[asterisk-speech-rec] How to enable N-Best decoding? CRM:00171167

[Stephen Keller]

> 1. Is there a way to change the value of vad_eos_delay 
> on-the-fly in my dialplan (instead of the lumenvox.conf 
> file)? 

Yes. Use Set(SPEECH_ENGINE(vad_eos_delay)=100) in your dial plan;
replace 100 with the value you want. Any value in lumenvox.conf can be
altered on-the-fly like this.

> 2. So far I have not worked with grammars with more than a 
> hundred rules. How large a grammar can one have before the 
> speech engine computation times become noticeable to the user 
> (i.e in your experience, can the engine handle a grammar file 
> with hundreds or thousands of grammar rules in reasonable time?)

This really depends on your hardware. An old P3 with 512 MB of RAM is
going to bog down much sooner than a new dual-core system with a few
gigs of memory.

But generally we find that it becomes noticeable when you are
recognizing more than 2,000 individual words at a single time. Note that
this is different from the total size of the grammar. A grammar may have
10,000 unique words to be recognized but that entire space may not be
searched all at once depending on how the grammar is structured.

Also there is not a perfect correlation between grammar size and number
of words to be recognized; we have seen grammars that contain a few
thousand items to be recognized but are around a hundred thousand lines
long. These take longer for us to compile initially, but once we've
compiled them decoding utterances is still quite fast.

Stephen Keller
LumenVox Support
P: 877-977-0707, just say "Support"
F: 858-707-7072
Support at LumenVox.com
www.LumenVox.com

Winner "Best Innovation in Speech Recognition"
AVIOS SpeechTEK Award