Maximum number of n-best answers that can be returned.
|
Value |
Integer: 0–999. |
|
Default |
2 (n-best length) |
|
How to set |
Shown in precedence order (see Rules of parameter precedence): In the browser, using the N-Best-List-Length header in a RECOGNIZE or SET-PARAMS method. In a parameter grammar. In Management Station set on the Nuance recognition service. If not using Management Station, set in a Recognizer configuration file (User-nrsxx.xml). |
|
Usage |
Seldom used, but is useful when confirming more than just the top answer, or when combining answers for especially difficult recognition tasks. |
|
Performance |
Higher values can increase CPU load to search for additional answers. |
For robust parsing grammars this parameter is automatically set to a specific value that provides a good quality of slot confidence values. This can lead to increased CPU time. If necessary, you can set this parameter to a different (lower) value in a meta tag in a robust parsing grammar. Carefully evaluate the effect of any change upon recognition accuracy and the quality of slot confidence values. For details, see Robust parsing grammars.
The value you set indicates your preference; the recognizer considers this value but is not bound to it. For example, if you set the value to 10, the recognizer returns fewer n-best entries if it has fewer hypotheses. Conversely, the recognizer typically attempts to generate at least 5 n-best entries internally (even if your setting is lower) to improve recognition accuracy.
Multiple n-best results are useful in the following cases:
- When the application wishes to confirm more than just the top choice answer with the caller.
- When several recognition results need to be combined to find a valid answer because the recognition tasks are too difficult for the top-choice answer to be reliable. For example, applications may want to collect the top 10 best answers from alphanumeric postal codes and city name recognitions, and correlate the two lists to find the top valid pair of postal code and city name.
Browsers usually set this parameter in a RECOGNIZE request, and the parameter automatically reverts to the previous value after the recognition event. (Alternatively, browsers can use the SET-PARAMS method. See Configuring Recognizer with the browser.)
N-Best-List-Length : 2
