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

[missivestoadrian-vxml at yahoo.com]

Hi Stephen:

Thanks for the tip. Lowering the value of
vad_eos_delay did help. A couple of other questions:

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)? As you have noted, in a given
speech application the value of vad_eos_delay may need
to change depending on the particular type of question
being asked. 

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?)

Warm regards,

Adrian


 
--- Stephen Keller <StephenKeller at LumenVox.com> wrote:

> > Also, I've been finding that a lot of times the
> Speech engine 
> > takes a long time (on the order of 1 or a several
> seconds) to 
> > recognize speech. 
> 
> There are a few things that affect the length of
> time before you'll get
> results:
> 
> 1. The end of speech delay is probably the most
> common. This is the
> amount of time that we have to detect silence before
> the Speech Engine
> begins doing a decode. If this is too low, it causes
> problems as callers
> get off before they've really finished speaking
> (it's especially
> important to set this high for utterances where you
> expect a lot of
> pauses between words, such as when collecting large
> strings of digits).
> You can adjust this by changing the vad_eos_delay in
> your lumenvox.conf
> file; by default it's set to 2000 ms. For really
> short yes/no types of
> prompts, you can set this value pretty low (800ms or
> less).
> 
> 2. Extra background noise that the Engine is
> mistaking for speech could
> also falsely cause it to not begin doing a decode,
> though this is a
> pretty rare thing.
> 
> 3. The Engine may also be taking a while to perform
> the actual decode.
> Speech recognition is a pretty resource intensive
> process, and so
> overworked hardware can sometimes cause this. The
> amount of time to
> decode goes up as the length of the utterance and
> size of the grammars
> go up as well (increasing the grammar size increases
> the Engine's search
> space). If you use our Speech Tuner, you can see how
> long a decode
> actually took by loading up some response files and
> browsing
> interactions with the Call Browser, and clicking the
> "View Details"
> button for a given decode. One of the details will
> be the decode time.
> 
> So I would recommend first seeing how long decodes
> are taking and then
> try changing vad_eos_delay. Let us know how it goes.
> 
> 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
> 
>  
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