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Re: Additional parameters to SpeechRecognition (was "Speech API: first editor's draft posted")

From: Glen Shires <gshires@google.com>
Date: Wed, 25 Apr 2012 13:20:04 -0700
Message-ID: <CAEE5bcgzEo3vgVCJuL2rYqSGi4DRo-cRxxL__KTHaNhw=652TA@mail.gmail.com>
To: "Young, Milan" <Milan.Young@nuance.com>
Cc: Hans Wennborg <hwennborg@google.com>, Satish S <satish@google.com>, "public-speech-api@w3.org" <public-speech-api@w3.org>
I heartily agree that it is typically best to filter low confidence matches
in the speech recognizer (reducing computation and bandwidth). Using JS
to process the confidence values returned in the results does not imply
that pruning is not done in the recognizer. The recognizer still uses a
confidenceThreshold. If a savvy JS developer chooses to set the
confidenceThreshold, he should do so such that the recognizer prunes (but
doesn't over prune) the data returned, so JS can sufficiently process the
returned confidence values.

Implementation of a readable confidenceThreshold with ABSOLUTE values
corresponding to the recognizer's default value is problematic when
supporting multiple speech recognizers. Therefore I propose the following
definition for a readable/writeable confidenceThreshold attribute that uses
RELATIVE values...



confidenceThreshold attribute

This attribute represents a relative degree of confidence the recognition
system needs in order to return a recognition match instead of a nomatch.
The confidence-threshold is a monotonically increasing value between -1.0
(least confidence needed) and 1.0 (most confidence needed) with 0.0 as the
default.



In this way, 0.0 is the default for all recognizers, and each recognizer is
free to define how to map the threshold into whatever confidence values it
returns with the results. In other words:

- For a confidenceThreshold of 0.0, one recognizer may return results with
confidence values no lower than, for example, 0.72 whereas another might
return confidence values no lower than, for example, 0.31.

- For a confidenceThreshold of, for example, -0.2, each recognizer will
return more (or at least no fewer) results.

- For a confidenceThreshold of, for example, 0.2, each recognizer will
return fewer (or at least no more) results.

I believe this is a good step towards consistent behavior across UAs and
speech engines.

(Note that I intentionally defined confidenceThreshold as a value between
-1.0 and 1.0 instead of between 0.0 and 1.0 for clarity. This is to
emphasize that these threshold values are RELATIVE and do not have any
ABSOLUTE correspondence to the confidence values returned.)

/Glen Shires


On Wed, Apr 25, 2012 at 11:08 AM, Young, Milan <Milan.Young@nuance.com>wrote:

