The Uni-directionality of VUI

Compounding the linearity of speech is its unidirectional character. Just as time is a one way street, speech is a one-way medium. When you hear something, you can’t easily go back and listen to it again. Contrast this to reading a piece of text where you can readily scan a couple of paragraphs, or even pages, back and re-read the text.

Offer to repeat: one obvious way to alleviate this limitation is to offer the ability to repeat information. Of course, make sure that the user is aware that they can have information repeated to them by informing them of this ability at the beginning of the call and any time where important information is given out to them.

Offer help: crucial information such as instructions given at the start of the interaction should be available for the user to tap into at any point in the exchange. Offer instruction on how to access help at the beginning of the call and at moments where the user seems at a loss over what to do (e.g., at no-input or a no match).

Offer summaries: in interactions where information is being gathered from the user or given out to them in a step-wise fashion, a powerful technique to overcome the uni-directionality of voice interfaces is to offer users the ability to ask for summary of information collected so far.