This document presents a method for controlling the affective content of pre-composed music using a symbolic approach. The method involves building a knowledge base through experiments with musical pieces and listener ratings on the dimensions of valence (happiness) and arousal (activation). The knowledge base contains weighted mappings between musical features and affective dimensions determined through feature selection algorithms and linear regression. This allows a system to transform music by modifying features to produce music expressing an intended emotion. An example demonstrates increasing the tempo and adding an instrument to a piece of music to change its affective ratings on the dimensions.

1. Controlling Music Affective Content:
A Symbolic Approach
António Pedro Oliveira
Amílcar Cardoso
University of Coimbra, Portugal
03/07/2008

2. Music Affective Content
 Valence represents the degree of happiness
expressed in the music. A value of 10 corresponds
to a very happy music and 0 to a very sad music.
 Arousal represents the degree of activation
expressed in the music. A value of 10 corresponds
to a very activate music and 0 to a very relaxing
music.
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3. Objective
 Implement and assess a computer system to
control the affective content of pre-
composed music, in such a way that
produced music expresses an intended
emotion.
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4. Method
 Control affective content:
 Knowledge base with weighted mappings between music features
and affective dimensions.
 Knowledge Base:
 Experiments with ≈110 musical pieces and ≈130 listeners.
 Algorithms of feature selection to define features and linear
regression to define weights.
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5. Simplified architecture
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6.  5 labelled musical pieces:
 Valence – 5.65 Arousal – 3.59
 Valence – 8.50 Arousal – 6.36
 Valence – 7.94 Arousal – 6.10
 Valence – 5.30 Arousal – 3.37
 Valence – 4.83 Arousal – 3.03
Example
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7. Simplified architecture
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8.  Original:
 Valence – 4.83 Arousal – 3.03
 Transformation
 Increase tempo
 Add instrument
 Transformed
 Valence – 6.83 Arousal – 3.71
Musical example
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