things people can do better to make the internet a more inclusive place, not just for people with disabilities but by making websites and applications easier and nicer to use for everyone. This is what I plan to address in the upcoming posts, some of the main points on how to make your site accessible, followed up in the future by evaluating real life sites on what they do well and what could be done better.