Sensory Characteristics

Hearing

Have you ever tried to have a conversation on a cell phone with background noise? Or tried to have a conversation in a noisy bar or restaurant?

In this user group are people who are fully or partially deaf, either from birth or from a loss of hearing resulting from illness, disease, blockages of the inner ear, damage from prolonged exposure to excessive noise, head injuries, stroke, or other causes. A common occurrence in aging is some level of hearing loss, usually beginning with difficulties with background or ambient noise and with high frequencies and progressing to lower frequencies. Ringing in the ears is also common. When these changes occur gradually, we may not recognize them until our ability to interact with our environment is affected. Hearing loss and the inability to com­municate can cause significant emotional stress, and potential negative effects can be reduced through design.

Concerns with hearing impairments include both the social isolation and difficulty communicating, and also, the safety issues related to not hearing audio cues. Whether hearing loss is a congenital issue or one that occurs later in life, it frequently leads to keener development of the other senses, especially visual skills.

Pay attention to design concepts such as noise control, redundant cuing, and visual cuing on all equipment, sound-absorbing materials, quiet ventilation and whirlpool motors, good lighting, and safety. Because a person with hearing impairments relies more heavily on seeing what is happening and in many cases, on lip-reading, a clear line of sight is also important. These and other design considerations are detailed in the sections that follow.

Vision

Have you ever driven west into a setting sun, or struggled to focus when entering a dark theater from a bright lobby?

Because vision changes are a natural part of the aging process, many people would not consider themselves disabled, but would benefit from responsive design. This user group also includes anyone who is blind or who has partial vision loss due to cataracts, glaucoma, retini­tis, macular degeneration, or eye injuries, as well as anyone with congenital vision impairments or those caused by other conditions. Depending on the condition, user needs will be different.

Physical changes in the eyes increase with age and can lead to vision impairment, such as difficulty seeing in dim light, increased light sensitivity, difficulty focusing on moving objects, and a decrease in peripheral vision. More time is needed for the eyes to adjust when transitioning between light and dark areas. Reading glasses become a common need beginning in the forties, and lenses begin to yellow, causing difficulty in distinguishing some colors.

A concern among people with vision impairments is their depth perception, and the ability to distinguish foreground from background. Their needs might also differ from day to night or sum­mer to winter. As eyes age, difficulty differentiating colors with minimal contrast increases, such as navy, black, brown, or pastels and varying whites. Again, if a person has vision issues, he/she will rely more heavily on other senses, particularly auditory abilities.

Pay attention to design concepts such as redundant cuing, eliminating clutter, tactile indicators, intuitive operation, increased and adjustable general and task lighting, careful use of color, con­trast, and pattern, and the selection of materials and lighting to reduce glare. These and other design considerations are detailed in the sections that follow.