>  You have ignored my two points about why it is often best to filter low
> confidence matches on the server (ie performance and clipping).  Just
> because Deborah points out that there are additional use cases for
> filtering on the client does not invalidate my claim.****
>
> ** **
>
> Yes, we should try to deliver consistent behavior across UAs, speech
> engines, and even dialog states.  But letís not throw the baby out with the
> bathwater if we canít nail it down in a v1.****
>
> ** **
>
> ** **
>
> *From:* Glen Shires [mailto:gshires@google.com]
> *Sent:* Wednesday, April 25, 2012 10:43 AM
> *To:* Young, Milan
> *Cc:* Hans Wennborg; Satish S; public-speech-api@w3.org
>
> *Subject:* Re: Additional parameters to SpeechRecognition (was "Speech
> API: first editor's draft posted")****
>
> ** **
>
> I think (hope) that most web developers won't have to worry about
> confidence values because the default set by the speech recognizer should
> be sufficient.****
>
> ** **
>
> However, a JS API developer savvy enough to understand how/when to
> properly set a confidenceThreshold, is also savvy enough to intelligently
> process the confidence values returned in the results. As Deborah mentioned
> [1], "For example, if the top two alternatives in the nbest have very
> similar confidences...".  Typically, processing the confidence result
> values is a much better strategy than trying to tune the
> confidenceThreshold.****
>
> ** **
>
> Only extremely savvy JS API developers will understand how to properly
> tune the confidenceThreshold so that it prunes (but doesn't over prune) the
> data returned.  I believe these developers can best adjust
> the confidenceThreshold by processing the confidence result values returned
> by prior recognitions (as opposed to simply bumping the default value by
> 0.05). ****
>
> ** **
>
> ** **
>
> Also, from an implementation standpoint, there's a major issue with
> making confidenceThreshold readable. If the developer switches to a new
> recognizer, the default confidenceThreshold may change. If the developer
> then reads the confidenceThreshold (for example, to increment it by 0.05),
> then presumably the browser needs to get the default confidence value from
> the speech recognizer. For a remote recognizer, this round-trip takes time,
> and the browser cannot stall the javascript processing.****
>
> ** **
>
> /Glen Shires****
>
> ** **
>
> [1]
> http://lists.w3.org/Archives/Public/public-speech-api/2012Apr/0031.html***
> *
>
> On Wed, Apr 25, 2012 at 9:47 AM, Young, Milan <Milan.Young@nuance.com>
> wrote:****
>
> The speech community has lived for 20 years with the fact that confidence
> values are not portable across engines.  I understand that we are courting
> a new class of developers with this HTML-based initiative, but I want to be
> careful not to dumb it down to the point where we impact the mainstream
> speech industry.****
>
>  ****
>
> Incrementally bumping up confidence (eg recognizer.confidence += 5) in
> response to a series of misrecognitions is a common technique.  I also find
> it generally ugly that confidence is special cased with a function instead
> of a property.  (Is it a JS limitation that you cannot mark a property as
> write only?)****
>
>  ****
>
> I would rather say something like ďRecognition engines generally do a good
> job of choosing the right confidence value for a recognition task.  If you
> do choose to read this property, know that itís value is not portable to
> other recognition tasks, other speech engines, or other user agents.Ē****
>
>  ****
>
> Thanks****
>
>  ****
>
> *From:* Glen Shires [mailto:gshires@google.com]
> *Sent:* Wednesday, April 25, 2012 8:11 AM
> *To:* Hans Wennborg
> *Cc:* Young, Milan; Satish S; public-speech-api@w3.org****
>
>
> *Subject:* Re: Additional parameters to SpeechRecognition (was "Speech
> API: first editor's draft posted")****
>
>  ****
>
> confidenceThreshold****
>
>  ****
>
> I think we all agree that speech recognizers have a concept of confidence,
> and that it can be mapped to a monotonically increasing range of 0.0 to
> 1.0.  However, specific values (for example 0.5) do not correspond to the
> same level of confidence for different recognizers.****
>
>  ****
>
> I believe that if the developer does not set the confidenceThreshold, the
> speech recognizer should use a default value that is appropriate for that
> recognizer.****
>
>  ****
>
> A complication with a confidenceThreshold attribute is defining the
> default value (if the value is read, but not written, what value does the
> BROWSER return? - particularly because the optimal default value may vary
> from one RECOGNIZER to another).****
>
>  ****
>
> Perhaps instead of an attribute, this should be a write-only value,
> specifically a setConfidenceThreshold method.****
>
>  ****
>
> /Glen Shires****
>
> On Wed, Apr 25, 2012 at 6:43 AM, Hans Wennborg <hwennborg@google.com>
> wrote:****
>
> On Tue, Apr 24, 2012 at 17:22, Young, Milan <Milan.Young@nuance.com>
> wrote:
> > There are two reasons for including confidence that I would like this
> community to consider:
> >  Efficiency - Similar to the argument Satish put forward for limiting
> the size of the nbest array, pruning the result candidates at the server is
> more efficient.
> >  Clipping - There are many environments where background noise and side
> speech that can trigger junk results.  If confidence is low, this will
> trigger a result and then the application enters a deaf period where it
> processes the result and discovers the content is junk.  If real speech
> happens during this phase, its start will be missed.
> >
> > Every recognizer that was ever invented has a concept of confidence.
>  Yes, the semantics of that value vary across platforms, but for us to push
> this to a custom parameter will confuse developers, and ultimately slow
> adoption.****
>
> Ok, I don't feel strongly about this, so I would be fine adding a
> confidenceThreshold if others agree.****
>
>
> > Regarding the timeout family, an open-ended dialog like "Tell me what is
> wrong with your computer", should have generous timeouts.  Compare this to
> "So it's something to do with your new Google double mouse configuration,
> is that correct?" which should have short timeouts.
> >
> > Our goal should be a consistent application experience across UAs, and
> that's only going to happen if we standardize timeouts.  I would also like
> to mention that the definition of these timeouts is clear and has been
> industry standard for 10+ years.****
>
> What do you think about my idea of just letting the web page handle
> the timeout itself, calling abort() when it decides a request is
> taking too long?
>
>
> Thanks,
> Hans****
>
>
>
> ****
>
>  ****
>
> --
> Thanks!****
>
> Glen Shires****
>
>  ****
>
>
>
> ****
>
> ** **
>
> --
> Thanks!****
>
> Glen Shires****
>
> ** **
>



-- 
Thanks!
Glen Shires
Received on Wednesday, 25 April 2012 20:21:15 UTC

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