Use of Colour Explained
Most estimates suggest that about 8% of males and 0.5% of females have some form of colour-blindness, ranging from an inability to see colour at all to minor deficiencies seeing specific colours.
Use of colour becomes a barrier for some people when it is used on its own in a meaningful way. For example, “click the green button to start and the red button to stop” is going to be problematic for people who may have trouble seeing greens or reds (the majority of colour-blind individuals) not to mention problematic for people who are blind. A solution in a case like this might be to add the word “Start” to the green button and “Stop” to the red button. Or, in the instructions, suggest using the first/left/top button to start and using the second/right/bottom button to stop.
A common issue in web content occurs when error feedback messages are presented in red or success feedback is presented in green, without some other indicator of what the text represents. A simple fix might be to include a checkmark icon with the success feedback (with alt text of course), and an X icon with an error message. Or, just include the word “Error” with an error message and “Feedback” or “Warning,” and so on with other forms of feedback.
Whenever colour is used in a meaningful way, some other element with equivalent meaning is required. Text as an alternative to colour is often a good choice.
Audio Control Explained
When audio begins playing automatically when a web page loads, it can make it difficult for screen reader users to navigate. Since they rely on the output from their screen reader, other sounds playing at the same time can make it difficult to comprehend either audio stream. Even if there is a way to stop the automatically played audio, finding the stop control can be difficult if one has to distinguish between the audio and the screen reader output in order to find the control.
Though automatically playing audio when a web page loads is discouraged, in cases where it is necessary you must include a way to control the audio volume independent of the system’s audio controls, which also moderates the volume of the screen reader output. Users should be able to reduce the automatically playing audio volume or turn it off without affecting the volume of the screen reader.
Web content developers should avoid using the HTML autoplay attribute.