The development of efficient speech dialog systems involves choosing suitable dialog strategies that are able to ask the right questions and return the information requested by users. The problem here lies in the fact that there are no set methods or clear criteria for outlining a good strategy. The criteria applied by the UPC for designing a dialog are based on extremely simple concepts:


  • To ensure users do not get lost.
  • To answer users’ questions directly.
  • To offer users the option of correcting themselves at any time.
  • To avoid misunderstandings.


Besides these basic principles of design, there are two significant factors that condition the development of dialogs: firstly, the range of application scenarios that must be resolved (i.e. the design of a dialog is determined by a system’s scope of application) and secondly, the performance of the speech recognition systems used.

In view of the above concepts, in most cases the dialog systems developed favor a certain style of control. These systems guarantee improved robustness by minimizing the number of mistakes or omissions made by users, in exchange for less freedom and a loss of naturalness.

Some of the most common strategies that form part of dialog that are designed to increase robustness and naturalness in these kinds of deterministic systems include :


  • The use of natural text generators.
  • The use of keywords, such as help, correct and repeat.
  • The use of reinforcement/simplification strategies for recognition, such as only obtaining one piece of data per utterance.
  • The use of an automatic help strategy.
  • The use of implicit confirmations in each utterance.
  • The use of explicit confirmations in key questions only. 
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