Emotion Annotation of Music: A Citizen Science Approach

The understanding of the emotions in music has motivated research across diverse areas of knowledge for decades. In the field of computer science, there is a particular interest in developing algorithms to “predict” the emotions in music perceived by or induced to a listener. However, the gathering of reliable “ground truth” data for modeling the emotional content of music poses challenges, since tasks related with annotations of emotions are time consuming, expensive and cognitively demanding due to its inherent subjectivity and its cross-disciplinary nature. Citizen science projects have proven to be a useful approach to solve these types of problems where there is a need for recruiting collaborators for massive scale tasks. We developed a platform for annotating emotional content in musical pieces following a citizen science approach, to benefit not only the researchers, who benefit from the generated dataset, but also the volunteers, who are engaged to collaborate on the research project, not only by providing annotations but also through their self and community-awareness about the emotional perception of the music. Likewise, gamification mechanisms motivate the participants to explore and discover new music based on the emotional content. Preliminary user evaluations showed that the platform design is in line with the motivations of the general public, and that the citizen science approach offers an iterative refinement to enhance the quantity and quality of contributions by involving volunteers in the design process. The usability of the platform was acceptable, although some of the features require improvements.