Understanding sensory impairment when designing a website

When dealing with website design and sensory impairment, we need to consider both Vision and Hearing.

Vision impairment

People with a vision impairment can be either completely blind, have low vision, or have colour blindness. You can be registered blind in the UK and still have up to 20% vision. The vast majority of people who are registered blind do not use Braille and have lost their sight at some point in their life, rather than being born blind. The majority are over 60 years of age and as such they can also have some physical difficulties when approaching the use of a computer due to dexterity issues.

Up to 7% of the adult population have a vision impairment. The majority have a mild to moderate impairment which can make reading a normal computer screen difficult. They can typically get around their difficulties by making text larger or by using software that takes a portion of the screen and enlarges it to fill the full screen (this is called Screen Magnification).

Those with more significant sight loss may use software that reads their computer screen to them. These are called screen readers; the more popular programmes are JAWS, Window-Eyes or IBM Home Page Reader. Others may incorporate both a reader and a magnifier by using software such as SuperNova.

Users who are deaf and blind will be able to access websites via a refreshable Braille device which converts the text on the web page into Braille.

What you can do

Simple techniques incorporated into the development of websites can ensure the accessibility for users with vision impairments:

Provide alternative (alt) text

Ensure that all images have meaningful alt text. This alt text is read out by the screen reader so that the user understands what is being shown on the screen.

Ensure that all functionality is available through the keyboard as well as the mouse

This can be checked by tabbing through links and forms using the keyboard to ensure they can be accessed – and in a sensible order. This is important because users with vision impairments will not have good hand-eye co-ordination and are more likely to interact with the website solely through the use of their keyboard.

Limit the use of graphical text

The use of images of text (often used for important items such as headings or navigation) is undesirable for a number of reasons.

Users who have low vision may prefer different fonts or colour combinations, may need to increase the text using browser options, or use magnification software to enlarge the text beyond the maximum size the browser can offer (an example of magnification software is the free Windows Magnifier found in Windows Accessibility Options).

No customisation possible

Images of text cannot have their appearance altered by the user – they cannot be enlarged in most browsers, cannot have their colours altered to a higher contrast combination (e.g. white on black) and cannot have their font changed to one preferred by the user.

Pixelation at high magnification

Unlike normal text, images of text become pixelated when enlarged by magnification software (particularly at higher levels), so users reliant upon this method of access can have significant difficulty in reading the information.

Ensure that font size can be increased

Ensure that text sizes are not fixed and can be resized in the browser (View menu > Text Size in Internet Explorer). It is important that text is not a fixed size so that vision impaired users can increase the size of the text to make it more legible.

Use colour carefully

Use good contrasting colours. Do not rely on colour alone to convey information. Blind users may not be able to get information about colour definitions from their screen reading software and using colour also presents difficulties for colour blind users.

Colour contrast can be measured. Juicy Studio’s colour contrast analyser can analyse colour combinations and let you know if they produce enough of a contrast against the W3C recommendations.

Provide skip links

Provide a means of skipping over often numerous navigation links with a ‘Skip to content’ link at the top of your pages, and ‘Back to top’ link between sections of long pages.

Hearing Impairment

People with a hearing impairment require visual representations of auditory information that your website provides.

With the increasing use of multimedia on websites (for example podcasts and video streaming) it is important to ensure that the information can be understood by users who do not have the ability to hear. This can be achieved by providing captions for the video content where users can read what is being said in the video, or transcripts of the spoken audio.

It is also important to appreciate that British Sign Language (BSL) users have a significantly different sentence structure and vocabulary to Standard English. Here great consideration should be given to the use of the most simple (whilst still appropriate) language and the inclusion of a glossary of terms giving explanations of more unusual or technical words. Ironically the word ‘Glossary’ is not in the BSL vocabulary so you may wish to use a term such as ‘A-Z index’ or ‘Jargon buster’.

For more detail on providing content for hearing impaired users, you might want to read the RNID’s factsheet on producing information for deaf people.

How we can help

For more information on the different Assistive Technologies (AT) disabled users use to access the internet, or to have in-house training on Web site design and building for AT users, use the details below to get in contact with us. We can put together a training package for you that will address your individual needs.

Back to the Articles home page.