Designing Effective Speech Interfaces

Keypads and Motor Actions

If the interface includes a keypad or a motor component, such as a keyboard or mouse, here are some guidelines for these devices.

Avoid Key Combinations

If the interface includes keypads, avoid key combinations. For example, do not require the user to press the # key after each command or the * key before each command. These add time and keystrokes to the task.

Use ISO Standard Letter Mappings

If you are using a keypad, for instance with telephone interactive voice response systems, use the ISO standard letter mappings as shown in Table 10.1

Key	Letter Mapping
1	None
2	A, B, C
3	D, E, F
4	G, H, I
5	J, K, L
6	M, N, 0
7	P, Q, R, S
8	T. U, V
9	w, X, Y, Z

Table 10.1 ISO Standard Letter Mappings

Q and Z are not printed on most telephone keypads. If you use these, you must remind the user where to find them.

Reserve 1 and 2 for Frequent Actions

Reserve the numbers 1 and 2 for frequent and critical actions. Do not use these numbers for destructive commands, such as delete.

Avoid numbers 5 and 8 for destructive commands. Since the numbers 5 and 8 on a keypad are usually surrounded on all sides with other numbers, they are the most likely to be pressed accidentally.

Use the Appropriate Word for Keypresses

Use the word enter when you want the user to press multiple keys on a keypad. Use press when you want the user to press one key.

Assign Command Labels Consistently

Be consistent with commands. Assign the same key or word to the same function ...