• • Visual impairment - moderate. • • Visual impairment - severe. • • • Blindness. • • Cognitive impairment.

A more convenient way of presenting display messages for those people who have difficulty in reading them is to make use of synthetic speech. A means of adjusting volume, and of initiating or repeating the message, will be required.

Poor quality synthetic speech can be difficult to understand by those with a mild hearing impairment.