Subject: [Speechsc] Small point on verification scores

From: "David R. Oran" <[email-masked]>
Date: Thu, 16 Jun 2005 08:08:28 -0400

The text says:

      "During verification, the higher the score the more likely
      it is that the speaker is the same one as the one who
      spoke the voiceprint utterances. During training, the
      higher the score the more likely the speaker is to have
      spoken all of the analyzed utterances. The value is a
      floating point between 0.0 and 1.0. If there are no such
      utterances the score is 0. It should be noted that though
      the value of the verification score is between 0.0 and 1.0
      it SHOULD NOT be interpreted as a probability value."

Ok, I'll bite. How can we say in the first sentence "the higher the  
score the more likely is is that the speaker is
the same one who spoke the voiceprint utterances", and then say it  
should not be interpreted as a probability value? If not a  
probability, then...WHAT?

Are you saying that verification servers can't even normalize their  
outputs to some credible statistical model?

That sucks, but if it's really so flakey we should say:

"it SHOULD NOT be interpreted as a probability value in the strict  
statistical sense."

Comments?

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---

From: Ran Zilca <[email-masked]>
Date: Thu, 16 Jun 2005 09:20:28 -0400

Normalizing the score to fit in a predetermined range has practical
advantages, but unfortunately it does not imply any probabilistic
interpretation. I believe that associating reliable probabilities to scores
is still an open research problem. Instead, vendors are more likely to
provide users with offline tools that will analyze data and recommend score
thresholds associated with desired errors (but the threshold values will
not have a direct probabilistic meaning).

To avoid further confusion I suggest to both adopt the new suggested
wording and also change the score range to be [-1,1].

-- Ran

Ran Zilca
Senior Software Engineer
IBM T. J. Watson Research Center
1101 Kitchawan Rd.
Yorktown Heights, NY 10598

http://www.research.ibm.com/CBG

Voice:      (914) 945-3013
Fax:  (914) 945-4490

"David R. Oran" <[email-masked]>@ietf.org on 06/16/2005 08:08:28 AM

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Subject:    [Speechsc] Small point on verification scores

  The text says:

Comments?