Every day, we hear a variety of musical compositions, including commercial jingles, nursery rhymes, and pure classical music.One kind of music is different from the other. We respond to musical compositions in various ways. Some we hum, some we like, some we dislike, some are monotonous, and some compositions are considered simple while others are complex.

If we generally divide musical compositions into categories like vedic recitations, nursery rhymes, folk, tribal, advertisement jingles, film songs, semi-classical music, and classical music (there can be other groups also if we consider western music), we can say that the degree of complexity of the musical composition is different in all these compositions. Vedic compositions sound very different from, say, a film song. Similarly, pure classical music sounds very complex. The complexity of a musical composition can be treated as one of the important variables of composition. What makes these complex or simple? How can we control the degree of complexity? Intuitive answers to these questions can be given. However, this study attempts to systematically investigate the complexity of musical and visual compositions.

Let us first try to understand complexity. It can be found in a lot of things. Just now we were discussing complexity in music. Likewise, a painting can be complex or simple to understand. Thus, complexity exists in visual compositions also. Some smells can be simple to detect, some can be complex. Some ideas can be simple enough to be converted into reality; some may be just too complex to even understand or explain. Many examples can be added to this list. Out of these, visual complexity and audio complexity are considered very close to each other. They are supposed to behave similarly in many areas and can be studied in relation to each other. We can define complexity in many ways. A composition can be semantically complex or structurally complex. This study deals only with the structural complexities of visual and audio compositions, using a direct subjective judgement of complexity by subjects or listeners, and reflects the difficulty experienced in encoding of patterns or the relationship between the compositions. One of the ways to study complexity is to give people different specially designed compositions and ask them to rate the complexity on a scale. Since the compositions are developed by controlling the variables, it is possible to study what factors are giving them that particular degree of complexity and how these factors can be predictably controlled to control the overall complexity. This is the general approach followed in this project.