| J. A. Bilmes and K. Kirchhoff. Directed graphical models of classifier combinations: application to phone recognition. In ICSLP, Beijing, China, October 2000. |
....and T60. Reverberated data was applied artificially to the speech via convolution with the room impulse response. 3. SIMPLE COMBINATION RESULTS There are a number of ways to combine probability estimates from several classifiers. These are usually based upon different independence assumptions [1]. A common method used by researchers is to average the logarithm of the probabilities, P #qjx1;x 2 ; x N#= exp# P i=1 w i log P #qjx i ## P q 0 exp# P i=1 w i log P #q 0 jx i ## where P #qjx i # is the posterior probability of class q given features x of stream i, and the weights w i ....
J. A. Bilmes and K. Kirchhoff. Directed graphical models of classifier combinations: application to phone recognition. In ICSLP, Beijing, China, October 2000.
....(the mean rule) computes a weighted average of classifier outputs. Another method (the product rule) multiplies and then renormalizes these probabilities. Other techniques compute the maximum, minimum, or median of the classifier outputs [22] Other methodologies combine using statistical models [5] or jointly train separate classifiers [28, 14] In ASR, classifier combination can occur at different levels including the feature stream [3, 19, 12, 20] the HMM state [21] or at higher levels such as at the syllable [32] or sentence [11] In ASR, HMM state level combination (e.g. combining ....
.... linear combinations of the output distributions (e.g. by averaging over, or multiplying, the outputs) 13, 22] combining the outputs by a higher level classifier, Dempster Shafer theory [29] and majority voting [24] An alternative approach is to model a dependence between classification errors [6, 31, 5]. Many studies on classifier combination focus on what we call single level classification. A typical single level classification system consists of two components: a featureextraction component which maps the input signal to feature vectors, and a classification component which assigns a class ....
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J.A. Bilmes and K. Kirchhoff. Directed graphical models of classifier combination: Application to phone recognition. In Proc. Int. Conf. on Spoken Language Processing, Beijing, China, 2000.
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