Accessible Design of Consumer Products

S-1 perceive hazard warnings

S-2 use the product without injury due to unperceived hazards or user's lack of motor control.

Hazard warnings (alarms) are missed due to monosensory presentation or lack of understandability.

Individuals with hearing impairments may not hear auditory alarms which have only a narrow frequency spectrum.
People who are deaf may not hear auditory alarms.
People with visual impairments may not see visual warnings.
People with cognitive impairments may not understand the nature of a warning quickly enough.

Using a broad frequency spectrum with at least two frequency components between 500 and 3000 Hz for alarm signals.
Using redundant visual and auditory format for alarms (e.g., flashing lights plus alarm siren).
Reducing glare on any surfaces containing warning messages.
Using common color-coding conventions and/or symbols along with simple warning messages.
Providing an optional, carriable, vibrating module for use by persons who are deaf.

For alerting devices the use of two or more spectral components in the 500 - 4500 Hz range is recommended based on ringer studies . Others suggest limiting the upper frequency to 3000 Hz to better accommodate people with mid-high frequency loss.
See I-6 for standard safety color coding conventions.

Users are injured because they are unaware of an "obvious" hazard or because they lack sufficient motor control to avoid hazards.

Individuals with visual impairments may not see a hazard which is obvious to those with average sight.
Individuals with lack of strength or muscle control may inadvertently topple a device while in use so that it injures them.
Individuals with incoordination or lack of muscle control may inadvertently put their limbs or fingers in places not intended for contact or other hazardous places (e.g., the casette tape drive of a stereo contains sharp edges which can cut fingers jammed inside with force).
Individuals with cognitive impairments may be unable to remember to shut off devices when not in use.

Eliminating or audibly warning of hazards which rely on the user's visual ability to avoid.
Making all surfaces, corners, protrusions and device entrances free of sharp edges or extreme heat.
Deburring any internal parts accessible by a body part, even if contact with body part is not normally expected (e.g. inside an open cassette tape door on a stereo).
Providing automatic shut-off of devices which would present a hazard if left on (e.g., irons).
Ensuring that devices have stable, non-slip bases, or the ability to be attached to a stable surface (see below).

In order to achieve maximum stabilization, devices should:
- have an area at or near a point of stability that is free of sharp or delicate parts (to facilitate grasping);
- have a widening (or flaring) of the lower base to allow a surface for the hand or limb to apply stabilizing pressure to avoid tipping (if device has a circumference greater than an open hand grip);
- ensure that extended switches or other attachments are firmly supported, as many individuals with stability and coordination problems may rely on them for support.
Threaded, tapped holes (or lined holes suitable for self-tapping screws) on the bottom of a product would allow the attachment of a more stable base for those who require it.