User Interfaces and Usability for Embedded Systems

Feedback to 'Wordsmith'- Murphy's Law, December 2004

Read the original article at http://www.embedded.com/showArticle.jhtml?articleID=53700319

return to Murphy's Law

Thanks for an illuminating article.

You briefly mentioned 'audio prompts' in the article. I have a long history in making programs with 'audio prompts' as the (only) interface the user. I designed and implemented one of the first 'voice mail' systems (1984), which was a bit of a technical stretch involving writing a multithreaded audioboard 'device driver' (TSR) in DOS.

I learned a lot about the human engineering of voice prompts:

  1. Voice prompts must be topical (immediately useful), short and non-technical.
  2. Humans comprehend and remember aurally about 1/20 of the content they hear versus what they can see!
  3. Directions must be carefully worded to make the action at the end of the prompt. For example: Do NOT say 'Press 1 to continue'. Say 'To continue, Press 1'.
  4. Never have a long message that requires a user to wait to the end before taking action. Usually the user will forget the action before the message is finished!
  5. Announcements should be broken into short pieces so a user can skip over them by pressing a key.
  6. If there is a 'tree' of menus there must be a consistent way to 'back up' in case you took the wrong path.
  7. Always allow the user to press '0' to speak to a human. If the human is not there, the voice mail announcement should clearly state when their message will be processed.
  8. Remember, shorter is always better. Instead of 'Enter the telephone number of your party', simply say 'Enter the Number'
  9. If you need to explain (or sell) something, make the long message an optional submenu item that the user can select (or not).
  10. If you need to give the user a phone number to write down, speak the number slowly and repeat it.

Great article ... we fight the gobbledygook battle every day with our Controlled English.

John Alderman

All your examples are excellent. The best example we saw was in China ... "Turn the valve 1 1/2 turn" ... OK they did 180 degrees - and $250,000 later figured out that error.

We have placed your article on our reading list - thanks for a job well done.

John Smart

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