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improving music mood classification using lyrics, audio and social tags

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Liu (2006) identified discriminative words in blog posts in two categories, “happy” <strong>and</strong> “sad,”<br />

<strong>using</strong> Naïve Bayesian classifiers <strong>and</strong> word frequency threshold.<br />

Alm (2008) studied affects of sentences in children’s tales <strong>and</strong> included a very rich feature<br />

set covering the aspects of syntactic (e.g., POS ratios, interjection word count), rhetoric (e.g.,<br />

repetitions, onomatopoeia counts), lexical (counts of words in pre-built, emotion-related word<br />

lists), <strong>and</strong> orthographic (e.g., special punctuations). Although the affect categories in Alm’s<br />

study were not from a dimensional model, Alm included in the feature set dimensional lexical<br />

scores calculated from the ANEW word list (Bradley & Lang, 1999). ANEW st<strong>and</strong>s for<br />

Affective Norms for English Words. It contains 1,034 unique words with scores in three<br />

dimensions: valence (a scale from unpleasant to pleasant), arousal (a scale from calm to excited),<br />

<strong>and</strong> dominance (a scale from submissive to dominant). All dimensions are scored on a scale of 1<br />

to 9. Alm’s features used the average scores of word hits in the ANEW list.<br />

Unfortunately, Alm did not evaluate which of these features were most useful in predicting<br />

affect categories. However, Alm’s study, among the few studies on text affect prediction, does<br />

suggest possible features for consideration in this research.<br />

6.2 LYRIC FEATURES<br />

Based on the aforementioned studies on text affect analysis, this dissertation research<br />

investigates a range of lyric feature types that can be categorized into the following three classes:<br />

1) basic text features that are commonly used in text categorization tasks; 2) linguistic features<br />

based on psycholinguistic resources; <strong>and</strong>, 3) text stylistic features including those proven useful<br />

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